The ongoing Deville thread

131 posts in this topic

Just thought I would update this. Been a chore with this one.

I seem to have all of the bugs worked out for now. 

Just put engine and trans mounts in it last week. Both trans mounts were shot. Would still like to make my own poly bushings for the torque struts.

I have almost everything to replace the front struts. think the only thing I am missing is the upper plates. I bought the Arnott struts for it.

Last year I replaced the rear shocks  with Arnott. 

I have to look at the air ride though as the compressor kicks on frequently (at least once every minute for about 20 seconds, dont hear a leak though)

The back bumper and lower valance have been broken since I bought the car, the chrome trim was off and in the back seat.

The trunk lid is rusted in the usual places (just under the chrome and at the bottom corners)

Today I found a near mint 98 Deville that was hit in the front. Everything in the back was excellent. I bought everything, bumper, valance, brace, whole lid. not a bad deal at 175 for everything.

I installed the bumper and valance. amazed how it all lined up. Everything will have to be painted though. Trunk lid will be installed once it is painted.

I have been looking for these parts since I bought this car and nearly every one of the lower valances were either broken or badly scratched.

Same with the rust on the trunk lid. Never found one til this one.

I have no idea what to do about the lock cover for getting it painted though.  Mine has a gold badge, replacement has chrome. I assume to get a proper paint job on it that I will have to remove it. Also for the lock cylinder.

But at least for now the bumper is not broken anymore.

Will post update once I get quotes for the paint jobs



Nice, clean, luxury= fine automobile

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I just read the whole thread from the start. This is quite an adventure! I'm glad to hear that you seem to have a smooth running and beautiful Cadillac running. I have a 2002 STS with "only" 190k miles on it so I'm sure that the Northstar engine can run long if well maintained and with headgaskets fixed if they blow :)

Did you ever open up the old engine? Many write about pulled head bolts. Just nit picking here, a blown gasket is a blown gasket but I think that the gasket blow and then that the bolts come loose. Not the other way around that would imply that either the thread material was weak to start with or that the thread locking compound failed or both. Since the Northstar engine has a die cast block the heads and gaskets sees more flexing and moving and this eventually causes the gaskets to blow. The same casting process probably also caused a different structural integrity in the block compared to a “regular” block. Perhaps a different alloy was used than in “regular” made blocks in order to enhance the overall casting progress. We have all seen and heard of aluminum in the head bolt threads but my belief is that it comes from when you loosen the head bolts (they loosen up really easy because of the high torque they are mounted with). What I am saying is that I’m confident that a properly done Time-serting is more than enough to get the car back in running order. As Logan mentions a lot of automakers use them so there is surely a need for them by design intent, not because of bad engineering… A cast iron engine or an aluminum engine with other loads on the heads, other clamping lengths on the screws, other running temperatures and applications and so on perhaps don’t need them. I’m just a bit tired of people saying it was a bad design or wrongly designed. Engineers can and do mistakes but this engine is also quite a different engine compared to the more common pushrod LSx V8s. Different engines and different designs need different solutions.

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By far....the most common TimeSert tool we rent is for the Toyota 2.4L block. Very common on that engine to have pulled head bolts. 

It is interesting to note: Both the Toyota block and most Northstars (thru 2003) use the same size head bolt thread. M11 x 1.5. They both use the same TimeSert 11155 insert.   

It is also interesting to note it is most often the 3 rear head bolts that pull on the Toyota block. 

Lots of info on Google about pulled Toyota 2.4L head bolts. Toyota has walked away from the problem. 

The big on the Toyota...the repair is doable with the engine in the car. Quite a bit room to do the repairs effectively. The repair can be done by most shade tree mechanics with limited direction.  

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Since nearly all Northstar head gasket failures are old and/or high mileage cars, usually with unknown coolant maintenance history, I'm convinced that it's not a design problem.  Any aluminum head or head/block engine will give trouble eventually if you run it for years with acid coolant.  The big deal with the Northstar is that it's the head gasket, arguably the worst coolant-related problem you can have, whereas in most other cars it's the manifold gaskets or the thermostat housing or whatever.

I'm not surprised that the Toyota four-cylinder is a source of problems.  I've heard tales of sludge accumulation and other things in vintage about 2000 Toyota fours, although they had a distinguished record for engine design prior to that.  Toyota has pushed to be the biggest out there for many decades, and the push usually results in cutting corners to offer better prices, and when this causes a problem with a model with huge sales volume, stepping up to it may not be feasible.  Welcome to the big time.

If you are considering a Toyota, look at the V6 models.  As far as I know, they have no underlying issues like cheater emissions software, sludge accumulation, or long-term mechanical issues.  Now, the back of my mind is saying, whatever you want, you can get it from GM, Ford, or Chrysler, and the relative long-term reliability and cost of operation is top-notch for GM and Ford cars, and some Chrysler cars.

That the Toyota is easier to do head-off repair in the car is an advantage if you are working on it.  If you are using a car as a daily driver, well, you get what you pay for.  Of course you can work on an inline four in the car.  I once did a valve job on a bow-tie 327 V8 in the car, outside.  The real challenge is not to need to do that.

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I honestly never took it apart. Working 2 jobs (or so) leaves me little to no time to even think about it.

It is nearly complete. Sitting in one of my garages at the moment.



Nice, clean, luxury= fine automobile

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Today was a huge accomplishment.

I remember the day I fixed my air ride on my 96 Deville and how it rode.

Well today I overhauled the 97 Deville. Brand new compressor and Arnott air shocks.

I swear it raised the back end at least 3 inches. I dont think it worked since I bought it.

It has rode nice but not like it does now. I find these cadillacs ride great even in the worst of conditions.

The tell tale failure was the compressor would run for awhile and shut off, then after 30 or so seconds it would run again. It never built air to the shocks.

I finally got a chance to look at it and found the exhaust valve corroded and stuck open. So anytime the compressor ran it all went out the exhaust.

Very common failure, either it fails and sticks shut jacking up the rear end, the other never builds air.

I am going to have to replace the rear insulator bushings. I am curious if anyone else here has changed them??

they are sandwiched between the body and rear subframe. I have replaced them in 2 out of 4 cadillacs I have owned. they are shot on this one and I have to change them before they get too bad on my Seville.

I will try to post pictures when I do them but they dont look good. I was going to do them today but the compressor took too long.




Nice, clean, luxury= fine automobile

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