CRANKSHAFT REPALCEMENT

[8543bob]

I HAVE LOCATED AND SECURED A NEW, CRANK FOR MY M. SPUN THE #6 ROD BEARING. ALSO HAVE A NEW ROD. MY QUESTION: WHEN I GET THE ENGINE OUT OF THE TRUCK AND ON THE STAND, REMOVE THE CRANK, PULL THE PIOSTON, CHANGE THE ROD; WILL I BE ABLE TO INSTALL THE PISTON FROM THE BOTTOM?? IF I DONT HAVE TO I DO NOT WANT TO DISTURB THE HEAD. THE ENGINE RUNS FINE, EXCEPT FOR THE KNOCK. THE GUY I GOT THE CRANK AND ROD FROM HAS A COMPLETE ENGINE, IN PIECES IN A STORAGE BOX. IF ANYONE NEEDS A PIECE OR THE REST OF THE ENGINE LET ME KNOW.
THANKS BOB

[snowdad]

Bob,
You have no choice but to remove the head. I restored a 1942 Dodge WC-51 which has the same engine last year. I ruined the #1 piston trying to drive it out the bottom. There is a small lip at the bottom of the cylinders that prevent this.
Where is the engine located? I am in Tennessee and might be interested if price is right. Thanks
Phillip

[HingsingM37]

Bob,
"Hypothetically" that could be done, however you may /will be asking for more grief trying to do this because:

1. You will have to pull the mains and the other rod caps, it seems to me it would be a pain trying to hold all of the rods in position while trying to lay the crank back in? All the while making sure not to gall a bearing? Some pistons will be under compression stroke, thus adding to the folley. You will need an octopus to assist, yes?

2. I have never attempted this, it seems to me it would be akward to use the ring compressor from the bottom of the cylinder. Thus risking ring breakage. What will you shove on to put the piston back in with equal force, the rod? While trying to steady the piston? Ideally the top of the piston center is pushed on to re-install it from above. I belive the block design will also prevent this?

3. It would take less than 15 minutes to pull the head. Why not to make the job easier as well as inspect your cylinder walls, valves, and valve seat and guides for play? You could also give the engine a carbon and ring ridge cleaning?

Just my two cents

[thejester]

i have done this ..i had the numder six rod bearing go out and had the crank redone..the piston will drop enough to get the pin out and put the new rod in but it will not come all the way out..it is a pain in the ass but can be done..As far as compression just pull the spark plugs out

[Master Yota]

Head gaskets are cheap...(in the grand scheme of things). Installing the piston(s) from the bottom isn't done by professional engine builder's for a reason. Its much easier to do it from the top.

While the head is off, do as suggested, clean the cylinders, check the tolerances, and machine the head so its flat again. If you do it right the first time, you (probably) won't need to do it again for a good long time...

[snowdad]

Somewhere I have the pictures from the rebuild. I will locate and show the protrusion that prevents removing the piston through the bottom. I have the ruined piston to prove it. Just trying to save you from some of my grief.
Phillip

[8543bob]

THANKS FOR ALL THE GREAT INPUT, I APPRECIATE IT. I HAVE REBUILT A "COUPLE" OF ENGINES, GAS, DIESEL, OUTBOARDS, NEVER HAVE I PUT THE PISTONS IN FROM THE BOTTOM, JUST A THOUGHT, NOT A VERY GOOD ON. SO THATS MY PROJECT FOR THIS WEEK. THE ENGINE THAT IS IN PIECES IS IN ROCKAWAY BEACH, NY ITS MISSING THE CRANK AND ONE ROD. DONT KNOW THE PRICE; BUT IS INTERESTED I WILL FIND OUT. AGAIN THANKS BOB

[Joe]

Head gaskets are cheap...(in the grand scheme of things). Installing the piston(s) from the bottom isn't done by professional engine builder's for a reason. Its much easier to do it from the top.

I absolutely agree. Ridges will form at the the top and bottom of worn cylinders and if you don't hone them out, there's a strong possibility of breaking the top and bottom piston rings. You also need to hone the cylinders to break the slick glaze that forms or else your rings may not seal well, leading to low compression, oil fouled spark plugs, burning oil and smoky exhaust. If it had overhead valves, or even worse, overhead cams then I might be tempted to not pull the heads but on a flat head motor it's the simplest job in the world.

[Joe]

Where is the engine located? I am in Tennessee and might be interested if price is right. Thanks
Phillip

Phillip, There's a guy down here in Sarasota (or somewhere close) that has an engine and a bunch of other parts for sale on Craig's list. I think he's asking $100 for the engine. Check Craigslist. If you can't find it let me know, I have his phone number and E-address.

FYI Other parts are chassis, some large body parts, suspension, stock wheels and tires, and drive train parts. He didn't have any of the GOOD stuff such as troop seats, winches, top bows, etc.