pgerst

Broke the rocker arm stud on the number 4 intake right where it bolts into the head (about half a thread showing on the stud, will require an e-z-out to remove remainder of the stud. Lucky its an easy one to get at.) Engine ran fine until...

The engine is stock with 117k on it with the exception of a fairly recently installed (appx 1000 miles) high volume oil pump. While well-maintained, it has been driven hard its whole life. At first I thought age/fatigue may have caused this but now I have this nagging in my head of maybe excessive oil pressure at the lifter? Getting about 65 - 70 psi at idle now, used to be about 30 psi. Is it possible that the additional 40 psi has affected the lifters enough to break the stud?

bw_hunter

No, the oil pressure isn't the cause. The oil pressure doen't equate into higher force at the rocker..if it did, you'd never be able to open the valve with it's spring pressures of 100 psi closed....even with the higher oil pressure you have. Additionally, people use solid lifters...that would be infinite pressure, right, and don't break rocker studs. Your first inclination...fatigue...is the most likely cause. Pull the broken one and replace all of them with a new set....I used ARP but there are others available.

pgerst

Was pretty sure I was thinking crazy thoughts; thanks for the logic.

David94TA

I broke a rocker arm stud when one of my lifters went bad.

pgerst

David94TA -- How do you think it happened? impact loading? I am thinking the lifter would not be pumped up and would slam into the push rod and into the rocker and snap.

David94TA

That's what I thought. I was just getting on it a bit and all of a sudden heard a clacking noise. When I pulled the valvecover off, there was the broken rocker arm stud. When I replaced the stud and was attempting to put everything back together, I saw that the pushrod wouldn't even come up to the rocker arm and I knew then that I had a bad lifter.

pgerst

Gracias. I will check that once I get the broken stud out and can put it back together.

rskrause

Take that HV pump offa there if you have a stock pan - that is a very bad combo. Do a search on it, please.

Rich

pgerst

Did not know about the oil starvation issue on stock pan. Since my oil pressure was so weak, I had previously plumbed an accusump into the oil cooler lines. Presumably this would re-solve the oil starvation issues if I re-installed it?

rskrause

If you need a HV oil pump to get acceptable oil pressure, there is a problem that you are masking but not fixing by using the HV pump. It's like running heavier oil in a worn motor, you see more pressure on the gauge but it's still worn out. Makes you feel better but nothing else. An Accusump will help momentarily if there is a sudden drop in oil pressure and potentially give you time to shut 'er down.

Rich

pgerst

Yes, 117,000 miles. Have been doing everything else on the car first (chassis, suspension, brakes -- next and last step before new engine is rebuild or replace 10 bolt rear). I had to replace the timing chain so put in the HV pump at that time as I had the pan off.