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1951 239, had battery checked and it was bad so replaced it. Now when I hit the starter button the fan turns but I do not hear the pistons going up and down. I checked the compression and get zero! If the fan turns that tells me that the crankshaft is indeed turning. What do you folks think, timing chain or gear broke? Any suggestions would be extremely helpful.
Did this truck run before ? The starter turns the crankshaft which is connected to your rods and pistons so if its turning the pistons are moving . Battery hooked up backwards ? I'm not familiar with those starters as most wouldn't work backwards .
After I read your post I think had an LSD flashback trying to hear my pistons moving. I could see it in my mind....
Anyway, please describe the compression check procedure used.
No compression on any of the cylinders? If so sounds like a lack of rotation of the cam and when the crank turns over there’s a possibility the pistons have hit an open valve and bent it.
No compression on any of the cylinders? If so sounds like a lack of rotation of the cam and when the crank turns over there’s a possibility the pistons have hit an open valve and bent it.
So if the 239 is a flat-head that is going to be one heck of a trick, ... I think to valves are in the block?
The distributor won't turn if the timing gear has sheared. That would be the quickest, easiest way to see if that's the problem. The cam gear is phenolic and after 60+ yrs they do fail.
You should remove ALL the spark plugs for a compression test, but it isn't going to get you off Zero. If you look thru the spark plug holes with a good light, you can watch the valves move (or not).