Oil Pressure Problem
Thread Starter
Team Owner
Joined: Jul 2004
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From: Hartford WI
Oil Pressure Problem
Can't seem to get a handle on it. Pressure is fine all day long except when you hit it hard. At which point, it can drop to 20 psi. This has been verified by an independent mechanical gauge so it is correct. Doesn't matter if it is stationary or moving. Hitting it makes the pressure go up momentarily and then drop as you keep the throttle where it is. Thicker oil seems to help but not eliminate the problem.
IF it were running out of oil, why doesn't the low oil light come on? I have put an extra quart of oil, run 15W50 Mobil1 but no joy. Thicker oil means it drops pressure slower.
Some have argued that the windage tray might be absent. So why does it still have that issue when stationary?
I have changed from a larger Miloden pan and pump to a stock volume and pressure pump and a stock pan but still the problem persists.
A theory is that everything is fine but the lifters are bleeding oil too fast.
IF it were running out of oil, why doesn't the low oil light come on? I have put an extra quart of oil, run 15W50 Mobil1 but no joy. Thicker oil means it drops pressure slower.
Some have argued that the windage tray might be absent. So why does it still have that issue when stationary?
I have changed from a larger Miloden pan and pump to a stock volume and pressure pump and a stock pan but still the problem persists.
A theory is that everything is fine but the lifters are bleeding oil too fast.
Thread Starter
Team Owner
Joined: Jul 2004
Posts: 28,424
Likes: 3,276
From: Hartford WI
Gauge in the dash could be bad or the sender but I removed them, hooked up a mechanical gauge to the very same port and it reads exactly what the dash gauge reads so it is hard to accept that both could be just as bad.
Drifting
Joined: Jun 2010
Posts: 1,853
Likes: 8
From: Westerly RI
Check valve where? In the pump? Shouldn't be since we changed pumps and had the same issue
Gauge in the dash could be bad or the sender but I removed them, hooked up a mechanical gauge to the very same port and it reads exactly what the dash gauge reads so it is hard to accept that both could be just as bad.
Gauge in the dash could be bad or the sender but I removed them, hooked up a mechanical gauge to the very same port and it reads exactly what the dash gauge reads so it is hard to accept that both could be just as bad.
Thread Starter
Team Owner
Joined: Jul 2004
Posts: 28,424
Likes: 3,276
From: Hartford WI
If I understand it correctly, the pressure relief valve opens the oil back into the system should the filter get clogged. This means that worse case scenario, it would bypass the filter so why would that be an issue?
If it were the windage tray, why is it that it also happens at WOT when the car is standing still? Isn't the windage tray more helpful when the car is moving?
If it is the height of the pickup, it might explain something. I did have the engine builder replace the old pan and pickup so I am not sure if he screwed up twice the exact same way.
Thread Starter
Team Owner
Joined: Jul 2004
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From: Hartford WI
Drifting
Joined: Jun 2010
Posts: 1,853
Likes: 8
From: Westerly RI
Not sure at all. I wish there was a more definitive answer than that from me. I suspect I will be beating dead horses by checking the pressure relief valve in the filter area and maybe trying to see if the windage tray was in and the height of the pickup was good but I am kinda doubtful it is those.
If I understand it correctly, the pressure relief valve opens the oil back into the system should the filter get clogged. This means that worse case scenario, it would bypass the filter so why would that be an issue?
If it were the windage tray, why is it that it also happens at WOT when the car is standing still? Isn't the windage tray more helpful when the car is moving?
If it is the height of the pickup, it might explain something. I did have the engine builder replace the old pan and pickup so I am not sure if he screwed up twice the exact same way.
If I understand it correctly, the pressure relief valve opens the oil back into the system should the filter get clogged. This means that worse case scenario, it would bypass the filter so why would that be an issue?
If it were the windage tray, why is it that it also happens at WOT when the car is standing still? Isn't the windage tray more helpful when the car is moving?
If it is the height of the pickup, it might explain something. I did have the engine builder replace the old pan and pickup so I am not sure if he screwed up twice the exact same way.
Just to clarify, the bypass, what we are calling a "relief valve", is not on the oil pump, it's on the oil filter base.
Last edited by sailorsteve; Nov 11, 2010 at 04:21 PM.
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Thread Starter
Team Owner
Joined: Jul 2004
Posts: 28,424
Likes: 3,276
From: Hartford WI
The pickup height could be an issue- too high or too low? Don't know about a spec for this but I wonder if a too-low pickup might not allow enough oil into the pump.
When I said "check valve" I probably misspoke as I was thinking of the pressure regulator, in the pump, but you tried two different pumps.
Grasping at straws here, could there be an internal oil leak that allows oil to bleed down? Don't exactly recall the oil gallery arrangement, but is there a place where an internal plug could be leaking? If the relief valve is too weak, you would think it would show up all the time, not just at higher rpm.
When I said "check valve" I probably misspoke as I was thinking of the pressure regulator, in the pump, but you tried two different pumps.
Grasping at straws here, could there be an internal oil leak that allows oil to bleed down? Don't exactly recall the oil gallery arrangement, but is there a place where an internal plug could be leaking? If the relief valve is too weak, you would think it would show up all the time, not just at higher rpm.
Supposedly, the guy installed a 2nd pump. I am thinking of just getting another pump altogether and try it for the hell of it.
But if it does, won't the internal oil leak show up more at idle where the pressure is lower? Well, an argument could be that at lower draw, it can't overwhelm the pump. At higher, it might.
I thought it wasn't too bad to drop the pan. Supposedly you take the cross beams out and the pan comes off easily. Anyone know that for sure or is there some complicated process like a virgin sacrifice?
Drifting
Joined: Jun 2010
Posts: 1,853
Likes: 8
From: Westerly RI
From what I read, it should be about 3/8 from the bottom. Obviously too high sucks air and they do say that too low doesn't allow it to suck enough oil.
Supposedly, the guy installed a 2nd pump. I am thinking of just getting another pump altogether and try it for the hell of it.
But if it does, won't the internal oil leak show up more at idle where the pressure is lower? Well, an argument could be that at lower draw, it can't overwhelm the pump. At higher, it might.
I thought it wasn't too bad to drop the pan. Supposedly you take the cross beams out and the pan comes off easily. Anyone know that for sure or is there some complicated process like a virgin sacrifice?
Supposedly, the guy installed a 2nd pump. I am thinking of just getting another pump altogether and try it for the hell of it.
But if it does, won't the internal oil leak show up more at idle where the pressure is lower? Well, an argument could be that at lower draw, it can't overwhelm the pump. At higher, it might.
I thought it wasn't too bad to drop the pan. Supposedly you take the cross beams out and the pan comes off easily. Anyone know that for sure or is there some complicated process like a virgin sacrifice?
There is nothing under the oil pan on a C4.
I am not an engine builder, but my brother in FL is a Chevy hotrodder, a year or so ago he told me of a problem with a 4.3 V6 that he had a shop build for him. I can't remember the details now (memory good but short) but that engine failed due to a problem with the relief valve in the filter base.
Thread Starter
Team Owner
Joined: Jul 2004
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From: Hartford WI
I was busy editing my post while you were responding.
There is nothing under the oil pan on a C4.
I am not an engine builder, but my brother in FL is a Chevy hotrodder, a year or so ago he told me of a problem with a 4.3 V6 that he had a shop build for him. I can't remember the details now (memory good but short) but that engine failed due to a problem with the relief valve in the filter base.
There is nothing under the oil pan on a C4.
I am not an engine builder, but my brother in FL is a Chevy hotrodder, a year or so ago he told me of a problem with a 4.3 V6 that he had a shop build for him. I can't remember the details now (memory good but short) but that engine failed due to a problem with the relief valve in the filter base.
Drifting
Joined: Jun 2010
Posts: 1,853
Likes: 8
From: Westerly RI
Thread Starter
Team Owner
Joined: Jul 2004
Posts: 28,424
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From: Hartford WI
As I understand you take the filter off then take the "bolt" off and the cooler comes off and you access the bypass.
Drifting
Joined: Jun 2010
Posts: 1,853
Likes: 8
From: Westerly RI
Thread Starter
Team Owner
Joined: Jul 2004
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From: Hartford WI
Melting Slicks
Joined: Jan 2009
Posts: 3,482
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From: folsom california
you seem to have addressed the oil pump issue, and neither of two (?) new pumps have solved the problem.
how many miles on the engine ? next time oil pan is off, pull the main bearing caps, check for obvious signs of wear or damage; then use plasti gage to get an idea as to what your bearing clearances are.
If its any consolation, bearing sets (crankshaft and rods) are not terribly expensive and can be replaced with the engine in the car. If your crankshaft is standard size, slightly oversize bearings (0.001") are available to compensate for normal wear on the cranfshaft itself.
And, you might consider a high volume, high pressure pump (although some will advise otherwise).
how many miles on the engine ? next time oil pan is off, pull the main bearing caps, check for obvious signs of wear or damage; then use plasti gage to get an idea as to what your bearing clearances are.
If its any consolation, bearing sets (crankshaft and rods) are not terribly expensive and can be replaced with the engine in the car. If your crankshaft is standard size, slightly oversize bearings (0.001") are available to compensate for normal wear on the cranfshaft itself.
And, you might consider a high volume, high pressure pump (although some will advise otherwise).
Thread Starter
Team Owner
Joined: Jul 2004
Posts: 28,424
Likes: 3,276
From: Hartford WI
you seem to have addressed the oil pump issue, and neither of two (?) new pumps have solved the problem.
how many miles on the engine ? next time oil pan is off, pull the main bearing caps, check for obvious signs of wear or damage; then use plasti gage to get an idea as to what your bearing clearances are.
If its any consolation, bearing sets (crankshaft and rods) are not terribly expensive and can be replaced with the engine in the car. If your crankshaft is standard size, slightly oversize bearings (0.001") are available to compensate for normal wear on the cranfshaft itself.
And, you might consider a high volume, high pressure pump (although some will advise otherwise).
how many miles on the engine ? next time oil pan is off, pull the main bearing caps, check for obvious signs of wear or damage; then use plasti gage to get an idea as to what your bearing clearances are.
If its any consolation, bearing sets (crankshaft and rods) are not terribly expensive and can be replaced with the engine in the car. If your crankshaft is standard size, slightly oversize bearings (0.001") are available to compensate for normal wear on the cranfshaft itself.
And, you might consider a high volume, high pressure pump (although some will advise otherwise).
