The Stovebolt Site Forums The Shop Area Engine Shop Engine Problems HELP!!!!!!!!!!!!!!!!!

I have a 1942 Chevy truck with a 235 engine in it, on may way to store it for the winter a loud rumble and vibration started to happen. I put in the clutch and shut it down right away. Check the driveshaft and u-joints all was ok. Put in the clutch and restarted the engine and the rumbling and vibration came back. I pulled the plugs and found all pistons moving up and down normal. Went under and pulled the flywheel cover and found if I turn the engine over by hand with the flywheel it moves about 1/2" before the harmonic balancer starts to move. Any ideas of what could be wrong???????? Would like to talk to someone over the phone if possible but will take any suggestions you may have. Thanks!!!!!!!!Send me your number 1-262-392-2989 or [email protected] Marv

One of three things to check.

One -loose harmonic balancer easy to check,also check the keyway between the balancer and the crank.

Two -loose flywheel,bolts are loose

Three -Broken crank,but I don't think it's that

I removed fan belt and harmonic balancer seems to be tight all bolts I can see after flywheel cover was removed look tight. The crank was one thing I was thinking of also. I guess I will need to remove the oil pan and see if I can see anything else. Thanks for the reply!!!!!!!!!

I have seen a 235 crank break before. Still ran but had the same symptoms as yours.

I have a 1963 John Deere 4020 tractor and have experienced 2 BROKEN crank shafts in that same block. I am now running a 6600 JD combine engine in this tractor. Engine ran but only on 4 cylinders. It is probably what is happening. Good Luck, Jerry

I saw a 6-71 Detroit break a crank smooth in half directly in the middle of a main bearing, it looked fine from the outside, but it didn't work. It would be a bad thing, but it sure sounds like that is what is going on.

As a diesel mechanic I've come across many problems with engines. You may not have a centre bolt on the crank, but I would recommend that you bar it over by hand, put a dial gauge on the front of the crank/damper and see if there is some excessive movement. Use your eyes and ears to detect problems, especially when barring over by hand.

Just saw this second thread on the subject - Did you find a broken crank Marvin?

Will see how things go this week I may be able to get another look at it and decide for sure what to do. Thanks to all so far trying to help!!!!!!! Will keep you posted.

Marv.

Removed the oil pan and found the crank broken, now what??????????? Do I find a crank,find a later model engine or rebuild the one I have and see if any one has up dated a 1942 235 engine to a high pressure system and how it could be done. If I can rebuild the old engine to a high pressure and the cost not to much I would like to go that way. Thanks to all for trying to help!!!!!!!

Marv.

You can fit a more modern 235 in very easily.

Please describe where the crankshaft was broken. I can't understand how it could be broken and still run, but I know it somehow does.

There is a new 1941 235 crankshaft on ebay right now. Search "235 crankshaft". Apparently, this one is standard diameter, new in the box, and the price isn't outrageous. It does need some polishing. Fitting a late model pressure-lubed crankshaft to a splash-oiled 235 requires some expensive machining on the main bearing webs in the block.
Jerry

Hotrod Lincoln I found that crankshaft was Sold already.

Marv.

Found a 1962 235 engine close to home with low miles got it running and installed. I also added a 1948-53 truck bell housing and SM420 trans behind it no more double clutching. I made a adapter plate to the bell housing to accept the clutch and brake peddle no need to have the piece with the three bolt holes added to the 1948-53 truck bell housing. Will post it as a Tech Tip at some point. If I say so myself it turned out great. If anyone would like to add a SM420 trans to their truck call me for the details will be happy to help. 1-262-392-2989.

Marv.