Today my 1995 850 turbo would not rev over 2700. Turbo appreared to have no boost. After running 10 miles (at 20-30 mph flat out), I let it sit for an hour, and everything worked. Had to drive through a blizzard yesterday. Any ideas what went wrong, and how to prevent it in the future? Doug
My 91 940 did the same thing about a year ago-I inspected the intake and found a tear in a hose and not much else. After putting it all back together, everything was fine until last week when it occured again. This time the turbo is seized up and I am looking at repair options. I am unsure if this is what happened earlier (although obviously in a temporary fashion) but perhaps check to see if anything may have become dislocated into the turbo itself. Look for worn or torn hoses, etc. You might also check the oil lines to the tubro for blockage.
I'll bet it was really cold where you are as well. Believe it or not, enough water can get into the bottom of the intercooler and completely block the air flowing into the engine. I can't explain why, but a clean PCV system prevents this from happening. This consists of the oil trap under the intake manifold and the hoses that are attached. The oil trap isn't really cleanable, the only option is to replace it. Also make sure the heated nipple where the hoses connect to the air intake hose at the turbo inlet is clean. Volvo even has an expensive heated PCV system kit to cure this problem.
To see if this is your problem, next time it happens, open the hood, rev the engine and watch for collapsing intercooler hoses.
On the bright side, this doesn't actually hurt anything, except maybe your punctuality.
To prevent this, put in a new oil trap and PCV hoses. Flushing the intercooler with solvent helps as well. Make sure the drain hole in the bottom of the intercooler is free.
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