Re: [Amc-list] noisy after rebuild

[Matt Haas <mhaas@xxxxxxx>]

Andy,

With 60 PSI cold oil pressure, you do not have bearing problems and 
tearing the engine down to inspect it is a waste of time and money. When 
hot, the oil pressure should drop down to about 12-15 PSI. The lifters 
making noise during start up for a few seconds is normal (if you have 
your owner's manual, it's mentioned in there). My 68 American does that 
every time after it sites over night and the 67 only does it every now 
and then (seems more frequent with the Fram filter that's on it now but 
that's what I get for not doing the oil change myself).

You said that there was no (or very little) oil getting to the rockers. 
Your noise is a chewed up rocker shaft and rockers (this is likely why 
your push rods don't rotate like they should). You can either buy a 
rebuilt assembly (new shaft and reconditioned rockers) or a new shaft 
and individual rockers. Lots of places carry these parts and prices vary 
wildly so shop around. You should also replace the push rods since the 
rocker end is likely chewed up on them as well. Also, the shaft rocker 
setup AMC used is very high friction and they wear out quickly. You can 
hear the rockers on my 67 American with the hood open and that shaft 
only has 44,000 miles on it.

You mentioned taking the rocker shaft bolts out with the engine running. 
There's a good chance you bent the shaft doing that but since it's bad 
anyway, it doesn't hurt anything.

Unless you live in a really hot climate, 15w40 is too thick of an oil. 
It will not hurt anything other than your gas mileage. I run full 
synthetic 10w30 in both of my Americans.

Also, the head bolt modification isn't needed if you keep up on oil 
changes. My 68 has it and the 67 doesn't and I don't think there's any 
noticeable difference in the oil volume. Make sure if you do that mod, 
that you round the machined part of the bolt down as specified in the 
page Frank S. pointed out or the head bolt may break.

Finally, as long as you have good oil pressure and the valves are 
getting oil, you are not going to hurt the engine running it with worn 
out rockers.

Matt

Andrew Blomer wrote:
> This relates to some discussions recently. This is on a 66 232 in a Classic
> 
> I just did a rering job along with a newly ground crank. I didn't change 
> the cam bearings, or cam. I did replace the lifters because I forgot 
> about them the first time I turned the engine over (physically) without 
> the head on. About half of them fell out and landed in the grimmy pan I 
> had under the engine stand.
> 
> It is all together and running now, but noisy. I have 60 psi oil 
> pressure at startup, and 45-50 when its warm. When I start it after 
> letting it sit overnight, I get very loud lifter/valvetrain type noises 
> for about 3 seconds, and then it quiets down. It is almost as loud as a 
> bearing type knock, but sounds like a valvetrain type sound. After that, 
> it sounds like a small Kabota deisel tractor. Kinda groully ticking. Oh 
> yeah, I did run the engine for 15 minutes to try to match the lifters to 
> the cam.
> 
> Thats what I have....so far what I have done...
> I removed the valve cover to listen and see if anything was wrong. The 
> rockers seemed a little dry so I removed the bolt where the oil comes 
> in, and found I had a partial clog. I cleaned that location out, along 
> with all the other bolt locations, in order, down the shaft to make sure 
> there wasn't another clog down the line. I did this while it was running 
> so the oil would push out whatever I got loose. When I was done, there 
> was plenty of oil up top, and the consistent noise had reduced some, but 
> not even close to what it should be.
> 
> Now I notice that the marks I put on the pushrods for reassembly are 
> spinning. All except for 3 of them at various unrelated locations. 2 are 
> spinning like tops (1 rev per second), and the rest are turning about 1 
> rev per 4-5 seconds. Concerning the 3 that arn't turning. If I turn one 
> (any) by hand about 90 degrees, it will rotate around at the 4-5 second 
> pace until it gets to its favorite spot and stop again.
> 
> My deduction.... I think the loud startup noise is from the old worn cam 
> bearings allowing the oil to drain down overnight. The lifters drain and 
> take a few seconds to pump up again. The quiter constant 
> clacking/ticking is from the new lifters not conforming to the old cam, 
> not rotating, and probably wearing down the cam lobe the more I run it.
> 
> The recent discussion content?... I broke it in with 15W40 rotela, and 
> had assembly lube on the cam. (new lifters, old cam)
> 
> Does anyone have any thoughts or suggestions? I just put this thing back 
> together and am not looking forward to taking it apart again.
> 
> I know this is long, but I wanted to get all the information I could out 
> there.
> 
> Thanks
> Andy
> 
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-- 
mhaas@xxxxxxx
Cincinnati, OH
http://www.mattsoldcars.com
1967 Rambler American wagon
1968 Rambler American sedan
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