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Cadillac Head Gasket Repair, Northstar Specialist!

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32Valve Northstar: Truths & Myths

Letter from the owner
So you want a Cadillac? Most people who desire the luxury of a Cadillac do! I thought I would write this for those who find themselves with a Caddy that seems nice--until they buy it and wonder what went wrong.  So before you hate the Cadillac and wish you had never bought one, read what I have to say before you start searching for one.
 
Before I continue, a question I get asked quite often is: what year did the Northstar improve? This is a misconception that gets tossed around between theorist. Regardless of years, the TTY bolt system was, in fact, never corrected throughout the entire run of the Northstar. In 2004, GM thought they would satisfy the expectations of buyers by slightly increasing the coarseness of their TTY bolts, and although an increase in longevity  seems to add a common 20k to its life span, they in fact failed equally. This increase in coarseness first took place in the LH2 before taking place in all Northstars in 2005. So as you can see, any corrections to permanently solve this issue is all folklore.
 
I was asked a question the other day concerning the 2000 to 2001 engine block. The question was: were these engines bad due to a thin wall issue that was corrected in later models? The answer is: NO. This too is a theory by the public in an attempt to come up with answers to explain block failures. These castings passed every conceivable test performed; however, there was failure due to bad castings. What does that mean?Air pockets involved in inconsistent aluminum mixing! Now you ask me, "Is this why those years failed?" No! We have  found these inconsistencies in every year, make, and model of the Northstar; no year was perfect. 

As I have already explained on this site, the Northstar engine is definitely an awesome piece of machinery, and as a Northstar expert, I definitely stand behind them. They do have their ups and downs, and as I have said before, the Caddy is almost free; it is the repairs that cost you!

Although GM knew about the issues with the Northstar, the revenue they brought in was more than the desire to correct it. This left it up to the likes of Northstar experts to do permanent repairs--if your lucky enough to find one.
With that said, you should understand that Northstar experts are far and few between. I can't emphasize this enough: DO NOT take your expensive Cadillac to a regular mechanic! I don't care if he has been a mechanic for 50 years. Unless the mechanic has been working only on Northstars and nothing else, then all you will get is an expensive bill with a damaged Caddy.

Too many customers have to bring me their Northstar due to a mechanic's mistakes, and as bad as it makes me feel, I have to charge what it cost to re-repair. Here are some things to watch out for:

1. Never allow someone to install a used Northstar without a complete rebuild, it's just not worth emptying your pocket book
only to have to take it to a real Northstar mechanic.

2.
If you are looking for a used Cadillac, make sure you see the carfax for its repairs, and always remember that a Northstar looses its head gaskets usually between 100k to 140k; although sometimes sooner, and if it is past 140k, then walk away.

3. Another important thing to keep in mind is that the split block seals collapse over time and will usually start leaking around 80k and will also progressively get worse along with the rear main seal. It is always a good idea to look under the car to see if there are signs of leaking at the rear of the engine. I tell you this because the main seal replacement is a 2,700.00 repair...OUCH. Yes, you read it right!

4. The most important thing to watch out for is if the person you are buying from has used fix in a bottle. Oh yeah, happens all the time .This temporary fix will last a couple days, and then it is too late!
One way to see if this has been done is to look into the expansion tank. If there is any type of copper color then walk away! If there is a purple or blue tint walk away. Sometimes, however, there is no visible evidence, and so the mileage without proof of repair should raise a red flag.

These repairs will need to be done on all Northstars eventually. The trick to having a great Northstar is to have these repairs done, and then you will have the perfect car. But having these repairs done affordably is to have them all done at the same time.
When we at C. C. C. do a head gasket repair, we offer a block resealing for around 500. Adding this to the head gasket repair becomes a fraction of the cost of separate jobs. So if you were to do a resealing of your block, your looking at 2700, and a head gasket job would be around 4500. But of course this is the dealership cost. Here at C. C. C. we make our prices much more affordable.

So you can see that if you were to do it all, knowing it will all need to be done sooner or later, you can save yourself thousands, literally!

You may ask me why I am willing to give out these secrets? Why not? I am more concerned about the longevity of your Caddy. And u
ntil you decide to sell or get rid of your car, it would benefit a Northstar mechanic more to do you right and have you as a long term, satisfied customer than to loose you as soon as you decide you want nothing more to do with Caddys.

So when you take your Cadillac to someone who cannot answer you in this manner, walk away.
I would like very much to change the negativive image of the Northstar, and if it was not for the non expert, I think caddys would have a much better reputation.

If you are local and need the Cadillac you want to buy inspected, we can help, and yes, we charge a fee. How else can we stay in business? We do however make it worth it, and if the Caddy you are looking at is a bad apple, then we can save you thousands. Also, w
e can mobile assist you if needed. We know that not everyone will allow you to bring it here, especially if they know there is an issue with it.

I could write a novel on the GM Northstar system, but I wont. However, I am also sure that you have lots of questions. So feel free to contact us anytime, and we will be happy to answer any questions concerning your Cadillac. There is no charge! Write us, call us, come and see us--
we are Cadillac enthusiast! Allow us to take the worry out of owning your Northstar!
Sincerely,
Tim Carroll
940-395-9839
503-895-2124
 
 

The high-output, supercharged Northstar DOHC 4.4L V8 engine, developed for the "V" series of Cadillac performance models, was based on the naturally aspirated rear-wheel-drive 4.6L engine released in 2004. Technologies specific to the supercharged version (seen above) include a precision sand cast aluminum block, multi-layer steel head gaskets, heavy-duty pistons and connecting rods, a piston cooling system and specially polished exhaust ports.
The Big Bang
Introduced in 1993, GM’s 4.6L 32-valve dual overhead cam all-aluminum V8 engine — housed in the Cadillac Allante, Eldorado and Seville STS — was considered a quantum leap forward for U.S. automakers.

Initially rated at 295 horsepower, the Northstar V8 has grown over the years to an incredible 469 hp at 6,400 rpm (STS-V Supercharged Northstar engine).

In 1995, the engine was ranked as one of the “10 Best Engines in North America” by Ward’s Auto World. It repeated the honor in 1996 and 1997, but it hasn’t cracked the Top 10 list in more than 12 years.

Like most other engines, the Cadillac Northstar 4.6 V8 has evolved over the years. In 1994, the first Northstar V8 (L37) was joined by a second version (LD8) with a different cam profile that lowered peak horsepower slightly to 270 hp but increased torque output in the lower rpm range for improved throttle response and quick acceleration. That same year, GM introduced a downsized and somewhat less powerful version of the original Northstar V8 into its Oldsmobile Aurora.

The L47 4.0L V8 was essentially the same engine as the larger 4.6L V8, but with a smaller bore size (87 mm vs. 93 mm). And the L47 4.0L V8 was rated at only 250 hp.

In 1995, the power rating of the L37 4.6L V8 (VIN 9) was bumped up slightly to 300 hp, and the LD8 4.6L V8 (VIN Y) was upped to 275 hp. Those two basic versions of the 4.6L V8 (275 and 300 hp) were used in various Cadillac models for nearly 10 years.

However, in 2005, Cadillac engineers gave their Northstar a boost when they introduced a new 4.4L Supercharged Northstar V8 engine and GM’s new Hydra-matic six-speed automatic transmission. The official power ratings for the 2006 STS are 469 hp at 6,400 rpm and 439 lbs.-ft. of torque at 3,900 rpm.

This cutaway of a rear-wheel-drive Northstar 4.6L V8 engine provides a good look at the intake cam phaser.
The automaker said that the Northstar V8 supercharged engine represents the most output ever for a production Cadillac. In fact, during the final stages of development, GM Powertrain engineers found more opportunities to push the boundaries of the Supercharged Northstar engine.

The Supercharged Northstar V8, which also powered the V-Series edition of the XLR luxury roadster, generated more peak power for the STS-V, compared to the XLR-V, due largely to the greater underhood space of the STS that allows more induction and exhaust capacity. On the other hand, the XLR-V will be a quicker car than the STS-V, given its superior power-to-weight ratio.

However, according to GM, that engine is no longer available for new Cadillac models.

And, while the 4.6 Northstar did make it into Cadillac’s 2010 models (DTS and CTS), it is unsure how long this engine will shine in the automaker’s lineup. As automakers look toward more turbocharging of six-cylinder engines as a way to reduce fuel consumption in larger vehicles, the Northstar may be on the verge of burning out.

A look at the piston and bore liner on the 4.6L  RWD version of the Northstar engine.
Northstar’s Unique Engineering
The Northstar V8 has a die-cast aluminum 90° block with a bottom end girdle that splits along the midline of the crankshaft bearings. This takes the place of the main bearing caps. For model year 2000, GM began using a new high pressure “squeeze” casting process for the lower crankcase to reduce porosity in the aluminum, which may allow oil to seep through and leak (this has been a problem on some engines).

The cylinders have cast-in-place iron cylinder liners that are not replaceable. Compression up to model year 2000 was a relatively high 10.3:1. It was lowered to 10:1 in 2000. Each head has two camshafts (one intake, one exhaust) and four valves per cylinder (33 mm intakes and 29 mm exhausts).

Direct-acting hydraulic lash adjusters are positioned over each valve. The overhead cams are all chain-driven, and use an intermediate chain sprocket under the front cover to connect to the crankshaft. Three separate hydraulic tensioners are used to keep the cam chains tight.

The Northstar V8 is an interference engine, which means if a chain fails or is disconnected when the engine is cranked over, the valves will hit the pistons. That’s something techs don’t want to happen with an expensive engine like this!

Finally, the intake manifold is Nylon 66 thermoplastic, which its engineers explain that this helps cool intake air by conducting less heat from the engine.

GM recommends cleaning the fuel rail with a spray-type engine cleaner (GM X-30A) if necessary. Do not soak the fuel rail in liquid cleaning solvent.
Fuel and Ignition
Fuel is delivered by sequential fuel injection with separate injectors mounted under the engine’s top cover. Under the top cover you’ll also find the MAP sensor, intake air temperature sensor and fuel pressure regulator.

If the fuel pump relay fails on a Northstar V8, the engine should still run because the fuel pump also can be energized through the oil pressure-sending unit.

A four-coil distributorless ignition with a waste spark set up provides spark to the plugs. Two crankshaft position sensors are used (A and B) plus a camshaft position sensor to provide timing inputs.

Both crank sensors are mounted in the block and the cam sensor is located on the rear head in front of the exhaust cam. There’s also a knock sensor on the rear head between cylinders 1 and 3 to retard timing if detonation becomes a problem under load.

If there is a head problem, normally a new one is recommended, since the heads are throw-aways, according to Cadillac. So, even if the valve guides are worn, Cadillac says replace the whole cylinder head.
The ignition system has two modes of operation: “module mode” and “ignition control mode.” In ignition control mode, the PCM controls ignition timing using sensor inputs. If there’s a problem in the PCM or with its sensor inputs, the module mode takes over and runs the engine with a fixed 10° of advance.

The engine continues to run (essentially a limp-in mode) but with reduced performance.

In model year 2000, the DIS ignition system was changed to a coil-on-plug design, which eliminates the spark plug wires and waste spark. Each head has its own ignition module that fits in the middle of the valve cover.

Another unusual feature you may see is a liquid-cooled alternator on the DeVille and Seville. Cadillacs are crammed with electrical accessories that put quite a load on the charging system, so using liquid cooling helps prolong the life of the alternator. In 2001, GM went back to an air-cooled alternator to “eliminate the coolant tubes and potential leak points.”

Later updates to the engine included variable valve timing (VVT), which GM engineers said can vary the intake valves by up to 40° and the exhaust valves up to 50° in order to increase power output. However, the VVT system was designed for the longitudinal LH2 engine and not for the transverse front-wheel-drive (FWD) engine.

GM explained that horsepower output on the FWD engine was already maxed out and adding the VVT feature to it would create excessive torque-steer issues.

Did You Know…
Another feature of the Northstar engines is a “limp home” mode that allows the engine to continue running if all the coolant is lost. If the PCM senses an overheating condition, it temporarily disables up to half of the cylinders. This pumps enough air though the engine to keep temperatures from getting hot enough to cause any damage. Even so, GM says the vehicle should not be driven more than 50 miles in the limp-home mode.

A view of the 2006 4.4L V8 head and exhaust ports.
Northstar Maintenance
One of GM’s goals with the Northstar program was to reduce maintenance to a minimum. The engines are factory-equipped with 100,000-mile platinum-tipped spark plugs and five-year/150,000-mile Dex-Cool antifreeze, and use chain-driven cams to eliminate the need to replace timing belts. Except for oil and filter changes, there isn’t much to maintain — unless something breaks.

The newer Northstar V8s use an “oil life monitor” light rather than a specific mileage interval or service schedule to indicate when oil changes are needed. The PCM tracks engine rpm, operating temperature, load, running time and ambient temperature to calculate oil life.

Up until 1999, the maximum oil change interval under ideal conditions was 7,500 miles. In 2000, GM bumped the upper limit to 10,000 miles. In 2002, they did away with the upper limit altogether stretching the oil change interval to 12,000 miles or more, depending on operating conditions. However, GM does say the oil should be changed at least once a year regardless of mileage.

Note: When changing oil on a 4.6L Northstar V8, keep in mind that this engine holds 7.5 quarts instead of the more common 4 or 5 quarts.

Service Issues
While the Northstar V8 is well engineered, like other engines they’ve had some problems. According to various sources, head gasket failures are not uncommon. Nor is oil burning or oil leaks.

• Cadillac service bulletin 01-06-01-011 deals with oil burning on 1996-’99 Northstar V8s. The cure, says Cadillac, is to do a ring cleaning procedure (seems those long oil change intervals weren’t such a good idea after all). Cadillac recommends using GM cleaning kit (P/N 12378545) and Kent-Moore J-45076 induction/evacuation tool to do the job.

The cleaner is added into the cylinders through the spark plug holes and allowed to soak the rings for two hours. The cleaner and dissolved crud is then vacuumed out of the cylinders through the spark plug holes, followed by an oil change. Cleaning the throttle body and EGR valve is also recommended.

• On 2000-’01 Northstar V8s, a buildup of carbon deposits in the combustion chamber can cause a cold knock condition. Bulletin 99-06-01-101A says to use top cleaner to remove the combustion chamber deposits.

• No oil pressure on a 1993-’94 engine? Debris between the oil pressure relief valve and its seat will prevent oil pressure buildup. The cure here is to clean or replace the pump (P/N 3543258), which is located on the front of the engine.

• Oil leaks around the rear main crank seal have been a problem on some 1996-’99 engines, so GM has developed a new rear main oil seal (P/N 12556107) that should cure this problem. It’s a press fit seal that takes a special tool (J-42482) to remove and install.

• In 1995, GM revised the original crankshaft balancer to provide smoother operation and longer durability. If the balancer is removed from the crankshaft for any reason, GM recommends installing the newer, improved balancer (P/N 12552437 or 12552436, depending on the engine).

• If you have to pull a cylinder head on a 1993-’99 4.0L or 4.6L Northstar V8 to replace a gasket or do a valve job, do not reuse the old 11 mm head bolts. Also, GM has revised the head bolt torque values and tightening procedure as follows:
- In sequence, torque all bolts to 30 ft.-lbs.
- In sequence, rotate all bolts an additional 70°.
- In sequence, rotate all bolts an additional 60°.
- In sequence, rotate all bolts another 60°.
- Torque the front three M6 head bolts to 106 in.-lbs.

Because the Northstar V8s are aluminum, thread damage is not unusual. GM’s recommended thread repair kit is J42385-500 for main and head bolts, and J42385-2000 for other fasteners.

 

Of course we do not use this repair and we do not recommend it, this repair is before the design of Head Studs for the Northstar.

Please click here for the proper repair: Block Studding

Information and photos courtesy of General Motors Corp.

The Northstar engine series of automobileengines is General Motors' most technically complex 90° V engine architecture. The family is most associated with Cadillac's NorthstarV8, but the family has also seen use at Oldsmobile (as the Aurora L47 V8 and "Shortstar" LX5). The Oldsmobile variants are no longer in production, but the Northstar family did expand with longitudinal and 4.4 L supercharged versions. The Northstar name was used outside Cadillac as well, with Pontiac and Buick versions carrying that moniker.

GM ceased production of the Northstar engine in July 2010. Production of the final cars to include the engine, the Cadillac DTS, Buick Lucerne, and Cadillac STS, ended in 2011.[1] Newer Cadillac V8 models like the CTS-V use the GM LS OHV engine, marking a return to simpler, more robust engine design.

Development and features[edit]

The Northstar's design was initiated as a response to the advanced dual overhead camV8 engines introduced by European and Japanese competitors of Cadillac in the late 1980s. At that time, Cadillac was using the aluminum HTOverhead Valve (OHV) V8 which had been pushed hastily into production because the c.a.f.e ratings for 1982 would not allow for the use of the V8-6-4 of 1981. At the time it was GM's corporate policy not to pass the gas guzzler tax on to the consumer.

Cadillac was developing new models like the Allanté and updated Eldorado and Seville STS which they hoped would compete against the best from BMW, Mercedes-Benz, and new to the luxury car market Lexus, and Infiniti. They developed a laundry list of items that must be included in these new models, including sophisticated steering, braking, and suspension technologies, which became known as the Northstar System. One key element was a high-tech V8 engine with all of the features and performance of the competitors' offerings.

Capable of producing 300 hp (224 kW) out of its 4565 cc displacement, the Northstar featured a cast aluminum 90° V8 block with 102 mm (4 in) bore spacing split into unitary upper and lower halves. The lower crankcase assembly supported the crankshaft without conventional main bearing caps. An oil manifold plate with an integrated silicone gasket forms the oil gallery under this. A typical oil change used 7.5–8 quarts of oil.

Cast-iron cylinder liners were specified and the cast aluminum pistons included valve clearance. Northstar is an interference engine, with bronze pin bushings and free-floating piston pins used.

Cast aluminum cylinder heads were used featuring 4 valves per cylinder. The heads used dual overhead cams which are driven through the "maintenance-free" cam-drive chain case. The cams act directly on hydraulic lifters on the ends of the valves and are fed with a lubrication passage drilled through the cylinder head lengthwise. The intake valves are inclined at 25°, while the exhaust valves are canted to 7° with center-mounted platinum-tipped spark plugs. The cam covers are magnesium for light weight.

Eight thermoplastic tubes were used in the induction system, leading to sequential fuel injection. The engine used a distributorless ignition system with a waste spark setup. The PCM controls spark and fuel injection timing as well as the shift points for the new 4T80-E transmission.

One notable feature, advertised at the time, was the "limp home" fail-safe mode which allowed the engine to continue running for a limited time without any coolant. Supplying fuel to only one cylinder bank in turn, the engine would "air cool" the inactive bank. This technique, combined with its all-aluminum construction and large oil capacity, allows the engine to maintain safe temperatures, allowing a Northstar-equipped car to be driven with no coolant for about 100 mi (161 km) without damage. However, the head gaskets are prone to leak, causing loss of some coolant, and high engine temperatures. It is not enough to cause the fail-safe mode so the high temperature can cause the block to crack.

Another unusual feature of some Northstar-equipped cars is a liquid-cooled alternator used on Cadillac's Seville, DeVille, and Eldorado. The liquid-cooling helped prolong the life of the alternator in these electronic-laden models, though GM reverted to a traditional air-cooled setup for 2001 to eliminate potential leak points and extraneous tubing.

All engines of this family share the same Northstar bellhousing pattern.

Later developments included direct coil-on-plug ignition, and variable valve timing, which can vary intake by up to 40° and the exhaust by up to 50°. VVT was devised for the longitudinalLH2 version, and has not, to date, been used on the transverse front wheel drive engines due to packaging considerations.

Northstar series[edit]

The engine was introduced in mid-1992 in the 1993 Cadillac Allanté, eventually ended up in most Cadillac automobiles, but is now nearly phased out of most Cadillac models. The original Northstar Allanté also introduced the Northstar System which included traction control, adaptive suspension, and antilock brakes. Early Northstar required premium grade gasoline to run safely.

The Northstar was sold exclusively by Cadillac for over a decade before being introduced in the 2004-2005 Pontiac Bonneville and 2006 Buick Lucerne. However, the 4.0L L47 V8 variant was used in the Oldsmobile Aurora and the 3.5L LX5 V6 in the Oldsmobile Intrigue. The engine received a forged steel crankshaft in October 2003. Cadillac had planned to introduce a V12 Northstar this decade, likely for use in the Escalade, but economics and new CAFE standards had killed the idea.

Most Northstar engines produce 275 hp (205 kW) to 320 hp (239 kW). The engines were revised for 2000 with coil-on-plug ignition and roller follower valvegear for improved fuel economy and reduced emissions. Though power output did not change, this update eliminated the need for premium fuel.

All but the supercharged Northstars displaced 4.6 L (279 cu in) with a 93 mm (3.7 in) bore and 84 mm (3.3 in) stroke. For better head gasket sealing between cylinders, the supercharged version is de-bored to 91 mm (3.6 in) for a total displacement of 4.4 L (266 cu in). The block is said[who?] to be capable of expansion up to 5.4 L, though no such engine has been produced.

The Northstar was on the Ward's 10 Best Engines list for 1995, 1996, and 1997.

The Northstar System was Cadillac's trademarked name for a package of automobile performance features. Introduced in mid-1992 on the 1993 Cadillac Allanté and later on that year's Seville and Eldorado, the Northstar name continues in use to this day, although only in the Cadillac DTS, since it was announced that the final production year of the STS will use the 3.6L V6 engine only.

The Northstar System included the following components:

    • L37 high-output 300 hp (224 kW) and 295 lb·ft (400 N·m)
    • LD8 high-torque 275 hp (205 kW) and 300 lb·ft (407 N·m)
  • GM 4T80-E 4-speed automatic transmission
  • Road Sensing Suspension
RSS was available in both standard and CV-RSS (continuously-variable) systems. It monitored damping rates of the shock absorbers every 15 milliseconds, selecting between two settings.
Magnasteer combines conventional hydraulic power steering and magnetized "doughnuts" mounted around the output shaft, which stiffen the steering as vehicle speed increases.

The later versions of the Northstar engine included the 4.6L 320 hp (239 kW) and 315 lb·ft (427 N·m) LH2 which began in 2004, and supercharged 4.4L 469 hp (350 kW) LC3 created for the STS-V which are detailed below.

General Motors employed a continuously variable system for the Cadillac Northstar System, VVT (Variable Valve Timing). The Northstar VVT provides a continuously variable system throughout the rpm range, increasing fuel economy. GM engines use the double overhead cam, varying both intake and exhaust for better performance.

L37[edit]

The L37 (VIN "9") was the original North star. It is tuned for responsiveness and power, while the later LD8 is designed for more sedate use. The L37 code had been used on all high-output transverse Northstars, even as the exact engine specifications evolved. Its displacement is 4600cc. The compression ratio for the L37 is 10.3:1 for engines built prior to 2000, and 10:1 for those built afterwards. The original L37 was specified at 290 hp (216 kW), but 1993 production examples were rated at 295 hp (220 kW). The engine topped out at 300 hp (224 kW) from 1996 through 2004 on the STS, DTS and ETC models, making these some of the most powerful domestic front wheel drive cars ever built.[citation needed] For 2005 the high output Northstar became Northstar NHP, and was downrated to 290 horsepower (220 kW) under the new SAE certified horsepower rating system. In 2006, the updated DTS "Performance Package" model got a slight bump to 292 hp (218 kW). Vehicles using the L37 include:

YearModelPowerTorque
1993Cadillac Allanté295 hp (220 kW) @ 5600 rpm290 lb·ft (393 N·m) @ 4400 rpm
1993–1994Cadillac EldoradoETC295 hp (220 kW) @ 5600 rpm290 lb·ft (393 N·m) @ 4400 rpm
1995–2002Cadillac EldoradoETC300 hp (224 kW) @ 6000 rpm295 lb·ft (400 N·m) @ 4400 rpm
1993Cadillac SevilleSTS295 hp (220 kW) @ 5600 rpm290 lb·ft (393 N·m) @ 4400 rpm
1994–2004Cadillac SevilleSTS300 hp (224 kW) @ 6000 rpm295 lb·ft (400 N·m) @ 4400 rpm
1996–2004Cadillac DeVilleConcours/DTS300 hp (224 kW) @ 6000 rpm295 lb·ft (400 N·m) @ 4400 rpm
2005Cadillac DeVilleDTS290 hp (216 kW) @ 5600 rpm285 lb·ft (386 N·m) @ 4400 rpm
2006–2011Cadillac DTSPerformance292 hp (218 kW) @ 6300 rpm288 lb·ft (390 N·m) @ 4500 rpm
2008–2011Buick LucerneSuper292 hp (218 kW) @ 6300 rpm288 lb·ft (390 N·m) @ 4500 rpm

LD8[edit]

The LD8 (VIN "Y") is a transverseV8 for front-wheel drive cars. Introduced in 1994, it is designed to provide more torque than the high-revving L37. The LD8 code had been used on all torque-tuned transverse Northstars, even as the exact engine specifications evolved. Compression ratio is 10.3:1 for engines built prior to model year 2000, and 10:1 for those built afterwards.

The 1998 revision is quieter than previous Northstar engines, due to hydraulic engine mounts, and performs better due to a tuned intake system.

Most LD8 Northstars are rated at 275 hp (205 kW) and 300 lb·ft (407 N·m).

YearModelPowerTorque
1994Cadillac Eldorado270 hp (201 kW)300 lb·ft (407 N·m)
1995–2001Cadillac Eldorado275 hp (205 kW) @ 5750 rpm300 lb·ft (407 N·m)
2002Cadillac Eldorado275 hp (205 kW) @ 5600 rpm300 lb·ft (407 N·m) @ 4000 rpm
1994Cadillac SevilleSLS270 hp (201 kW)300 lb·ft (407 N·m)
1995–2001Cadillac SevilleSLS275 hp (205 kW)300 lb·ft (407 N·m)
2002–2004Cadillac SevilleSLS275 hp (205 kW)300 lb·ft (407 N·m)
1994Cadillac DeVilleConcours270 hp (201 kW)300 lb·ft (407 N·m)
1995Cadillac DeVilleConcours275 hp (205 kW) @ 5750 rpm300 lb·ft (407 N·m)
1996–2001Cadillac DeVille275 hp (205 kW) @ 5750 rpm300 lb·ft (407 N·m) @ 4000 rpm
2002–2005Cadillac DeVille275 hp (205 kW) @ 5600 rpm300 lb·ft (407 N·m) @ 4000 rpm
2006–2011Cadillac DTS275 hp (205 kW) @ 6000 rpm295 lb·ft (400 N·m) @ 4400 rpm
2004–2005Pontiac BonnevilleGXP275 hp (205 kW) @ 5600 rpm300 lb·ft (407 N·m) @ 4000 rpm
2006–2007Buick LucerneCXS275 hp (205 kW) @ 6000 rpm295 lb·ft (400 N·m) @ 4400 rpm

LH2[edit]

The Northstar was designed originally for transverse front-wheel drive applications. It was modified substantially in 2004 for longitudinalrear- and all-wheel drive use in the STS, SRX, and XLR, as well as receiving continuously variable valve timing on both intake and exhaust sides. The RWD (LH2) Northstar produces 320 hp (239 kW) and 315 lb·ft (427 N·m). An increased compression ratio of 10.5:1 enables most of the increase in power from the L37 and LD8 Northstars.

YearModelPowerTorque
2004–2009Cadillac SRX320 hp (239 kW) @ 6400 rpm315 lb·ft (427 N·m) @ 4400 rpm
2004–2009Cadillac XLR320 hp (239 kW) @ 6400 rpm310 lb·ft (420 N·m) @ 4400 rpm
2005–2010Cadillac STS320 hp (239 kW) @ 6400 rpm315 lb·ft (427 N·m) @ 4400 rpm

Supercharged LC3[edit]

A 4.4 L (266 cu in) supercharged Northstar was used in the 2006 Cadillac STS-V and Cadillac XLR-V. The bore was reduced for increased strength and improved head gasket sealing. Variable valve timing is used on both the intake and exhaust sides. The STS-V engine produces 469 hp (350 kW) at 6400 rpm and 439 lb·ft (595 N·m) at 3900 rpm with 9:1 compression and the XLR-V engine produces 443 hp (330 kW) at 6400 rpm and 414 lb·ft (561 N·m) at 3900 rpm.

YearModelPowerTorque
2006–2009Cadillac STS-V469 hp (350 kW) @ 6400 rpm439 lb·ft (595 N·m) @ 3900 rpm
2006–2009Cadillac XLR-V443 hp (330 kW) @ 6400 rpm414 lb·ft (561 N·m) @ 3900 rpm

L47[edit]

An L47 inside an Aurora's engine bay

The L47 Aurora engine was a special V8 designed for the Oldsmobile Aurora, based on the Northstar engine. It is a DOHC 3,995 cc (3.995 L; 243.8 cu in) V8 which produced 250 horsepower (186 kW) and 260 lb·ft (353 N·m) of torque. The bore was 87 mm (3.4 in) and the stroke was 84 mm (3.3 in). The L47 had a 10.3:1 compression ratio and used premium fuel.

An early version or prototype of this engine was used in the 2nd generation Oldsmobile Aerotech.

Although most of the Northstar's features, including the coolant loss system, remained intact, the decreased bore increased weight unacceptably. To reduce it, Oldsmobile used a one-piece glass-filled thermoplastic intake manifold and simplified AC Rochester sequential fuel injection. A new die-cast structural aluminum oil pan incorporated baffling to reduce oil starvation in hard driving. A starter interlock prevented the starter from engaging if the quiet L47 was already running.

A highly modified 650 hp (485 kW) version of this engine was used by General Motors racing division initially for Indy Racing League competition starting in 1997, then was later used in the Cadillac Northstar LMP program in 2000. Both engines retained the 4.0 L capacity, but the Northstar LMP version was twin-turbocharged.[2]

The Aurora was also used in the Shelby Series 1 car.

The Aurora engine was introduced in 1994 for the 1995 model year, and General Motors has not used this engine since the demise of the marque in 2004.

YearModelPowerTorque
1995–2003Oldsmobile Aurora250 hp (186 kW) @ 5600 rpm260 lb·ft (353 N·m) @ 4400 rpm
1999–2005Shelby Series 1320 hp (324 PS) @ 6500 rpm290 lb·ft (390 N·m) @ 5000 rpm

LX5 (Shortstar)[edit]

The LX5V6 is a DOHC engine from Oldsmobile, introduced in 1999 with the Oldsmobile Intrigue. It was produced by the Premium engine group at GM and was thus called the Premium V6, or PV6, while it was being developed. It is based on the L47 AuroraV8, which is itself based on the Northstar engine, so engineers called it the Short North, though Oldsmobile fans have taken to calling it the Shortstar.

It is not a simple cut-down V8. Although it has a 90° vee-angle like the Northstar and Aurora, the engine block was engineered from scratch, so bore centers are different. It has chain-driven dual overhead cams and four valves per cylinder, but is an even-firing design with a split-pin crankshaft similar to the Buick 3800 engine. The LX5 displaced 3,473 cc (3.473 L; 211.9 cu in) and produced 215 hp (160 kW) @ 5,600 rpm and 234 lb·ft (312 N·m) @ 4,400 rpm. Bore is 89.5 mm (3.52 in) and stroke is 92 mm (3.6 in). It was also one of GM's first engines to use coil-on-plug ignition. Compression ratio is 9.3:1.

The cost of building this engine was high, and it was not used in many vehicles. It was said at the time that a family of premium V6s would follow, with displacements ranging from 3.3 L to 3.7 L, but only the LX5 was ever produced before GM axed the Shortstar in favor of their current flagship V6, the High Feature, in 2004.

The LX5 was entirely different from any other V6 in the GM inventory - the only other DOHCV6 engines ever offered by GM include the troublesome-to-maintain Chevrolet Twin Dual Cam produced from 1991-1997 (which was made by heavily modifying the traditional Chevy 60-degree OHV block for the dual overhead cams rather than building a DOHC engine from the ground up), and the Cadillac/Holden HFV6 available from 2004 to the present day. These three designs are completely unrelated and oddly enough leave two gaps in 1998 and 2003 where no DOHCV6 was available from GM. (Except for the 54 degree Opel V6 used most notably in the first generation Cadillac CTS at launch as well as the Saturn L Series.) This contrasts starkly with competitors practices of evolving engineering over multiple, continuously improving designs.

As with the Aurora V8, production stopped with the demise of Oldsmobile.

YearModelPowerTorque
1999–2002Oldsmobile Intrigue215 hp (160 kW) @ 5600 rpm234 lb·ft (317 N·m) @ 4400 rpm
2001–2002Oldsmobile Aurora215 hp (160 kW) @ 5600 rpm234 lb·ft (317 N·m) @ 4400 rpm

The 3.5L LX5 was on the Ward's 10 Best Engines list for 1999 and 2000.

See also[edit]

Notes[edit]

  1. Jump up ^"Sitemap". Autoblog. Retrieved 2012-06-04. 
  2. Jump up ^Weitzman, Larry (2001).The Aurora by Oldsmobile (2001), Better in every respect. Autochannel. Retrieved on June 28, 2009.

References[edit]

  • Frank Markus. "1993 Technical Highlights". Car and Driver (October 1992): 59–60. 
  • "Technical Highlights". Car and Driver (October 1993): 115. 
  • Joel D. Pietrangelo. "Northstar is heart of Allante re-do for '93 - V-8 engine, General Motors' Cadillac Motor Car Div.'s new model roadster". Ward's Auto World (February 1992). 

External links[edit]