1983 Cadillac Coupe DEVILLE

[mknoblau]

I am thinking about purchasing a 1983 Cadillac Coupe De Ville.  It has 23K documented original miles. I would appreciate and pros about this model and year.

thank you

[35-709]

Do all the research you can on that HT 4100 engine.  Many consider it the worst modern engine GM ever built (including me).  There are a few that have run to a reasonable mileage, but the majority did not.  There were many Lincolns sold to former Cadillac owners because of that engine. 
My personal opinion, unless you are a qualified and experienced HT 4100 mechanic I wouldn't touch the car for any amount of money, except possibly for its salvage value, no matter what the speedometer says.  The transmissions in those cars weren't much good either.
Been there done that!
 
   

[Rusty Shepherd CLC 6397]

Geoff is absolutely correct.  As nice as those cars are (beautiful, comfortable, quiet, smooth), the HT4100 makes it far too risky a buy.  Block deterioration has been going on for the last 25 years (assuming it's the original engine and even with only 23K miles, that's not a given) and you'd likely be headed for one of two HT4100 finales: increasingly more sluggish acceleration until it can't get out of its own way due to increasing play in the camshaft or BANG and coasting to the side of the road when the crankshaft breaks or other catastrophic internal engine failure occurs. Prior to that the chances are good that you'll be listening to main bearing knocks. Also, a 1983 HT4100 does not have many, if any, of the improvements that made the later ones slightly more reliable before they were replaced with the night and day better 4.5 V-8 for 1988.

[CraigC]

Of course, if your state allows it and you don't care about authencity, you could always replace the engine and tranny with a Chevy 350 and a TH400 combo.  Then you have a big, comfortable cruiser that is also reliable.  Just a thought.

[TJ Hopland]

I would buy another one if the price was right.  I especially liked the Fleetwood Coupes. The 4100 would definitely make it worth less.  How much they asking?  Many 4100 got replaced one way or another and the replacements were much better but with that low of mileage its unlikely.   There are swaps that would be easier if you are looking that direction.  the 81's used the 368 which was the same basic block as the 472/500/425.  The 86 broughams (same basic body) used the olds 307.  79-85 all had the olds diesel as an option which is the same basic block as many of the olds v8's. You could even get a buick V6 around those years. The Chev's didnt come in till 90. I have never looked into a chev in an earlier car but at least they are cheap.  The later 4.5 and 4.9 were the same basic engine but too many things changed to make them a bolt in swap.  Most of the updates from the later motors did apply to the 4100.  Same goes for the transmission, with later updates and more modern materials they will hold up to anything you should do to the thing. 

[Stampie]

Of course, if your state allows it and you don't care about authencity, you could always replace the engine and tranny with a Chevy 350 and a TH400 combo.  Then you have a big, comfortable cruiser that is also reliable.  Just a thought.

That sure is boring.  Let's replace a crappy engine with a cookie cutter engine.  Why not drop a 472/500/425 in there since they are bolt on.  Also why put a TH400 behind a small block chevy?  Not like you really nead a strong trans behind a weak motor.

My 2 cents,
Stampie

[Guidematic]

 Read up on the engine here. No biased opinions from heresay. Then make your own decision.

 http://autos.groups.yahoo.com/group/HT4100exchange/

 Mike

[Rusty Shepherd CLC 6397]

That's definitely true, but there's a prohibitive problem with putting one in an '83 CDV: the 4.5 and 4.9 were built only for transverse installation unlike the HT4100 which had one version for transverse and one for longitudinal installation.

[Guidematic]

 The real problem was that there was a fundamental differance in the longitudinal and transverse blocks. Not so much as in the "improvements" The 4.5 and 4.9 were available only as a transverse FWD application. But, these blocks were very similar to the transverse HT4100's. The main differance being in porting in the heads and intake manifolds. Of coarse a 4.5 is a bored HT4100 and a 4.9 is a stroked 4.5.

 Mike