: Need Technical Information about Northstar engine/drivetrain.

11-02-04, 01:29 AM
Hello Cadillac forum members,
I am a newbie here and to cadillac engines, I have a 1985 cadillac seville which is a great looking car, but the 4.1L engine took a s**t and now the water,oil, and fuel seem to be mixing together and its just a huge pain.

Instead of trashing such a nice looking and functional car, I have decided that maybe, a Northstar engine and drivetrain could be swapped in. Now I know mounts, and electrical systems wont match up, but I have a few questions regarding other details about the Northstars.

1. What year did Cadillac offer Northstars, and which years are best ones?
2. What kind of displacement do they have, good bottom ends? How much does it take to modify them and which is the best mod, porting heads, increasing the flow of the exhaust, intake and fuel system upgrades? etc.
3. Which year of Northstars are the best stoutest engines, and how long do they last compared to a regular sbc thats maintained well?
4. what are the problem areas with these engines and what should I avoid?
5. How much can I find a Northstar engine/tranny/ and prob front axel, and what models had these cadillacs.
6. How wide is the front axel of the FWD Northstars, where the axel shafts mount with U joints?, I want to know if It is close to the same width as the sevilles current axel.
7. and Lastly, is the Northstar mounted sideways or is it conventionally mounted with the pullies up front?

I know these are a lot of questions, but I wouldnt ask any other forum to help me out and provide information to this extent on the Northstar engine. thanks for the help.

11-02-04, 02:30 AM
There is a bit of a problem with your plan.... Your 85 seville is a FWD car but it has a longitundinally mounted engine and longitudinal trans (albeit beside the engine) with a right angle final drive unit. The Northstar FWD packages are a transverse mounted engine with a transverse transaxle. The two basic packages just do not interchange.... Anything is possible but adapting a Northstar engine to that platform will be very difficult and expensive. And that is just the mechanical bits....the electronics to run the Northstar engine are completely foreign to the system that is in the 85 seville and vice versa.

Fixing your 4.1 is not that difficult. That engine is very simple to work on and likely the problem is easily repaired by replacing the intake manifold gaskets. Likely that is where the coolant in oil leak is.

1.Northstar engines were first installed in 1993 model year cars. The first version of the Northstar engine was produced from 93-99. The engine was redesigned in 2000 with roller cam heads and such. The first longitudinal version of the Northstar engine for RWD was produced for the 2004 SRX and XLR Cadillac and is in the 2005 STS. The longitundinal Northstar is a 3rd generation of the engine with variable valve timing as well as a completely different accessory layout for RWD.
2.Northstar engines are 4.6 liters. There are not a lot of aftermarket parts available for them and they are difficult engines to "hop up" simply because they are already very high specific output engines. The L37 engine makes 300 HP from about 280 cubic inches so the low hanging HP has already been picked. The engines are pretty strong as is. The stock parts are often used in sand dragsters making over 600 HP with blowers.
3.There are L37 versions that make 300 HP and LD8 engines that make 275 HP. Either are equally strong.
4.Problems you will read about on this forum are head gaskets with high miles and the head bolt holes when the engines are torn down for replacement of the gaskets requiring timeserting the head bolt holes , oil leaks on some of the older engines, the need to maintain the cooling systems to prevent damage to the engine internally due to depleted coolant.
5.There have been millions of FWD Northstars produced so they are somewhat common in scrap yards....
6.Since the Northstar is set up for a transverse mounting with transverse transmission/transaxle the width of the unit is not really comparible to the seville setup you have.
7.The Northstar is transversely mounted (sideways) in all applications from 1993 thru 2004. It continues transversely todate in the Deville. The 2005 and later RWD Cadillac SRX, XLR and STS are specific longitudinal engines with conventional drivelines.

As I mentioned what you propose is far far from a bolt in proposition. The parts just do not line up. I do not believe a Northstar will bolt up to the transmission you have in the Seville currently as it will not clear the barrel of the trans even if all the bolts to the trans bell housing would line up. In any case, even if it did I do not believe that there is room for the water crossover casting at the rear of the engine where it would come into contact with the firewall. Lots of fabrication of some major parts to think about doing this. And that would be the easy part. Gettting the electronics to work would be even more difficult as the PCM for the Northstar is not a "stand-alone" unit. All the Cadillacs have highly integrated electronic control systems that integrate the vehicle electronics with the engine control. Even if it was made to run the engine would not talk to the dash and you would loose all functions of the dash system.

If you want a Northstar it would be far simpler and less costly to just buy a car with a Northstar in if from the factory and work on that. If you really want to get your 85 Seville back on the road it would be much simpler to either fix the 4.1 and just drive it or to swap in another powerplant like a small block chevy that could be made to fit easier and that would have a carbureted manifold available. You would loose the dash in that case but it could be made to run easily.

I would fix your 4.1 or buy a re-manufactured 4.1 engine for the seville and just swap it in.

11-02-04, 02:43 AM
Thanks for all the help Bob,

Damn, this really changes things, I was hoping for it to be mounted conventionally, then atleast I'd have a chance. I'd really like to change this tired turd of an engine trying to pull the heavy seville anywhere, when it was running correctly, it could barely go up a small hill.

Anyway, what engine did cadillac have before 93; the northstars, that had the same layout like the 4.1 with the engine conventional, and transmission output to the drivers side?

11-02-04, 12:00 PM
Thanks for all the help Bob,

Damn, this really changes things, I was hoping for it to be mounted conventionally, then atleast I'd have a chance. I'd really like to change this tired turd of an engine trying to pull the heavy seville anywhere, when it was running correctly, it could barely go up a small hill.

Anyway, what engine did cadillac have before 93; the northstars, that had the same layout like the 4.1 with the engine conventional, and transmission output to the drivers side?

Those systems with the longitudinal engine and FWD were only manufactured with the 4.1. The Eldo and Seville both had that setup and changed to the transverse engine and transaxle configuration for 1986....

The 4.1 is not that speedy but I have driven lots of those FWD pre-86 packages and they could certainly go up a hill and ran fine under normal conditions. Maybe the 4.1 was loosing power for a long time.

That engine is very very easy to work on and rebuild. Likely if you pulled it and completely dissassembled it it would run like new with a new cam (likely some lobe/distributor gear wear if coolant was getting into the oil) and a new set of lifters and a new timing chain and gear. Clean up everything, put new bearings and gaskets in the engine and reassemble it. Generally, those engines look very very good inside even when they are in distress like you describe. I have looked at lots of core engines returned from scrap yards to the re-man facility and the pistons, cylinder bores, cranks, valve seats, etc. most often look like very low mile parts with minimal wear. The only wear items are the cam/lifters (easy to puchase and replace), the timing gear on the cam and gaskets. Possibly the timing gear has worn and the engine has "jumped time" which is why it is so lethargic. Rings would be an option but even with 100K the rings I have looked at from those are usually perfectly serviceable. The hardest part of the whole deal is pulling the engine and cleaning up the parts. It is easy to tear down/reassemble and easy to put back together. I would highly recommend finding a service manual for your engine/car before starting as there are some special bolt tightening and assembly techniques required for the engine but it is actually very simple to work on with the correct references. It is easy to screw it up if you do things wrong which is one reason it has a poor reputation in the service industry but in actuallity it is fairly robust and easy to fix. It made it 20 years and how many miles originally????

11-02-04, 05:17 PM
Actually we bought the car about 6 years ago, and my parents paid 2K for it, later on the engine distributor blew, so that was changed, then the engine got screwed up. After it was toast, we had a shop put in a reman engine and plus the labor to go with it added about another 4K. Fast forward a few years, we hired a mechanic who lived maybe 12 miles from our shop, and he drove the cadillac for a few days, unfortunatly, somehow the radiator was leaking or the engine was burning oil/water. This guy just adds more water to it all the time and we figured the engines head gasket is no good. So it sits in our shop for almost a year, and Im looking at it one day and wonder, how bad is it, car looks good, interior is supurb, so whats the deal. Anyway, I add a battery, add some gasoline, start it up and sure enough black smoke is pouring out the exhaust pipe, check the dipstick and its caramel, creamy and foaming, plus theirs barely any water in the radiator.

So Instead of trying to mess with this wet liner engine that has no power, I'd rather swap it out for something else. I'll go to the junkyard and see if I can find any northstar parked out front, take some measurements and see if it can actually fit between the fenders and the chassis and go from there. Thank you for providing the information i needed, it was really helpful. :thumbsup: :yup: