Oil pressure in fresh rebuild...

[ferreed]

All,I just finished rebuilding my wife's KA24E in her '90 240sx. We broke the motor in, checked for leaks, and put about 200 miles on it and it's doing great, but I'm worried about the oil pressure. Manual calls for a minimum of 11psi at idle and 60-70psi at 3000rpm, and we're above spec, but what is normal for a new engine? I'm reading about 60psi at 3000rpm and 15psi at idle hot.

I'm worried that I may need to pull the crankshaft and have it ground .010 undersize for .010 oversize bearings. It measured out ok against the spec and didn't have any obvious damage so I installed new OEM bearings. Sort of kicking myself for not having it ground and polished now anyway....

Any opinions on using a high-volume oil pump or heavier weight oils to artificially boost pressure? I appreciate any help or guidance y'all can provide.

[p00t]

i dont understand those numbers look perfect :O

are you worried that they "should be 10 higher than minimum so that it stays 11psi or above when broken in" ?

I dont think those parts would wear enough to drop it below minimum. But i dont have any experience with fresh rebuilt motors. Would be interesting to hear other people opinion (that have experience in this subject).

[ferreed]

Hey, p00t,Do you mean that those numbers sound like they are good? I guess I had expected 25psi or so hot at idle, but I've never put a mechanicla oil pressure gauge on a KA before, so I really don't have any point of reference...

Edit to add: I know that oil pressure will drop slowly over the life of the engine as the bearings wear. I guess what I really need are baseline numbers for a fresh engine hot at idle and at 3000rpm.

Thanks for the reply.

[deviousKA]

Your oil pressure is good. If your not satisfied you can easily modify the spring in the pump for some added pressure, or even make it adjustable.

As you said the journals looked good and spec'd within the std range. Rod journals wear faster than the mains. If they measured good you have a nice clean crank that you didnt need to grind.

I go a bit wide on the tolerance range for rod/main on my ka's, nothing extreme but most likely somewhat similar to yours. Race tolerance.

[ferreed]

Devious,Thanks for the advice. Yeah, I was hoping that leaving them slightly loose would make for an easy break-in. (And it really has.)

I looked back at a thread on shimming the regulator in the oil pump to raise pressure. Sounds like it would raise maximum pressure but shouldn't affect pressure at idle (unless I'm way off base.) 15 psi just seems like such a low number for an idling engine. I mean, our 1950's farm tractor runs about the same oil pressure at idle. Man, I've got a lot to learn.

Thanks for your help again.

[p00t]

Devious,Thanks for the advice. Yeah, I was hoping that leaving them slightly loose would make for an easy break-in. (And it really has.)

I looked back at a thread on shimming the regulator in the oil pump to raise pressure. Sounds like it would raise maximum pressure but shouldn't affect pressure at idle (unless I'm way off base.) 15 psi just seems like such a low number for an idling engine. I mean, our 1950's farm tractor runs about the same oil pressure at idle. Man, I've got a lot to learn.

Thanks for your help again.

You are right about the regulator, you will only increase its max psi , not its set psi at idle. 15 does sound low in the scheme of things, but i bet you 90% of the KAs normally run around there (mine included! though i never checked) and the motors are perfectly healthy.