<!-- / icon and title --> <!-- message --> Hello hope you guys can help me with some direction, I'm going to post a couple of pictures of cylinder #4 and 5 of my Dodge flathead, it's a 1960 Sweptline pick up with 72000 miles on it. These two cylinders both have some spots that are actually indented into the wall, you can feel that they are lower than the rest of the cylinder wall. Can anyone comment on what could have caused this, they had about 120 psi compression taken just before disassemble started. Pistons and rings look good and felt tight in the cylinder, I was hopping to hone the cylinders put new rings on and reseal the motor, which is why I took it out, it ran good but leaked oil. How do you guys recommend I precede from here?
never worked on one, but as a crude guess you have a thin sleeved engine, with a damaged wall behind the sleeve, and the pressures in the chamber have indented the sleeve. Am I wrong? Who knows, but that is the only thing I can think of that would cause that! traderjack
Maybe it broke the top ring(s) at one time. The pieces rolling up/down in the groove could have done that, then someone just replaced the piston and ring without repairing the cylinder damage? I know you said it only had 70someK miles, but could it have been apart in the past?
It does not look as the engine has ever been apart, I have the pistons out and will inspect the rings a little closer in the effected areas. The only thing I can think of is a build up of rust in these areas maybe from sitting a long time and it ate it's way into the cylinder wall and from being run it's cleaned it away and left this indented area. I'm just guessing.
The top of the piston looks pitted, and I have seen detonation do damage like that. were there any brokem rings?
My first guess would be that it sat around for a long time and got some water in it from condensation that rusted deep pits in there while those pistons were up high in the bore, then someone got it running again which burned and scraped out the rust leaving those pits. Maybe someone drove it into a river and then they dragged it out and let it sit out for a few years with some water still in those two cylinders. The block could have been leaning on the side of a barn for a few years. Who knows, but it looks like pitting you'd see when a puddle of water sits on cast iron. You might be able to use a telescoping gauge to get an idea how deep those pits are compared to the un-pitted smooth part of the bore's diameter. If the pits are only about .010" deep at most, maybe a .030 over bore and hone and a new set of pistons and rings would do it.
Thats caused by broken rings,the ends move up and down and eventually wear a hole in the piston and the the bore where the piston moves up then starts to move back down again. After 49 years anything could have happened to the engine. It needs a rebore to fix that. I have filled holes like with JB weld before today. yes,it works. Have you checked the piston crowns for piston resizing marks? Often a rebore won't fix damage like because the holes are too deep and it's possible someone has bored the block and fitted o/s pistons but been unable to remove the holes completely. The main cuase of broken rings in engines of that era was overheating,again over 49 years have passed since thew engine was built and sometime n the past anyone could have driven the truck without water for some reason or other so when you are working on a engine nearly 1/2 century old it's damned unusual to find one that has never been touched.
I think you had water sitting in the cylinder. If you want to feel 100% about it, bore it and buy new pistons. But if your from Arkansas hone it and go..
Ran lots of Dodge sixes worse than that in combines back in the '60's. A set of cast iron rings will seat in and run for years, if the pistons are tight in the holes and the ring grooves aren't worn. It'll burn a little oil, but it IS old enough to be in a home somewhere! The holes in the finish are above the oil ring travel, so they don't get full of oil every cycle.
Another cause of cylinder wierdness is localized over-cooling, something that is blasting those areas with water straight from radiator continually while other areas are less well fed. Ford bangers sometimes have an area like this bear water inlet... Area runs at a different shape than hotter areas, wears and settles to a low spot when cold
no broken rings and the pistons look like they will clean up nicely. I will mic the cylinders and decide how to proceed. I know a over size re bore would be best but pricey.
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