Oil pressure

[omgjacki]

My friend's got a recently rebuilt GSR motor that was turbo'd, went for a tune but the oil pressure only reads between 20 and 25lbs. Any idea what it could be? Oil pump, maybe?

[sponsored1]

Oil pressure problems are almost never the fault of the oil pump. 20-25lbs of pressure at idle is normal when hot. Typical "old school" rule of thumb is 10lbs of pressure per 1000rpm. First thing to check is the oil pressure gauge and location of the sender. If he has a ballbearing turbo he should be running some sort of restrictor for the feed. Ls/Vtecs sometimes lose pressure because they use too big of a feed for the vtec solenoid. Also unlikely is that his vtec solenoid might be stuck open. And if it was just rebuilt, get the the oil clearance specs for the mains. Aluminum blocks need tighter tolerences because they expand so much when they heat up and sometimes machine shops who arent used to working on them will leave the clearances too big and you'll be left without oil pressure.

[omgjacki]

The motor was just rebuilt from being seized. Do you think there's a chance that that could have caused debris in the oil pump? All the clearances are the same and the vtec soleniod feed is the same as when the car was running without any problems.

[sponsored1]

It's possible, but the oil pump gear clearances should have been checked when it was rebuilt. If it spun a main bearing and the block was line honed you have to check the oil pump spacing with the crankshaft as well. If it was line honed a lot, it can cause the pump to be off center with the crank and it will wear one side of the pump housing. The first step is to verify that the pressure is actually what he thinks it is with a mechanical gauge. What are his pressures at cold idle, hot idle, hot cruising?

[omgjacki]

It did spin a bearing and had the crank replaced as well. The block was sent out to be sleeved and then was honed to match the pistons. Pressure was checked by a mechanical pressure guage and was reading low 20's at idle. I never got far enough to have it running with it that low so I don't know what it is a cruising etc. I was told by the tuner that it should be around 40 at idle and as high as 80-90 under load.

[dragonfly2k3]

20-25 at idle is not bad pressure at all(when hot) Under load some cars will peg out 100psi gauges.

[omgjacki]

Figured it out.

[MTuning]

that's normal at idle...but what was the problem?

[omgjacki]

I'm gonna try my best to remember what he told me this morning when I was half asleep =P

Apparently the oil jets/squirters at the bottom of each cylinder/valve, whichever he said, aren't reusable and when the engine was sent out to be repaired and sleeved after it seized they were taken out and disposed of, so there weren't any jets at all.

[MTuning]

wow um...yeah those are important haha that'll do it, glad he found the problem...hope there wasn't any damage. idle pressures normal but yeah im sure any load after that will be funky.

[TurboGSR96]

I was just going to say someone probably forgot to put the squirters back in, I typically see 30psi of Oil Pressure at idle and almost 100psi @ WOT

[redline]

Originally Posted by dragonfly2k3

20-25 at idle is not bad pressure at all(when hot) Under load some cars will peg out 100psi gauges.

I peg 100 up top. My 350Z buried the 120 mark up top.

[na is best!]

Originally Posted by omgjacki

I'm gonna try my best to remember what he told me this morning when I was half asleep =P

Apparently the oil jets/squirters at the bottom of each cylinder/valve, whichever he said, aren't reusable and when the engine was sent out to be repaired and sleeved after it seized they were taken out and disposed of, so there weren't any jets at all.

you dont need em, its not that big of a thing, the oil squirters in a gsr is a very debateable issue, I kno alot of fast/pro cars that run them and alot that dont. Golden eagle actual sells cap specifically for them... talk to ur tuner and builder and make a choice. Depending on your setup and parts used you can make that descision.