Technical turbo boost probs help pls

[Timoracing]

Hi we have a mk1 turbo which is boosting for about 3 miles then looses boost and a howling noise comes from turbo.If you stop car switch off and wait ten mins the car boosts then 3 miles later does the same.

Any ideas pls someone has fitted a bleed valve we have tried turning both ways but it makes no difference .

 

[HP]

First thing I'd do is remove the intake piping and feel the compressor wheel for movement, check to see if the bearings are worn and it's catching the housing.
Disconnect the bleed valve and see if you can get it running in standard form first, then have a play with the boost.

Have you got the right amount of the right grade oil in, is the engine oil pressure ok?

 

[SteveNZ]

Remove the bleed valve and connect the actuator as factory. check the that actuator is secure and no loose on the wastegate, Give that a try. Does it make any noises? exhaust leaking etc?

 

[sumplug]

check for a blockage.it maybe takes three miles to suck the object in.when you stop it falls out again and so on.or it maybe overheating on the turbine bearing.check turbine,spindle and oil feed.

 

[LuiPoland]

If you stop car after boost looses, check wastegate, it could jam. Maybe turbo is overheating.

When engine is running check hose with coolant from turbo, when coolant doesn't flow its means that is somthing wrong with turbo cooling system