4.2 DTS turbo about to die?

[Steve_GQ]

Here's a tricky one. When accelerating in the higher gears as the boost starts to build, it feels as if the turbo is spalling(binding up) for a second or so, then as the exhaust pressure builds it forces the turbo to spin up.

It doesn't happen all the time, only randomly in the first hour after starting or under heavy acceleration. But after an hour on the highway its pretty constant.

Symptoms
- Boost guage flatlines ( stays at a constant pressure, usually around 6 psi) for a second or so
- EGT 's continue to rise
- Engine continues to accelerate, although a lot slower


When i replaced the clutch a while back, i had the engine out. I had a look at the turbo and noticed that it was tight to turn by hand. Any how hoping for the best, it went back in and has worked fine for 12 months.

other info - Turbo has been on since 1998 (don't know odo reading)
- Odo now has 190 000 klms
- Max boost is 17 psi waste gate has a heavy spring added

One last thought, the boost has always been very linear (raises with revs), it won't reach full boost untill over 3000 rpm, maybe the turbo has been on the way out since i bought the truck.


any ideas guys

thanks steve

[B.D.R]

Check you're shaft play, if it is exsesive, then it will be time for a rebuild.

It was more cost effective to get my T3 highflowed than do a rebuild, so it might not be all bad

[macneil]

check all the bolts on the turbo are tight and there is no cracks in the dump pipe.. my old rx7 had a crack on the back of the turbo where is leaked and did the same sort of thing

also take a intake pipe off after the turbo there shouldnt be any oil in it if there is probably bearings/ shaft play

[busman]

What size exhaust? On my DTS kit the exhaust was updated to 3 inch but the DTS dump pipe was 3 inch then goes down in diameter to match the standard exhaust, whoever did the 3 inch left the standard flange causing a restriction. I had similar symptoms where my car would stumble for a split second and then pick up again. After i made the exhaust 3 inch all the way through the stumble was gone.

[Steve_GQ]

the dump pipe is a DTS i think, from there on is 3 inch no mufflers.

there is a little oil film in the intake pipe, i thought this was normal.

IF the turbo is had it, whats the $ damage for a new DTS one or a ball bearing one that will fit the existing flanges