jams up while spinning over

[therigwelder]

I have a 2003 ram 1500 with 5.7l I just acquired, the PO claimed it needed a new flex plate and starter. After pulling the starter and looking at the ring gear I do not believe this to be true. We put the starter back in and got it to bump a revolution or two, but it hits a hard spot and jams up, stops spinning. I took a breaker bar and socket and turned the crankshaft, and it jams up unmovable tight, so I back off till its free again and spin the motor with the key and when it hits that jam up spot it just stops. I have repeated this back off and spin over several times and same result it hits hard and stops. what are the probable causes?

 

[barr0208]

sounds like it may be something internal in the engine

 

[therigwelder]

Yes,I assumed an internal but what are the usual suspects in the 5.7? Bent valves,timing components?

 

[barr0208]

Yes,I assumed an internal but what are the usual suspects in the 5.7? Bent valves,timing components?

you didnt mention how many miles on it but it could be a sloppy timing chain which could cause the valves to hit the pistons. have you tried manually rotating the crank ?

 

[therigwelder]

230k,is the 5.7 an interference fit motor?

 

[PolarisCobra]

I had a Pontiac that did that many years ago. It was the timing chain. I believe it jumped a tooth. I think valves that should have been open were in fact closed, causing the compression to lock the motor. Replaced the chain and gears and it started right up.

 

[Wild one]

230k,is the 5.7 an interference fit motor?

Yup,if the timing chain is sloppy or it's jumped a tooth,the valves will hit the pistons,and bend the valve stem quite often.