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'87 SDV
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Discussion Starter #1
The idea for this thread actually began in another one, but maybe it's worth carrying on to a fresh line discussion.

This HT-4100 owner is of the opinion that our little engine has gotten a bad rap. Yes, it's underpowered. Yes, it has design flaws. Yes, it's higher maintenance than Paris Hilton on a bad hair day. But doggone it - when it runs right - can anyone argue that this is not a sweet little powerplant? Mine runs so smooth and silky you almost have to step on the gas to make sure it's actually running. (I know, when you saw smooth and silky you thought I'd return to the Paris Hilton analogy, didn't you? Tsk tsk.)

As for long-term reliability, consider this random sample taken from eBay motors this morning. There are forty one HT-4100 equipped 1982-1987 vintage Cadillacs listed, 16 of which have from 100 to 200 thousand miles.
By contrast, there are only seven full size Buicks of the same vintage, one of which is a hearse. There are seven Lincolns, three full size Fords, three Chryslers, and one (You asked for it, You got it) Toyota Camry.

So how about a thread - maybe even a sticky thread - where those interested can post their HT 4100 success stories, instead of always posting whatever our current problems may be. All that negativity can be pretty discouraging to new members.

If you love your HT 4100, this is the place to say so! :xgrin:
 

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1992 Town Car Cartier & 2014 Accord LX MTX
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34,087 Posts
When I first heard the HT4100 in the '83 Eldorado Coupe in "Gone In 60 Seconds" I thought it had a cool smallblock V8 sound to it.
 

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1991 Deville / 1989 BMW 635csi
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896 Posts
My HT4100 has 152,000km (94,000 miles) on the clock and runs absolutely perfect with an exception of a lifter mallot knock when warm, no power loss and sounds sweet with a FLWOMASTER 40 series delta flow. My dads same HT4100 has 270,000km on the clock and the piston rings are starting to let go, no smocking or anything like that, just really bad on fuel, 10.5 MPG. It has served him well for the past 9 years with absolutely NO problems whatso ever. Just waterpump, fuel pump, radiator, and alternator. The tranny is original also. It still has tons of power and also has the same lifter mallot knock when warm. It had that knock for the past 9 years with oil changes every 2500miles (5000km). Anti-freeze hasn't been changed until last year, and coolant tabs have never been added until last year. We took 4 LOONNGG 5 hour uphill trips every summer with ABSOLUTELY NO QUESTIONS, we were going faster than anyone up the hill, including SUV's. The most reliable car my dad ever owned, and he owned almost everycar out there, mostly german till '97 (too long of a list). (we moved to canada in '97 from Ukraine:alchi: )
 

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1995 Sedan De Ville (4.9 L)
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581 Posts
I used to own a 1983 Eldorado with a HT4100 in it for about 5 years (1998 to 2003). When I bought it it had about 90k miles on it. When I gave it my friend's brother, I think I put about additional 65k miles or so, making the total of 155k miles. I have done a round trip from Albuquerque, NM to LA and SanDiego area, CA and another trip from Albuquerque to SanFrancisco to LA back to Albuqurque with no problem. Something was wrong in the engine so she was always running a bit rich and not with a lot of power (I even don't know how powerful it should have been), but she was running fairly fine.

I needed to replace the fuel pump right after I purchased her, the ignition coil (I think it must have been a rare case, but the coil developed open-circuit), the ignition module, alternator (the terminal stud broke off), and exhaust. But I have never experience the head gasket problem. In 2003, while I was driving on an interstate, the coolant temperature warning came on. The water pump broke and started leaking coolant. Unfortunately, the next exit was far away. I think I had to drive it for 20 miles or so at 40-45 mph without coolant. Just before I stopped the car, I started feeling a loss of power and light knocking. When I parked the car, the engine was hot and smoking. Well, next day, when I tried to start up, it started up right away! So, I decided to replace the waterpump and the car was fixed without any problem! I was quite amazed since I knew how bad the situation was. Since I bought a newer car (95 Sedan DeVille), I gave it to my friend's brother, but she was still running fine.
 

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Triple Yellow 88 Biarritz, 92 Allante, 05 STS
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My first car was an 1983 Cadillac Seville Elegante, two-tone silver & black and was in excellent shape when I got it-It was a one-owner estate sale car. It had 104k when I got it. I always changed the oil on time(2000 miles), and coolant every year with the tabs. The car ran as smooth as silk. I drove the car till 124,500 miles then gave it back to my dad. My dad had it until 145,000 miles, he didn't take as good care of it as I did to say the least!, rarely changed the oil and it still ran perfect(it was his beater, as bad as that sounds). We sold it aug of this year and I see the car driving around at least once a month, so I bet it has at least 150 on it now and still goin strong.

People complain about 4100's, but that last 4100 was made in 1987 making the youngest nearly 19 years old, and look how many are still on the roads.
 

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1992 Cadillac Sedan Deville
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175 Posts
My Grandma has an 82 Seville with 95,000 miles, the only problem it had with the 4100 was that it overheated due to a idiot leaving the radiator cap off at the Cadillac Dealership. Cadillac took full responsibility and replaced a bad main bearing. Car has been running fine since then. The only thing it has done was knock in really hot weather and that is even rare. The engine is a little sluggish in that heavy of a car but is very smooth, I believe it is smoother then the 4.9 in my Deville.
 

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2003 STS w/BoseNav, 1993 Deville, 1985 Deville
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My 1985 Deville had 238,000 miles when the waterpump had a catastrophic seal failure and let all the coolant go. This was under full throttle, middle of summer, going up a slight hill, airconditioner on, 80-85 mph. Engine overheated as a result. It still ran, so I took it to a local mechanic who did a pressure test on the cooling system. When he did so, air came out the exhaust - blown head gasket.

I didn't want to fix that engine so I gave it to a friend.

Up until then, it was purring like a kitten.
 

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70 Fleetwood, 87 and 90 Brougham, 94 Fleetwood
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215 Posts
I remember the first time I saw an HT4100powered car in the fall of 1981. I always wondered why Cadillac would put such a small engine in these cars, but this engine ran so smooth and quiet, I could not help to be impressed.

My parents now have a 1982 Fleetwood. It just had an engine replacement from a 1985 Seville, which was replaced with a targetmaster in the mid 90's. This engine will make a convert of anyone. It is smooth and quiet, And quite powerful. It will peel rubber from a stop. And it routinely gets mid 20's fuel economy in daily driving.

There was a guy in the local Cadillac club that had a 1983 Sedan deVille. This car at the time had over 350,000 km on it, and it still ran strong. His relatives were so impressed by the car that they went out and bough new Cadillacs, but they were Cateras. That immediately tarnished their image of Cadillac, and this poor fella was all of a sudden a black sheep in that family.

I also had a 1984 Coupe deVille. It had 124,000km on it when I bought it. I drove that car for 4 years and put on almost 60,000km on it. It always ran very strong and could get as much as 33 mpg on the highway. I eventually scrapped the car, the body was falling apart around the engine. I never touched the engine, save for replacing the rocker cover gaskets.

Mike
 

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1995 Sedan De Ville (4.9 L)
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581 Posts
Just for my curiosity...

What does "HT" means? I am sure that 4100 =4.1 liter or 4100 cubic centimeters, but HT??? Maybe it stands for High Technology??? Why 4.5 and 4.9 are not called that way? I remember on the door of my Eldorado said "DFI(=Digital Fuel Injection)". I am wondering why 4.5 and 4.9 don't say that proudly...??? Maybe most injectors are now digital and it is no longer a big deal?
 

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70 Fleetwood, 87 and 90 Brougham, 94 Fleetwood
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Yes, HT stands for "High Technology". Other acronyms, less friendly were "Have Two" "High Trouble" and "Have to Tow"

I think Cadillac tried to space themselved from any Identifier associated with HT4100 by simply calling it the 4.5.

I'll proudly call the engine (when finally finished) in my '85 Eldorado an HT4500.

Mike
 

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1987 D'Elegance 4.1L 1993 Eldo 4.9L 1993 STS 4.6L N* Z rated
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170 Posts
231,000 miles on mine, still going strong, knocks like hell and mis fires once and a while but what can ya expect. Its on its 5th transmission too. :suspect:
 

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85 Eldo Biarritz
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808 Posts
100:

this is way off topic - you shouldn't hijack a thread. Why not start a new thread - it is not *that* difficult...

No, knock sensors are only installed on Northstar engines.
Why there isn't one? I guess it is because knock sensors are newer technology which wasn't incorporated into the older HT engines. It is not just knock sensor - the entire computer (ECM or PCM) is totally redesigned.


Peteski
 

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1995 Sedan De Ville (4.9 L)
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Thanks for your advice.

You are right. I will be more thoughtful about your point...

How can my previous reply and your response be re-posted as a new thread? I suppose a user does not have such an authority to do so...

Oh well...

peteski said:
100:

this is way off topic - you shouldn't hijack a thread. Why not start a new thread - it is not *that* difficult...

No, knock sensors are only installed on Northstar engines.
Why there isn't one? I guess it is because knock sensors are newer technology which wasn't incorporated into the older HT engines. It is not just knock sensor - the entire computer (ECM or PCM) is totally redesigned.


Peteski
 

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1992 Town Car Cartier & 2014 Accord LX MTX
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I guess the HT4100 was pretty advanced for 1982
Kinda like the Northstar was in 1993 :)
 

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Had a 83 elorado with a HT4100 in it that dam car wouldnt stop ran till 426,000 miles and then i got rid of it and it was still running just fine and i gave that car hell the whole time i drove it loved it my favriot car..:)
 

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