AMC 304 Oil Pressure Issue

[mtnwhlr]

Then thats where I would start.

 

[Lumpy Grits]

I don't see a loose wrist pin going away after warm-up?

I have-
One way to maybe find the cyl where this is.
Pull, one at a time and replace-A spark plug wire and see how much worst the knock gets.
Old fart way to find'n a bad con-rod bearing.
LG

 

[Span24]

I have-
One way to maybe find the cyl where this is.
Pull, one at a time and replace-A spark plug wire and see how much worst the knock gets.
Old fart way to find'n a bad con-rod bearing.
LG

Did that already. No change noted. And, YES, I AM an 'Old Fart'!

 

[Lumpy Grits]

Did that already. No change noted. And, YES, I AM an 'Old Fart'!

Good to hear on both counts
Take one valve cover off at a time.
Start engine-Push down on each rocker(push rod side)and see what happens.
You can also squirt some gear oil down each push rod and on each rocker-arm, see if there is any change.
You may have a worn rocker--
LG

 

[zzzhopperzzz]

Hey Span24, I had a similar problem.. What I finally resolved was weak valve springs and oil residue! The previous owner had obviously used an oil that was high in paraffin. Some oil companies use it to raise viscosity, but it leaves a brown residue in the lifter bores (slowing the lifter speed).. If your dipstick has a brown residue on it, be suspect.. Also with any "heat" event, the valve springs weaken.. Then you'll have a "loss of contact" problem, hence the tapping.. I changed my valve springs,, was NOT costly at all, and it made it rev much better.. No more tapping.. I even changed the valve seals while at it.. After plug/rocker removal, just "float" the valves with a compression test hose hooked to an air source, (after hose valve removed), bump the edge of the valve retainer tops, compress tops with lever remover.. ect.. took about two hours..

 

[Span24]

Well, I pulled the valve cover. Ran the engine to see if I could find anything obvious (video to come later). I noted that nearly every rocker was tapping. Perhaps it just seemed that way because the cover was off? I pushed on the rockers as suggested and noted that nearly every one changed as I pressed on the pushrod side.

After shutdown I removed the rockers and pushrods, looked them over and observed the following:

1) No bent rods
2) No clogged rods
3) As someone here suggested, I did find a brown film on the rods which easily wiped away. At the time I considered it normal?
4) The aluminum bridges seem quite worn with visible grooves
5) No broken valve springs
6) No visibly broken lifters (looking down the bore)
7) Oiling was a little slow but started to flow as the engine warmed (about the time the tapping stops)
8) I did notice a dried blob of some black 'form-a-gasket' like material dried on the top of one of the rockers. This same material was used on the front of the intake mani (AAARGH!!, WHY DO PEOPLE USE THAT ?)
9) While running the engine with the cover off the rockers all chattered as if to be loose
10) Rocker bolts were properly torqued

My thoughts:

1) I'm a little concerned that my cold oil pressure is 75 PSI and warm is 55 PSI yet I get so little at the rocker oilers until it warms up (worn lifters? clogged oil passage?)
2) The tapping is ONLY on the right side. WHY?

Here are some pictures:



Thoughts?

 

[Span24]

Here is a link to the video:

79 AMC 304 Rocker Chatter - YouTube

 

[Span24]

Hey Span24, I had a similar problem.. What I finally resolved was weak valve springs and oil residue! The previous owner had obviously used an oil that was high in paraffin. Some oil companies use it to raise viscosity, but it leaves a brown residue in the lifter bores (slowing the lifter speed).. If your dipstick has a brown residue on it, be suspect.. Also with any "heat" event, the valve springs weaken.. Then you'll have a "loss of contact" problem, hence the tapping.. I changed my valve springs,, was NOT costly at all, and it made it rev much better.. No more tapping.. I even changed the valve seals while at it.. After plug/rocker removal, just "float" the valves with a compression test hose hooked to an air source, (after hose valve removed), bump the edge of the valve retainer tops, compress tops with lever remover.. ect.. took about two hours..

That certainly sounds like my problem. Was yours only on one side? Did I read that you changed valve springs without removing the heads? :drool:

 

[zzzhopperzzz]

Span, yep, you can change the springs without removing the heads.. Hearing that you found some silicon in the process, I would check the pickup on the oil pump to be sure it is not clogged with the stuff. Have seen that many times.. Can do through drain hole..
Spring replace process;
Remove spark plugs and the rockers, screw the compression hose into plug hole (after removing the "tire" valve in it). Plug into a compressed air line, the engine will sometimes rotate a small amount, normal. Tap the edge of the valve top retainers on the compressed cylinder. Then use a valve spring compressor lever to drop the top retainers. I use a magnet to remove the two small locks on the top of each valve stem. (small magnet on telescopic pen).. As long as the air is pouring into the cylinder via the plug hole, the valves will remain topside.. Do both intake and exhaust on "that" cylinder being sure the tiny locks seat after new spring/seal/top install, then move to the next one.. Takes about two hours..

 

[steve1973]

Is that your idle oil pressure? If so 55 is way to high at a warm idle. Try 5w-20.


Sent from my iPhone using Tapatalk

 

[Span24]

Time to close this thread with some final Thoughts:

Well here is what I did and what fixed my problem:

Ran 1 quart of ATF in Oil for 5 minutes then fresh oil & filter: NO CHANGE

Changed the oil to Castrol 20w50 & drove the hell out of it!: NO CHANGE

Inspect heads; valves, springs, caps, rockers, rocker bridges: NOTHING BAD

Inspect bottom end; piston skirts, caps, cam lobes,

Changed 16 Valve Springs: NO CHANGE

Changed 16 Lifters: NOISE IS GONE!!!, ...FIX!!

So, oil pressure is fine (after installing a mechanical gauge), and the problem with the clatter ended up being hydraulic lifters which had either failed or clogged, effectively becoming solid lifters which, as many of you may know, are noisy as hell!

So, here it is, she is running like a top, after about 6 hours of troubleshooting (including these forums), 12 hours of maintenance, $200 in parts and misc, and $45 to take my understanding wife out to dinner!

Thanks to all for your suggestions and assistance!

Hope this thread helps someone else!

 

[mtnwhlr]

I'm glad you got it fixed and even more glad that you closed out your thread with what you found and how you fixed it
I see to many threads started and never see how it ended.

 

[Torxhead]

Agreed.