90 Subaru Loyale Turbo dropping oil pressure

Tiny
INSANITYRUS
  • MEMBER
  • 1990 SUBARU
90 Subaru Loyale Turbo manafacture date 1/89 Mileage over 200,000, 1.8 FI Engine. For about the first 10 -15 minutes that the car runs the oil pressure reads approx. 45 then starts dropping and goes to 0. When the car is stopped at a traffic light the pressure stays at 0 but when I hit the gas to accelerate the pressure comes up but only to 20. When I let off the gas the pressure drops back down again almost to 0 again. When we bought the car the whole engine was covered in oil. I have since cleaned the engine and it doesn't appear to be leaking oil from anywhere. I have also replaced the air filter, changed the oil and oil filter, replaced the distributor cap and rotor, spark plugs and wires. Flushed the radiator also. The antifreeze in the radiator was pink.

What could be causing the problem with the lack of oil pressure? When I changed the oil is was black and really thin. The new oil I put in 10w40 a month ago is still brown like it is suppose to be but appears to be not as thick as it was when I put it in. It appears to be watered down, the oil dripped off the dip stick when I checked the oil but the oil level remains about the same. The car gets driven approx. 100 miles per week if that.

Also why was the antifreeze pink, any ideas?
? : :Idea: :roll:
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Tuesday, July 3rd, 2007 AT 11:24 PM

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Tiny
LAWNDART
  • MEMBER
I have a JDM 2.0 turbo in my sand rail that had a similar problem and I'll find out if I have fixed the problem this upcoming weekend. Anyway here is what I observed:

When the engine was cold the pressure was around 75psi once it warmed up the pressure would practically be nonexistent at idle. The engine would produce pressure under cruising speeds and acceleration; however, would hover around an unreadable pressure at the gauge on the dash when idling. A friend that owned a mechanic shop said that it was probably due to the bearings being worn and were therefore unable to keep the pressure up. I talked to a few other friends that worked at Crawford Performance and their prognosis was the same. Spoke with the owner at a shop who produces engine packages for buggies from JDM imports (Johnson in spring valley, ca), he said that it is not uncommon that the pressure relief valve will stick giving the same behavior. My decision was to either buy a new block $1500 or try a new pump ($107), I opted for the new pump. When I removed the old pump I found the plate that is responsible for holding the pump gears together was loose. I found this is really common problem on these engines on NASIOC. Com's forums. So I replaced the pump anyway and used loctite on the new pump's retaining plate as I do not ever intend on doing any maintenance on the pump itself; just assume replace it if a problem arises. The engine now idles around 30-40psi at idle once warmed up. Will need to test it under heavy load condition though.

The mechanic shop owner I referenced above gave me a helpful tip, if you suspect that you may have damaged the engine by driving it with low pressure and need to make a determination if you want to invest the resources to fix it, you can take the oil to a tractor maintenance shop and they can analyze the oil to determine if you have worn through the outer coating of the bearing and into the copper cores by the contents of material in the oil.

If you do the work yourself be sure to follow Subaru's procedure for compressing the idler pulley. Also be absolutely sure to put the timing belt on correctly as damage to the valves will occur.
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Sunday, October 14th, 2007 AT 9:12 PM

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