Oil pressure drop

[taillights]

Car starts fine and sounds fine pressure at #40 at idle when cold The warmer the car gets the lower the pressure will go but only at idle. When I am going it stays at around 25 at around 2000rpm which my shop manuel says is normal. Could the engine getting to hot cause this oil pressure to drop at idle. I may not have enough airflow because it has a air to air intercooler up front and tend run on the high side 220 to 230 and it's not really that hot here around 88deg outside when testing this. I run mobil1 synthetic oil and it is full. any suggestions Thanks, Trojan

 

[SoCal Rebell]

Car starts fine and sounds fine pressure at #40 at idle when cold The warmer the car gets the lower the pressure will go but only at idle. When I am going it stays at around 25 at around 2000rpm which my shop manuel says is normal. Could the engine getting to hot cause this oil pressure to drop at idle. I may not have enough airflow because it has a air to air intercooler up front and tend run on the high side 220 to 230 and it's not really that hot here around 88deg outside when testing this. I run mobil1 synthetic oil and it is full. any suggestions Thanks, Trojan

What year Gen2? '96 & '97's only have 7 quart pans. If you have a later year with a 10 quart pan, and if it's not the pump, switch to a 15-50 weight, that's what I used. You can also buy a new trap door windage tray. I ran my '00 at 250 on a track with this setup with no problems.

 

[taillights]

SoCal My car is a 98 GTS and the shop manuel shows 8.5qts with this car which is what I put in it and the dipstick shows it to be right on the money. If I switch to a heavier weight oil Do you think this will raise the oil pressure at high operating temps? Also I have a buddy and his viper runs 40lbs all the time idle or not but his car does'nt have a blower and runs alot cooler than my car.

 

[Tom F&L GoR]

Studies show oil viscosity grade won't make as much a difference as you'd like it to. Oil temperature makes a big difference. Can you measure the oil temp somehow? Or is the 220-230 the oil temp (or water?)

The gauges are also subject to poor performance - and there are three sending units (one for gauge, one to the PCM, one for the idiot light.) Can you temporarily install a mechanical gauge?

 

[taillights]

Studies show oil viscosity grade won't make as much a difference as you'd like it to. Oil temperature makes a big difference. Can you measure the oil temp somehow? Or is the 220-230 the oil temp (or water?)

The gauges are also subject to poor performance - and there are three sending units (one for gauge, one to the PCM, one for the idiot light.) Can you temporarily install a mechanical gauge?

The temp is the water temp. My guage seems to be working correctly because as soon as it drops real low the idiot light will come on and I highly dought that both are bad I seen where I can hook in a mechanical guage. I think I will try to tackle the temp problem first with either a high volume water pump or higher cfm fan set-up or probably both. It already has an aftermarket radiator. I really think I need more air flow because when I am driving down the highway It seems to run cooler than when going at slower speeds.

 

[dave6666]

...when I am driving down the highway It seems to run cooler than when going at slower speeds.

That is normal.

How old is your coolant, and what is the mix?

Do you have the upgraded fan? (dunno what year they switched)

When was the last time you cleaned the front of your radiator? Requires removal to do it right. Drink cups, leaves, trash bags, cig butts...

What t-stat?

 

[Tom F&L GoR]

The temp is the water temp. My guage seems to be working correctly because as soon as it drops real low the idiot light will come on and I highly dought that both are bad I seen where I can hook in a mechanical guage. I think I will try to tackle the temp problem first with either a high volume water pump or higher cfm fan set-up or probably both. It already has an aftermarket radiator. I really think I need more air flow because when I am driving down the highway It seems to run cooler than when going at slower speeds.

I agree both sending units won't be bad. The idiot light is set pretty low, so I see why you are worried. When you drive in a manner that keeps coolant temps lower, what exactly is the oil pressure then? As above, I'm not a believer in 30 degrees lower coolant temp making 30 psi more oil pressure.

 

[taillights]

That is normal.

How old is your coolant, and what is the mix?

Do you have the upgraded fan? (dunno what year they switched)

When was the last time you cleaned the front of your radiator? Requires removal to do it right. Drink cups, leaves, trash bags, cig butts...

What t-stat?

Cleaned all radiators today but I found a big problem. The fan was'nt even coming on so I rewired the stock fan wiring with another relay to come on as soon as I turn on the key, So if I ever need to let it cool off I can just turn the key on without the car running for the fan to work. This probably fixed the oil problem too. I let the car run at idle for quite awhile and the water temp stayed at 155deg and oil pressure stayed at 30lbs idleing I'll test drive it tommorrow. Hope this fixed it.

 

[taillights]

I agree both sending units won't be bad. The idiot light is set pretty low, so I see why you are worried. When you drive in a manner that keeps coolant temps lower, what exactly is the oil pressure then? As above, I'm not a believer in 30 degrees lower coolant temp making 30 psi more oil pressure.

I think I got it figured out read the post aboe to dave666. Thanks for the input and wish me luck on the test drive.

 

[dave6666]

If I understand all of this correctly...

You had a cooling problem that led to an oil pressure problem. Problem appears to have corrected itself.

Someone chime in if I'm a little off base here, but I would think that any cooling problem that shows up on the oil pressure gauge has left a permanent mark of sorts.

I would at minimum change the oil, just for cow's rear ends and big smiles.

And get your fan working like it should, based on the thermostatic switch.

 

[taillights]

If I understand all of this correctly...

You had a cooling problem that led to an oil pressure problem. Problem appears to have corrected itself.

Someone chime in if I'm a little off base here, but I would think that any cooling problem that shows up on the oil pressure gauge has left a permanent mark of sorts.

I would at minimum change the oil, just for cow's rear ends and big smiles.

And get your fan working like it should, based on the thermostatic switch.

This is correct when the oil wwas getting to hot it would drop pressure at idle It only happened the other day. So I hope I caught it before any bearing damage was done. I have'nt had a chance to drive it yet, but at idle in my shop it was staying at 150deg water temp and 30psig oil pressure after running for some time.. And I'm going to leave the fan the way I have it. I don't like the factory set-up It has a 2 speed fan controled by 2 relays and a t-stat. I now have 1 relay controlled off the ignition switch and on high speed only' Cooler is better IMO especially in the Texas heat of summer. And I am going to change my oil again I drained a little out and it looked black already but did'nt smell burnt. And I just changed it about 150 miles ago. Wish me luck and I'll be coming down sometime for those [lonestars] Sorry Buds (I almost forgot we're upgrading our BREWS )Thanks, Trojan

 

[dave6666]

Running the engine too cold, like 150 deg F, is not good. Normal operating temp should be more like 180. If your fan is always on now, then the coolant thermostat becomes the coolant temp regulatory devise. I think the fan on-off usually controls that. Let us know how it works out doing it that way.

 

[taillights]

Running the engine too cold, like 150 deg F, is not good. Normal operating temp should be more like 180. If your fan is always on now, then the coolant thermostat becomes the coolant temp regulatory devise. I think the fan on-off usually controls that. Let us know how it works out doing it that way.

I will keep you informed on how it affects it but I'm sure this summer the T-stat will run in open loop while driving anyway. Thats the reason in the old days people used to take out their T-stats in the hot summers no restriction at all.[Just ask any old farmer. I know this is'nt a farm truck but I'm betting it'll be fine. That's the reason I have a 165 T-stat in my turbo charged ls1 camaro.

 

[GTS Bruce]

I would opt for the ACR oil flter adapter if you can find one. Stock bypasses the oil cooler at idle and low pressure (presumably idle) to maxamize AC function. ACR adaptor gives you full flow all the time and a little higher psi. GTS Bruce

 

[taillights]

I would opt for the ACR oil flter adapter if you can find one. Stock bypasses the oil cooler at idle and low pressure (presumably idle) to maxamize AC function. ACR adaptor gives you full flow all the time and a little higher psi. GTS Bruce

Thanks for the info I'll check into that.