Got mother's 1985 Fleetwood Brougham with HT4100
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HT4100 4.1, 4.5, 4.9 Discussion, Got mother's 1985 Fleetwood Brougham with HT4100 in Cadillac Engine Technical Discussion; just got mother's old fleetwood brougham out of a metal barn in arkansas. Brother drove it last ten years ago....he ...
  1. #1
    dhuberasu's Avatar
    dhuberasu is offline Cadillac Owners Member
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    Got mother's 1985 Fleetwood Brougham with HT4100

    just got mother's old fleetwood brougham out of a metal barn in arkansas. Brother drove it last ten years ago....he said that over about a 3 month period the car just continued to slow down...would only go 65....then 45.....then slower.... and then would just not start one day....

    Is this the camshaft failure I have read about....do the lobes just wear off...does it break....how severe is the damage left behind??

    thanks everyone
    david

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    ehall's Avatar
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    Re: Got mother's 1985 Fleetwood Brougham with HT4100

    The lobes wear down to nothing but the car usually keeps running, just with no power.

    It sounds more like fuel line blockage or something simple like that.

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    dhuberasu's Avatar
    dhuberasu is offline Cadillac Owners Member
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    Re: Got mother's 1985 Fleetwood Brougham with HT4100

    I was checking on another site and there was mention of the distributor gear wearing and the motor quitting....it is unbelievable the things that go wrong with this motor....guess there are oiling problems or too dense metals rubbing on pourous ones....thanks

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    carnut is online now Cadillac Owners Master
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    Re: Got mother's 1985 Fleetwood Brougham with HT4100

    Change the fuel filter, could be original? then have a muffler shop check for possible plugged cat. converter. What you describe sounds like one of these two, not an internal engine issue. Also, VERY IMPORTANT! change antifreeze and install the sealant pellets mentioned on the radiator crossbrace. If antifreeze is not changed every 2 years and sealant added you WILL have camshaft failure! Barsleak gold is the same as the GM pellets. Any GM dealer stocks the cooling system pellets. Any autoparts store should have Barsleak gold.

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    Re: Got mother's 1985 Fleetwood Brougham with HT4100

    Sounds like a plugged exhaust or fuel issue. My cat came disconnected a couple months back, had a test pipe installed and it missed/lack of power when accelerating. Changed the dist cap, rotor, wires, plugs, fuel filter, air filter, pcv valve. The fuel filter had undercoating on it, so it was probably the original one. The car (86 Seville w/ht4100, 46k miles) runs soooooo smooth now, and actually has decent power for what it is. I used delco parts, and would recommend the same.

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    Re: Got mother's 1985 Fleetwood Brougham with HT4100

    carnut: Would you explain the connection between pellets and camshaft failure? My guess is that without the pellets, water will slowly leak into the engine oil and will cause loss of oil film between lifters and camshaft. I had to replace the camshaft in my '86 Eldorado HT4100 at around 97,000 but never knew why its lobes were so worn. It now has 176,000 on it. I bought some pellets just a couple of days ago to put in there. I reckon I should change the anti-freeze and put the pellets in before it's too late.

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    carnut is online now Cadillac Owners Master
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    Re: Got mother's 1985 Fleetwood Brougham with HT4100

    You are correct. Coolant wipes away the oil film. The pellets are added at the factory to seal small leaks in an aluminum engine block. The gaskets eat away with lack of fresh coolant every 2 years. Its much like servicing a swimming pool! The PH level goes up with lack of maintenence. The coolant looses its additives over time.

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    ehall's Avatar
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    Re: Got mother's 1985 Fleetwood Brougham with HT4100

    The camshafts in the HT4100 used a soft metal that wore out very fast.

    The HT4100 also has problems with metal separation--the block and intake manifold are aluminum, but the heads are cast iron, so the head gasket and intake gaskets both undergo tremendous amounts of heat separation stress. The pellets can help slow down coolant pollution, but they will not stop it from happening.

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    Re: Got mother's 1985 Fleetwood Brougham with HT4100

    Interesing.

    You mentioned the camshafts were made of softer steel. By chance, were the replacement camshafts made with better materials? I bought the replacement camshaft and lifters at either OReillys or Advance at the time.

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    carnut is online now Cadillac Owners Master
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    Re: Got mother's 1985 Fleetwood Brougham with HT4100

    I dont entirely agree with ehal. The cam shaft is no softer than any other GM cam. Back in 91 Cadillac issued a bulletin regarding non GM cams being available and said that these "aftermarket" cams could possibly be "softer" or less reliable. It gave some pointers to identify these cams but only in relation to GM pieces. (Mainly a warranty payment concern). I would not worry. Assuming sealant is used, I dont believe they will wear out any sooner than any other engine's. Virtually all the cam failures I've seen have to do with coolant intrusion, not the cam itself failing on this engine.

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    ehall's Avatar
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    Re: Got mother's 1985 Fleetwood Brougham with HT4100

    Well I wasn't involved in production so I can't say 100% certainty, but

    http://www.popularhotrodding.com/fea...nes/index.html

    Cadillac HT 4100
    Standing for High Technology, the 249 cubic-inch V-8 was anything but. Through some bizarre thinking, the engine was an aluminum block with cast-iron cylinder heads. Developing less horsepower than some four-cylinder engines of the day, the Caddy was always working hard pushing around the behemoths that it resided in.

    The cylinder heads were fitted with very small oil drainbacks that were no larger than a pencil. This spelled disaster when teamed with excessively loose valve-stem-to-guide clearance. It was common for an HT 4100 to fill the valve covers with oil after the drain backs plugged. Then the oil would get sucked past the valve guides, creating not only excessive oil consumption, but carbon in the guide. This resulted in sticking valves. Another problem were soft camshaft cores that would wear to such an extent that the valves would hardly open. Amazingly, the engine would sit and idle at 400 rpm in drive as smooth as silk with the only driver complaint being a lack of power. After disassembly and inspection of the camshaft, one would never believe that an engine could idle so nicely with round lobes!
    Somebody else here said that GM confirmed that the factory camshaft was soft

  13. #12
    carnut is online now Cadillac Owners Master
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    Re: Got mother's 1985 Fleetwood Brougham with HT4100

    I was a assistant service Mgr with a Cadillac dealership when the 4100 was introduced. The reason I was told cast iron heads were used was because technology at the time couldn't produce an aluminum head that would wear the same with regards to valve guides or valve seats inexpensively. So rather than raise the cost of development cast iron was chosen. While I agree the design had major flaws, if the engine was religously maintained, frequent name brand oil changes and 2 year coolant change intervals, it would go 100,000 miles.

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    Re: Got mother's 1985 Fleetwood Brougham with HT4100

    carnut, Good point... I didn't take good care of my '86 Eldorado and it did make it to 97,000 when the camshaft failed. There were lots of other problems with the car during that 97,000 mile period (lots). But, the engine did OK. It has done well since a camshaft replacement until just recently at about 177,000 miles.

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