AMC 304 Oil Pressure Issue

[Span24]

Thanks for all the helpful replies!

I changed the oil and filter (Castrol 20w50 and WIX 51258 filter). No immediate change to the tapping .

The more I research this, through forums and youtube vids the more I think that it is either a bad or clogged lifter or valve.

I pulled the valve cover off and looked things over. No obvious damage or loose components. Heads are post-73 so are pedestal and bridge type which eliminates any chance of adjustment. I guess I could ensure that they are properly torqued. 20 ft lbs?

Also, I read in several places that folks were adding a quart of ATF to their oil, running for 5 minutes, then changing the oil. In many cases it appeared to eliminate lifter tapping. Any thoughts on this practice, pro or con?

I really don't want to pull the head if I don't have to.

Michael

 

[Hedgehog]

I've used ATF in the past, but as I get older I'm less and less confident that it's a good idea. ATF works with the rubber in your engine, swelling it some to seal leaks and such. Some pople believes that ATF actually rots or destroys your engines rubber parts.

 

[Lumpy Grits]

Put a few miles on the new oil.
If no change. Drain out a qt of oil and add MMO.
Then put some miles on to let it work.
GOOD LUCK,
LG

 

[Hedgehog]

Often there is one more old school suggestion. "Drive it like you stole it!" Shake things up a bit at high RPM, don't blow it up, but for just a little bit run the snot out of it.

 

[Lumpy Grits]

Get it on a freeway for 50-75 miles and see what's, what.
LG

 

[steve1973]

Pull all your pushrods and check both ends. I have seen more than one where the rounded head is chipped off.


Sent from my iPhone using Tapatalk

 

[Span24]

Pull all your pushrods and check both ends. I have seen more than one where the rounded head is chipped off.

Thanks! Next time I pull the valve cover, I will.

 

[Span24]

Well, here is an update:

I have put about 50 miles on the jeep in two days with the same results. It taps loudly until it gets up to operating temperature then it is quiet. I can drive it as I please while it is at operating temp. Once it cools it taps nearly to the point of a knock.

Thoughts?

 

[mtnwhlr]

I would quit driving it until you find out whats wrong before you do serious damage to it. IMO

 

[Span24]

I would quit driving it until you find out whats wrong before you do serious damage to it. IMO

What do you think is more likely? lifter? rod? spun bearing? valve? Really, any of those could be noisy until the engine warms...

 

[steve1973]

My feeling is the noise is coming from the top end. A loose main bearing will be quiet when cold if you use thick oil as you have. They get ticking when warm. In my experiences. Others may feel differently.

 

[Fastatv]

Well, here is an update:

I have put about 50 miles on the jeep in two days with the same results. It taps loudly until it gets up to operating temperature then it is quiet. I can drive it as I please while it is at operating temp. Once it cools it taps nearly to the point of a knock.

Thoughts?

My son had a 3000 Gt that smoked a little when idling. To reduce or eliminate this smoke, we changed the oil, added one can of V8 Engine Restore, and one can of red CD oil treatment. This did reduce the smoking but...another thing happened that was unexpected. When his engine was cold, it had several lifters that would tap, and sometimes tapped when started up warm. The additives made the tap go away....even when starting the engine at 25 degrees outside, or 90 degrees outside. The tapping went away....and stayed away. My best guess is that the additives..mixed together, did a thorough cleaning of the lifters....and other things I imagine.

 

[Hedgehog]

Well now that's something different, a "knock" is typically bottom end. Time to get a littlemore serious before something happens to ruin your engine.

 

[Lumpy Grits]

Well now that's something different, a "knock" is typically bottom end. Time to get a littlemore serious before something happens to ruin your engine.

THIS-
My bet is a con-rod bearing or wrist pin is loose
LG

 

[Span24]

Well now that's something different, a "knock" is typically bottom end. Time to get a littlemore serious before something happens to ruin your engine.

'Knock' might be a little harsh. However, it does go away when the engine warms. Truthfully though, I cannot tell if it is top or bottom.

 

[Span24]

THIS-
My bet is a con-rod bearing or wrist pin is loose
LG

I don't see a loose wrist pin going away after warm-up? And really, when it stops, it just STOPS. Last tap, no fade...

 

[Hedgehog]

When your engine warms up metal parts expand tightening up tolerances. A cold engine might very well tick or have a light knock that will go away in a hot engine, that does not mean damage isn't being done.

When I ws young we had an older John Deere 110 lawn tractor. One day I started it up with a small tick I hadn't noticed before. When it the engine was idled up to mow the lawn the tick went away. 1/2 way throught our very BIG lawn the connecting rod let go destroying the engine. It would have been a big job pulling the engine and replacing the rod bearing, but a cheap fix. It was still a big job pulling the engine, but it was an expensive job putting in a new short block. Lesson learned.

 

[Span24]

Looks like, as much as I hate to, I'm gonna be dropping the pan and opening the valve covers back up.

Anyone know the torque values on rocker studs and end caps?

 

[mtnwhlr]

It should be easy to tell if it's coming from the top or bottem. When it's doing it do you hear it more with your head under the hood or with your head under the Jeep?

 

[Span24]

It should be easy to tell if it's coming from the top or bottem. When it's doing it do you hear it more with your head under the hood or with your head under the Jeep?

HAHAHA! My vote is TOP then...