673 Engine Won't Turn... An Update

[steve s.]

Hello again,

This is a follow up on my 673 diesel that broke down in my garage and will only turn a bit more than a 1/4 turn, back and forth but no more. I've been working on it but still have not found the problem. As was suggested earlier I pulled the injectors, and found no anti freeze. I removed the rocker assemblies, no stuck valves . Pulled the pan (no sign of anti freeze or metal in the oil or pan) , Pulled the main and rod bearing caps one at a time , still won't turn more than that 1/4 turn or so. Oil pump is ok, tappets are all free to move with the rockers off. cam looks good, I don't see any metal chips or hear any noise when trying to turn it. Yes, the transmission gears are in neutral and I tried all of this with the clutch pedal in, just in case. The fan belts are off too.

The process of elimination ,I think, tells me that what's left is the timing gears, the injection pump or some freak thing like a loose bolt stuck somewhere it doesn't belong ( like the flywheel ? ) . I'm kind of leaning toward the inj. pump, but I can't convince myself .

I really don't look forward to pulling the radiator and the timing cover, or for that matter the injection pump ( this engine is not the original, it is a "leaner " tilted to the inj. pump side like a B 67 - not much room to work in ) , so if you have any thoughts on which of these jobs you'd do first, or maybe if I'm overlooking something, I'd appreciate your input.

Thanks , Steve

[Rob]

Hello again,

This is a follow up on my 673 diesel that broke down in my garage and will only turn a bit more than a 1/4 turn, back and forth but no more. I've been working on it but still have not found the problem. As was suggested earlier I pulled the injectors, and found no anti freeze. I removed the rocker assemblies, no stuck valves . Pulled the pan (no sign of anti freeze or metal in the oil or pan) , Pulled the main and rod bearing caps one at a time , still won't turn more than that 1/4 turn or so. Oil pump is ok, tappets are all free to move with the rockers off. cam looks good, I don't see any metal chips or hear any noise when trying to turn it. Yes, the transmission gears are in neutral and I tried all of this with the clutch pedal in, just in case. The fan belts are off too.

The process of elimination ,I think, tells me that what's left is the timing gears, the injection pump or some freak thing like a loose bolt stuck somewhere it doesn't belong ( like the flywheel ? ) . I'm kind of leaning toward the inj. pump, but I can't convince myself .

I really don't look forward to pulling the radiator and the timing cover, or for that matter the injection pump ( this engine is not the original, it is a "leaner " tilted to the inj. pump side like a B 67 - not much room to work in ) , so if you have any thoughts on which of these jobs you'd do first, or maybe if I'm overlooking something, I'd appreciate your input.

Thanks , Steve

I would pull the starter and try to rotate the engine assy. again. I've seen the spring for the "Dyer" drive used on these trucks broken and not letting the starter pinion retract. It then binds.

Rob

[theakerstwo]

Also when you torque those rod brgs make sure and check the side clearence on them from side to side on the crank witha feeler gage. should have about .007 clearance or you can burn the thrust surface on the rod. Very important. If you did not i would and i mean have some one hold pressure on the crank against the locked place and get under and shavk each rod for side clearance like i said and if you find a cylinder that is holding the engine from turning then that rod cap will not be able to shack back and forth like the rest. It could have some rust on the cylinder walls of the liner and that is a way to find if it is a piston in a bind. You can check back lash between the cam gear and the fuel pump drive gear by removeing the small cover in front of the fuel pump and with some one holding pressure on the crank against the locked place then try to get some back lash between the cam gear and fuel pump drive gear and letr off of the crank and see if you have any more. I you dont get any back lash and i am talking about using a screw drive then they may be a problen in the pump drive or pump. I dont think i have ever saw a fuel pump lock a engine. Have you tryed to turn engine with the clutch down? glenn

[steve s.]

Rob- the starter has been out through the whole process so far, I kind of wish that was the problem. Glenn- Yes I have tried my tests with the clutch disengaged, just to eliminate it as a source of trouble. As for the rods, I took each cap off one at a time , pushed the rod up just enough to clear the crank, and tried with my bar to turn the flywheel. I am now sure that none of the rod/piston assemblies is the cause of the problem. I did see in my manual about the connecting rod side clearance you mention, but it seemed to me that it would not be a critical thing on an old worn engine, thinking that the rod would find its own "spot". But I will follow your advise and set it with feelers when I torque it up. I do have the cover off the front of the inj. pump gear an I will check for back lash. Thanks again, Steve

[eagleeye1958us]

hi steve

i'm kinda coming into this post late i guess but does this engine have an air compressor, back in my younger days i saw this cause various problems from leaking oil bad enough to ruin an engine to tying one up. hope this helps

[steve s.]

Eagle Eye,

The background history of the problem is in an earlier post with a similar title, if your interested. I'm glad to hear your opinion . The air compressor was one of the first things I checked - took off the bottom plate on the crankcase - but everything looked ok so I didn't go any further, but I could do more to be totally sure it is not binding up, and since it would be an easier task than my other possibilities, maybe I'd better do that next. Thanks Steve.

[eagleeye1958us]

hi again steve.

just out of curiosity did it set over the winter with the intake or exhaust manifolds open as i have seen that "critters" or other objects seem to land in there. hope this helps

mike

[theakerstwo]

Also when you torque those rod brgs make sure and check the side clearence on them from side to side on the crank witha feeler gage. should have about .007 clearance or you can burn the thrust surface on the rod. Very important. If you did not i would and i mean have some one hold pressure on the crank against the locked place and get under and shavk each rod for side clearance like i said and if you find a cylinder that is holding the engine from turning then that rod cap will not be able to shack back and forth like the rest. It could have some rust on the cylinder walls of the liner and that is a way to find if it is a piston in a bind. You can check back lash between the cam gear and the fuel pump drive gear by removeing the small cover in front of the fuel pump and with some one holding pressure on the crank against the locked place then try to get some back lash between the cam gear and fuel pump drive gear and letr off of the crank and see if you have any more. I you dont get any back lash and i am talking about using a screw drive then they may be a problen in the pump drive or pump. I dont think i have ever saw a fuel pump lock a engine. Have you tryed to turn engine with the clutch down? glenn

What i am saying to do is hold pressure like trying to turn the engine and when it is locked shack each rod and the rods should be free and that will show you that there is no problen with somthing in the cylinder or with rust in the cylinder locking the piston cause if the piston is locking the you will not be able to mone that rod on the crank. And the side clearence has to be checked ever time the rod cap is taken off ever time new or worn out engine and the way to get your clearance is losen the cap a little and pry the rod over against the rod and hold it there and use a small harmer and tap the cap the same way then torque and check clearance and if ok go but if not make some clearance or you cane ruin the rod or crank or both. i have seen it done.

[paulbrook]

Steve

Where are you trying to turn the crank from? An engine doesn't have to be that tight to be all but impossible from the crank pully end, and the fact that you can turn it 1/4 turn doesn't mean that it will be free all the way around. Sounds like you have maybe some rust in the tops of the bores (has the manifold been off?) and as soon as one or more pistons starts to get there it tightens up. I have a Dodge fire truck that had stood for ages, all I did eventually was strip the thread off the crank nut - mind you I did have a wrench with a 10foot extension on it at the time...

I won the day by gently (well, gentler than the 10' extension anyway) using a pry bar on the flywheel ring gear, with hot oil poured into the bores. Messy, but effective.

Paul

[steve s.]

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Edited May 14, 2008 by Steve S.

[steve s.]

Mike, I would not rule out critters being part of the trouble. I did find a pretty harmless mouse nest under one valve cover, but when I first got the truck I had to spend a lot of time vacuuming things out of the intake pipes. I did run the truck a good amount after that though. The air compressor intake pipe was off in the garage this winter, and some little so and so could have filled it with nuts that got sucked into the compressor, maybe just wishfull thinking, but the compressor is next to come off.

Glenn, I've been unable to turn the crank past it's tight spot with the rods free and clear of the crank journals, so I am comfortable ruling them out as my trouble. I will for sure pay attention to the rod side clearance .

Paul, I'm turning the crank with a bar on the flywheel, I can't even get a wrench on the crank pulley nut, as this truck has the deeper radiator. I really don't think rust in the bores is it. I did have the truck running a good bit earlier this year and it gave no signs of a problem then.

Thank you all . Steve.

[theakerstwo]

Steve

Where are you trying to turn the crank from? An engine doesn't have to be that tight to be all but impossible from the crank pully end, and the fact that you can turn it 1/4 turn doesn't mean that it will be free all the way around. Sounds like you have maybe some rust in the tops of the bores (has the manifold been off?) and as soon as one or more pistons starts to get there it tightens up. I have a Dodge fire truck that had stood for ages, all I did eventually was strip the thread off the crank nut - mind you I did have a wrench with a 10foot extension on it at the time...

I won the day by gently (well, gentler than the 10' extension anyway) using a pry bar on the flywheel ring gear, with hot oil poured into the bores. Messy, but effective.

Paul

If you had side way movement on the rods with pressure on the crank then you can say the pistons are not holding any pressure from turning so that is the simple way to see if you have rust or gravel or any thing on the top of the pistons or rust on the cylinder walls now you can check some thing else like ???