its all good
89 corvette oil pressure
Team Owner
Joined: Jul 2004
Posts: 28,495
Likes: 3,298
From: Hartford WI
Team Owner
Joined: Jul 2004
Posts: 28,495
Likes: 3,298
From: Hartford WI
Just checked oil pressure. No joy.
The pressure was fine all the way until you hit it. At WOT, it will drop to 20 psi. I know when we did the oil change we put in 5 quarts. That is the capacity, right? 15W50 Mobile 1 with AC Delco Filter. Should I be filling more in spite of the capacity? This is with a stock pump and pan. Guess I will have to drop it to check the windage tray or any other suggestions from here?
Pressure is fine for what it is until it gets into WOT. This is verified by both the gauge pressure gauge and the mechanical one I installed. I put this in the gauge port by the distributor and removed the OEM one. That way, it reads the pressure at the same place.
Any other suggestions?
The pressure was fine all the way until you hit it. At WOT, it will drop to 20 psi. I know when we did the oil change we put in 5 quarts. That is the capacity, right? 15W50 Mobile 1 with AC Delco Filter. Should I be filling more in spite of the capacity? This is with a stock pump and pan. Guess I will have to drop it to check the windage tray or any other suggestions from here?
Pressure is fine for what it is until it gets into WOT. This is verified by both the gauge pressure gauge and the mechanical one I installed. I put this in the gauge port by the distributor and removed the OEM one. That way, it reads the pressure at the same place.
Any other suggestions?
Team Owner
Joined: Jul 2004
Posts: 28,495
Likes: 3,298
From: Hartford WI
You didn't specify what your oil pressure was before you lost 20 PSI. It could be that you're at the max pressure before the relief valve in the oil pump opens (especially since you're using 15W-50 oil); or since you're "standing on it" you've pumped all the oil up into the heads, and it isn't draining back into the sump fast enough to maintain the oil pressure. (A drop in oil pressure could mean you're gulping air along with the oil due to either low oil levels in the sump or uncovering the pickup during acceleration.) Check your drain back openings in the heads as well as your oil pump pickup height above the oil pan as a starter.
If you have the factory oil cooler, it isn't the source of the problem as it's merely a flow-through liquid heat exchanger (engine oil to engine coolant).
Good luck!
If you have the factory oil cooler, it isn't the source of the problem as it's merely a flow-through liquid heat exchanger (engine oil to engine coolant).
Good luck!
Team Owner
Joined: Jul 2004
Posts: 28,495
Likes: 3,298
From: Hartford WI
Dumping in an extra quart of oil seems to help. Not eliminate the problem but help. Someone suggested that the lifters are passing too much oil thru and the drainback system cannot cope with it. Any ideas on that?
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Thread Starter
Navigator
Joined: Oct 2010
Posts: 9
Likes: 0
From: Houston TN
I just finished a brake system overhaul on this 89 corvette. Its time to start troubleshooting my oil pressure problem. So it looks like I should start with the oil pressure sending unit...is that correct?
Intermediate
Joined: Mar 2022
Posts: 45
Likes: 6
From: Illinois
Spun rod bearing
I apolgize for going off on a tangent.
While the mileage is not high, where the oil pressure has recently dropped off over a short period of time, and none of the easy fixes (new filter, heavier oil, independent check of oil pressure with mechanical gage) have helped, it could be time for a new oil pump; at the very least, the pump may have a relief valve which is hung up partially open, or some other such malady.
lower end bearings can be replaced in the car too, but at only 52,000 miles ? I think the pump would be more suspect.
sorry again for going off topic.
While the mileage is not high, where the oil pressure has recently dropped off over a short period of time, and none of the easy fixes (new filter, heavier oil, independent check of oil pressure with mechanical gage) have helped, it could be time for a new oil pump; at the very least, the pump may have a relief valve which is hung up partially open, or some other such malady.
lower end bearings can be replaced in the car too, but at only 52,000 miles ? I think the pump would be more suspect.
sorry again for going off topic.
I'm starting to wonder if low oil pressure is due to worn out rod bearings... Hindsight, I wish I would have replaced all the bearings at 50,000 miles.
Einstein I wish I would have downshifted to keep the RPMs out. Keep the oil pressure up. You can't just let the thing idle. Of course I was breaking and all kinds of lack of oil. I should have thrown an extra quarter oil in before I left. How much can you overfill a stock oil pan?
