Mike C.

Perhaps a defective belt? It sounds like you took proper care of things. Any sign of hot running before it happened? Water pump siezure would create problems. It is also possible that the B/S belt was the culprit - the debris often takes out the T-belt after the fact. From what I've read on this forum, the pistons are almost always re-useable. I wouldn't be terribly concerned with a ding on top of the piston. This doesn't seem like an area subject to high tensile stress (a guess), which is where fatigue cracks are most likely to start. You could try to blend the ding with a dremel tool but this might unbalance the pistons (piston wieght relative to each other)...

Peckster

That you know of. Sure there aren't any little tiny curves in some of the other valve stems?

If you only bent two you have horsehoes up yer **** and your car was probably idling when the belt went.

Scuba Steve

Mine was checked out by the machine shop. When the belt broke the PO stopped turning the engine because he already saw what happened the first time he broke it.

My pistons have met the valves twice and they have no marks from the valves on them. Odds are that yours would be ok.

Zero10

The pistons are very tough. I wouldn't worry about any nicks in the piston crowns if there are any. But, it's a goood chance to clean up the tops of your pistons =)

Best of luck to you in getting this sorted out.

Strange that it broke given that you seem to have kept up on the belt maintenance. Guess you just have bad luck?

Charlie944

Thanks guys for the replies and stories of relief about the pistons. I will be much happier if this pistons are OK. Mike: the car was running a stready temp of ~160F (1st mark on gauge) so no probs with H2O pump. Although like you said the Bal Shaft Belt could have been the problem. I'll see when I get in there, but first I am going to check the 83' just to make sure all is well with that given it is my mode of transportation for the time being.

Bad luck is definitely a possibility!!

Take care everyone and I will keep you posted, and again thank you for all the replies and encouragement!

Charlie944

Quick update: The Balance Shaft belt is still on and gave no problem. The T-belt has 9 teeth stripped off of it and in the middle of where the teeth were sheared off is where it broke. There was no wear on the sides of the belt causing it to thin out. Looks like something seized and sheared the teeth off and then snapped in two. I will post again with more info. BTW: I am borrowing a friends borescope so I will hopefully 'see' what happened to the valves without yanking the head just yet.
Please take care!!

Mike C.

A siezed tensioning roller ?

Bill

As others stated, pistions should not be an issue.

Do you have the updated water pump with the belt protection plate? Also check all your rollers as the bearings can sieze. The rollers should turn freely with no grinding or binding. I have seen guys change the rollers with every belt change, but this should not be required.

When you tensioned your belt was the engine dead cold? Rember that an aluminum engine expands at twice the rate as a cast iron engine (this is why our engines need a flexable belt in the first place). I personally did a test to show guys how important a dead cold engine is. I installed a belt for PorscheG96 as a favor. G96 was in a hurry and did not want to wait. I installed the belts on his engine after sitting for one hour. Perfect tension with the factory gauge. Then we went about our buisness. 4 hours later, we checked again. Belt was way, way, too loose. I spun the engine by hand, CAREFULLY, slowly, and it actually stopped on a valve. G96 became a believer. I personally never install a belt until the car has sat for 24 hours (so I am too carefull, better that the alternate).

Also your problem could have originated in the head or cam tower, but this is less likley. Valve guides can fail. Valve stems can seize. Lifters can seize. Valve springs can break. Cam bearings can seize. When the top end stops spinning with the bottom end, you are gonna spend money. Have all these items checked when you repair the valves. The higher your mileage, the higher the chances of these types of failures.

Since your belt did not reach its design service life (30k miles), I would not just blame belt stretch. Especially since you were so dilligent at maintaining it. Check for other problems in the system, one that would cause the belt to fail as an effect not a cause.

Markey552,

If you read the first post, he was in third gear at 3,000 rpm. That is a lot of stored energy. Remember physics, an object in motion, tends to stay in motion. Of course, Charlie944 will find out soon enough.

Charlie944

Update: I got a chance to tear into the car today after the holidays and there was no seized or even tight roller, tensioner, or H2O pump bearing to speak of. The cam and crank both spin freely. I am not sure what the root cause of this was, but the damage has been done. I through a used but good belt on, timed it all up, and investigated if I had compression or not. Result: I have no compression on cyls 1 and 2. I stopped there, seeings how I will have to yank the head. I got the intake off, fuel rail off, coolant drained, all belts off, and the cat-pipe free from the exhaust headers. Next step is to pull the cam assembly and then the head itself. Time for shopping, any suggestions on where to get a 'kit'. I am looking for a one-stop shop preferably.
Take care and I will keep you informed.

Charlie944

Anyone have a good source for factory head stud kit, or should I just go with ARP or Raceware?

Uranium-235

I got my parts through Vertex, www.vertex.com. Pelican also has many parts.

Bill

www.lindseyracing.com

They will have all the parts you need, and can do the machine work on your head. I sent them my 951 head all the way from California, they do first class work.

Charlie944

Update again: I got the head off, and hopefully will have pics to follow (need to borrow friends dig camera). All but the #2 Intake valve are bent. Headgasket was in decent shape and the only knicks in the pistons were present in the valve reliefs, and minor at that. I pulled the head with the exhaust header still on which was recommended by Tim Richards, and I highly rec. it!! Saves a ton of time. I just disconnected the cat-pipe from the header via a die grinder (for the rusted bolts) and voila! . Also I see no reason why the belt snapped other than the belt itself. I noticed on the ContiTech belts the structural cords are pretty visible from the underside of the belt, while the OEM Gates 944.105.157.04AE belt that was made in the UK does not have the cords showing. I will from now on go with the OEM belt for it is a small insurance that this does not happen again.
Time for some shopping, thank you all and I will keep you updated.

PaulStewart

Try ebsracing, they usually have everything you will need at a good price.

http://www.ebsracing.com/

These guys are GOOD! It's best to call them, not email.

father2nate

Click that link again, I don't think a software company will be selling us any 944 parts.