Hey guys, long time no post for me, actually over a year I think, anyways going to see if you guys can help solve a puzzling sound I have. I have a 1989 F250 4X4 5-Speed SCAB, it has a NON-wastegated ATS turbo on it, fuel turned up alot (coal until boost then light/medium black) and 229,000 miles currently, when I am getting up to speed (think getting on freeway, floored, max rpms each gear) when my turbo finally spools up around 2,200 RPMS and I get boost (empty about 3-4psi) the turbo makes a funny chirping noise (think crickets on coffee) that comes from the engine area AND exhaust, it has been doing this since I have owned the truck going on 5 years and 29,000 miles now so if it were a turbo or valve going bad I think it would have self destructed by now. I am just curious as to what it may be, it is also VERY loud when following my truck for my friend behind me in his car can hear it when I go up a hill to my house (cause of boost). I have no intake leaks, and no exhaust leaks that I know of, 6,000 miles ago I did an Auto-RX treatment (and an oil filter every 1,000 cause they plugged up) and now it doesnt burn/leak any more oil (I know ALL engines burn oil but this thing is now below using/leaking 1/4 quart every 2,000 miles I consider that no oil :P ) Thanks ahead of time for your help!!!! Oh and always tie your loads down in your trucks, you wouldn't want to make someone crash their car now would you? (Check my gallery)

 

Bump...........I know most here don't have diesels but any ideas would be great and MUCH appreciated.

 

Does it have a recirculation valve?

 

EGR? No, just a CDR valve (PCV like)

 

No. A boost deverter/recirc valve

 

Whats that? Never heard of that before, whats it do?

 

It regulates boost pressure. Otherwise you would get 44 psi at full boost. It diverts boost pressure back into the air box rather than into the intake on regular turbo cars and trucks. But then again they also have wastegates.

 

I dont think it has one, I dont see anything mechanical at all on the turbo, just the turbo and piping, nothing like a bypass line or anything that I can see (dont have a plastic airbox, just the housing with the filter all cast aluminium) maybe its integrated with the whole housing? When the truck is loaded it is louder AND it is completely different than the turbo whistle.

Normal boost (no load, flat road) specs are as follows
0 PSI until about 2100RPMs
1-2PSI until around 2600RPMs
3-4PSI until around 3000RPMs
5PSI steady up to 4100RPMs

Under load boost specs
0 PSI until 1700 RPMs
then it jumps fast up to 6PSI until about 2300RPMs
after that it climbs to 13-15 PSI and stays there until 4100RPMs

 

do you have the stock muffler on it? Cause if you do it might be plugged from soot and cause a lot of back pressure on the turbo. We had a truck do this and it made a sound like what your describing i think. We straight piped it and it went away.

 

Hmmmmmmmmmmmmmm I dont think its stock BUT it has been on there since I have owned the truck, did the stock ones have a small outlet pipe? Mine is about 3 inch now but I would bet is at least 6-7 years old.......or older. I will make a video of the sound tomorrow and email it to all who want to hear it.