Northstar

1996 NORTHSTAR ENGINE REPLACEMENT

Recommended Posts

Can someone point me to where it says what year range of engines I can use for my 96 STS?

Thanks!

Share this post


Link to post
Share on other sites

Not sure if it is specifically documented but a '96-'99 VIN 9 engine should work. What is the issue that you are trying to solve? Is there any reason repairing the existing engine is not an option?


Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

Share this post


Link to post
Share on other sites

There was a platform change in 1998 that may change some accessory mounts or even a motor mount. Full interchangeability is just 1996-1997, but if you have both motors side-by-side you should be able to work out just about anything. You may need a custom motor mount pad or two.


CTS-V_Dashboard.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

Share this post


Link to post
Share on other sites

I have 270k on this engine and the head gaskets went out but I kept on driving it in Limp home mode maybe 30 times so I was thinking to just replace it with a low mileage engine or a studded replacement engine. The engine I have now does still run good until it gets hot.

Share this post


Link to post
Share on other sites

I would not install a used engine without going through it first. Your 270,000 mile engine can be repaired - have the cylinders honed to the factory specs., new rings, rod bearings, head gaskets, time serts and new main bearings and it will go another 270,000 miles.

How is the transmission holding up?


Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

Share this post


Link to post
Share on other sites

I was thinking of studding the used engine that I was going to swap in. I don't have the time to repair the original engine and am having a shop do a swap for me for $800.00

I'm on my second transmission and will be replacing the torque converter during the swap to fix the lockup stuck on code.

Edited by Northstar

Share this post


Link to post
Share on other sites

I would replace all three solenoids. It's probably a wiring or solenoid problem that causes your TCC sticking. Replacing both is good because when the TCC is stuck on it has a high failure rate.

I would consider Timserting your existing engine. At least it's a known quantity. While it's out, consider changing the case half seal and the oil pan gasket. I would also change the oil pump and the timing chain tensioners. You may want to put a caliper on your cams (with them in the heads) and change them and the lifters if they are out-of-tolerance.

Others will have more suggestions. That way you will have a bulletproof engine for as long as you want to drive your car.

You will need an engine stand and a FSM to do this job. If you have it done, Don't trust it to anyone who does not do work on Northstar engines at least once a month. A professional mechanic is not going to have the stake in the car and the patience to figure out how to do every little thing right, and if he is unfamiliar with the engine you can predict that short-cuts will occur. Like my mechanic dropping the cradle without disconnecting the EBTCM connector and trashing it. The FSM step-by-step will prevent such blunders.


CTS-V_Dashboard.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

Share this post


Link to post
Share on other sites

I love the 71 Riveria, post some photos if you have any, that was a beautiful car


Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

Share this post


Link to post
Share on other sites
On 12/8/2011 at 3:23 PM, BodybyFisher said:

I love the 71 Riveria, post some photos if you have any, that was a beautiful car

Thanks, I still have the Riviera! My first car! 

Share this post


Link to post
Share on other sites

That is a Beautiful Riviera.

USed engines are hit or miss. Just know that it is a chance you take. 

270k miles is great. These things are tanks. If body is in good shape it is worth fixing. 

My 96 failed at 200k IIRC. First the torque converter, then shortly after it started using coolant. Wish I still had it. If it was worth fixing I would have.

Best of luck to you. These members are extremely helpful here. 


GM FAN FOREVER

Nice, clean, luxury= fine automobile

Share this post


Link to post
Share on other sites

I remember Scotty AKA Body By Fisher

 

I still have my 1996 STS and it still needs a freshly studded Norsthar block using the kit from NP.

Basically I'm going to re-power her along with the 50hp Stage 3 tune from NP and a tire burning shift kit for the 4T80E when it hits 2nd gear.

I will then try to get above 155mph since my speed limiter will be removed out in the desert.  (new set of Z rated tires installed first)

Does this sound like a good plan? Do you have better advice for me?

 

16422519_10154908524255270_7655538634437487111_o555555555.jpg

6666666666669999999.jpg.ca26c927d914209948924c26b6f2f916.jpg

Edited by Northstar

Share this post


Link to post
Share on other sites

The STS and ETC don't have a speed limiter.  The engine redlines at 150 mph.  The final drive ratio could be changed from the STS/ETC "performance" 3.71 ratio to the SLS/ESC 3.11 ratio, or the 3.43 ratio used in the Aurora, but that will trigger P0730 "Incorrect gear ratio" with your stock PCM.  This might or might not be something that you could fix with the reprogrammed PCM; if you are getting the chip from Northstar Performance, ask them about that, and also about changing the final drive ratio when they rebuild your 4T80E.

Tire-chirping hard shifts as a regular thing are a bit much for daily drivers.  In other cars, I've heard of such changes causing problems in the driveline over time, such as gears or bearings in the differential giving up and such.  You can get exactly the same effect by pulling the shifter down in to 1 for a manual shift to 2 or just to 2 and let the transmission give you the performance shift at redline.  I wouldn't ask for a tire-burning shift if was going to drive the car every day.  They should have a performance shift programming scheme for people that drive the car every day that matches up well with the Stage 3 chip, or even is part of the Stage 3 chip.

I personally like high drive ratios.  You give up snap off the line for more legs in the lower gears, lower cruise RPM, and possibly higher top speed.  You may get better gas mileage and, depending on the terrain that you drive in and such, longer gears can be easier on the engine.  Performance as measured in the quarter mile may actually improve, or if you have a big flat spot off the line, times will increase - but I don't think that you will have any such flat spot off the line with the 4T80E.


CTS-V_Dashboard.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

Share this post


Link to post
Share on other sites

I'll go past redline then, hehehe

I thought there was something about the torque converter not locking up at top speed.

I do know the non Z rated 1996 STS's were top speed fuel cut off rated at 130mph because I've seen it a few times on my STS's DIC

The Z rated cars I always thought were limited to 150-155 (drag limited or fuel cut off limited) I'm not sure.

NP says it will remove the top speed limiter with the stage 3 tune but maybe that's for the 130mph limited cars.

I will not be changing the transmission gear ratio's, don't wanna deal with any issues from that.

I've gotten 2nd gear chirps with stock 4T80E's before many times.

I do think the VIN Y engines are more everyday user friendly with the torque down low where you use it most.

Whatever I do it will be video documented.

 

 

Share this post


Link to post
Share on other sites

Wow. What a beautiful Seville.

They are not so common. I rarely see any. And finding parts is fairly difficult. 


GM FAN FOREVER

Nice, clean, luxury= fine automobile

Share this post


Link to post
Share on other sites

Thanks for the compliment!

I have access to any Northstar powered car parts you need out here in the Nevada desert, they are still plentiful and rust free.

Is there any worry about the head gasket issue on the 2008 DTS?

Edited by Northstar

Share this post


Link to post
Share on other sites

A few small mods on the STS: SLS inner larger tail lights (1 more bulb per side and no more Euro plate gap) and the 2000-2005 17" DTS "Turbo Fan" wheels and of course 2% limo tint all the way around to blend in with the blk/blk color scheme. Front window has 70% "clear" tint to block the harsh Nevada desert sun. SLS hood since someone backed into mine and it was the only decent black one I could find at that time so I have 2 emblems in front.

16422519_10154908524255270_7655538634437487111_o555555555.jpg.74b52b3aba1949db05750cac14f0f29e.jpg

6666666666669999999.jpg

Edited by Northstar

Share this post


Link to post
Share on other sites

Whoops, I forgot about the Z-rated-tires requirement for no speed limiting.  The speed limiting is by retarding the spark and cutting the spark and possibly the gas on the same cylinder(s) intermittently to keep the power down, I believe.  Cutting the gas alone would be hard on the engine and could result in a holed piston.

Going much over redline won't work well.  The valves will start to float pretty close to the top of redline and the torque will drop off precipitously.  150 mph is pretty much all there is with the 3.71 gears.  Shimming the valve springs may be an option for a bit more redline; check with your engine tuner.

I'm not aware of any torque converter lockup issues at top speed.  If you use a 4T80E from the 2004 model year or later, the torque converter lockup changed to an electronically controlled converter clutch that year, eliminating all RPM loss once lockup is established.

If you do go to the Aurora final drive ratio of 3.48, the speed at redline increases to 160 mph.  Using the SLS/ESC final drive ratio of 3.11, the speed at redline is 180 mph, meaning that you will be drag limited.  If you are serious about top speed, I would seriously consider a later 4T80E and the 3.48 final drive ratio from an Aurora transmission.  Check with your performance chip people about disabling P0730 or programming it for your new final drive ratio; it should be a no-brainer with their performance changes because it's just one number to change, and a number that's normally part of the factor/dealer programming of the 4T80E.  That same number in the PCM is probably used in speedometer calibration.

I believe that GM made a lot more gear ratios for the 4T80E because the RPO range FV0-FV9 includes final drive ratios 3.11 and 3.71, but cover final drive ratios from 2.86 to 4.12.  If you include the FQ2-FQ9 range of RPO codes that includes FQ2 for 3.48, the Aurora standard final drive ratio, the range of final drive ratios goes to 4.53.  There are a handfull of other transaxle ratios listed here:

https://www.crawlpedia.com/rpo_axle_codes.htm

but those include other transmissions besides the 4T80E.

Then, there is use of tires with a larger rolling diameter.  The standard tires for the 1990's E/K platform is 26.6 inches, which is pretty big already.  A clean-sheet-of-paper look at things may have you going to different wheels and tires that have a smaller rolling diameter, which would force you to look at changing the final drive ratio.


CTS-V_Dashboard.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

Share this post


Link to post
Share on other sites

Thanks for all the great information! You are a wealth of knowledge.

I'm trying to beat my 1991 Lexus LS400 that I got up to 155mph in the desert before. (GPS confirmed)

That Lexus has only 250hp and 260tq, Front engine RWD.

Can you image if GM had built the STS with RWD? The wrecking yard wouldn't be so full of them here I guarantee it. 

One other top speed record I did was a 1990 Honda Prelude Si 4WS with 140hp got it to 130mph (GPS confirmed) very light and aerodynamic car.

Are the 2008 DTS's immune to the head gasket issue with regular coolant changes?

I'm also seeing the 2006-2011 DTS's start to come into the wrecking yards now.

Edited by Northstar

Share this post


Link to post
Share on other sites

If all you want is 155 mph, I think all you need is the 3.48 final drive ratio and a tune-up that gives you factory-new ignition and fuel injector performance.  I'm assuming that the P0730 doesn't do anything other than display the code.  Check the compression and see if it is in spec.  Except for the head leakage, the compression should check OK if you plan to push the performance envelope.  If not, you need to look at valves or stuck rings.

When my car was a few months old, the dealer reprogrammed my PCM for performance.  The car is a 1997 ETC, which probably has the same PCM as your car.  No matter what they tell you, you can program the stock PCM within some limits, and anyone with a Tech II and the proper training should be able to do it.

My personal opinion is that every Northstar is safe from head gasket failure with regular coolant changes.  I know of only one that was driven regularly, was well maintained, and had a head gasket failure in under 100,000 miles, was a young fellow in Boston with another 1997 ETC, and his happened at about 80,000 miles, I believe.  Since I didn't maintain or tear down his engine, I can't comment on what happened.  He was ripped because one limit on the drivetrain warranty for 1997 was 60,000 miles.  Another personal opinion that others here may not share is that the Timeserts are a perfectly good repair.  One advantage is that with a Timesert repair and new GM head bolts you get the clamping force versus engine temperature that GM designed for this engine.  Just don't cut corners, vet the block for sound bolt holes and don't be afraid to get another block if there is any doubt, and take your time in both the drilling and tapping operations.


CTS-V_Dashboard.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

Share this post


Link to post
Share on other sites

Here is mine. Had my center caps off for a thorough cleaning. Very difficult to maintain in NY.

Only mod is the RDS radio. Which is oem and direct replacement. 

Sorry no tips on a 08. I stick with my 90s

20180626_165008.jpg


GM FAN FOREVER

Nice, clean, luxury= fine automobile

Share this post


Link to post
Share on other sites

A really slick Seville.  My last upgrade was new center caps with the raised gold wreath and painted coat-of-arms on the logo.  CardioDoc on Wheels has them.  The dealer tried to sell me those when I bought the car but they were $125 each, $500 for the four, so I waited to do that for a mid-life upgrade.

 

ETC_Wheel_IMG_5736-Edit.jpg


CTS-V_Dashboard.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.