almost seized 2.7..ideas?

[exhaustfumes]

1977 2.7 with low oil pressure, but runs OK, no noises/knocks/rattles. park it one night, next morning starter won't spin motor. check out starting circuit, all OK, even try a new starter, still not one degree of rotation. try spinning engine using crank pulley nut, and it's stuck. add a cheater bar to this wrench, still no movement. try like heck, and it just won't rotate.

so, i drop engine and trans, and try spinning engine with impact wrench on crank nut. nothing. then while stripping it all down, and removing the pressure plate, the engine turrns!! wow!! i tried spinning the crank clockwise using the crank pulley nut, and i can get 2 revs before it gets stuck again, like it is hitting something hard, but if i do a little back-n-forth, it comes free again.

what's in there? dropped valve? who wants to venture a guess?
and yes, i am looking for a used 3.0 to replace this 185,000 mile mush-block motor.

joe

[kenikh]

A 185,000 miles 7R 2.7? That's like a human living to the ripe age of 140!

That is odd that it sat fine the night before, then it seized. I won't even venture a guess.

[cstreit]

You'd have heard a dropped valve, trust me on that. There's no mistaking it. Are you running stock induction or something else?

I'd definitely back away from the impact and the cheater bar. If something is busted, forcing it is only going to make it worse.

Try removing the spark plugs and turning again to eliminate fluid lock (ie full of gas or water or oil) If that doesn't work:

1. try removing your valve covers and inspect.
2. Next check the cam chain covers... Is the chain slack and jammed?
3. REmove your sump plate and take a gander in there...

[exhaustfumes]

chris..thnx for reply.

i pulled the valve covers and plugs tonight. i can see 6 intake valve stems, so they are probably still intact, but of course i can't see the exhaust side. all fluids are drained, and even with plugs removed (no cylinder compression), i am still bumping up against the dark force inside my engine.

would an exhaust valve loose it's head after the engine is shut down? heat soak? it was running OK before it locked up....matter of fact i was biking and my wife passed my in the car just before she parked it for the last time, and i would have noticed any wierd noises, like a valve head flinging itself around the cylinder.

joe

[exhaustfumes]

oh yea, forgot to add i did pull the chain covers, and the chains are both running OK. this engine may have been rebuilt before, i don't have any records, but if not, i agree 185K on a 2.7 is kinda like an early alumnium block vega lasting 100,000 miles, or getting 20,000 miles out of a set of R compound tires.

[cstreit]

Valve heads break off for a variety of reasons, heat, too many cycles from being bent, etc.. but they break while the engine is running for sure.

It's got to be something else...

That is a TON of miles for a 2.7 and I suspect it must have been done before, at least a top end.

The fact that this happened while shut off is the really curious thing... I'm thinking about what could happen during this time...

1. Piston seized up (but it turned a bit backwards)
2. Hydro-lock, but plugs are removed
3. tensioner collapse allowing chain to get fouled on the crank sprocket (but you checked the chains)

I could speculate all day but you've got to dig into it and find out why it won't turn. I would suggest checking things out from the outside in. Look in the exhaust and intake ports as well.

1. First Check the flywheel and crank pulley for obstruction!!!
2. Remove the fan belt and make sure the fan isn't stuck and dragging.
3.. Cams,
4. rockers,
5. valves,
6. chains and sprockets.
7. Pistons and rods
8. Crank.

That covers basically all the rotating components right? Work your way in I suppose...

[911quest]

It is possible that the thrust bearing was seized and when you removed the flywheel you just broke it loose

[cstreit]

I wouldn't think it would "re-seize" though....

[davidppp]

Hello there.

I have actually stripped a 2.7 which had exactly the same symptoms..

Also high miles, would not turn over after sitting a week..

Exhaust valve head dropped off.

Giudes and stems worn about 1/8 inch!

The sodium eats them when a tiny faitigue crack reaches the core..IMHO..

You had a lucky escape..

[cstreit]

No kidding?

Sodium is highly reactive I know, but that's really suprising...

[davidppp]

Yes, only one I have seen..but a friend who has also done "one or two" motors has seen it too..

His was a 2.7 Rs Carrera motor which was in stroage for years..

Kind regards
david