School of hard knocks
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HT4100 4.1, 4.5, 4.9 Discussion, School of hard knocks in Cadillac Engine Technical Discussion; ...
  1. #1
    83CADMAN's Avatar
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    Question School of hard knocks

    The saga continues.
    As I have posted in past threads, I have been chasing a hard knock or miss in my 83 Eldo that occurs when in gear and brake applied. My first thought was transmission problems, but it checked out to be in good shape.
    So I started messing with was the TPS…replaced & adjusted to specs.
    Then I fought with getting the ISC adjusted…replaced & adjusted to specs .
    Then it came to timing adjustment…at spec. a hard knock or miss with a pop out the TB persisted.
    With no codes displayed, I systematically began checking and replacing as necessary the following:
    Spark plugs…….replaced all 8. (#1 plug was fouled, the others were passable)
    Ignition cables….replaced
    Distributor cap…replaced
    Rotor…………...replaced
    Ignition module...tested good
    Pick-up coil…….replaced
    Sensors…………tested good
    Air filter………..replaced
    Fuel filter………replaced
    Vacuum………..replaced hoses, (no detectable leaks)
    Egr valve………functioning
    Fuel pump….…replaced
    Injectors.......tested good, (fuel pressure ok)
    Cat converter...functioning
    muffler........replaced

    Any ideas fellas?

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    daniel58 is offline Cadillac Owners Fanatic
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    Re: School of hard knocks

    I don't see O2 sensor, they can go bad with no code.

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    83CADMAN's Avatar
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    Re: School of hard knocks

    The o2 sensor was also replaced. The coil also tested good.
    Why would a failed or week O2 sensor cause ONLY the #1 spark plug to missfire and foul?

  5. #4
    aeronca36606 is offline Cadillac Owners Enthusiast
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    Re: School of hard knocks

    I would pop off the valve cover and make sure that the valves are opening and closing properly. These HT4100's are known for wiping cam lobes. They leak a small amount of water from the intake manifold into the valve lifter valley. Sludge builds up and starves some of the cam lobes of oil. This happened to me on an 85 Eldorado my father owned. The engine ran remarkably well and smooth while running down the road but had a lope when at idle. If the cam is bad enough, You can get backfiring through the throttle body. I hope this is not the case with yours.

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    83CADMAN's Avatar
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    Re: School of hard knocks

    Thanks for your Very interesting post, it reads very close to my situation.
    I wonder; Could the fact that the PCV, located in the valve cover near the #1 cylinder valve location, is drawing heated crankcase vapors to that end of the valve cover, contribute to lifter failure or worn cam lobe?
    Could the 2 lifters themselves be stuck (not completely pumping up) due to sludge/varnish?
    I’ve heard about stuck lifters getting unstuck before.
    What I've heard is; Pull valve cover, set cylinder in question to TDC, spray carb cleaner (or equivilent) down the push rod, let set to dissolve sludge/varnish at the lifter and then, (engine off) lightly tap on the rocker/push rod, carefully as not to bend the push rod. Restart and observe for the lifter to pump up, repeat.
    Anyone tried this?

  7. #6
    carnut is offline Cadillac Owners Master
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    Re: School of hard knocks

    Apply the brakes hard in gear ( sitting still ) and bring the engine RPM up and hold steady. If it pops thru the throttle body steadily, you most likely have a failed cam shaft. There is a remote chance that a rocker arm pivot is broken which would decrease the valve lift and act the same. With one cover off at a time, start the engine, you should see all the rockers pivoting the same amount. Most times once the cam fails the crankshaft bearings are pitted as well. Remove the oil filler cap, turn it over, is it dry and just have black residue on it or does it have a light chocolate milky residue? If its milky chocolate looking, you have coolant leaking past the intake gasket and it has ruined the cam. This engine has dissimilar metals (cast iron and aluminum) which can corrode the thin intake gasket under the coolant cross over passage allowing a perfect path for coolant into the lifter valley. This eventually occurs because people forget to change the antifreeze every 24 months regardless of miles driven.

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    Re: School of hard knocks

    Thanks for the insight; I just wish I had received it sooner.
    Re: http://www.cadillacforums.com/forums...ing-funny.html and http://www.cadillacforums.com/forums...nect-tach.html
    Out of frustration I recently took the car to a local shop to have them try to tune/adjust hoping to resolve the misfire condition. After fiddling with what I put my hands on and $230.00 later the news was #1 intake and exhaust valve rockers were just quivering rather than moving the way they should. Their diagnosis; flat cam lobes.
    They did get the car to idle without replacing any parts through. I had it adjusted pretty close.

    I’ve got the car home and in my shop now and plan to do the camshaft replacement my self.
    Is it wise to replace only the cam/lifter/timing gear & chain?
    Parts are only $300.00 and the work can be performed with the engine in the car.
    Any tips?
    I do not want to pull heads or touch the bottom end; If the engine must come out I would rather go with a replacement or used long block, if I can find one.
    I’ve heard that the HT4100 crank & bearings are a matched, color-coded set and reground crankshafts are discouraged. Is this true?

  9. #8
    aeronca36606 is offline Cadillac Owners Enthusiast
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    Re: School of hard knocks

    I would recommend that you get an accurate Oil pressure reading with a mechanical gauge with the engine hot. The cam bearings are critical to keeping good Oil pressure on these engines. If the pressure is low, You may have worn cam bearings. (Bear in mind that these engines idle hot with less than 10psi when worn in. These are not replaceable without specialised tools. You may also want to get an oil analysis done looking for Coolant in the oil. This can come from 2 places. A failing intake manifold gasket. (There is a reseal kit recommended by a GM PSP to solve this problem) It can also be from a failed O-Ring seal on one of the Cylinders. (Most of the time it is from the intake) Coolant in the oil can be the cause of your worn cam lobes.

    Pay attention to the condition of the cam bearing surfaces when you remove the cam.

    The timing chain will last a long time as long as both sprockets are steel. Of course they are not expensive and therefore can be replaced out of course.

    If the rest of the car is in good shape and you are doing it yourself, Then i say go for it! $300 isn't a lot of money if all else is good and you like the car!

    The rings and liners last a long time and the bottom end will also last as long as the oil is kept clean and fresh. (By the way regrinding the crank is perfectly ok as long as it is kept to 10 thousandths. The rod journals oil drilling's can become a problem with 20 thousandths or more. The colour coding of the main bearings is for oversized replacement bearings. (To stop main bearing thump) As long as the machine shop measures the new installed main bearings and grinds the crankshaft to maintain correct clearances, Than all will work OK.

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    83CADMAN's Avatar
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    Re: School of hard knocks

    Good info!
    I’ve got no engine rod thump as you put it, oil & coolant has been kept up to snuff and there is absolutely no trace of coolant in the oil.
    I think I’m going to run a compression test before I make any more decisions.
    Under Camshaft removal in my books it mentions that one might be able to un-bolt and move aside the A/C condenser with out evacuating the A/C system. Any one tried this?
    Everything else is straightforward, and since I replaced the water pump already I’ve acquired the right pulley puller for the job.
    Photos of the car are posted in my album.

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    Re: School of hard knocks

    I’ve managed to get the 83 Eldo’s HT4100 engine torn down some. The objective; Replacement of the cam shaft and lifters.
    So far everything has come apart with out mishap. Took some pics along the way.
    The underside of the valve covers showed no trace of milky oil and the lifter valley looked clean as well, just a light brownish film.
    I was reading the procedures how to pull the “Balancer Hub” off of the crankshaft. Removal should be no problem but reassembly it states “requires a special tool”.
    Can anyone enlighten me as to what tool I need?
    Is it the same install tool used on the power steering pump pulley?
    I greatly appreciate any input.
    83 Eldo camshaft teardown (37).jpg
    Left Side
    83 Eldo camshaft teardown (38).jpg
    Right Side
    83 Eldo camshaft teardown phase two 001.jpg
    Lifter Valley
    83 Eldo camshaft teardown (39).jpg
    Distributor Gear
    Any observations?

  12. #11
    carnut is offline Cadillac Owners Master
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    Re: School of hard knocks

    When we replaced an engine the install kit always included a new drive gear for the distributor. Not because they assumed it was worn out, but because of premature wear with a new cam.

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    83CADMAN's Avatar
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    Re: School of hard knocks

    Thanks carnut for the advice, I'll add distributor drive gear to my list.
    A little more pressing is:
    Quote Originally Posted by 83CADMAN View Post
    I was reading the procedures how to pull the “Balancer Hub” off of the crankshaft. Removal should be no problem but reassembly it states “requires a special tool”.
    Can anyone enlighten me as to what tool I need?
    Is it the same install tool used on the power steering pump pulley?

  14. #13
    83CADMAN's Avatar
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    Re: School of hard knocks

    Pulled the lifters and camshaft this morning, went very well. I used a 3' length of threaded rod as an asist.
    check out the pics of the lifters at #1 cylnder and the camahsft lobes at #1.
    83 Eldo camshaft teardown phase three 002.jpg83 Eldo camshaft teardown phase three 003.jpg
    The brng jornals look very good as well. Off to the parts store.

  15. #14
    83CADMAN's Avatar
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    Re: School of hard knocks

    The new cam and lifter set installed!
    While installing the water pump through, one of the 3 studs spot-welded to the timing cover failed. A trip to the salvage yard and wala, replacement timing cover.
    Everything is together now and it starts, runs good for a about 3 minutes then stalls.
    I haven’t been able to keep it running long enough to get it to operating temp.
    Sooo….back to f*%#ing around with the TPS / ISC adjustments.

  16. #15
    83CADMAN's Avatar
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    Re: School of hard knocks

    Damnit! I've got coolant puddling on top of the timing gear housing.
    I suspect the O-rings at the thermostat housing are seeping.
    I'm gona try to remove it without pulling belts, fan, pulleys and waterpump and apply some sealant to the rings.
    Anyone had to deal with this situation and has some tips?
    Thanks

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