My Baby's 235 threw a rod today. #5 connecting rod snapped off at the wrist pin. The wrist pin bolt was still in place, but in the bottom of the oil pan. I drain the oil into a 7 quart drain pan and it almost went over the top. Had quite a bit of coolant in it. I pulled the oil pan and looked up to see coolant slowly streaming down the side of the cylinder. The piston is all the way to the top and the coolant appears to be passing by the piston. I am hoping that the piston got slammed into the head hard enough to crack the head instead of having a cracked block. There is a chunk missing from the bottom of the piston skirt, indicating that the lose rod caught it and possibly slammed the piston into the head hard enough to crack it. I could not tell how bad the rod may have scored the cylinder. Hard to get a good look with coolant dripping into ones eyes. I will be pulling the head tomorrow morning before it reaches 157 degrees like it was this afternoon. Humid too. I will keep you posted.
1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission
You've probably got a cracked cylinder wall, but don't trash the block. As long as it has at least 1/2"-3/4" of undamaged cylinder wall at the top and bottom, a sleeve can be installed and the block can be salvaged. Most likely, you've also got a badly scored crankshaft on the cylinder with the broken rod- - - -that type of failure is usually caused by the rod bearing locking up and snapping the rod off. Good luck! Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
That's always a sick feeling in the pit of the stomach. Hope for the best, but prepare for the worst.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
I am, but I don't want to have to wait months to receive the 261 from my machine shop. Its not the only shop in town, but is the only one that I trust. If I do find a rebuildable 261, I will snatch it up, have it built and keep it in my inventory. I will have the engine on a stand tomorrow morning to assess the extent of the damage. I have my fingers crossed that a sleeve will be an option. My machine shop should be able to knock that out pretty quick. The '53 full pressure 235 only had 22,000 miles on a complete rebuild and ran like a top. Idled smooth as silk, plenty of oil pressure, and impressive power for what it is. To be continues...
1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission
Update! Got the engine out of the truck, on an engine stand and took off the head. I have a 2" vertical crack which begins 2 1/4 inches below the top of the cylinder. Just like HRL predicted. I will be taking the stripped block to the machine shop tomorrow to see it they will sleeve it and bore it to .040 oversize like the rest of the cylinders.
1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission
Dropped off the block to get magafluxed to see if the crack isn't worse than it appears. A buddy of mine has a '58 parts engine and he said he'd bring me a connecting rod. The machine shop will order the piston for me. They ordered the pistons when they rebuilt it 22,000 miles ago. On a side note, does the attached picture of my cam appear to have the correct cam lobe profile for hydraulic lifters?
Last edited by 52Carl; 07/14/20202:04 AM.
1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission
I've been degreeing cams for about 50 years, and I've never met anyone, including the guy I shave every morning, who can eyeball a cam and tell if it's ground for hydraulic or solid lifters. The difference between a solid lifter and a hydraulic lifter cam is a tiny, but vitally important area where the lobe meets the base circle, one that can only be measured with a dial indicator and a degree wheel. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Update. I got a call from the machine shop. They magafluxed the block and found a second crack at the very bottom of the bore on the lifter side of the block. It is about one quarter of an inch long. The bottom of the bore on a 235 in this area is not adjacent to the water jacket. I do not know how far up from this location before you encounter the water jacket. The manager of the shop won't be back from vacation until Monday. I will follow his advice on whether a sleeve will reliably fix this block, unless someone in here thinks its a no go.
1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission
If there's no danger of hitting water, I'd stop-drill the end of the crack and install a threaded plug to keep it from spreading, then go ahead with the sleeve job. Of course, getting a close-up look is a much better method of evaluating the problem than listening to some keyboard commando (even me) from a couple of states away! Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
I was pondering the idea about drilling a hole to stop the crack, but never thought of tapping it for a threaded plug. I like that idea. I will have an extra set of experienced eyes on it Monday when he gets back from his rare vacation. He runs the only machine shop worth going to around here.
1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission
The bearings and journals look very nice by my eyes. I am taking it in to be checked by better, more experienced eyes tomorrow, same for the camshaft to make sure they aren't bent.
1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission
