Expert: Sean Halliday - 11/23/2007

Question
Hi, I own an '89 Subaru wagon, (manual)  and have recently had a knocking
noise coming from the engine.  A subaru dealership mechanic did a
diagnostic and told me it is the crankshaft, which would require an engine
rebuild, more than the value of the car.  The knocking noise follows the revs,
it gets louder and quieter randomly, but is always there.  The car doesn't
suffer in performance (highway speed, hills no problem).  The dealership told
me that I shouldn't drive it at all, then tried to sell me another subaru with a
trade-in on my current car, so I'm a little sceptical.  If it is a crankshaft
knocking, can I drive it?  Could it be something else??  Is there any way for
me to assess this before I drive the car a long distance??  Thanks for your
time.

Answer
The symptoms sound like a worn main bearing on the crankshaft.There is no way to tell how long it will last but it isnt good to drive, as it eventually will let go and most likely seize the crank or blow the rod through the side of the block.Although it may be the crank,it could also be something such as the power steering pump or water pump bearing which i have seen before, so best way to check is take off all the belts and start it up for a few seconds and if the noise is there then its in the motor,i.e.the crankshaft.So,sorry but thats all i can tell you.I assume there are a lot of miles on the motor?This bearing failure occurs usually around 150000,miles on these cars.Depending on regular oil changes and maintenance.