Oil Pressure Issues

ASSISTANCE Stock Engine-Bay Components
1

Ok guys maybe some of you may have some insight on the situation at hand. My brother has put together a GSR shortblock with B16 pr3 pistons (81.5mm) block was bored/honed.

An ITR crank was installed and ACL bearings were used in this build, they were all within spec both main/rod. So now the problem is we started it up, primed the engine with no spark plugs for some time. Then plugged everything back in, it started right up, i let it idle for some time got up to operating temp. It does have a light knocking noise and has a fluctuating idle due to a bad IACV, and when it drops down to 1k RPM the oil light will flash momentarily, now with that said we replaced the pressure sensor with a new one and no fix. So we decided to replace the entire oil pump.

We hooked up a mechanical oil pressure tester, it held 8psi at idle and 30psi at 3k RPM, shortly after it lost all oil pressure. So we shut it off. Now I currently have the oil pan off possibly looking for metal shavings or anything of the sort. But i’ve found nothing, i replaced the oil filter and nothing in there also. Oil pick screen is clear. Now one thing i noticed was the rod caps have some play between it (i retorqued them also) , if moved rapidly with your hand you can hear the knocking noise I hear when the engine is running.

Now when the bearings were installed he opted for the ACL due to it being an ITR crank instead of the original GSR one, and even though using a micrometer would have been the best choice he went with plastigage. Now is it possible that the rod caps being as loose as they are cause a loss in oil pressure? The bearings look to be wearing normally. Let me know what you guys think. Thanks in advance.

2

If you can wiggle the rods on the crank and you hear a knocking, that’s bad. you have the wrong size bearings on there. plastigauge is perfectly fine but that is a big problem. it may not be the only reason your oil pressure is weird but it shoudl be addressed immediately. you need to go get new bearings and have that crankshaft looked at immediately. you need to get some oversized bearings, acl sells them, and in fact i think i have a set in the garage. those should be snug enough to have NO play in them or you’re liable to spin a rod bearing. btw the 3k rpm oil pressure is about 30psi short of where it should be. at 3k i’m closer to 70psi on my gauge.

Where did you get the crankshaft? Had it been turned?

3

He purchased the ITR crank from a member on H-T some time ago, it did however have some markings which i thought were OEM, maybe you can tell me otherwise, here are a couple pics of the crank.


Thanks for the quick responses!

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it’s been machined. see those dimples. thats how they balance the crank. those look like machining marking to me, iv’e never seen an oem crank with those markings. take a caliper and measure the journals. get back to me and i’ll giv eyou the part numbers for the correct bearings if available. i have the charts in front of me now.