Advice on Tri-7's

[Uhegej]

I am considering purchasing a very nice 1979 Fleetwood, I went and looked at the car today; it's a really good looking car.  Any advice on common repairs and issues these cars have.  Anyone with a 77-79 would be glad to hear from you.

[T J Lankes]

There are some minor issues but nothing major.

These models frequently blow the original style blower relay.  A newer type relay can be installed to take care of the issue.

The fix was posted on the forum by TJ Hopland but I can't locate it now.  I followed the procedure for my '79 and have not had any more relay issues.

This is the new type relay:  https://www.amazon.com/gp/product/B000C2M9KA/ref=ppx_yo_dt_b_asin_title_o01_s01?ie=UTF8&psc=1


Power antenna and power trunk pull down failures are common.

A factory shop manual, usually on eBay, is very useful.

Best of luck.

[Eric DeVirgilis CLC# 8621]

A picture/s is worth a thousand words...<hint-hint> 

[Scot Minesinger]

The tri-7 Cadillacs owners really seem to enjoy them and strongly list their attributes.  Surprised more have not chimed in.  And as always aside from items geenral to any car you buy, rust, mechanical, everything works and etc:  The major thing I noticed back in the day when they were new and slightly used cars is like much of GM, those late 1970's paint jobs were not quality, and so to me a high quality respray would be a plus.  Also, back in the day GM suffered low quality interior plastic piece trim items, so a good interior will be important.  The squared off front end that was designed to drive 55mph gets noisy at highway speeds of today that approach 80 mph all day long in many states.

Enjoy and have fun!

[Barry M Wheeler #2189]

A near mint shop manual will be included. And of course the trunk pull-down works as does the antenna. Sorry, it's so dirty. I haven't cleaned it up in a year or so.

[cadillacmike68]

No rear center armrest??

[V63]

Having had all 3...i have a personal opinion.

While beautifully appearing...I find the 79 lacking significant quality. The burl wood finish is much more prone to fade, and the dElegance carpet has terrible durability. More and more plastic components were introduced. One example, The glove box stop was a continuation of the mini braided cable in 1977 ...that was reduced to a cheap plastic strap by 1979.

[Barry M Wheeler #2189]

Mike, it was cold that day I took the pictures. I also forgot... Is it "de'rigure" to show the rear armrest? (Boy, I wish someone would "fix" the spell check!)

[cadillacmike68]

Mike, it was cold that day I took the pictures. I also forgot... Is it "de'rigure" to show the rear armrest? (Boy, I wish someone would "fix" the spell check!)

Barry, You can put the armrest up or down, you preference.  Most cars never had any center armrests back in the day, so I like showing them. I keep mine down on all the cars unless there are three people actually sitting in that seat.

But from the pics, it looks like there is no rear center arm rest, or am I not looking at that pic correctly?

[Barry M Wheeler #2189]

When it's warmer, I will take a picture with it "down." The lady I purchased it from had bought it "off the floor" from the agency in Gary, IN. It was washed and gotten ready so quickly there is still the round "lot tag" on the back of the rear view mirror. It has a dealer add-on security system that I asked her for the special key to be mailed to me. But I've never turned it on as I'm afraid that it might get stuck and couldn't turn it off.

If John doesn't take it, I'm going to drive it more this year. I haven't registered the '81 Seville for Louisville as yet so I might just bring the Fleetwood instead.

[Eric DeVirgilis CLC# 8621]

At least as far back as '59, rear center armrest was standard in DeVille & up models except for convertibles and FWD Eldorados until '78 (unless Biarritz).

[jdemerson]

The 77-80 DeVilles and Fleetwoods are excellent cars, and one will probably be my next Cadillac. Although I don't have a reason to disagree with the comments above about 79s, I'd point out that 79s also have small advantages. What is most important is the condition of the individual car.

Here are a few comments on differences among the three years, based on a features list that I've compiled for ALL Cadillac from 1948 through 1980:

1977     All-new RWD models, Fleetwood 900 pounds lighter, 12.5 inches shorter with same 121.5 inch wheelbase as Deville, same interior room (except for width) as 1976 Fleetwood, no four-door hardtop, 4-wheel disc brakes standard on Eldorado, Seville, and Fleetwood Brougham models. Discontinued air cushion restraint system until 1990s. Lighter 425 cu. in. V8, derivative of 472 and 500, optional 40-channel CB radio, first halogen headlights, electronic cruise control

1978     First digital dash (trip computer, speedometer on some models), signal-seeking AM/FM Stereo radio made standard

1979     Electric power side mirrors

Personally, I'd LOVE a 1977, 78, or 79 Fleetwood Brougham with all leather. Good luck!

John Emerson
1952 Cadillac sedan 6219X

[Eric DeVirgilis CLC# 8621]

Trip Computer was available on Seville only in 1978 & 1979.

[cadillacmike68]

In what year did Cadillacs start having the PCM - AKA powertrain computer?  I'm guessing from what Eric just posted it was 1978 for Sevilles, but what about the other years?

And what was the last year for a QuadraJet carb?

[TJ Hopland]

Short simple answer to the 'PCM' as we kinda know it today question is 80 was a mix and 81's had them.

Long answer......

Mid 75 EFI became an option and then was standard on the Seville.  These were analog electric but didn't have a microprocessor cpu.  Trip computer I would guess had a cpu.   HEI ignition modules had a microprocessor in them.  79 was the last year for that system in most cases, it did hang on as the CA emissions engine for the 80 Eldo and Seville.

80 was the first year for what we would now consider a computer.  Cadillac called it the Digital Electronic Fuel Injection.  It had a microprocessor based PCM.  It had On Board Diagnostics and the digital fuel monitor built in.  It was the 49 state standard engine on the 80 Eldo and a no cost option on the Seville who's standard engine was the diesel.   Other cars still had the Quadrajet with a unique ignition module that I think had a coolant sensor or something like that to adjust the timing for emissions.    Also mid 80 the 4.1 V6 became an option which had a Qjet.

81 the standard engine except for Seville who's standard was still the diesel was the DEFI which now also featured the 8-6-4 mode.   Same system as the 80 they just added the 8-6-4 feature.    IF you got the 4.1V6 option you got the computer controlled Quadrajet.  It was a very similar computer to the one for the DEFI.  Carbs got a throttle position sensor, idle speed control motor, and a mixture control solenoid.  Timing was fully controlled by the computer too.  The mixture control solenoid could allow for roughly a +/- 10% mixture adjustment which really did help economy and emissions.   V6 that year came with the overdrive transmission and locking torque converter.

82 the standard engine became the HT4100 which had the now further refined DEFI that only got minor changes through 89.   This was basically the same system that the trucks used 87-95.   Looks like a carb but has 2 injectors hanging where the choke should be.   Transmissions in most cases were OD with locking torque converter.

84 with the 4.1 V6 no longer available all Cadillacs were fuel injected.  Notice there was no electric in that statement because of the diesel option.   Diesel by nature is fuel injected but it was a mechanical system back then.  85 was the same deal. 

86 the diesel was gone and the new transverse FWD full size cars were in full production so the 'old' RWD car became the Brougham and got the computerized Quadrajet.   That stayed through 90 when they came up with the towing package which was basically the 5.7 chev truck motor that more or less had the DEFI system on it.   91-93 they were all the DEFI like either 5.0 or 5.7 truck motor. 94-96 was the LT1 Corvette motor.   

The other cars 86-90 stayed with the DEFI either HT4100 or 4.5 except for Allante that got a different intake and multiport fuel injection.  Allante kept its own system till 93 when it got the Northstar.   90 the other cars got a sequential multiport system on the 4.5 and then on the 4.9 that went 91-95.

I think most of the Cimmarons were EFI and I assume included the Cadillac OBD via the climate control but I'm too lazy to go make sure that was available every year.   The few I tangled with all had both the climate control and EFI.  Guessing no one is really shopping for one at the moment.   

[Eric DeVirgilis CLC# 8621]

OP interested in Tri7 models which refers to 77-78-79 DeVille/Brougham models w/425 engine. Unless equipped with FI, these were essentially computer free. This remained the case on the 1980 DeVille/Brougham models with 6.0 Liter 4 bbl. CA version of these models got a computer controlled emission system of sorts which also had a "Check Engine" dash light. No check engine light on the "49 state" cars.

FI option was discontinued in the 1980 RWD models but it was standard with Eldorado/Seville equipped with 6.0 Liter. I would say 1980 was the first "real" year for ECM which featured on-board diagnostics; the earlier FI cars (optionally available beginning in 1975) had a more primitive analog computer (which did not have on-board diagnostics) so I'll leave it up to individual interpretation as to which year qualifies - 1975 or 1980.

[35-709]

Referring to the Q-Jet ---

According to Wikipedia (which admits there may be some verification issues) ---
"Its last application was on the 1990 Oldsmobile 307 V8 engine, which was last used in the Cadillac Brougham and full size station wagons made by Chevrolet, Pontiac, Oldsmobile, and Buick."

[TJ Hopland]

I would agree with that.   I had several wagons in that era and was amazed when I bought the 90 to see it had a carb and that the Caprice wagon had an Olds engine in it when the sedan had an EFI chev.  Those last few years the differences between the brands had to be the emblems.

Trucks used them through 86.    The E bodies (toro riv) through 85.   G body (cutlass regal monte) I think was 86 or 87.   I'm not sure about some of the sort of odd cars like the Canada built Parisienne in the mid 80's.   I also think there may have been some of the joint projects like Geo and Isuzu that ran carbs pretty late but I don't think they were Rochester. 

There were very few transverse engine cars with carbs.  I think the 4cylinder were always EFI but very early 80's the first little V6's had carbs.     

[Gene Beaird]

Aren't the plastic bumper extensions also kind of fragile on those models? 

[Eric DeVirgilis CLC# 8621]

Aren't the plastic bumper extensions also kind of fragile on those models?

With age and/or exposure to sun/heat - yes.