[Notaguru]

I have a 1990 DeVille about to reach 24,000 miles - really! - but time, not wear and tear, requires maintenance. It's fitted with an impressive transverse V8, 4.5L, front wheel drive. I don't know the transmission designator.

Normal maintenance items are available across the NAPA counter, but for many parts my best source is pick 'n pull. There are at least 100 possibly compatible Cadillacs in the various yards near me, but only a few that are nearly identical.

In which Cadillacs of what years will I find generally compatible engine and running gear parts? I plan to keep this car for a while, so what parts should I stock up on?

Thanks!

 

[drewsdeville]

Some, but not all powertrain parts will swap out with other years. The '90 4.5 was a one year motor, using the 4.5L block and crank, special sized rods, with 4.9 pistons, heads, and intake manifold. Most older 4.5 parts will not be able to be used, since in 1990 with the new intake manifold, the engine was fitted with sequential fuel injection rather than the older throttle body style fuel injection. While similar, it isn't necessarily compatible with 4.9 parts either since a few minor differences existed (ex. the deletion of the A.I.R system and introduction of an electronically contolled trans on the 4.9 in 1991). I have a '90 Eldorado, and I also rely on the junkyards for a few odds and ends. You just have to be sure to match anything you want with the old part. Good luck and have fun!

 

[Notaguru]

That's what I was afraid of - a 1-year motor. It seems to be a good engine, however.

 

[drewsdeville]

That's what I was afraid of - a 1-year motor. It seems to be a good engine, however.

Yes, a fantastic engine. My '90 Eldo has 170k on it, still runs like a champ. I find the '90 4.5 to feel the strongest of all of this series engines. It really moves considering what else it was against in it's time.

 

[Notaguru]

For a normally aspirated engine in a car weighing two and a half tons, this thing moves very well. And it just has the "feel" of a rock-solid powerplant - instant starting, clean idle, never a stutter, and WOT WOW.

But nothing lasts forever. When I visit a yard, what parts should I pull just to stock up? What non-NAPA items, no longer available from the dealers, should I have on hand?

 

[quins90lac]

Yes, a fantastic engine. My '90 Eldo has 170k on it, still runs like a champ. I find the '90 4.5 to feel the strongest of all of this series engines. It really moves considering what else it was against in it's time.

i love my 4.5 for all the same reasons . mines got about 190,000 on the engien and 134,000 on the car .no granted the body rusting really bad but the motor just don't know when to quit (knock on wood) . thanking about getting a catera just so i can park it and fix her up. cause i cold never bring my self to get rid of her

 

[Notaguru]

So assume you want your 4.5 to last a long time and you're visiting a parts cafeteria -- what do you take home for future repairs?

 

[red_ghost]

All the stuff I've had go on my 4.9L hasn't been stuff you would want used. The first 4.9 I had, the head gasket took a crap and somehow the crank got f'de up, but before that it was a starter, ignition coil, isc motor. Since I replaced the engine with one that had 30k miles on it, I replaced the ISC motor,tps,exhaust flange gasket, and cleaned the egr valve twice. After all that stuff though, I rebuilt the upper portion of the engine and replaced almost every sensor and bead blasted everything.

 

[Notaguru]

Good info - thanks!
It's economical to buy $200 worth of often-used parts in advance rather than desperately need something that's not available, later. It makes for a pleasant afternoon at the junkyard with my son.
So I'm building my shopping list.

 

[Edahall]

I'm glad to hear that there are people like you who are planning to practically drive this car forever. These are excellent cars and worthy of such treatment. Probably the weakest link in your car is the transmission. They tend to suddenly go out leaving you with few options. What I would do is pick up a used 4T60 from a wrecked/previous running FWD 88-90 Cadillac. I would then rebuild it myself on my spare time and have it staged in the case my transmission goes out. You can rebuild these transmission for under $150 but it'll take some time.

You don't really have to have stick in another one and only 1990 4.5 engine. The 4.9 engines from 91-93 will fit in just fine and pretty much plug and play. There is someone from another forum who just recently completed this swap and he's reporting back sucess.

 

[drewsdeville]

Good info - thanks!
It's economical to buy $200 worth of often-used parts in advance rather than desperately need something that's not available, later. It makes for a pleasant afternoon at the junkyard with my son.
So I'm building my shopping list.

I actually haven't had a problem finding powertrain parts at local auto stores, though there are a few I've pulled from the junkyard for cost savings (ex. Diverter valve). However, I do find myself going to the junkyard regularly for miscelleneous trim and interior pieces. I don't know what to recommend to you otherwise. If you are wondering what the problematic parts are, those are probably exactly the parts you'd want to buy new instead of risking used.
On my '90, I've replaced the fuel pressure regulator, diverter valve, and AC compressor, none of which you'd really want to pull from the junkyard save for teh diverter valve since that little thing is a few hundred dollars new! I recommend you just drive it and enjoy it. Worry about problems when they are actual problems. For now, let the car please you

 

[steelybill]

The items I've had to look for were the heater/AC fan module, and the cooling fan module. Had to use a later AC fan module, and a jumper/adapter from GM, 12 inches of wire and two connectors, for $73 bucks !! GM can kiss my ass.:bonkers: A used Caddy is a good buy though. Had a few that were like 2 years old back in the 50s, 60s, and 70s, for the same price as a new Olds or Pontiac. and a lot better car. I've replaced the AC pump, the air pump, the alternator,and the tensioner. Soon I'll have all new parts except for the POS 4.1 engine:hmm: Which has a problem right now:shhh: