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Old 08-18-2010, 02:19 AM   #1
Saintsp
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Default low oil pressure

engine is a build 2.7 with bc kit.Having this problem of low oil pressure.When i rev the oil pressure on stays at 4 bar.What could be the cause of low pressure?
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Old 08-18-2010, 02:37 AM   #2
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Fluctuating oil pressure? Or just low in general?
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Old 08-18-2010, 02:45 AM   #3
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Fluctuating oil pressure? Or just low in general?

Will not go over 4 bar.Bearing issue?oil pump is new 12mm.
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Old 08-18-2010, 02:45 AM   #4
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So it stays at 58psi even when your driving it at higher rpm and in boost?
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Old 08-18-2010, 02:48 AM   #5
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So it stays at 58psi even when your driving it at higher rpm and in boost?
yes.What could cause this?i just want to find out what could be the cause
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Old 08-18-2010, 06:49 AM   #6
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anyone to share?
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Old 08-19-2010, 12:27 AM   #7
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What oil are you using? What are the bearing clearances?
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Old 08-19-2010, 03:14 AM   #8
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What oil are you using? What are the bearing clearances?

Whats the difference between loose or tighter bearing clearance in term of oil pressure?
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Old 08-19-2010, 08:44 AM   #9
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Whats the difference between loose or tighter bearing clearance in term of oil pressure?
The bigger the oil clearances, the lower the pressure, the thinner the oil the lower the pressure...

If clearances are not known and the engine is otherwise mechanically sound the thickness of oil can be looked at first. Built motors with larger clearances are going to need thicker oils. Also if the motor has had some oil relieving work it may need thicker oil to get proper pressure at operating temps.

So again, what are your clearances and what oil are you using?
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Old 08-19-2010, 10:48 AM   #10
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Quote:
Originally Posted by soobaviator View Post
The bigger the oil clearances, the lower the pressure, the thinner the oil the lower the pressure...

If clearances are not known and the engine is otherwise mechanically sound the thickness of oil can be looked at first. Built motors with larger clearances are going to need thicker oils. Also if the motor has had some oil relieving work it may need thicker oil to get proper pressure at operating temps.

So again, what are your clearances and what oil are you using?
^ Right on!

When running a stock motor with stock clearances, as we know 5W30 will work fine.
I have a sleeved, O ringed motor, with a BC billet crank with coated ACL bearings.
The motor was built by AR Fab.
During my discussions with Howard at AR on break in oil, operating oil, etc., I was told that I should use 10W40 oil to begin with, this was due to the greater bearing clearances my motor was put together with.
He said when I track the car, I need to monitor my oil pressure, but more importantly my oil temperatures.
He said that if I notice oil temps rise and pressure begins to drop off, say on a hot day, or pushing the car hard, I may need to go to an even heavier oil, or perhaps blend two different weight oils to maintain my oil pressures.
As the larger than stock bearing clearances are used on this type of motor, it is very important to maintain high oil pressures as the oil acts as a cushion. A thin oil, or low oil pressure will not provide this cushion between oil fed surfaces.
FYI, when I start my car on a cool morning my oil pressure runs around 95-100 psi at idle, once the motor warms up, my oil pressure at idle is around 50-60 psi and at 2000 rpm, up to red line, it runs 85-95 psi depending on the ambient temps.
As mentioned above, you should first go to a heavier oil, if you still don't see higher oil pressures, I'd be talking to the guy that built your motor real soon!
Good luck.
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Old 08-19-2010, 01:21 PM   #11
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Originally Posted by blackacres View Post

As mentioned above, you should first go to a heavier oil, if you still don't see higher oil pressures, I'd be talking to the guy that built your motor real soon!
Good luck.
Where on the engine do you measure your oil pressure from?
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Old 08-19-2010, 01:26 PM   #12
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Check you oil pump relief too.
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Old 08-19-2010, 01:33 PM   #13
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Where on the engine do you measure your oil pressure from?
You have a few options. You can get a gallery plug adapter and mount the sender and electrical gauge of your choice. There are two spots on the top of the block for oil gallery plugs.

You could also buy a sandwich adapter and use it to plug in multiple sensors like temp and pressure gauges. You should have both actually.

I use the gallery plug adapters and a very good mechanical gauge to test oil pressure on engines. This is not the most convenient method (the gauge has to be mounted outside the car for testing) but I get accurate pressure measurements for reference and diagnosis.

I was lucky enough to pick up a couple of Omori 45 mm gauges a few years ago as they fit the OEM 3 gauge pods I have in my GDA WRX's. I would not go cheap on gauges.
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Old 08-19-2010, 02:18 PM   #14
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I would look at the relief setting. If oiL pressure hits 58 psi and stays constant throughout the rev range it sounds like a relief valve adjustment/ setting issue.
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Old 08-20-2010, 12:11 AM   #15
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I would look at the relief setting. If oiL pressure hits 58 psi and stays constant throughout the rev range it sounds like a relief valve adjustment/ setting issue.

well we removed the oil cooler and oil press went up.Tried to isolate the problem so we bypass the core with the sandwich plate in and oil press drop again.How could a sandwich plate cause this?just don understand
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Old 08-29-2010, 11:09 PM   #16
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well we removed the oil cooler and oil press went up.Tried to isolate the problem so we bypass the core with the sandwich plate in and oil press drop again.How could a sandwich plate cause this?just don understand

Now er put back te oil cooler system,change the line and the oil press drop to 4 bar again,it somehow lose 2bar from just oil cooler?
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Old 09-04-2010, 11:29 PM   #17
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Now er put back te oil cooler system,change the line and the oil press drop to 4 bar again,it somehow lose 2bar from just oil cooler?

Final try we changed an oil cooler,change a new 12mm oil pump with 2 added shims and it still does the same thing.cold the oil pressure can go up to 7 bar but when hot,oil temp bout 80 plus the oil pressure dropped to 4 bar and it just stayed there even when on boost.Motor was tuned to 9k rpm and without the oil cooler everything was fine.ANy help here?WHat could be causing it?Crack pick up?seems like the oil pump wasn't strong enough.
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Old 09-05-2010, 12:38 AM   #18
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Where do you have the oil cooler mounted?
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Old 09-05-2010, 01:21 AM   #19
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What size lines are you running to and from the oil cooler? How large is the cooler? How long are the lines from the engine to the cooler and back?
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Old 09-05-2010, 02:06 AM   #20
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What oil is being used???
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Old 09-05-2010, 09:09 AM   #21
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Fittings should be at least AN10, and you should have a good Mocal or Setrab cooler made for those size fittings. Buying a tranny fluid cooler designed for AN-6 lines is not going to help you here.
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Old 09-05-2010, 08:26 PM   #22
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You tried a different oil filter?
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Old 09-06-2010, 02:26 AM   #23
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You tried a different oil filter?

Ya tried a different oil filer,changed to the mocal oil cooler with -10 line.exactly the same thing.where is the oil pump relif?oil used is 5w50
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Old 09-06-2010, 07:13 AM   #24
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I would look at the relief setting. If oiL pressure hits 58 psi and stays constant throughout the rev range it sounds like a relief valve adjustment/ setting issue.

How do we actually adjust the relif valve?Its a 12mm new oil pump
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Old 09-06-2010, 09:10 AM   #25
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There is one built-into the pump. The spring is under the cap screw that comes in from the side. There is another built-into the filter too.

I don't think the pump bypass has a problem since your pressure is low at startup, bit checking it wouldn't hurt.
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