mazdaverx7

As many of you have read, I have been repairing an 86 that I bought with bent valves. Turns out that all 8 valves were bent. In taking it apart, I found no obvious signs of failure in either belt or any of the tensioners. The belts were all tensioned properly but the timing belt had somehow jumped time and cause catastrophic results. Once I put the freshly rebuilt head on, I decided to take a look at replacing the seals in the cam box. Going through the procedure for disassembly, I found this:





It appears as if the cam sprocket shifted on the cam itself and allowed the timing to become misaligned, thus causing valve and piston contact. I'm not sure at this point what I will have to replace. Maybe just the cam sprocket and woodruff key..maybe the entire camshaft. I'm having issues getting the woodruff key out and removing the sprocket. Any thoughts on this damage?

Fara

That is honestly the first time I've seen that failure point on any car.
I have to assume that something in the valve train seized to cause a failure of that nature.

Not much I can really suggest for getting it off rather than more force (slide hammer) or some freezing spray on the end of the camshaft.

Once you get the cam out, I'd be interested to know if you can find the source of the damage.

lart951

You might need a new camshaft and cam gear as well
I'll can do both for $74.99 shipped in excellent condition.

mazdaverx7

Sent you a pm lart951

fejjj

LART FOR THE WIN....Again!

konakat

I would just replace the whole head at this point. You have no idea what else might be wrong, plus it would be way faster to just do everything as a whole unit. Might end up being cheaper too.

mazdaverx7

Here is another angle of the damage:

HICKS

I wouldn't even try and pull that, complete cam towers are a dime a dozen.

mazdaverx7

I already had the entire head rebuilt. That part is covered.

lart951

yup

ramius665

Dougs951 and I parted an early 944 that the PO claimed suffered from a timing belt failure. After getting the engine out of the car, it was clear 1) the timing belt was intact 2) it had mechanically over-revved. It was quite the sight to see a valve head broken off that had flipped over in the combustion chamber and then slammed into a piston. Punched a dime-sized hole into the piston head and split the cylinder.

Van

What does the key way of the "nut" (distributor drive) look like? I have seen similar key-way damage when people don't know about the cheesehead bolt and try to "unscrew the cam nut".

mazdaverx7

I'll post some pics of that. The cheesehead bolt was finger tight. I took everyone's advice and got a new one on order fearing it may be extremely tight and may strip the hear and that its a stretch bolt, etc. I put the cheesehead bit in and tapped it lightly with a hammer per the Clark's Garage instructions, attached my ratchet and there was no resistance. At first I thought that the bolt was broken. It threaded right out and I placed it on the work bench. Right then and there I knew something was not right.

cruise98

The keyway in the cam does not look good. I would just replace the cam and sprocket. Chalk it up to previous bad mechanic work.

sstrickstein

5 years ago when I bought my 86 944 the belt system failed. It did this because when I replaced the seals on the cam I over tightened the nut and cheese bolt and fatigued the nose of the cam. If it looks bad replace everything. Its too costly in time and money at this point to not. As of today I have another 60000 miles on the rebuild. Still running and autocrossing strong. A rebuild is the best way to start. That way YOU know what to expect.