Cam pin

[P0ZBURN]

I have a 3.1 v6 vin "M". I starting having a small knock in the engine that sounded like a exhaust leak. The knock got way worse in hurry and the engine died. I checked compression and have zero compression on all cylinders. First I thought the cam broke, but I have oil pressure while cranking the engine. I looked in the spark plug hole of #1 and can see the valves moving up and down. Does the cam have a dowel pin for gear alignment or a key on the shaft? Kinda confused what could have happened like maybe the cam gear jumped tooth? Any help appreciated Thanks.

[1988GTU]

Pull the valve cover and crank the engine over watching all the rockers. Do they all move in harmony? If not, you snapped the cam and the oil pump is tied into the "rear" of the engine. Even tho the chain might move, the pump side will be dead.

[P0ZBURN]

Thanks for the quick reply. I haven't taken the valve cover off yet, but I did look in the oil fill and the two rockers I can see are moving. I looked in #5 cylinder and those valves are moving as well. If I have oil pressure then doesn't that mean the cam is turning right?

[1988GTU]

The cam has to turn to build oil pressure.

If nothing is broken, you might have hydrolocked the engine from a failed lower intake gasket and bent the valves.

[carbon]

Wouldn't that be bent rods?

[1988GTU]

The valve train could have experienced irreversible damage.

[P0ZBURN]

Is this a interference engine?

[1988GTU]

yeps

[3400-95-Modified]

There are very few non interference engines these days.

[Guest]

To answer your question, yes there is a dowel pin on the cam. Being a genIII 660, if the pin breaks or backs out (I've heard of both happening) the cam gear could potentially spin and change the cam to crank timing, that would result in little or no compression built. If the change is severe enough the valves could be damaged as well.