Flat cam or bad lifter?
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HT4100 4.1, 4.5, 4.9 Discussion, Flat cam or bad lifter? in Cadillac Engine Technical Discussion; Hi all-- I have a 1985 Cadillac Deville with the 4.1L V8 and 36,000 original miles. I've owned the car ...
  1. #1
    awadecki is offline Cadillac Owners Enthusiast
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    Flat cam or bad lifter?

    Hi all--
    I have a 1985 Cadillac Deville with the 4.1L V8 and 36,000 original miles. I've owned the car since 30,000, and it has been VERY reliable, but I've had one problem since I bought the car: it always felt a bit low on power.

    Well, the other day I removed both rocker arm covers in the hopes that my issue was sticky valves (I had ruled out fuel pressure, engine sensors, etc.--believe me, I've been tinkering with the car every few hundred miles to see if I could remedy the issue). When I started the engine, I noticed that all valves on the firewall-facing 4 cylinders moved up and down fine, but one intake and one exhaust valve (on different cylinders) on the radiator-facing bank were hardly moving up and down at all, irrespective of the rpms.
    Here's my question: is this definitely a flattened camshaft, or could it be that I have 2 bad lifters? There is NO engine tick, although there is a noise somewhat akin to nearly inaudible (I have sensitive ears) valve float when I push the pedal down more than 1/2 way. The engine amazingly runs silenty, and quite well, except for a lack of power when I depress the accelerator more than 3/4 of the way down.

    A little history behind the car: I bought it for $400 with a blown intake gasket and cracked radiator (cooling fan relay broke, idiotic old man kept driving it around after it overheated). I put everything back together, and the car has run fine, but I obviously have some sort of mechanical problem. Regardless of the issue, the car has certainly served me well for $400 and 6,000 miles (1 year) of service--and it's still going strong, and my daily driver.

    I'd be inclined to say a camshaft if it weren't for the super low miles on the car, and the fact that I'm guessing some anti-freeze seeped into the lifters when the intake gasket blew, but then I'd hear a ticking, wouldn't I? Can anyone help me to identify what my exact problem is? The other strange thing is that the problem has gotten no worse (literally, none) in the 6,000 miles that I've owned the car. It actually runs much better now than when I bought it! How much longer can I expect the engine to last if it is a camshaft? Since the cam is hardened, if I keep good oil in it, could I feasibly drive it like this for 10,000 more miles or so? I currently have no backfiring.

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    awadecki is offline Cadillac Owners Enthusiast
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    Re: Flat cam or bad lifter?

    New thought...maybe I just have bent pushrods on the front side. My hypothesis: the intake gasket started leaking on the front side, causing the valve guides to get sticky, which then bent the pushrods. I think this is highly probably given the low miles on the engine and the fact that 3/8 valves on the front bank had issues, and NONE on the back bank did (where the underside of the rocker cover was visibly cleaner, and, presumably, less contaminated with coolant).

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    caddeville's Avatar
    caddeville is offline Cadillac Owners Enthusiast
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    Re: Flat cam or bad lifter?

    bent pushrods sounds like the problem if there isn't any noise. My lifters on my 4.1 have a sticky sounding tick, and my engine has ALOT of power, goes off the line very quick. My lifters start making noise when an oil change is necessary.

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    The Ape Man's Avatar
    The Ape Man is offline Cadillac Owners Connoisseur
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    Re: Flat cam or bad lifter?

    Bent pushrods would most likely result in an audible valve tap. The cam and lifters will have to be replaced as a pair. If the lifters were where most of the wear occured, the cam would have some also. The lobe on the cam is crowned off center to make the lifter rotate. It only takes a little to wear the crown off. Typical of an engine whose oil contained some coolant..

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    carnut is offline Cadillac Owners Master
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    Re: Flat cam or bad lifter?

    It has a flat cam!! Will it run like this for 10,000 more miles? yes assuming good oil is used. The cam flattens, then the lifter drops down lower and fills up with more engine oil so no lifter noise will be present! To verify a backfire, you would power brake the car and usually it will backfire thru the throttle body if the cam is flat. The engine will idle very smoothly because the compression is not affected. To power brake, simply apply very hard foot pressure to the brake pedal with the left foot, then, in gear, apply slow gradual pressure to the gas pedal. At about half throttle it will probably back fire! POP, POP, POP. When coolant enters the oil it wipes oil off the cam lobe and it flattens very quickly.

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    awadecki is offline Cadillac Owners Enthusiast
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    Re: Flat cam or bad lifter?

    Thanks...I'm just deciding what to do. So far, the cheapest price for labor on the repair is $600 from a guy who is an ASE master mechanic at a local Cadillac dealer. He'd do it at his house (he has a hoist and everything...has 25+ yrs experience servicing Cadillac engines and transmissions). With parts (camshaft, lifters, dist. gear, gaskets, etc.), it'd be about $850. A normal shop would charge about $1500 total for the job.

    I'd have it done, but I only paid $400 for the car, put about $250 into it, and have already gotten 1 year and 6,000 miles out of it, and, presumably, can get at least another year without putting more than general maintenance into it. Plus, it's not really going to hurt it if I continue driving it, as both valves that are failing to open are intake valves--what can't get in, can't hurt the engine. So, I can drive it until it dies, or buy another 1985 or similar Deville.

    They're just so cheap to buy--they only cost about $1500-2000 for a near-new car--that I can't rationalize spending $800 on a car that has already paid for itself. Plus, it has always had a transmission pump whine that worries me, so if I fixed the engine, and the trans went out, that would be a waste.

    That being said, the car drives still drives very nicely, and I love it, so it's tough not to fix it.

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    Re: Flat cam or bad lifter?

    You will be very hard pressed to find another with 36k miles. If the rest of the car is in good condition then $1k is as good as you will get for the quality.

    On the other hand, having the tranny fall out immediately after would also suck.

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    Re: Flat cam or bad lifter?

    Problem. Your engine trouble is a symptom of another failure. That problem is most likely engine coolant getting mixed with engine oil and rendering lubrication of the camshaft/lifters ineffective. Replacing the broken parts is fixing the symptom but not addressing the cause. Camshafts don't wear out at 31K unless there is something very wrong with lubrication.
    I've seen information from a few people who suggest that intake manifold leaks can be the source of coolant leaks into engine oil with these engines. If so you might be OK as the intake has to come off to replace the cam. I'd keep a REAL close eye on coolant loss afterwards and make sure you use the magic pellets.

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    awadecki is offline Cadillac Owners Enthusiast
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    Re: Flat cam or bad lifter?

    When I bought the car the intake gasket was leaking, and the previous owner was still driving it...hence the cam wear. I corrected that leak, but it was too late. Nonetheless, I'm still driving the car around. Only paid $400 for it, have about $800 into it, and I've already driven it 7,500 miles (just went from Detroit to Memphis and back with no problems at all). It has paid for itself. I'd still like to have it fixed if I can find someone who will do it for a reasonable price. I'm not going to put $1200 into a $400 car.

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    awadecki is offline Cadillac Owners Enthusiast
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    Re: Flat cam or bad lifter?

    I decided to have my car fixed. Found a guy who works at a Cadillac dealer and does work out of his house. He's doing the entire job for $600 labor.

    I went over to his house today to take a look at the cam and lifters. I think that there might have been 1 good lifter out of 16, and at least 6 or 7 lobes worn down on the cam. I can't wait for him to get the motor back together and take it out for a spin! It'll feel like a Corvette! Well, not quite, but maybe a 1975 Corvette (back when they were only 145 hp).

  12. #11
    cadillac_tech is offline Cadillac Owners Fanatic
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    Re: Flat cam or bad lifter?

    I know every tech operates differently, but I haven't known one who'd do that repair. The coolant mixed with oil caused the wear as mentioned above. How many other parts do you think were compromised from the lack of lubrication?
    It may run great with a new cam and lifters, but be prepared for a lack of oil pressure since the bearings are all worn. Just my thoughts.

  13. #12
    awadecki is offline Cadillac Owners Enthusiast
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    Re: Flat cam or bad lifter?

    Crank, all main bearings, and the oil pump were already replaced after the intake gasket blew. For some reason, they idiotically didn't replace the cam, though, so I should be good

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