Know The Symptoms But Not The Problem

[icydude]

Ok so i have a 1990 r32 gtr and recently i have been having some issues,

Coolant overflow spitting out stuff

Compressor surge/turbo chatter what ever you want to call it but there is back pressure regardless, i have a single hks ssqv mounted on the stock bov with the other opening blocked off.

both the bov and the comressor surge are audible.

runs quite rich - on the dyno ran a 9.3:1 at redline

no coolant in oil so thats all fine

[mad082]

is the compressor noise on full boost, or just low boost. if it is just low boost then thats normal and can be taken out of the equation.

when you say the coolant overflow is spitting stuff out, you just mean there is coolant coming out? and is it coming out of the resevior onto the ground, or just from the radiator into the resevior?

[RANDY]

Every car i've seen or owned that has done the overflow spit, ended up having a dead thermostat in the upper radiator housing. The water gets pressurised and really hot, but it doesn't circulate.

You'd think it'd be more of a symptom of a dead radiator cap though, so perhaps change/check that first.

[icydude]

Thanks for the suggestions guys.

I am ordering a new apexi 1.3 bar rad cap to replace the .9 unit that is in there.

The turbo chatter is only on low boost but it still does not seem right.

Both rad hoses are hot and the water pump was replaced 8000 km ago.

Can it still be a stuck thermostat if im not overheating and both hoses are hot?

also the coolant resevoir is spitting the fluid out;)

Edited July 18, 2006 by icydude

[mad082]

ok the turbo noise is normal. it is caused by there not being enough boost pressure to hold the bov open. you can llosen the spring so it dumps properly at low boost, but it might leak a little bit at high boost.

also i wouldn't go too overboard with changing the pressure rating of the cap. it is there for a reason (like a fuse) so that if the pressure rises it lets the pressure out before something else gives. it could be that the thermostat isn't opening far enough, but is still opening enough to cool the motor down (since it is winter so temp isn't a major issue).

[icydude]

i pulled out the thermostat and hung it on water and heated it up

it open enough to drop off the string at 85

should open at 76.5

I will be replacing that because its cheap and easy.

Also the hks ssqv does not have an adjustable spring pressure.

the new version does not even have a screw on the back.

Thanks for the suggestions guys

I will try some out and let everyone know.

[mad082]

what shape is your bov? my mate has the same bov (latest model) and his is adjustable.

[IMACUL8]

Good start ould be to put the stock BOV's back on - seem to be a quality unit and cause alot let dramas.

[icydude]

what shape is your bov? my mate has the same bov (latest model) and his is adjustable.

shaped like all of them.

the original ssqv had a adjuster screw on the back but it did not change anything. It wasa design flaw by the makers as it would have been better without it.

The ssqv knows when to open and it does.

the new version doesnt have the adjuster.

Also i wont be reverting back to the original bov's.

Edited July 20, 2006 by icydude

[icydude]

well the thermostat got changed and that only partially fixed the problem.

there was no coolant spraying out but rad hoses did not have pressure.

The apexi 1.3bar rad cap solved the later problem.

Everything is working top notch.