Vilhuer

I know 16V engine cams tend to snap at front end when belt breaks but how common is that cam breaks while belt is good? Heard recent case were shop had fixed bad thread at cams end by drilling few mm larger hole and puting new threads and bolt in it. Fix lasted only few months. Failure happened while owner was driving slowly with low rpm. Autopsy will start soon and we should find out quickly if this 310 hp Euro S is interference engine or not. If you have used cams for sale please let me know.

FlyingDog

I'd guess they cracked it when drilling and it just came apart while driving. I'm interested to find out whether it is interference. Greg Gray has some newly reconditioned S2 cams for sale.

karl ruiter

I broke a 16V cam, but only after I had tensioned it without a tension gauge (at that time the current inexpensive gauge was not available, and nobody had them for rent yet). My theory is that this happens after the belt has been over tightened.

Imo000

This happed to a fellow 928 owner from the Ontario group. His car is an '83 US 16V and after talking to him, the only reason he came up with was that the t-belt could have been over thightened a bit. This and the fact that the driver side cam has a longer snout, cause the cam end to eventually crack and break off.

slate blue

Hi Errka sent you a PM, the 310 hp engine is interference. However you may get lucky. The engine I have just rebuilt, must have had a failure at one stage and the pistons had some slight marks near the cutouts. I would describe it as the valves kissed the pistons.

Cheers Greg

Cheburator

I concur - the S2 is of interference design. My 1984 S2 had a cambelt failure 500 miles after I bought it, whilst doing 120mph. 4 bent valves... Cost me GBP1000 to fix

k1woods

same, here - only 1 bent valve though...guess it depends on what position the cam stops and if the camshaft continues to turn. In my case the snapped cam (right) appears to be caused by a combination of an belt over tension and most importantly the bolt holding the cam gear was not torqued to spec.

- k1woods 84 S2

blau928

I had a similar failure, and got away with just replacing the cam and cam gear. GRANTED, IT WAS ON MY 32V....! 4,000rpm on the freeway.... Like I said, I got lucky..

I had a post a while ago on it with pixx.... It seems that the keyway might have had some corrosion and caused the cam to snap..

HTH,

drnick

my S2 had the cam break as well, the one on the passenger side during its previous owners time. valves bent as well.

Jim bailey - 928 International

The cast cams are very brittle and very easy to break. I think sometimes in removing the cam gears some one levers more on one side of the gear than the other and starts a crack . And we know for a fact that many times the belts are over tensioned which puts a lot of stress on the 5-8 cam.

Vilhuer

Patient is in operation and drivers side cam tower is out. Turned out workshop had put in shorter bolt than original and cam had snapped right behind cam gear. They did measure blowby and seems only one exhaust valve is leaking. Before the incident engine was in perfect health. Shop is paying the bill and cams and valves are soon on their way from down under. Thanks Matt for the tip.

FlyingDog

You're welcome. Nice to know the shop is paying for it and there is so little damage.