Causes for a seized engine?

[chuckstp]

I am working on a '64 Series IIA. The other week, I replaced the fuel line which was clogged with rust, cleaned the fuel filter and carburettor. I managed to get it started and it ran for 15 seconds before stalling. Then I had my dad hold the throttle when I started it and ran it for about a minute. It backfired and was coughing back out the carburettor.


The next day, I attempted to start it and the engine turned, would begin to fire, but didn't start. After a few attempts, I got nothing. Figuring the battery was getting low, I did some other things for a bit, but quickly realized the battery was fine. At that point, the engine acted as if it were seized. I pulled the starter and it was good. When I put in the hand crank, I was completely unable to turn the engine.


While it acts as if it is seized, it wasn't running which is the typical case for locking up the engine. Besides the starter being stuck, are there any other things that might cause this?

[SafeAirOne]

You don't say in your original post--when I first read this, I presumed that this was on some Rover you just hauled out of the barn after 2 decades of sitting.

Re-reading it, it looks like it may be on a recently-previously-running rover?

If so, then the only way things generally backfire out of the carb is if either the ignition timing or the valve timing is way out of whack.



If it's the VALVE timing, then there's the possibility that something is causing a valve or valves to remain open when they should be closed and a piston or pistons can't rise to their top dead center position because they're hitting an open valve. I'd have a look at the timing chain

I figure that what I described is the worst case scenario and your valves are now all bent up and the piston tops have holes knocked in them from hitting the valves. The good news is that if this is NOT the problem, you'll experience a brief feeling of euphoria.


If the backfiring through the carb issue is an IGNITION timing issue, then it's easy to fix by properly timing the ignition, but it doesn't explain the engine seizure.


Does the engine turn backwards by hand? if so, do the valves move when you are turning it? If so, does the crankshaft rotate then come to a definitive clunking stop? Does it rotate with the starter removed?

Oh, and I hate to ask, but was the transmission in neutral when you tried to rotate the engine by hand?

[yorker]

I had one do something similar once, the timing chain got jammed, IIRC the pad it runs on came loose and jammed into the cam sprocket. It ended up breaking the end off the cam.

[chuckstp]

As far as the history, the car had been sitting for over a decade with rust in the tank and a clogged fuel line. My dad had occasionally run the starter to make sure it still turned, but never started it. When I went through the troubleshooting after it stopped turning, one of the first things I did was to make sure that the transmission was in neutral and the overdrive, and 4 wheel drive were all disengaged. One thought was that the drive train was somehow still engaged, but I raised it and made sure all four wheels freely turn. I needed to do that anyway so I can get it out by towing it rather than getting a trailer.

I haven't tried to turn the engine backward. Based on enough comments about never doing that, I decided it wasn't the best thing to do. I'll give that a shot today. With the exception of turning it backward, it sounds like any other check involves removing the head or timing cover.

[yorker]

I haven't tried to turn the engine backward. Based on enough comments about never doing that, I decided it wasn't the best thing to do. I'll give that a shot today. With the exception of turning it backward, it sounds like any other check involves removing the head or timing cover.

Did you pull the plugs and check the cylinders from there?

[chuckstp]

I've had the plugs out and attempted to look in one with a submersible,2 an but its picture is better submerged. I probed w/ a screwdriver today and 2 & 3 are up although they don't seem to be at the same height. After removing the fan blade, I managed to get the engine to turn backward. Turning it forward again has a hard stop again, although no noise, but I can feel it quite clearly. Using the angle of the hand crank to measure, it looks like it goes freely and stops just shy of one full rotation. Regardless, I can feel it hit something in both directions.

[yorker]

Did you pull the valve cover?

[chuckstp]

Yes, I pulled it, and saw that the rocker arms moving up and down as I turned.

[SafeAirOne]

When you hit that hard stop while rotating the engine, are some of the pistons just shy of the top dead center position?

[chuckstp]

I am pretty sure 2 & 3 are close, so yes. I did find that when it stops at either extreme, I am able to depress both valve springs for 2 & 3 and can see that the valves drop when I do that. Still, the next step appears to be the same no matter what. The head and or the timing cover needs to come off. First though, I need to get it out of its current location so I can take it somewhere to work on it. It's clear the engine isn't going to help out in this matter.

[chuckstp]

An update for anyone who might follow this. Based on the questions and feedback so far, I managed to turn the engine backward and forward through a rotation of just under 360 degrees of the crank shaft. It appears as if all the valves move properly and the ones on cylinders 2 & 3 are up when it stops. I pulled off the sump yesterday and everything looks good from underneath. I confirmed that pistons 2 & 3 are up, but stop shy of TDC in both directions.

It looks like the next step is to remove the head and see if I can find anything there. When I looked at the pictures of the front cover and the timing chain, I didn't see an easy way to account for an obstruction at 360 degrees of rotation. Thanks for the feedback so far, and hopefully I will get a chance to lift the head over the weekend.

[triumphtr7guy]

Sounds like its time for the head to come off, from what you have described, it sounds like you dropped a valve. The rockers will move as you turn the engine, but you would have to look and see if the valve stem is there, and it may have broken during the rapid ignition of fuel source re= the bang! And if the vehicle is as you said been sitting, probably wouldnt hurt to have the head done at this point, save some aggravation down the road with other problems that could crop up. Good luck, Bruce

[chuckstp]

Mystery solved!!! Once I popped the head off, it became fairly clear exactly why it got stuck like it did. At first this posed another mystery of how the lock washer got in there since it was too large to fit in the spark plug port. My neighbor suggested it may have gone in through the carburetor which is fairly likely. My guess is it dropped in when I first took it off to empty the stale gas.

[bugeye88]

How about a pic of the head #2 cylinder. The Piston doesn't look too bad.
Rob
Bugeye88

[westcoastkevin]

Hopefully you have not bent the connecting rod.