1996 Pontiac Grand Prix GTP
3.4 overhead cam
GM codes = had a purge valve issue, but was replaced
work done prior = resealed a oil leak at the oil pump drive shaft plug,
but didn't remove head or cam housing, just the intake. This was a
year ago, not related to this problem.
Work done to repair = The engine ate the timing belt for the 4 overhead
cams. The belt was replaced, engine started, but very noisy and
stalled, not to restart. Next the cylinder heads were removed. One replaced
because of cracks, and both completely rebuilt. At this time the o2
sensor was replaced, a complete tune up, starter, just a basic really going
over on wear items.
Tech = KK
question = Now with all the repairs made regarding the timing belt
failure. The engine now starts and runs with power. But has a very loud
buzz saw or chain saw noise coming from the front of the engine. I removed
the serpentine belt eliminating all the accessories. Removed timing
belt covers to verify timing belt is not rubbing. I'm a professional
mechanic by trade. I've work on Toyota industrial equipment for last 22
years. Not familiar with this 3.4, but with info can repair as to factory
procedures. Looking at a picture breakdown of engine, there's also a
timing chain and tensioner driven by crank to balancer shaft, which drives
timing belt. My gut response is this may be it. Could the destruction
of the timing belt damaged this chains tensioner, and now it's slapping
the cover? Or maybe you know this is something else. Due to the fact
these are difficult cars to work on, I don't want to repair something
that isn't broke.
KK:
If you have verified that nothing was rubbing on the timing covers, i would
have to say that i have not had a belt failure cause damage to the chain or
tensioner. I have however had several of the timing belt idler pulleys fail
and cause noises. Many times this is the cause for the timing belt to fail.
Spin each of the idler pulleys to listen to the noise. Of course this would
require removing the belt. Could also use a small pry bar to see if pulleys
have any play or seam to wobble. This can be done with belt still on.
3.4 overhead cam
GM codes = had a purge valve issue, but was replaced
work done prior = resealed a oil leak at the oil pump drive shaft plug,
but didn't remove head or cam housing, just the intake. This was a
year ago, not related to this problem.
Work done to repair = The engine ate the timing belt for the 4 overhead
cams. The belt was replaced, engine started, but very noisy and
stalled, not to restart. Next the cylinder heads were removed. One replaced
because of cracks, and both completely rebuilt. At this time the o2
sensor was replaced, a complete tune up, starter, just a basic really going
over on wear items.
Tech = KK
question = Now with all the repairs made regarding the timing belt
failure. The engine now starts and runs with power. But has a very loud
buzz saw or chain saw noise coming from the front of the engine. I removed
the serpentine belt eliminating all the accessories. Removed timing
belt covers to verify timing belt is not rubbing. I'm a professional
mechanic by trade. I've work on Toyota industrial equipment for last 22
years. Not familiar with this 3.4, but with info can repair as to factory
procedures. Looking at a picture breakdown of engine, there's also a
timing chain and tensioner driven by crank to balancer shaft, which drives
timing belt. My gut response is this may be it. Could the destruction
of the timing belt damaged this chains tensioner, and now it's slapping
the cover? Or maybe you know this is something else. Due to the fact
these are difficult cars to work on, I don't want to repair something
that isn't broke.
KK:
If you have verified that nothing was rubbing on the timing covers, i would
have to say that i have not had a belt failure cause damage to the chain or
tensioner. I have however had several of the timing belt idler pulleys fail
and cause noises. Many times this is the cause for the timing belt to fail.
Spin each of the idler pulleys to listen to the noise. Of course this would
require removing the belt. Could also use a small pry bar to see if pulleys
have any play or seam to wobble. This can be done with belt still on.
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