Where Has My Boost Gone

[nemini90]

Hi guys i hope you can help me with my problem.

I have a 25/30 setup running a 35/40 turbo 20psi.

i had a cometic head gasket go on me about 5000km ago so i removed the haed and had it checked with no faults found.

I replaced this gasket with a nitto one and have had no problems till last weekend. I was up it for the rent and things were all going good till i got of the power and then about 1 min later i went to get back on it and the car made no boost. first thing i thought was that i had blown a cooler pipe but this was not the case so drove the car home which was about a 90 min drive in last sundays heat (car did not get hot).

when i got home checked turbo intercooler but no problems. i then removed radiator cap to find it had very slight milky warter. i then tested the head gasket with a die tester and it was inconclusive.

so im about to remove the head and check gasket by my biggest problem is where did all my boost go i have had a gasket blow befor and the car still made boost but now i cant even make 2 psi.could there be something more serious i a missing. i have no blow by and car still runs fine of boost. any help on what to look for would be great. i will be testing the head again for warping cracks and all so crack testing the top of the block. just so you know it is all forged,drysump,head drains,vct,all bolts are arp,car is/was making 450kw on pump

Any help would be great

Thanks Neal

[SargeRX8]

Do a compression test, you will know if your headgasket is out. So when you flat foot it, no matter what rpm you are at, you don't make any boost? Can you hear the turbo spooling? if you can hear the turbo spooling, I would say the exhaust side is fine. IF the turbo does not sound as strong, loud and high pitched as it used to then you can assume that there is something wrong with the exhaust flow spinning the turbo. You can drop your exhaust, make sure you still have your exhaust wheel in tact. Damaged head gasket, you should be able to create some boost and see air in your water... I very much doubt that you will be losing ALL your boost through a blown gasket and all you are seeing is slightly milky coolant...

[nemini90]

this is what has got me stumped the turbo is fine form what i can see wheels are intact no damage an with motor running at idle blows air out the turbo outlet.

i tried to get it to boost and reved it to 5500 under load with only 2 psi of boost to be made it sounded like it was spooling so could it be somthing more serious with the turbo.i dont run a show of valve

[SargeRX8]

Compression test, you need to eliminate the motor from the equation.

[SiR_RB]

Blocked/melted cat?

Also possible head gasket probs

[Rolls]

Blocked exhaust/melted cat will stop it boosting.

[GTR260]

have u checked ur waste gate?

[nemini90]

ok an update on my problems.

i have removed the cat and muffler both are 4 inch there are no blockages with these i have checked the wastegate which it a 50mm turbosmart that is ok

all vacume and boost lines are ok and i have remove inlet which is ok aswell.so now all i have left is the motor. i know your ment to do a compression test with the motor warm but since i have removed the inlet do you think it will be ok to do the test cold. i will have to wait a few days to do this i dont have a guage have to borrow a mates.

[nemini90]

new update.

i comp tested the car so it was done cold with both manifolds off. 1=145psi 2=145psi 3=145psi 4=145psi 5=150psi 6=145psi

[zebra]

Blown a manifold gasket?

[nemini90]

yeah gasket is fine no water leaks or strange idle. and cant see any marks on the gasket where it has blown out

[zebra]

then I'd say the turbo is dead

any shaft play etc?

[nemini90]

no shaft play on turbo both wheels are in mint condition. i will be taking my turbo and wastegate to gcg tomorrow to have it looked at but i only had the turbo serviced 3000km ago

[SargeRX8]

Before you do that try an intake pressure test. If you can eliminate leaks and the motor, which you have, then it would be safe to say the turbo isn't creating boost.

[Rolls]

Before you do that try an intake pressure test. If you can eliminate leaks and the motor, which you have, then it would be safe to say the turbo isn't creating boost.

also drop the exhaust

[nemini90]

new update

i checked everything external of the motor it all came up good i have removed the head and sent it to my workshop ill wait to see what they have to say befor i pull the block down and have it tested

also i found a lot of oil in the water jackets