Interference diesel engine

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Question about an interference diesel engine.

If the timing belt is removed, would the engine still be able to rotated or will it stop when pistons contact the valves?

When a timing belt breaks, engine goes a few more revolutions to chew up the valves, would it be easier to rotate the engine without camshaft turning?

I ask because I looked at an Isuzu I-mark diesel fastback w/ auto trans. 0 compression in #1. I rotated the crankshaft a few times and there was no resistance. Turned the camshaft a few times, still no resistance but noticed the cam sprocket would move a bit once while rotating crank.

Sounds like its blown. Since it's an auto, the engine would have stopped quicker than if its a manual, = less damage?

Thanks for your feedback.

Mike
 
The cam's going to want to rest with the valves, at most, half open. The springs will force the issue. If so, the pistons won't kiss like they would at full-open. Of course, coast-down is going to get the top and bottom out-of-phase and smash stuff.

AFAIK all diesels are interference design; they have to be to make enough compression.

How are you rotating the cam? Is this half apart? Someone else ahead of you gave up already, it seems.
 
After one revolution any interference valve (intake or exhaust, or both) that is open (remember that the cam is not turning so the valves that the cam has open will remain open) will have hit the piston and will be damaged.
 
Even without interference the cam will have some intake and some exhaust open, so that there will be 0 compression on the cylinder(s) that happen to have an open valve (open because the cam has caused it to be open). There may be no damage if it is not an interference engine, but there will still be 0 compression on the cylinders that the cam has caused a valve to be open. In this case, you would not have to tear the head(s) off, all you would have to do it repair the cam drive (chain, belt, or gears) and the engine will run fine.
 
More than likely valve stems were bent if the belt broke. As for rotating the crank, you will be able to turn the crank until a piston fetches up on an open valve.
 
If it's got bucket lifters it'll have a broken camshaft, in at least 3 places. With rockers maybe they'll break and save the valves if there is enough clearance between cam and valve stem...otherwise the valves will be toast. They don't bend valves, they are vertical, so the valve sorta gets squashed. The only safe belt drive diesel is a pushrod engine, then they just bend pushrods.
 
So it would be safe to assume all the valves are squished (if they open straight up and down) and the pistons may be OK?

It was towed to a shop for diagnosis that said 0 compression in #1. They didn't button everything up.

Turned the camshaft a little, rotate crank a full revolution and felt no resistance, saw the cam sprocket turn slightly on its own. Think maybe that was from slight valve-piston contact?

I didn't go any further and walked away after hearing his asking price of $1000-1500. Nobody wants to trade a running truck for this car.

Back to scouring craigslist. Thanks everyone for feedback.

Mike
 
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