Are '80-'85 coupe devilles reliable as a daily driver?

[Mihai Tarţa]

A friend of mine, long time fan of Cadillacs, is going to move to the US this year and he asked me to post this question in hopes of feedback from current/previous owners.
What would constitute "typical" problems for these models.

Thanks,
Mihai

[Walter Youshock]

LOTS of changes during those years.  1980 is probably the most reliable as far as engines go.  It was a 368 cast-iron block.  1981 was the 8-6-4 version of the same engine but the 8-6-4 solenoids were problematic and many were disconnected.  1982 brought the infamous 4100 aluminum-block time-bomb engine that continued through 1984.  Those that survive either have replaced engines or their original engine condition is really unknown.  Some blew up early with 40.000 miles, my '82 self destructed at 146,000 miles, some have held up well.  Those are the exceptions.  When they die, they just go BOOM!  And the power is less than stellar.

1985 was the 4100 in a front-wheel-drive car that had many of the same drive train issues as the rear-drive  '82-'84 models, but the car was 2/3 the size.

My personal choice would be a 1980.

[Eric DeVirgilis CLC# 8621]

1980 is the most reliable as far as anything goes, 1980-1985. In fact 1977-1980 is probably the most reliable overall Cadillac made- ever. 

Your friend should extend his search in the opposite direction- 1977-1980 with either 425 (77-79) or 368 (1980) if searching for a Coupe deVille.  I would also advise staying from fuel injection (77-79) unless he has the expertise to tend it. The above powerplants are virtually indestructible and the THM 400 transmission with which these cars are fitted is similarly bulletproof.

As my friend above noted, things begin sliding drastically downhill after 1981 and absolutely should be avoided.

1985 is a completely different animal altogether- small, front wheel drive and dreaded 4100.

[TJ Hopland]

Why did he pick 80 as the first year?  77-79 were very similar cars and there are just as many of those still around, maybe even more than the 80-85.   There were RWD 85's so we will assume that is why he is including 85's in his question.

Walter, no mention of the 5.7 diesel in your speech?

I don't have time to do a lot of typing now but later I can let you know what my recent experience has been daily driving and maintaining an 80's car.

[Walter Youshock]

The only RWD '85 was the Brougham sedan with the carbed Olds 307.  Only guessing that he's concentrating on a coupe.  Plus, '80 was the redesigned body.  I'll agree with Eric--the '77-'79's are great cars and far more plentiful than an '80 or '81.

Even FINDING a Diesel of that vintage would be an accomplishment, not to mention the Buick V6 credit-option available in the '82's!

[Eric DeVirgilis CLC# 8621]

Why did he pick 80 as the first year?  77-79 were very similar cars and there are just as many of those still around, maybe even more than the 80-85.   There were RWD 85's so we will assume that is why he is including 85's in his question.

Walter, no mention of the 5.7 diesel in your speech?

I don't have time to do a lot of typing now but later I can let you know what my recent experience has been daily driving and maintaining an 80's car.

The question specifically asked 1980-1985 Coupe deVilles; not RWD in general. There was indeed an 1985 Fleetwood Brougham Coupe but they very rare. As far as diesels, go- they're virtually impossible to find nowadays therefore are often omitted from discussions for the years pertaining to the OP's query. There was also a Buick 4.3 V-6 engine available as well as a diesel option for the 1985 FWD C body- again seldom mentioned- all but forgotten.

The only RWD '85 was the Brougham sedan with the carbed Olds 307.  Only guessing that he's concentrating on a coupe.  Plus, '80 was the redesigned body.  I'll agree with Eric--the '77-'79's are great cars and far more plentiful than an '80 or '81.

Even FINDING a Diesel of that vintage would be an accomplishment, not to mention the Buick V6 credit-option available in the '82's!

The 1985 Fleetwood Brougham was standard with the HT 4100, not the Olds 307 which debuted in the 1986 Fleetwood Brougham.

1980 was the rarest of model years 1977-1985.

V-6 became available as credit option mid 1980 model year until 1982.

Agreed- diesels are very scare today but have developed somewhat of a "cult" following. Values of diesels seem to have remained steady- even surpassing similar gasoline counterparts lately. Quite a far cry from the 3 year old diesel used car- when they sold for 35 cents on the dollar.

[Walter Youshock]

OOPS!  I didn't consider the Brougham Coupe as "Coupe deVille" was in the subject line and they're as rare as hen's teeth.  And the '86 was the Olds engine in the Brougham, not '85.  A guy I work with had a FWD '85 Diesel.  He said his wife was embarrassed by the noise, so he had to get rid of it.

The only V-6 of this vintage I've ever seen was an '82, and that was 25 years ago.

[Retro_Husky]

I myself have an 84 Coupe Deville as a daily driver and so far its been pretty good to me. However the engine was rebuilt before I had it after it blew up. One thing about the 80-85 is the computers they used in these cars tend to just stop working, or other electronics. Despite the looming doom in the back of my head about the ht4100 its a good car. Although I would definitely recommend getting one from 1980.

Tim

[Eric DeVirgilis CLC# 8621]

One thing about the 80-85 is the computers they used in these cars tend to just stop working, or other electronics. Despite the looming doom in the back of my head about the ht4100 its a good car. Although I would definitely recommend getting one from 1980.

Tim

No computers on 1980 DeVille/Brougham 368 V-8, it was also the last 4 bbl V-8 Cadillac engine made.

It remained in production until 1984 on commercial chassis only.

[Mihai Tarţa]

Thank you all for the prompt answers.
As far as I understand, he would like a coupe, preferably RWD, and also price and fuel economy (as far as it applies to these cars) are important.

[Eric DeVirgilis CLC# 8621]

Thank you all for the prompt answers.
As far as I understand, he would like a coupe, preferably RWD, and also price and fuel economy (as far as it applies to these cars) are important.

Whoa- exactly what kind of fuel economy is the party expecting? Most the cars recommended here seldom get much better than 14 mpg, closer to 10/11 mpg in real world use.

Marginally better fuel economy can be had with an HT 4100- but only very marginal- at a tremendous penalty for reliability, durability not to mention enjoyment of operation & relative freedom from worry.

And all those pennies saved at the pump will be forfeited- and then some- when a problem does occur.  And it will- sooner or later.     

[Mihai Tarţa]

by fuel economy I meant: preferably not the most gas-guzzling model ever made.

[Retro_Husky]

I get around 15-17 MPG with my HT4100. As long as its running tip top!

Again, that impending doom of having that engine. As long as you don't run it hard... at all. You should be fine with regular maintenance, up to 150,000 miles. However, again... they can be quite unpredictable.

[Eric DeVirgilis CLC# 8621]

by fuel economy I meant: preferably not the most gas-guzzling model ever made.

I once read the lowest MPG Cadillac ever was the 1974 model.

Downsized C body of 1977 shed ~1,000 lbs from their '76 counterparts which allowed for a significant mileage improvement that year. 

[TJ Hopland]

Besides the loosing weight over the years and at least slightly improving aerodynamics the next big improvements in MPG were the DEFI and the locking torque converter and overdrive.   DEFI in most cars and options was 81.   The V6 cars got the OD in 81 and the rest for the most part got them in 82.

The last 8 years I have been semi daily driving a 70's or 80's car.   By semi daily its not my only means of transport so if I have to go somewhere that has special requirements I can or will drive something else but if its just a matter of getting me point a to b its the old car.   8 years ago there were zero issues getting any of the typical wear and tear parts for these cars.  Most of the parts were in stock at local stores.   Never got anything in a beat up dusty box.  The last 3 years I have had my 80 which needed quite a lot to get it up to safe reliable condition.  Seems like only 1/3 of the parts were in stock locally.   1/3 came from a regional warehouse, and the last 1/3 had to be searched out online or ebay.  I would not say that I considered anything difficult to find but it was not one stop shopping.   That car had a problem with a deer last fall, I got it patched up and drove it till spring but it just was not the same so I spent the summer looking for something else.  Found an 81 that the previous owner got in 2000 and since then has been putting money into it and driving it so its better than most as far as what it needs.  Just in the 3 year span since the last similar car I have noticed parts are harder to find.  Almost noting was in my local store.   Some of the parts came with a lot of dust on the boxes.  Parts with rubber in them will be dried and cracked right out of the box which tells me the stuff has likely not been made for a long time and we have been running off existing stock for several years. 

My point is that it appears that many parts may not currently made but are still around so you should not count on being able to get one when you need it which could be a problem if you are counting on this type of car as your primary transport.   I don't think that for the most part that you won't be able to find parts for this era car but it may take time.   You also have to consider who will be doing the work.  I do 90% of the stuff myself so I have not had to find a shop to deal with them but I suspect that you would have to be pretty lucky to find a shop with experience and equipment to deal with the OBD1 stuff.   Again I'm not saying or thinking you can't find a shop that is willing and able but its not something you should count on where ever you may happen to break down. 

If I have to haul or tow something the old car is out since its not a truck.  The rest of the time locally I will drive the old car.   If I got a road trip I look at the distance and what it would cost me to get the car transported home if it died and what sort of issues or additional inconveniences I may encounter if it did quit.  This usually means I don't drive it more than about 150 miles away or in extreme (usually cold) weather.   If my schedule is not real tight and its not going to be so cold that being stranded out nowhere could be life threatening I will take the old car on the short trips.   

[Walter Youshock]

For price and economy, a 4100 would be a viable consideration.  Price wise, their reputation for being less than reliable makes people shy away from them.  Sad because they really were beautiful cars with a true "Cadillac" look and feel.  Economy was very good once the driver got used to the lack of power and learned how to coax the car along--climbing hills, for example.  On hilly terrain with cruise engaged, these cars hunt for gears.  I had the pleasure of driving my friend's '83 SDV with 23,000 miles home from Boston and it all came back to me how anemic these care were.  Of the 4100 lineage, the '82 was probably the worst as it was the first generation.  The '83 and '84's were tweaked for better performance and some self-destructing issues were addressed, but they weren't as bullet proof as their predecessors.

Regardless of how much weight was cut from these cars, the 4100 is HALF the size of the 8.2 liter 500!  A 6-liter (365/368) is an ideal engine size to comfortably propel a car of this size.  The 365 was first used in 1956 through 1958 and those cars could MOVE!

[Thule]

another funny thing is that though those caddys are truly smaller than the 71-76 calais/deville/fleetwood.  they arent small at all, they are almost as big as my eldo.

i've had a few bmw 7 series,, and mercedes S class,  they are big cars. but the size diffirent between a 7 series and a 80 deville is as much as the diffirent between a 7 series and a 3 series! and this is for real,

if i was getting a 80's deville/brougham i would check out swapping a LT1 or even a ls1 in it, if i intended to use the car as daily driver

[Eric DeVirgilis CLC# 8621]

another funny thing is that though those caddys are truly smaller than the 71-76 calais/deville/fleetwood.  they arent small at all, they are almost as big as my eldo.

Looks are deceiving: 1971-1978 Eldorado curb weight exceeds that of 77-84 DeVille by 1,000 lbs, +/-.

1977 Eldorado even outweighs a 1977 Limousine(!) by ~ 300 lbs.

[Thule]

yeah mine weights 5100, sdo that is true