Oil Pressure drop when warm [Archive]

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Bolomanmd

10-14-2018, 11:55 AM

I need the wisdom of the this forum to help me solve a concern of mine.. In April i had an intermittent low oil pressure warning problem.. i decided to park the car until i could test the oil pressure with an external gauge.. So this weekend i finally installed a prosport oil pressure gauge.. so here is what i am getting

startup 64-72 psi
cold idle 25-32
cold 2k 52-62

warm idle (it steadily drops from 20 to 10)
warm 2k 44-54

my main issue is the pressure nose dives when coming to a stop at one point it plunged to 8psi but when back up to the 30s when i drove off..
So it seems my problem is when the oil warms up.. when car is up to temp and i am driving pressure readings seem to be within specs but as soon as i let off accelerator and come to a stop pressure takes a dive.
quick note..
-2 years ago i had an intermittent oil pressure issue, but that was solved when i changed my PCV valve
- while i installed the oil pressure gauge i replaced my oil cooler gasket (it was leaking) when i removed my oil cooler i noticed it had a lot of gunk i cleaned it the best i could and reinstalled it.. i don't know if there could be any relation with the oil not being properly cooled and oil pressure.

any ideas would help

67Twisty

10-14-2018, 07:09 PM

vce1232000

10-14-2018, 08:08 PM

partially clogged oil pick up screen [confused]

Ringsby4

10-14-2018, 08:35 PM

partially clogged oil pick up screen [confused]

Maybe-just maybe....ask me how I know [=(]

vce1232000

10-15-2018, 05:14 AM

Maybe-just maybe....ask me how I know [=(]

[:(]..... I felt your pain on that 1 [;)]

Bolomanmd

10-15-2018, 05:43 AM

Has your low oil pressure light come on recently? What type of oil are you using? Have you checked the prosport calibration with an external guage? Where did you connect the sender? Your other numbers seem within reason, but hot idle is low.

Min oil pressure at hot idle should be 1 bar or ~14.5psi. I’ve had a gauge for awhile now and I typically run 1.2-1.4 bar (17-20 psi) at hot idle. I use Rotella T6 but noticed when running Mobil 0W40 that my pressure dropped some at idle. That oil tends to sheer quickly, especially in turbo applications.

no i have not had the oil pressure light yet, but i was told the light does not come on until you hit 2k.. at 2k my pressure readings are within specs.. i have not checked the calibration of the gauge... it is connected at the turbo feed line.. i do use Mobil 0W40..

how safe is the Rotella T6 in our cars?
i have some time today, i could do a quick oil change to see if that helps out

Bolomanmd

10-15-2018, 05:49 AM

partially clogged oil pick up screen [confused]

would a partially clogged pick up screen give readings within specs at 2k and above?

vce1232000

10-15-2018, 06:03 AM

would a partially clogged pick up screen give readings within specs at 2k and above?

[up]. Because the engine is now able to supply the psi vs @ idle its not. Because of the restriction.

Bolomanmd

10-15-2018, 06:20 AM

[up]. Because the engine is now able to supply the psi vs @ idle its not. Because of the restriction.

ok that makes sense, i was hoping not to have to drop the oil pan if not necessary. Is there a way to strengthen that suspicion before jumping into such a big job?

Theiceman

10-15-2018, 06:51 AM

some guy drilled a hole in his pan to clear his then patched it . I thought it was pretty darn ingenious vs dropping the sub frame. See if you can find it on a search

67Twisty

10-15-2018, 07:15 AM

no i have not had the oil pressure light yet, but i was told the light does not come on until you hit 2k.. at 2k my pressure readings are within specs.. i have not checked the calibration of the gauge... it is connected at the turbo feed line.. i do use Mobil 0W40..

how safe is the Rotella T6 in our cars?
i have some time today, i could do a quick oil change to see if that helps out

I’ve been using T6 for years in VWs and BMWs. Although it’s technically a diesel formula, it works well in these cars and you can check out plenty of Blackstone used oil analysis reports over on BITOG. Switching to it from the Mobil 0W40 reduced my blow by consumption and I now get very little oil in the intercooler boots. Seems to hold idle pressure better.

BTW- if you do suspect it’s the oil pick-up screen dropping the subframe is the only way to go. I’ve done it before over a weekend and it gives you the opportunity to put in a fresh OPG. Not particularly difficult but it is time consuming because of all the fasteners and labor involved. Drilling a hole in an aluminum oil pan that can’t be patched easily sounds a bit unorthodox.

Bolomanmd

10-15-2018, 08:24 AM

I’ve been using T6 for years in VWs and BMWs. Although it’s technically a diesel formula, it works well in these cars and you can check out plenty of Blackstone used oil analysis reports over on BITOG. Switching to it from the Mobil 0W40 reduced my blow by consumption and I now get very little oil in the intercooler boots. Seems to hold idle pressure better.

BTW- if you do suspect it’s the oil pick-up screen dropping the subframe is the only way to go. I’ve done it before over a weekend and it gives you the opportunity to put in a fresh OPG. Not particularly difficult but it is time consuming because of all the fasteners and labor involved. Drilling a hole in an aluminum oil pan that can’t be patched easily sounds a bit unorthodox.

I will start with switching the oil and crossing my fingers. I agree with you about drilling the oil pan, I cringe at the though of the patch failing on the highway..

Bolomanmd

10-15-2018, 08:26 AM

I found this thread
https://www.audizine.com/forum/showthread.php/792246-Low-oil-pressure-only-after-warming-up-and-only-at-idle
the OP has the same symptoms as I do. how similar are the B8 engines to our B7 engines ?

Theiceman

10-15-2018, 10:13 AM

Bolomanmd

10-15-2018, 11:08 AM

yeah it was very unorthodox, but +1 for people thinking outside of the box , that's what pushes science forward. Imagine if it came with an access port and a gasket from the factory, how much easier life would have been for people ..

that's true

in fact its negligent of them not to have done that given the history of these cars and their clogged pickup tube

vce1232000

10-15-2018, 01:51 PM

ok that makes sense, i was hoping not to have to drop the oil pan if not necessary. Is there a way to strengthen that suspicion before jumping into such a big job?

Im a ole skool [wrench]. If this was my car. I would drain the oil. Add 2 qts of cheap synthetic walmart oil. Add 2 qt of automatic transmission fluid. Let the engine idle for about an hour. [race] the engine to 2500 rpm a few times in between. Drain and repeat process again. ATF contains detergents that gets rid of varnish and sludge build ups. Then [o_o] if your oil psi gauge has improved @ idle

Theiceman

10-15-2018, 01:59 PM

Im a ole skool [wrench]. If this was my car. I would drain the oil. Add 2 qts of cheap synthetic walmart oil. Add 2 qt of automatic transmission fluid. Let the engine idle for about an hour. [race] the engine to 2500 rpm a few times in between. Drain and repeat process again. ATF contains detergents that gets rid of varnish and sludge build ups. Then [o_o] if your oil psi gauge has improved @ idle

IS THERE NOT A WAY TO REVERSE FLUSH THE OIL SO IT WILL PUSH OUT AT THE PICKUP ? damn caps lock

I'm not sure if I read about this somewhere or just dreamed it .

Jet08

10-15-2018, 03:37 PM

Although a reverse flush may be possible can you image the shhht that would go back in to the cam journals etc .....

viperdsa

10-15-2018, 09:50 PM

I've been dealing with this on my car. Changed a leaking oil filter housing and it didn't change a while lot. It still drops down to 10psi when warm and no oil pressure light. Only difference is this is a new motor so I doubt it is sludge.
Have been running a 5w30 oil for break in, going to switch back to 0w40 and see what it does.

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