Crankshaft pulley turns but not cam

My daughter was driving her 88' accord and when she stopped in the
driveway, it would not start later. When cranking it, it sounded like the
timing belt had broke. I pulled off the cam cover and the belt was still
in place. When I cranked the engine the crankshaft turned, but not the
cam. I tried turning the cam with a socket,but had no luck. I pulled the
gasket cover but could not see anything out of place with the valve
springs, etc. Any ideas what is going on?

 

If the bottom end spins and the top doesn't, then you are missing some teeth
on the belt somewhere (in the very least). What caused this could have just
been age of the belt, but something could have locked up too. The camshaft
is one of the last things to get oiled, so if you run low on oil, you can
seize the shaft in the journals in the head. Also, a locked up distributor
can keep the cam from turning.

 

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Take the distributor cap off and inspect inside for the infamous 'red
dust'. If the distributor bearing siezes up (usually very loudly) it
will shred the TB if not treated, because it puts so much load on the
camshaft. Do a google groups search for 'honda red dust' if you need
more info.

'Curly'

 

The teeth have stripped off the timing belt at the crankshaft.

When you shut down, the engine kicks back a bit as it stops, stripping the
teeth off. Normally, this happens because the belt is very old. But as
motsco says, you may have a seized distributor, which would also lead to
stripped belt teeth.

However, the fact that the cam won't turn could just as easily have to do
with bent valves as with a seized distributor. Considering that it's
ordinarily 1992+ distributors that are prone to the "red dust", It's
possible you have valve damage.

Do not drive this car or attempt to start it until the problem is resolved.
You may do even more damage to the valves, if you have not already done so.

 

i'm guessing the cam bearings seized. even if you had bent
valves the cam would still turn. you might move the crank some and
try again. If you get the cam to turn you can run a leakdown test
with no timing belt. May save some time and money.
Chip

 

cam won't turn if the op has pistons at t.d.c. ensure crank is at 90
degress from t.d.c., then try turning. if it's still locked, remove
distributor. if it's now free, the problem is diagnosed. if it's still
locked, the valves that touched the pistons when the belt broke have
bent stems & they're locked in the guides. for an 88, the cheapest
repair is to get a replacement head from a junk yard because if the
valve guides are damaged, it's a lot of work & requires special
equipment to replace them.

 

"jim beam" wrote

It's possible but rare. It's possible to move or rock slightly at TDC.

I once found a cam stuck with no movements. Turns out someone used the
wrong torque and bearing on the cam. In this case the timing belt shatters.