Oil Pressure Relief Valve Info.

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Jan 23, 2008
East York, Canada
In regards to the 2H, does anyone know if the oil pressure relief valves (located on the front oil pump case and on the oil filter housing) are identical?
Also are the two springs the same? Do they share the same part numbers?
No, they are different size. Been posted a heap of times. The one on the filter is a bypass valve in case the filter blocks. Buy a longer piston valve from Oz Ebay and clean up the housing ridge created by the old piston with some wet and dry. cheers
I'm on the fence as to whether or not I even need to replace mine. I know if you do, replace it with the improved, longer aftermarket one.
I have never come across any posts on the 'bypass valve' by the oil filter. I've read many posts on the relief valve on the front oil pump case.
I replaced the front oil pressure relief valve with one if them longer piston ones you mentioned because my 2H experiences high oil pressures when first started and cold. Oil pressure drops to a normal level after the engine warms up though. However replacement with the longer valve hasn't solved the high oil pressure on startup.
That's when I figured maybe it's the other valve by the oil filter. I had a fellow MUD member buy me a piston and spring from their Toyota dealership in Scotland because it was impossible for me to get one frommy local dealer. Anyways when I removed the plug by the oil filter I noticed the spring was not as heavy duty as the one in the front case. Also the piston looked a bit different from the other one. But the spring and piston that was bought for me was supposed to be the replacement parts for the relief valve by the oil filter. They look like they're for the front case because the piston I got is the same as the one that goes in the front and the spring is beefy.
So the parts I got must be for the relief valve and spring in the front!!
Any ideas now where to look at what's causing the high oil pressure at startup???
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Old 10-20-06, 03:19 PM #18 (permalink)
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Join Date: Apr 2005
Location: N.Q. australia
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Originally Posted by Beast View Post
There are 2 releif valves in my FSM. One above the oil filter and the other behind the power steering pump. Which one needs to adjusted?


Cheers Paul, It's the one in the oil pump behind the power steering pump. It is not adjustable. Also they are both different sizes and not interchangeable.You can change it with out removing the pump.After I removed the bung and springI found I could not get something in there to get the piston out so I just put a plastic bag around it and briefly hit the key and it shot out into the bag with a bit of oil. Be sure to clean the bore up before replacing it with a new one.cheers
I did change the oil pressure relief valve at the front case with one of the longer piston ones. I bought it from RooDogs 4WD in Australia. And yes I also replaced the spring with a new one. But like I mentioned, the oil pressure is still high at cold startup: ~90psi @ idle and >100psi @ 1500rpm!!
What else can cause the high oil pressure???
I did change the oil pressure relief valve at the front case with one of the longer piston ones. I bought it from RooDogs 4WD in Australia. And yes I also replaced the spring with a new one. But like I mentioned, the oil pressure is still high at cold startup: ~90psi @ idle and >100psi @ 1500rpm!!
What else can cause the high oil pressure???

Cheers, Did you clean up the bore in the pump housing so the piston does not stick on the groove worn from the old piston but sits straight? If you have done this properly it is most likely not back to normal because the bore in the oil pump housing is now oval shaped. If you look at the old piston you will see it is a small amount out of round however the housing bore wears considerably more being soft alloy. I would not stress too much about 100lb at start up especially in the cold place you live but the motor should drop back to around 80lb at 3,000 RPM when the motor is at normal operating temperature. Also buy quality oil filters as the cheaper filters have less material inside [cut one open for yourself] Toyota are best.
LOL look at the picture of my old oil guage it was way past 100 to get the pointer bent. One good thing to think about is if the filter splits/ bends or the O-ring blows the motor will most likely be cold and not catch fire LOL but it sure makes a big mess.:whoops: There were a couple of better threads but I could only manage to go back 40 pages on my posts.:D
I did look at the original 'piston' and it does have wear on one edge. I haven't looked closely at the housing though. I do remember that when I put the new longer piston into the bore it went in smoothly and didn't feel like it was getting caught up.
But even if the housing was worn and is slightly oval would this affect how the piston moves within it? The minimum diameter of the oval is still the diameter of the original piston and the widest part of the oval is slightly larger that the diameter of the piston. How can this cause the piston to stick? Also I have the longer piston installed now. And isn't the whole reason behind the longer piston is to prevent sticking even if the housing bore is slightly 'oval'?
As mentioned at cold startup the pressure is high and goes to above 100 psi as I'm driving until the motor warms up and then the pressure drops back down to normal. It worries me at times as I see my oil pressure gauge pegs. It's marked to 100 psi and it goes beyond that!!
I'm using original Toyota oil filters so I'm hoping they'll hold up to the high pressures.......
Yes, my pointer [see pic] went way past the 100lb and bent on the rest peg. Diesel mechanics Lintch [sp] the bore, I was told to do this so I did it to achieve the best possible result.
My thinking why this is done, the piston has a sharp edge at the top and two more at the groove this in the position of the old piston [see picture link above] what is to stop this snagging on the rough bore where it has been worn ,similar to a damaged cylinder sleeve or bore. MHO The piston is made longer for stability in the bore but a lip on the bore can still interfere in it's travel in and outward. Alternative buy a new housing I was quoted $850.00 several years ago. cheers

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