TJ

I have been having this sound for a little while. At around 3000 rpm, there is a noise like a long sqeak of some kind (best description I could think of) lasting around a full second or two, depending on how fast I am accelerating. I thought that it might be the wastegate surpressing the increase in exhaust gasses because it usually happens right around 1 bar when the boost starts to build. However, I talked to someone else who said he saw something similar on a post on rennlist. I have had no luck finding it. He said that it was the oil pressure sending unit making the noise. Anyone have any thoughts on what it could be?
Thanks for your time.
-TJ

Chas

I am assuming by 1 bar of boost, you are talking about atmosphere (1 bar on the stock vdo dial).

If this noise only occurs when you are accelerating just right (right when you start to build boost...I would start to point fingers at the turbo and plumbing. The turbo can make some fun noises as it starts to die. I suppose a really blown BOV could squeak as you start to apply pressure to it.

if you very slowly accelerate (as not to get the turbo spinning) to 4k rpm, and then kick in the boost just above atmosphere, can you recreate the same sound?

rcldesign

I had a similar problem. For me it happened if I held the boost right at where the wastegate would start to open, and I could get a nice long squeak out of it.

TJ

Chas,
I have tried to recreate it at other areas in the rev range and different conditions. It only occurs at 3K, and it happens in every gear. THe sound can be really long if cruising at around 70 at 5th on the highway and just ease on the gas, not accelerating hard. Accelerating hard, noise is still there, just not as long. As soon as it gets a few hundred rpm above, it goes away. I also want to clarify that the sound only happens when I accelerate.
I would really hate it to be the turbo, cant afford that right now.
Thanks for the help.
-TJ

AlexGlacierBlue

I had a very similar problem with my '89 at exactly 3000rpm. Turned out to be one (or more)of the timing belt/balance shaft belt rollers. Had all the rollers changed when I changed the belts and the noise went away.

TJ

I had the all the rollers and belts changed about 5K miles ago, and had them retensioned about 3K miles ago. It could be that, but unlikely.
Any more suggestions would be great. THanks for all the help.
-TJ

Chas

T3, sounds like the wastegate. Is it the original? How many miles?