Author Topic: 1985 Eldorado - HT4100 Engine Problems?  (Read 5853 times)

Offline xcaret

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Re: 1985 Eldorado - HT4100 Engine Problems?
« Reply #20 on: November 22, 2012, 11:36:21 AM »
The 80 v-8 368 eng was a problem for my mechanics here in Canada .We had a custom come in with some weird stuff going on and we failed to make sense of how to cure the problem so I phoned the local Cadillac dealer who told us there was no way to scan or diagnos the problems on that car , and they just replaced everything when a customer came in. After that I stayed away from them
 Also does anyone remember the guy who bought one new ( I think it was the 4-6-8 ) and the dealer wouldn't honor the warranty so he hoisted it with a crane 80 feet or so in the air above a cement block and called the newspapers and told them since GM wouldn'thonor the warranty he was going to drop it ,and he did. That was in L.A. as I recall.

Offline ericdev

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Re: 1985 Eldorado - HT4100 Engine Problems?
« Reply #21 on: November 22, 2012, 12:12:56 PM »
I tend to take stories (such as the LA example) with a grain of salt as there's usually more to the tale. I once read of a similar one involving a (new at the time) early '70s Lincoln Mark in which an unhappy owner set ablaze in front of Ford's Dearborn plant after numerous failed attempts by the dealer to remedy its ills. Seems like an awfully expensive way of making a point: Insurance typically does not cover willful damage by owner.

As to the 1980 example- are we talking about the FI 368 (Eldo & Seville) or 368 carburetor (DeVille/Brougham)?
« Last Edit: November 23, 2012, 11:08:51 AM by ericdev »
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Offline wrefakis

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Re: 1985 Eldorado - HT4100 Engine Problems?
« Reply #22 on: November 23, 2012, 07:07:17 AM »
Guys I was a dealer all those years,and owned a 1984 coupe bought new as a road car,these engines were SO BAD,that you had to sell them AS-IS at dealer auctions even if they were still under factory warranty,again AS-IS for all engine knocks.

JUNK,in 72,000 miles on my 84 coupe,I did more major repairs,than in the last 550,000 town car miles.

Yes I love 59 and 65-70 Cadis,but as a dealer and owner that had 100's of these cars they were sharp looking cars with an engine that was JUNK from day 1 !!!

Offline ericdev

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Re: 1985 Eldorado - HT4100 Engine Problems?
« Reply #23 on: November 23, 2012, 08:42:12 AM »
Back in the day the infamous 4100 helped bolster the value of the '80 model because if you wanted the newer style with a good reliable driveline, 1980 (and to a lesser extent, 1981) was your only option. I have a #2 '80 Coupe deVille with 22,000 miles and absolutely love it. 1977-1980 DeVille/Fleetwood were the best Cadillacs ever built from a standpoint of simplicity, comfort, usability and functionality- in my humble opinion.
« Last Edit: November 23, 2012, 11:07:39 AM by ericdev »
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Offline 76eldo

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Re: 1985 Eldorado - HT4100 Engine Problems?
« Reply #24 on: November 23, 2012, 08:50:57 AM »
1980 was a good year for sure.

I went crazy when I found this one and paid a lot to get it.

I also have other Eldo's and a Seville with the 4100.  If taken care of they can last, with some luck.

Brian
Brian Rachlin
Huntingdon Valley, Pa
CLC # 22443
Current collection:
1960 62 Series Convertible
1970 DeVille Convertible
1976 Eldorado Convertible
1980 Hess & Eisenhardt Eldorado Convertible
1981 Hess & Eisenhardt Eldorado Convertible
1985 Eldorado Biarritz Convertible
1985 Eldorado Touring Coupe Convertible
1984 Seville
1985 Seville
1999 Eldorado Touring Coupe

Offline 66 Eldo

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Re: 1985 Eldorado - HT4100 Engine Problems?
« Reply #25 on: November 23, 2012, 04:03:46 PM »
Being an ex auto wrecker and driving an 1982,1985 and 1983 Eldo in the past ,Plus parting a few out , the thing I noticed besides not a lot of power was when the eng started going bad you could often hear a dull thud,thud sound coming from the engine at an idle. Being that I was only selling them used for $600.00 I never thought of repairing one ,just sold them to the core eng buyer. My 83 and 85 started doing the same thing. As for the rest of the car I have no complaints   

Based on my experience,  these engines had problems through the 4.9 versions. I had a 92 Sedan DeVille 4.9 liter with about 70k miles when I bought it. It had that dull thud or knocking not at idle but at first start-up for a few seconds until the oil pressure got up. You could also make it knock under a light power brake anytime.  Engine main bearings was the problem and was confirmed by an independent Cadillac repair shop operated by an ex-Cadillac tech.  He said that the 4.1, 4.5 and 4.9 engines all had a technical service bulletin (TSB) addressing undersize main bearings installed from the factory. The fix was to install the proper size  bearings. He had a Cadillac issued tool to do this with the engine in the car by "fishing in" the upper bearings. When he told me the price for the job, I didn't even want to do the job myself. It was reasonable,  under $800, which also included a new updated oil pan (another TSB) which was less prone to leakage. This was in 2002. He also mentioned that if you do this bearing update, install the pellets for the cooling system and don't overheat these engines, they can last a very long time.

As a side note, my brother-in-law was the general manager for a Cadillac dealership in the 80s and 90s. He said he had a lot of trouble selling used Cadillac with the 4.1 liter engines and had an arrangement with the factory rep to warranty a Goodwrench engine for all his used Cadillacs that were out of warranty even if they showed no signs of problems. There was no way he could sell one without a fresh motor because the public was well aware of the 4.1's problems. This was not a factory approved deal but since the dealership was high volume status, they got taken care of.
« Last Edit: November 23, 2012, 04:06:28 PM by 66 Eldo »

Offline ericdev

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Re: 1985 Eldorado - HT4100 Engine Problems?
« Reply #26 on: November 23, 2012, 04:52:56 PM »
The 4.9 bearings would get noisy but they were surprisingly inexpensive to replace. Last time I had one done, the local ex-Cadillac tech charged me $400 for a 4.9 main bearing job. 4100s were a completely different motor to work on. 
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Offline Dave Shepherd

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Re: 1985 Eldorado - HT4100 Engine Problems?
« Reply #27 on: November 23, 2012, 06:48:31 PM »
The mains failed from the long crank snout and the resulting overtightening of the belts pulling the nose of the crank up wearing the front upper main.

Offline Guidematic

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Re: 1985 Eldorado - HT4100 Engine Problems?
« Reply #28 on: November 24, 2012, 09:33:34 AM »

 Main bearing knock was an issue with the 4.1, 4.5, and the 4.9. But it was an easy fix, and no special tools were required. This knock generally occured when the engine was at operating temperature and at idle in gear. Noise at startup would likely bec caused by something else, like oil drainback after shut off. I have performed this job many, many times. part of the procedure was to check clearances before the new inserts were installed. In every case the clearances were within spec. Then you rolled in #1 and #5 inserts, torqued the mains then rolled the engine over by hand to make sure they were not too tight. This fixed the problem in every case.

 Also, the 4.9 is of the same engine family as the 4.1 and 4.5. It is not a differant animal.

 I have spent some time thinking about this problem. I don't know if my theory is correct, but it makes sense to me. The block is aluminum, the bearing caps cast irion. Aluminum has a very differant expansion rate than cast iron, and hence expands to the point where the clearances can increase where the crank can float causing the knock when the cylinder closest to the bearing fires. Also, this was not generally regarded as a detriment to the durability of the engine. Bearings that I removed showed no excessive wear.

 Mike
1970 Fleetwood Brougham 68169
1985 Eldorado Coupe 6EL57
1988 Eldorado Biarritz 6EL57
1990 Brougham d'Elegance 6DW69
1994 Fleetwood Brougham 6DW69

Offline ericdev

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Re: 1985 Eldorado - HT4100 Engine Problems?
« Reply #29 on: November 24, 2012, 10:03:24 AM »
On a couple of 4100s I've owned, the thump-thump-thump would be heard only at idle with the engine fully warmed up. Shifting into gear would make it disappear. On others it was just the opposite. One good thing about the 4100 is that they never had the piston slap the 4.9 had when cold. I passed on a ton of 91-93s before I realized the racket they made when cold was normal.

 Although 4100/4.5/4.9 and even Northstar are genetically similar, I believe accessibility made the 4.9/4.5 bearings easier to replace. Not sure about 85-87 4100 (FWD). RWD was supposedly much more difficult. One thing I know for sure: I'd never be able to get RWD 4100 bearing job done for $400. Probably not a Northstar either but I've never had to have bottom end issues with N* to date.
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Offline Guidematic

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Re: 1985 Eldorado - HT4100 Engine Problems?
« Reply #30 on: November 26, 2012, 09:18:59 AM »

 Cold piston slap was an issue with the '91 4.9's. But is was never a concern for reliability or durability. I replaced many piston/sleeve assemblies under warranty and none showed any eveidence of even minor scuffing. I would not hesitate to buy one of these cars.

 The Northstar is a completly differant engine from the 4.X engines. They share nothing with them at all. The architecture and even the basic configuration is differant. The only thing they share with the 4.X engines is the aluminum in the block.

 Mike
1970 Fleetwood Brougham 68169
1985 Eldorado Coupe 6EL57
1988 Eldorado Biarritz 6EL57
1990 Brougham d'Elegance 6DW69
1994 Fleetwood Brougham 6DW69

Offline ericdev

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Re: 1985 Eldorado - HT4100 Engine Problems?
« Reply #31 on: November 26, 2012, 09:32:30 AM »
Yeah, it was a while before I realized the cold piston slap was normal and was not cause for concern. As I'm sure you're aware, a lot of other GM engines did it as well: The 3100/3400 V-6, 4.8/5.3/6.0 liter V-8 in GM trucks and others. I'll tell you, the noise of a cold 4.9 sure scared many customers off back in the day.

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Offline Guidematic

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Re: 1985 Eldorado - HT4100 Engine Problems?
« Reply #32 on: November 26, 2012, 10:10:20 AM »

 The Chevrolet 5.7 did that from day one as well. I have had several examples of this engine over the years, and they have all exhibited it to some degree. Both the LO5 in my '90 Brougham, and the LT1 in my '94 Fleetwood have it. Even the L-69 in my '76 Bel Air I had did it, and that engine was original and in excellent condition.

 It was also common for the Cadillac 500 to do this. I have heard several examples of it. The 500 in my '75 Coupe deVille did it from the day I got it. I had that car for 12 years and it never got any worse.

 Granted, it is a bit unnerving to have such a noise in your new Cadillac. But there is no cause for alarm. The noise often goes away after 20-30 seconds after cold start-up.

 Mike
1970 Fleetwood Brougham 68169
1985 Eldorado Coupe 6EL57
1988 Eldorado Biarritz 6EL57
1990 Brougham d'Elegance 6DW69
1994 Fleetwood Brougham 6DW69

Offline TJ Hopland

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Re: 1985 Eldorado - HT4100 Engine Problems?
« Reply #33 on: November 26, 2012, 10:11:12 AM »
So why did piston slap become such a problem in the 90's?

I was going to comment on the comparison between the Northstar and 4.x's.   They are V8's and say Cadillac on them but that is about all that is the same.  If the 4.x had an iron block it would have pretty much been the same as any other pushrod V engine.    The Northstar I dont think had any one feature that was that new or innovative but it was the first engine where someone had put a bunch of new and innovative all together on the same engine.  If I remember correctly its like a lot of engines now where there is a whole lower layer to the block that contains the main caps and most of the oil passages.   As far as I know that and a lot of other features that engine had is pretty much a standard design on most engines now. 
StPaul/Mpls, MN USA

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75 Eldo rusty but trusty
80 Eldo Diesel
And other assorted stuff I keep buying for some reason

Offline Guidematic

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Re: 1985 Eldorado - HT4100 Engine Problems?
« Reply #34 on: November 26, 2012, 10:53:06 AM »

 The 4.9 is really just the 4.5 with a longer stroke. To accomplish this, part of the piston skirt was removed to allow the piston to travel lower in the bore. Typically, that skirt prevents the piston from rocking back and forth in the bore. When the engine is cold, the clearances are such that some of this rocking can happen, leading to the nopist that we call piston slap.

 The tolerances can be tightened up, but that leaves precious clearance when the engine waqrms, and can actually become too tight causing scuffing on the skirt. This was an issue with the 1990 3.1 V-6. I replaced many entire engines under warranty for severe piston scuffing. The 2.8 from which it was derived already was prone to scuffing, and the tighter clearances exasperated the problem. Further versions of this engine, the 3.4, 3.5 and 3.9 are even more prone.

 As many of us know, the 500 is the same engine as the 472, just with a longer stroke. The only differance in the engine is the crankshaft and pistons. The pistons have an abbreviated skirt which can lead to cold piston slap as well.

 Mike
1970 Fleetwood Brougham 68169
1985 Eldorado Coupe 6EL57
1988 Eldorado Biarritz 6EL57
1990 Brougham d'Elegance 6DW69
1994 Fleetwood Brougham 6DW69

Offline ericdev

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Re: 1985 Eldorado - HT4100 Engine Problems?
« Reply #35 on: November 26, 2012, 12:52:11 PM »
Thank you for that detailed clarification Mike. Learned a few new things yet again.

*When referring to "customers being scared off" I should've explained this was in reference to selling 4.9s on my lot as used cars- not new. I kind of think the slap wasn't too pronounced on the 4.9 when they were new. Once I had gotten to understand the reason, I was in a better position to explain it to my customers and most were okay with it. But you can imagine how I'd cringe when a customer would insist on first lifting the hood before starting the car on a cold winter day! The engine sounded like it was falling apart for those first 30 seconds.  :o
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Offline Guidematic

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Re: 1985 Eldorado - HT4100 Engine Problems?
« Reply #36 on: November 27, 2012, 08:13:24 AM »

 Yes, they could be quite noisy on a cold day.

 When we diagnosed which cylinder was making the noise, we would have the customer leave the car overnight outside. We would go out in the morning and start the car. Shorting out individual cylinders with a test light would reveal the noisy ones. The noise woukld quit once you shorted out a noisy cylinder.

 Sometimes there would be more than one, and the engine would be quite noisy. I remember one particular customer that had several piston/liner assemblies replaced while the car was in warranty, some cylinders being replaced more than once.

 Mike
1970 Fleetwood Brougham 68169
1985 Eldorado Coupe 6EL57
1988 Eldorado Biarritz 6EL57
1990 Brougham d'Elegance 6DW69
1994 Fleetwood Brougham 6DW69

 



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