I just finished a timing chain service on a customer's 92 Corrado SLC. He
initially came in with a loud clatter from the driver's side of the engine,
which had him worried that he had something majorly wrong internally. The
sound and location made me think timing chains, and sure enough I was right.
I pulled the upper tensioner (located near the EGR, or at 2 oclock position
from oil cap on non EGR VR6s) and inspected it. There were score marks on the
tip which pushes on the rear chain guide. A visual inspection through the
tensioner bore with a dental mirror showed unusual marks at the contact point
on the back of that tensioner. I installed a good used tensioner and fired up
the engine, and the noise was greatly abated. However, I warned the customer
that it was most likely a temporary fix.
Sure enough, two weeks later, the clatter was back. To replace the affected
upper rear chain guide, the lower chain guard has to be removed, which entails
dropping the trans. Unfortunately, I had recently rebuilt his trans and
replaced his clutch!
Once the trans, intake and valve cover are removed, replacing the chains and
guides is straight forward (as long as you pay close attention to mechanical
timing). His upper guides were both shot, and the lower guide was also
cracked. He was lucky that the chains did not skip teeth and cause valve
During a conversation with a European contact, I mentioned the chain overhaul
and he said this was becoming a more common problem on the older VR6s.
Remember that Europe got the VR6 almost 2 yrs before we did, so they have a
jump on uncovering mileage related problems on these engines. From now on I
will recommend chain service to customers having their clutches replaced near
the 100k mile mark. SLC above has 102k.
Total chain related parts (guides, tensioners, double row 92-95 upper chain
and single row lower, rear main seal) is about $340, with an extra 3.5 hrs to
remove the intake and perform the chain service itself. Add the cost of
removing the trans, and this becomes a $1k job. However, if you're in there
already to do a clutch...
Air & Water
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