7MGTE Oil cooler relief valve question

[Negative Boost]

Hey, I was looking at the oil bracket on the 7M today and noticed that the relief valve has to be open in order for oil to run through the oil cooler and return to the sump. This seemed a bit wierd to me as i thought oil would've ran through the cooler all the time. So i thought that maybe the relief valve was temperature operated. But looking through the TSRM it has a spring in the relief valve which suggests its pressure operated.
So the relief valve only opens when there is x ammount of pressure, correct?
If so, does anyone know what that pressure is, that the relief valve opens at?
And if anyone can explain why Toyota have designed the system this way, that'd be appreciated.

Cheers
Sam

[pilot]

How does that valve work? it lets oil going through the radiator when there is high pressure or the opposite?

Cold oil results in much higher pressure figures than hot oil.

[Shifty]

Taking a bit of a guess here, but I'd say it's to maintain an appropriate oil pressure. If that valve stays closed until 'x' pressure is reached then the engine sees that amount of pressure and gets a good oil feed. Once that pressure is exceeded then the valve would open in part/full as appropriate and let excess oil flow back to the sump - closing up again as the pressure drops back to the desired level.

[pilot]

Shifty´s point of view might be correct too. Can you explain a bit more? does this valve by-passes the oil cooler?

[Negative Boost]

Yup, i think your right shifty. Once oil pressure exceeds x ammount, the relief valve opens and lets oil flow straight into the sump. But the thing is, when the relief valve opens the oil flows through the oil cooler first then into the sump. Why would toyota do that?

[ed]

its a low pressure oil cooler system

if it was full time open circuit then it would need to be a high pressure system

as it it, its a pressure bypass circuit (similar to the pressure bypass ball valve built into the oil pump itself). no idea what the bypass pressure is, but its up there. as shifty has already suggested, this preserves the operating system prssure. the gte blaock has a few pressure check valves, namely the pump, the cooler, and the 6 oil squirters themselves.

the system is pretty effective. i set up a gte block in the 61, and the cooler was always roasty hot after hard runs, but rarey got flow in sedate driving. seemed to work well...

cheers
ed

[Negative Boost]

Awsome. That explains everything now. Thanks guys.

Sam

[e30-323ti]

What are the pro's/con's of this type of setup Vs a high pressure cooler (say a thermostat controlled plate off the filter housing).

[AdrianS]

Thread Revival !

no-one answered these 2 questions :

... noticed that the relief valve has to be open in order for oil to run through the oil cooler and return to the sump. ....
does anyone know what that pressure is, that the relief valve opens at?

What are the pro's/con's of this type of setup Vs a high pressure cooler (say a thermostat controlled plate off the filter housing).

I would like to know if anyone has an answer to #2.

As I see it, the bypass cooler will cool the oil at high rpm, but not at idle, so when stuck on traffic, there's no oil cooling, as the oil pressure isn't high enough. This would also apply when cooling down after a hot run.

Major plus - the oil pressure drop across the cooler won't affect the system oil pressure. Also applies if the oil cooler gets blocked : no drop in bearing pressure.

Minus : the engine oil pressure is limited to the pressure the bypass valve opens at + the pressure drop across the cooler.

Big question : what pressure does the cooler bypass valve open at ?

I know the standard 4AGE oil pump bypass opens at 57 psi according to toyota, and someone tested it and got 64 psi, but I can't find anything about the cooler bypass pressure anywhere.

I'm interested because I have a 4AGE blacktop in an AW11 MR2 : some say the 16v bypass cooler will be fine, some say don't use it under any circumstances.

The BGBs give the same oil pressure specs for both motors, so it all depends on that bypass pressure relief, and whether it will rob the engine of oil at high revs.

I know about other oil cooler options; I was wondering if anyone had hard data on the OEM cooler system.

[mattysshop]

I'm interested because I have a 4AGE blacktop in an AW11 MR2 : some say the 16v bypass cooler will be fine, some say don't use it under any circumstances.

The BGBs give the same oil pressure specs for both motors, so it all depends on that bypass pressure relief, and whether it will rob the engine of oil at high revs.

I know about other oil cooler options; I was wondering if anyone had hard data on the OEM cooler system.

i've used the stock 16v sandwich plate setup (4afe ae92, same as twinky's) on a high revving smallport build.. no drama's.. it's still running 5 years on..

and NO valve/thermostate at all on a mates 3SGTE, with a 11 row aftermarket cooler with dash 10 fittings, and a remote mount oil filter in the line, all plumbed in a series.. again been running for 3 years like that.. no dramas..

[paradox616]

thermostat controlled is a good idea, but i believe toyota used pressure relief as it is more reliable.

if the cooler was open all the time you'd loose the desired viscosity of the oil as it cooled down.