CA18DET Overboosting problem

[CAE86]

Hey there,

As the topic says, I have a CA18det in my sprinter, and when the temp gets warm (up around 90+) The car starts to overboost (usually 8-9psi but goes up to 20psi) Anyone know what could be causing this? I was thinking it may be the boost control solenoid as it is sitting close to the turbo. But if anyone else has any ideas, please let me know.

Thanks,

James B

[upgarage]

thats a strange one
check the actuator line for leaks

[CAE86]

Cool, will check that, also, any idea what would cause a sudden rise in oil pressure? When I first got the car back, it wouldn't go over 60psi, but now it can go off the dial (100+) when i give it some.

[mattysshop]

wow.. thats a bit more than a little boost spike!! holy shit http://www.ae86drivingclub.com.au/forums/emoticons/smile.gif have you serviced it?? i have seen oil pressures around that befor on a cold day in my old celica nice thick oil gave it phenominal pressure, but once warm would only go to about 4/5 that, and come back down to around the 40 mark on idle..

[psi_72]

a mate of a mates 180 was doin that the boost was sittin around 16 psi i think and it was when it got warm i think it was the turbo manifld had a crack in it or somethin and when it got hot it opened the crack and thus got worse each time he drove it. It got to the point where it detonated! but im not 100% sure if it was the manifold or not i will try and find out.

[upgarage]

if the turbo manifold had a crack, i thought the boost would drop as there is less pressure to spin the turbo

[CAE86]

I think I have found the boost spiking problem. there is a small outlet on the front of the turbo that is supposed to have a hose plugged onto it and it didn't. Have put a plug on it, and as yet no boost spike, but am more worried about the high oil pressure at the moment. Anyone know where the oil pressure relief valve is(or oil return valve)? (with pics if possible) I think that might be the problem

[upgarage]

re: the oil pressure problem
where have u run the two breathers on the cam covers?

[CAE86]

one breather is running to the standard location behind the inlet manifold, the other is currently venting to atmosphere. I found out today that it should be going into the inlet pipe just before the turbo, which should hopefully fix the problem. If not, then I'm gonna have to check the pressure relief valve in the oil pump. Anyone know if it the valve is internal or external?

[Gilly]

my guess would be internal in all pumps i,ve seen you have to pull the pump off to play around with the pressure relief valve, which unfortunately means timing belt off which you don't want to put back on wrong!