No oil to rockers... Please help!

pfabricy

Here's a quick and dirty history of this 304 that has no oil coming out of the push rods. Given to me by a friend and said that it sat in a field for 10+ years but it ran great. Got it home and pulled it apart and put new gaskets in it and inspected as well as cleaned it. I ran the motor for a few months and it seemed great. Then it started running rough. Did a compression check and it came out great. Found first two cam lobes in front of engine were worn off. I replaced the cam, lifters, rebuilt the oil pump, and put in new crank bearings. Just trying to bump up oil pressure. Engine runs great again. Ran it for a few months and it started running rough and it sounds like an egg beater. I have 40 to 60Lbs of oil pressure at all times. Did another compression check and all cylinders good. Pop off valve covers and the upper valvetrain is bone dry. Start up motor and notice that no oil is shooting out of the push rods. I have oil pressure. Crank must be getting oil or the engine would have seized by now. I suspect a blockage somewhere that is preventing oil from getting to the lifters. Any ideas where to look to find the blockage?

AMX69PHATTY

Are the Pushrod passages free & clear ?

pfabricy

Yes. I cleaned them extremely well. Flushed them with brake clean until they flowed clean. Lifters are very noisy and go flat quickly with RPM. Engine acts like I floated the valves and flatened the lifters when run it hard. I suspect the lifters are getting little or no oil.

CJim7

This is the same issue i've been dealing with for the past month or so. Good oil pressure, lifters getting oil, and yet, dry valvetrain resulting in replacement of pushrods, rockers, and pivots. I finally bit the bullet and replaced all the lifters...but i couldnt see a problem with any of them. None were collapsed. Anyway, it ran good for about a week this time and i have some sort of noise again. :roll: granted, i havent pulled a valve cover to check oiling, but it just sounds like a lifter issue all over again. Maybe i have a bad cam. :(:

pfabricy

What about bad cam bearings? I've read that they are an intregal part of getting oil to the top end. I did not replace mine since they such a pain in the ass and since the cam rotates at half the speed of the engine. Engine runs nice when it's cold. Soon as it warms up it starts clicking. Push the motor hard and it sounds like an egg beater and runs rough. When it's in it's foulest running condition it reminds me of my old drag racing days if I missed a shift and pushed all the oil out of the lifters. The engine just stumbled along until the lifters filled with oil again.

pfabricy

What I'm reading in my Chevy SB engine rebuilding manual is that under the cam bearings is a small groove that allows oil to flow to the lifters. They mention that if there's been a lot of dirt in the engine then they get clogged. The mention that if you round off a lob(which I did) then there's a good chance they are clogged. I'm not sure what to do other than pull the engine and do a whole rebuild since I have to get the cam bearings out and make sure the passages are clean. :smile:

jeepsr4ever

Doesnt sound good! I would suspect a bad cam bearing most likely the first bearing. Did you say oil doesnt come out the passenger or drivers side? Could be a oil pump issue

runnamuck

pfabricy wrote
What I'm reading in my Chevy SB engine rebuilding manual is that under the cam bearings is a small groove that allows oil to flow to the lifters. They mention that if there's been a lot of dirt in the engine then they get clogged. The mention that if you round off a lob(which I did) then there's a good chance they are clogged.

I'm not sure what to do other than pull the engine and do a whole rebuild since I have to get the cam bearings out and make sure the passages are clean. :smile:

not the right book to judge a amc by. i think the problem is crappy lifters. there is only like two companies makeing lifters for all engines now, yes all engines, and i have ran into some bad metallergy in replacement lifters at work. same problem as descried but not as bad. other engines oil the bottom end first.

runnamuck

moreover, the majority or raw steel, well not in the ruff but stock, now is comming from india. pretty good engineers, horriable q.c. but its cheaper an usa steel. so cams are affected too. but if you got one or the other, better to replace both.

tufcj

Cam bearings (unless they're literally gone) shouldn't affect oil to the rockers on a AMC. The oil goes from the pump straight to the lifter galleys, then down to the cam and main bearings. That said, I have seen about 40% of the AMC engines I've rebuilt have damage to the cam bearings, particularly #4. The factory coating likes to flake off after high mileage. They've still made pressure, just lose maybe 15 PSI throughout the RPM range. Did you remove the galley plugs under the top cam gear during the rebuild? Is it possible they were put in too deep, they can block oil flow from the pump. Bob tufcj