HT4100 FAIL!

[TJ Hopland]

Hate to keep getting off topic somewhat but got the day off so what the heck....

People seem to forget that many aluminum or aluminum/steel motors have had or still have all these issues.  The 4100 was just out several years before most of the rest.  If it would have come out in 91 I bet no one would have noticed or though it was anything unusual.  I do think that being out a little ahead of schedule and being put in the big cars that were designed in the 70's did not help.  Every catastrophic failure I saw or heard about either back then or even now all were showing signs of an issue that was ignored.  Back in the old cast iron overbuilt days if the temp light came on you were usually alright to go far enough to get off the busy road.  You then popped the hood and let her cool down while you found some water.  You dumped it in and took the side streets home or to your mechanic.  9 times out of 10 things did not get any worse.   Its just not that way with aluminum, you have to shut em down as soon as possible and figure out what happened.  Aluminum seems to be much like other modern things like computers, they work great right up to the point they fail.   

[Ohio57-62Sedan]

Right on TJ.....  and they are expensive buggers to fix too...   

[Rusty Shepherd CLC 6397]

The HT4100 was ahead of the majority of aluminum engines, but it was far from the first..even for GM. The 1961-1963 215 Oldsmobile/Buick V-8 was the first and it gave quite a bit of trouble to GM before Rover bought the rights to it.  My first car was a '63 Buick Skylark which I bought from the original owner with about 60,000 miles on it and it tended to overheat in traffic with the AC on as did most of them.  Following that was the Vega engine with its linerless cylinders and Chrysler and AMC both built aluminum block versions of their sixes during the sixties. So it seems to me that 21 years after the 215, the HT4100 should have been a much better engine than it was.

[Ohio57-62Sedan]

The HT4100 was ahead of the majority of aluminum engines, but it was far from the first..even for GM. The 1961-1963 215 Oldsmobile/Buick V-8 was the first and it gave quite a bit of trouble to GM before Rover bought the rights to it.  My first car was a '63 Buick Skylark which I bought from the original owner with about 60,000 miles on it and it tended to overheat in traffic with the AC on as did most of them.  Following that was the Vega engine with its linerless cylinders and Chrysler and AMC both built aluminum block versions of their sixes during the sixties. So it seems to me that 21 years after the 215, the HT4100 should have been a much better engine than it was.

Awww They were better... if the owners did not drive them into the ground.. 

[Walter Youshock]

Coming off a 30-plus year "high" of building the best, most balanced, tested and precise OHV engines, all the typical Cadillac owner was used to was basic oil changes, a new set of tires and brakes.  This was especially true of the 2-year cycle buyer.  If you bought a '76, then a '78, an '80 and traded that '80 on an '82, chances are, IF the '82 was still running properly, it was traded on an '84 Town Car.

The 4100's weren't all driven into the ground.  Most of them self-destructed with no warning at all.  Many did that with less than 50k on the odometers.

[Dave Shepherd]

Agreed, that is the bottom that some of us have " tried" to say. I was there!

[Walter Youshock]

So, what did YOU buy after the explosion?

At least the '82-'84's looked like a Cadillac.  Those FWD '85 DeVilles and Fleetwoods looked like they were made out of LEGOs.

[Johnny]

The 4100's weren't all driven into the ground.  Most of them self-destructed with no warning at all.  Many did that with less than 50k on the odometers.

Everything I have read, and its been a lot, says that the engines fail between the 40k and 60k range.

[Ohio57-62Sedan]

Honeatley Guy's if the Oil was changed every 2500 to 3000 miles and not beat on serviced vy a good tech.. they are a fine motor...
quit beating a dead horse...

[Owen Nacker]

 I hope you've changed the oil and coolant! 

 Mike

[Walter Youshock]

"You don't have to pamper a Cadillac.  A Cadillac pampers YOU!"  was an ad slogan in the early '70's.

Cadillac owners were not used to, nor did they make such an investment in a car that they had to leave at the dealer.  Furthermore, that engine was simply too small for the car.  If you went from a 7-liter 425 to 250 4.1-liter, you HAD to pound the crap out of it to get the same performance.  Maybe if it had been a 5 or 5.5, it would have been adequate for the demands of both the car and the driver.  It may have worked in the FWD '85 DeVilles, but not the RWD land yachts.  Chevy, Pontiac, Olds and Buick had no trouble in the early '80's--just Cadillac!

ALL Cadillac engines up to that point were indestructible.  It was Cadillac's downfall of mechanical superiority.  Cracked dash pads, armrests and steering wheels were a nuisance, but blown engines--inexcusable!

Sadly, they were standard equipment in some of the most beautiful cars Cadillac built--and the ones from MY youth.

[Ohio57-62Sedan]

I would own a 93 Coupe  I really like the Special red with white leather interor w/white quarter top moonroof. Bose gold series CD player....  4.9 W/T60E trans... so if you know where I can find one I would prefer a low mile blown up verson of this car...LOL

[Owen Nacker]

 I do believe the original intent of the HT4100 was that it was to be installed in the lighter FWD cars that came out in '85 right from the start. These cars were delayed a year, so it would have been '84 for the intended introduction. Also, the 368 was not a fuel miser, and the HT4100 was, so with the new CAFE regulations that were beginning to take effect, and fuel miser engine was a good thing. So the engine was introduced even sooner that anticipated. Perhaps another year of development would have benefited the engine.

 Also given the specific output of engines of the era, the initial 125HP, then 135 was not out of line. An engine that gave 150 hp was considered powerful then, and that was from a much larger engine.

 The 80's was generally considered a bad time for all automakers. Quality was off everywhere, engines had low performance and there were just a lot of bad cars out there. But GM had more good cars than anyone. Electronic engine controls were in their infancy still, but would prove to be the technology that would bring these engines out of the dark ages. Cadillac was at the forefront of this having introduced the first digital self diagnosing system ever. It was and is one of the most significant breakthroughs ever for the internal combustion engine. If this engine were equipped with a carb, I would be sure power would be down even more. Engines of similar displacement were lucky to break the 100 hp barrier in that era.

 But over the years this engine, and others that were developed from it, turned out to be pretty much bullet proof in the Cadillac tradition. The 4.9 is an incredible engine. It has a long flat torque band that is the envy of any engine builder, makes plenty of power and is very economical on gas. I would prefer a 4.9 over a Northstar in an equivalent car anyday.

 Mike

[Walter Youshock]

All great points, Mike.

I agree that it was brought out too early.  The 368 was very adequate for the size cars they were building then, but the 4100 was just too small.  Size and untested reliability of the aluminum block/cast iron heads just threw insult to injury.

The onboard diagnostics, Fuel Data panel, Electronic Climate Control and Digital FI were all important advancements.  The real shame was when they put the 307 Olds in the '85 Broughams with a 4bbl carb.  Had those cars been fuel injected...

[Ohio57-62Sedan]

And just thing about it the almost had it perfected by 79 too...  I still have a couple EFI setup for the olds motor... and the factory breakout box too hahaha.... at least I know what Im getting into... 

[Walter Youshock]

The plan was to kill off the Brougham by the mid-80's.  Part of the problem was that the '85's weren't as well received as the '77 downsize, so the Brougham not only continued, its sales increased.  By '87, they had cut back on the standard features so much that they were really just '84 SDV's.  Vanity mirrors, reading lamps, power passenger seats were options.  Still couldn't kill it, though.

[76eldo]

I know a few people that bought Eldos and Sevilles new during the HT4100 era.  They never bought another Cadillac after experiencing that.

My brother had an 82 Eldorado that he bought from a Cadillac dealer in 84.  It was a beautiful car, I don't remember the mileage, but it was low for a 2 year old car.

It was always serviced at the dealership since new, and the manifold leaked coolant into the motor.  They gave him a decent trade on a brand new 86 FWD Coupe Deville, which I never liked as much as the Eldorado.

It leaked oil like a pig at 50,000 miles, so he bought a Lincoln LSC coupe.  They guy he sold the Caddy to called him after 2 days and said the car died, his mechanic said it was the gear on the back of the cam that drives the distributor, and he was very upset.

By the time they made the cars bigger in 89, and went with the 4.5 and 4.9, you rarely heard about engine problems any more, but a lot of damage had been done.  First, by the 4100, then by the reduced size of the DeVille line.  Then they made the Seville and Eldorado into cars that were too small for their target market.

If they didn't come up with the Eldorado and Seville with the Northstars in 92/93, Cadillac would have been sunk.  They were nice looking cars, great performance, advanced electronics, and had an international flair that people loved.  They were great cars.

They are still making great cars, but the 4100 was a bad design, crated ill will, and lost them a lot of customers forever, in my opinion.

Brian

[Owen Nacker]

 In 1986 the Fleetwood was decontented. It kept all the same trim and interior equipment, but ALC, and some other features were made optional. But it still sold like hotcakes compared to years previous. It was a good money maker for Cadillac. The equipment level would return after a few years, though.

 The '85 was kept because of the protests and the high sales of the '84 when it became apparent that the Cadillacs would become smaller yet again. Generally the second wave of downsizing was not very well received but the cars went on to sell well enough to generate some good profits for all divisions. It was also quite uneconomical to produce a singular version of an engine for what was a relatively low production car. It was to be discontinued after the '85 model year but strong sales saved it. The '86 was re-engineered enough that it had a stronger frame and the car just seemed more solid and substantial than previous versions. The 307 was chosen because it was used in the B-cars already and was pretty much a drop in for GM. Also it was better suited with higher torque numbers genberated at a lower RPM than the HT4100. 240 vs 200. The '86 Fleetwood also got a much taller gear, 2.74:1 compared to the 3.23:1 in the HT4100 cars. In '87 it went to 2.93 where it stayed.

 A good running 307 is a good engine. It does generates more useable power than the HT4100 in the larger body. Also Olds enjoyed a reputation of building very good reliable engines. But they have to be kept in tune which can be a bit of a feat considering the jungle of hoses, wiring and sensors. It is no powerhouse, but it can move the car acceptably.

 The '89 Brougham I have was a mess when I got it. Lucky to get 12mpg and had absolutely no power. Bit by bit I got it where I'm getting 24mpg and it will cruise easily at 75 MPH.

 Mike

[Owen Nacker]

They are still making great cars, but the 4100 was a bad design, crated ill will, and lost them a lot of customers forever, in my opinion.

Brian

 I can't agree that it was a bad design. It had problems, but the overall design lasted through the 4.9 which proved the technology. It did lack development, though. Had it been properly developed from the outset we wouldn't be having any of these discussions.

 Also the way GM looked after many long time Cadillac owners, and many dealers share a lot of blame as well, did as much if not more damage than any engine problems caused. But GM did address each and every concern one by one until the engine was fixed. But by then the damage was done and many long time Cadillac owners were gone forever.

 Cadillac also PO'd a lot of owners in the 90's as well with leaky Northstars and unreliable electrical systems.

 Mike

[Johnny]

The plan was to kill off the Brougham by the mid-80's.  Part of the problem was that the '85's weren't as well received as the '77 downsize, so the Brougham not only continued, its sales increased.  By '87, they had cut back on the standard features so much that they were really just '84 SDV's.  Vanity mirrors, reading lamps, power passenger seats were options.  Still couldn't kill it, though.

In addition, Lincoln was going to continue with their full sized town cars, which was what luxury car buyers wanted back then.