Swapped in a rebuilt motor - low oil pressure

[SC61 MK3]

Well I purchased a 7mgte that just got rebuilt. I got it for a good price and needed a motor asap because this is my only car and I was moving in a few days. I got the long block and everything looked good it has a mhg and arp studs. He claims that the crank was cut and new bearings were installed. Well I swapped in the motor and everything seemed fine. I was obligated to drive about 230 miles to help my girlfriend move her stuff out and another 250 miles to our new home. I had no other choice but to drive the supra the day after i swapped in the motor.

Well the only problem I have is the oil pressure, after the oil fully warms up at 2500 - 3000 rpms the pressure is only slightly above the 20 psi mark, I'd say somewhere between 25-30 psi. I was running 10w30 and didn't like the oil pressure so I pulled off the highway and bought some 10w40 and changed the oil in a parking lot. The 10w40 is still the same just above the 20 psi mark at 3000 rpm. I was worried about the low oil pressure but it made the 500 mile trip split into two 250 mile drives just fine.

So I have looked around and it could be the valve that opens at 40 psi in the oil filter head is stuck open. If I start the car with the line to the oil cooler off nothing should come out until it reaches 40 psi correct? I am going to try this first, Anyone have any other ideas?

 

[nosman4]

If you are worried about that valve being stuck open, I think it would be easier and less of a mess to clamp the hose shut and start the car to see if it makes any difference. Just an idea, I would hate to have to clean up that mess when I was done.

 

[SC61 MK3]

well i would just put the hose in a bucket and not let it drain on the floor lol

 

[sogi99]

I had that same problem before what oil filter are you using? I swapped to napa gold filter and put some pennzoil 10-30 platinum that did the trick for me at least. just my 2 cents

 

[SC61 MK3]

its a new Purolator oil filter the blue one

 

[viper92086]

i wouldn't trust ur stock guage if thats what ur using. my stock one is off. it wont go any higher than 40psi. i'm getting a new one soon. what happened was when i went na-t i dropped the sender. so perhaps urs is messed up too?

 

[spoolint78]

^^^ get an aftermarket gauge as mentioned.
The stock one is not accurate.

 

[897mgte]

quick ? are u using synthetic oil or just regular oil ull want to use a good synthetic oil

 

[Zumtizzle]

So I have looked around and it could be the valve that opens at 40 psi in the oil filter head is stuck open. If I start the car with the line to the oil cooler off nothing should come out until it reaches 40 psi correct? I am going to try this first, Anyone have any other ideas?

Ditch this and go full temp based and then let us know.

Deja Vu?

 

[figgie]

The stock one is not acurate?

Please explain (and notice who is asking that question!).

 

[Poodles]

Stock one is accurate...if a bit slow like the boost and fuel gauges.

10w40 is going to nothing but make the situation worse if the valve is bleeding off pressure too early.

Read the oil section of the forums before replying please...

 

[SC61 MK3]

if the bearings tolerances were off would it have made the 500 mile trip ok?

I have not boosted it yet just slow driving

 

[FullNelson]

So if the valve is opening at 40 psi, how would it being routed affect the pressure? Either it would drop, and the flow to the cooler would be cut by the valve. Or the colder oil would give you a higher psi in your oil? The only wy you would loose pressure in the oil cooler circuit is if it had a leak in it. So to test it you would park the car and raise the oil pressure (with the gas pedal) to open the valve. It should pass the test unless your car just puked oil.

 

[jdub]

So if the valve is opening at 40 psi, how would it being routed affect the pressure? Either it would drop, and the flow to the cooler would be cut by the valve. Or the colder oil would give you a higher psi in your oil? The only wy you would loose pressure in the oil cooler circuit is if it had a leak in it. So to test it you would park the car and raise the oil pressure (with the gas pedal) to open the valve. It should pass the test unless your car just puked oil.

Boy...you sure got this one wrong

The oil cooler circuit does not function till the valve relief pressure (40 psi) is met...the spring will keep pressure at least at that psi. If pressure drops, the valve closes and oil stops flowing through the cooler circuit. If the valve is stuck open, that means this regulating effect is lost and oil flows through the cooler circuit at a lower psi...effectively causing a pressure bleed.

The same type thing can be caused by the oil pump relief valve or the oil squirters in a turbo motor stuck open (they function at ~40 psi as well).

 

[CTsupra]

Was the oil pump rebuilt with this rebuilt motor? A tired pump may also be the culprit.

 

[FullNelson]

Boy...you sure got this one wrong

That did run through my head, but i think my head was in the clouds during that post and anything seemed logical. ::dunce::

However, what sorta psi are we talking about being dropped through this cooler? Everyone can recite the pressure drop for thier intercooler, but how about the oil cooler?

 

[jdub]

The problem with the stock cooler circuit is it empties to the pan, so whenever it's working the oil running through it contributes nada, nothing, zilch to pressure in the motor. That's the purpose of the relief valve...keep pressure inside the motor at least 40 psi.

That is exactly why one of the 1st things I do with a 7M is convert the stock cooler routing to a full flow, thermostat controlled circuit. That alone will garner you a pressure increase, especially at high RPM.

 

[supraguy@aol]

I have a similar problem with my setup- low oil pressure after warm-up. roughly 25psi@2800 rpm cruise. I have removed the oil filter mount, and have a 7mge oil boss in it's place, and so that's not the issue, and I shimmed the oil pump spring by about 5mm. I have only put on about 500 miles since rebuild, and no problems other than the low pressure. My plan is to pull the motor, replace the oil squirters and oil pump, and check the condition of all the bearings.

 

[Poodles]

No oil cooler?

It's all but required on a turbo motor since oil flows through the turbo. You're probably getting the oil too hot.

 

[supraguy@aol]

I have a full thermostatic oil cooler circuit, but I left it isolated for the breakin period(and I haven't been boosting much during this time). I didn't have an oil cooler circuit at all on the last 7MGTE, and the oil pressures were very normal on that one.