Turbo Problems

[RJM3]

Can anyone help?My turbo boosts to .4 bar then makes a high pitched sound and boost drops to 0. ..no smoke....Engine runs fine other than this. checked hoses and o rings and checked cool side impeller still rotates?Any thoughts would be greatly appreciated..thanks jerry mccabe

[beagle911]

Have you checked out the wastegate? Could be opening too soon.

[RJM3]

Originally posted by beagle911:
Have you checked out the wastegate? Could be opening too soon.

Thanks but the wastegate was rebuilt about 6 months ago??? I'll take it apart tonight and see...thanks any other causes???

[beepbeep]

Check out pop-up valve that recirculates air around compressor on decceleration. If it's open you'll get no boost and turbo might overspeed, resulting in catasthropic shaft-failure.

First of all, detach rubber hose going to compressor-part and try to spin the shaft with your fingers. If it spins and doesn't have lots of play, turbo is OK.

Then check out all hoses for rupture/leak, the popup-valve.

Good luck!

[machintek]

My turbo rebuild experience is limited to a unit on my 1964 Corvair Spyder but it sounds like there may be too much clearance in the oil pressure bearing or insufficient oil. It sounds like a chatter where the shaft is oscillating inside the bearing and then stops rotation. But it will spin freely for you by hand. If my memory is correct, it turned about 18K at idle and went up to 80K at full boost. I would be curious to know what you find. A good machine shop can help you measure all the components.

George
83 911Sc Cab/Euro

[RJM3]

Originally posted by beepbeep:
Check out pop-up valve that recirculates air around compressor on decceleration. If it's open you'll get no boost and turbo might overspeed, resulting in catasthropic shaft-failure.

First of all, detach rubber hose going to compressor-part and try to spin the shaft with your fingers. If it spins and doesn't have lots of play, turbo is OK.

Then check out all hoses for rupture/leak, the popup-valve.

Good luck!

COOL THANKS FOR THE REPLIES...While digging on the hot side of the turbo I found the impeller to be scraping the cast iron housing causing the groaning noise ...I caught it just in time >>>thanks for all yor help....Get my wallet out...ouch!!!!!!!!!