Oil Pressure Too High?

[Walt]

So, I have a rebuilt bottom end I bought last fall. It was a complete engine that the original buyer backed out on and I just needed the bottom end.

Basics: balanced, 94mm 10:1 forged pistons, etc. Builder is local, has good reputation and alledgedly worked for Metric Mechanics years ago.

I broke it in easy, a week or so around town, jaunt from Seattle to SD for 'fest and still haven't tracked it or run it too hard. It has +/- 10k miles now.

He said he shimmed the oil pump for more pressure. I get >90# at 5000 on a warm engine, reaches 100# at 6000 and it's climbing. Could be seeing 120# at redline.

My mechanical gauge pick up is on the filter housing. We (builder and I) tested at the head and saw 50-75# with a test gauge. Same gauge showed the 90-100+ at the housing. He thought I should run lighter oil.

I replaced the housing with a non-cooler housing also tapped for p/u and readings are the same.

Fresh filter, Kendall 20-50. Same situation w/ straight 30w. Haven't tried w/ synthetic.

My old motor had a real MM oil pump and never saw >80-85#.

Is it agreed that 100# hot is too much?

Is there a pop off in the pump that may be stuck?

Should I swap that pump back in, and how much of a pain is pump R/R with the motor in?

Walt

[Velocewest]

That's too high. The pumps have a pressure relief. It's not uncommon for the piston to sieze in the pump body, causing overly high pressure.

R&Ring a pump is not too tough. Drop the pan, and I'd pull the radiator too just for elbow room.

[Walt]

Thanks VW. I thought so, didn't want to get half way and find out it was a no go.

Walt
ps, are you in W. OR? I'll be in Eugene tomorrow and PDX Thurs. eve and Fri.

[Velocewest]

I'm in Portland. I think we met at the Lucky Lab a few weeks ago.

[Walt]

you're right, Tony.

Sent a PM when I remembered.