The Stovebolt Site Forums The Shop Area Engine Shop Scratch one old 235!

Well, looks like I won't be running a 235 in my '52 GMC any more. It's got a cracked cylinder.

What happened was that I lost my water pump at first. It still pumped, but the bearing was so gone that while going down the highway, the fan would pull the shaft of the water pump out, and water would drain everywhere. When I smelled it, I got right off the highway, but when the engine returned to idle, the shaft would move back into the water pump and it would stop leaking.
I was carrying 3 gallons of water with me and put half of it back in. I had 20 miles to go to get back home, and that lasted me 10 miles. Then I pulled over and put the other half of the water in, filling it back up. That got me home, but as I pulled into the driveway, steam was coming out the exhaust.

I pulled the head off and replaced the bad water pump. Sure enough, the head gasket was blown pretty badly. I figured that was it.
But then I got it back together, started it up and it ran perfectly. Figured I fixed it.
This morning though, I went out to start it and it started out okay, but only got a block and noticed a little vapor out the exhaust. I drove it around the block and by the time I got home, it was a real steam cloud and was missing again. Pulled the dipstick and I had mocha again!
Only one thing left that it could be, a cracked cylinder leaking water in from the water jacket.

Well, I found a 292, and it may be a runner. He doesn't know. It ran when he pulled it out of the 60's truck. It's worth $200 bucks to go and get it. Figure it'll be a lot easier than putting a V8 in. And should have a lot more torque than the horribly under-powered 235 had.

Figure I'll squirt oil in the cylinders, make sure it rotates, then support it, change the oil and put in new spark plugs, transfer my Pertronix distributor and 2bbl over, and try to fire it up. If it runs decently, I'll clean it up and drop it in. If it doesn't, I'll pull it apart and rebuild it.

Anyone know if a 235 head has a smaller combustion chamber and will bolt up to the 292? Wouldn't mind having a little higher compression and the hardened valve seats.

I may have some perfectly good 235 parts for sale, if anyone's interested. Only the block's bad. Let me know and I'll contact you when I've got it out.

The 235 and 292 are completely different animals. The heads do not interchange. The 230/250/292 have a combustion chamber that is similar to the smallblock, and many parts interchange, such as valves, pistons, etc. I seem to recall that the rods and rod bearings are the same, too. One thing that you will need that is the same as putting in a v-8 is the bellhousing, the bolt pattern for the 292 is the same as the v-8.
Good luck on the swap.

If you don't use the head, I may be interested in the rocker assy. Mine is a bit too noisy even after adjustment and the machinist tells me that resurfacing is a lost art.

Yeah my rocker arm assembly is in terrific shape. The head is really nice. That's why it's such a shame that I lost the block.

I have that bellhousing somewhere. Just have to dig it out. The 292 also has the side engine mounts like a V8, doesn't it?

Bummer! The 292 is a mean engine, and a good choice.

Hot Rod Dad,

I have never seen one of these blocks crack. It sounds like you are set on something else so it might be a moot point.

My bet is that the head is cracked or warped, or the head bolts got so hot they stretch when you try to torque them.

On my list of usual suspects, Mr. Block would be near the bottom.

Stuart

It's a GMC. Why not put a real truck engine in it? Get a 270 or a 302.

It is unlikely that an iron head would warp, but possible. And I scraped the entire head surface with a razor blade cleaning it up, and noticed no cracks at all. I guess I'll find out, because I will be doing an "autopsy".

The cylinders are emmersed in the water jacket. I saw that when I replaced the water pump. If the water level got low enough, on an almost 50 year engine, a hairline fracture could develop into an honest crack. Especially if I introduced cold water into the system trying to bring the water level back up.
This is what I think happened. And that is a mistake on my part. I should have probably let the engine cool slowly, even if I had to abandon the truck on the highway and replace the water pump on the side of the road later.

The motor could possibly be resleeved, but I don't know that I would trust a compromised cylinder.

However, yes, I am set on something else...as Cletis says, a "real truck engine".
292's were installed in "real" GMC's in the 60's, I believe, and are often listed with other GMC engines, even though technically, I think it's a Chevy. Isn't that right?

Like I said though, after the autopsy, everything good will be sold to help finance the bigger stovebolt. Block (if salvagable), crank, rods, pistons, the new water pump, the head and valve train, intake and exhaust manifolds.

Hot Rod Dad,

I don't know what happened to your engine, but I must disagree with you on the head.

It is not uncommon at all for a big ugly cast iron head to warp. If you were to stop in at a automotive machine shop and ask the owner how many heads (iron) he surfaces, I will bet the answer would surprise you.

If you asked him how many 235 blocks he has seen crack, I will bet the answer would surprise you too. It could happen, but diagnosing is based on past experience as well as the here and now.

Good luck with your 292 project, let us know the results of the autopsy.

Stuart

HRD, been researching doing the 292 swap on my 53 350 series GMC. I believe you need to changeout the crossmember at the trans to use the bellhousing needed for the 292. I also think that an aftermarket type front engine mount will be the easiest solution. Most of all take plenty of pictures and post them. Good luck

Pulling the head is not very difficult. In fact, it'll make pulling the 235 easier, smaller and lighter.

That way, I can really make sure, beyond a doubt, if it was due to a warped head or a cracked cylinder. If it's just a warped head, then the 235's got a new lease on life. But I'll still buy the 292 just because $200 is a good deal.

Thanks for your feedback...it is worth verifying before going beyond the point of no return. I'll post back here when I know.

My grandfather rebuilt a 235 many years ago because the block was cracked. I don't remember the name of the test (magnaflux maybe?) that they ran to determine that it was cracked, as I was a young lad at the time, but he seemed certain. He got another block from a junkyard that was supposed to be good. After he finished rebuilding it and took it out on its maiden voyage, he got about 1 mile before the engine started acting up. He drove it back home, and pulled the engine again. Dismantled the engine and had the new old block tested. More hairline fractures. This time he had the replacement block from the junk yard checked before he rebuilt the engine. No problems with the block and none with the rebuilt engine when he got done. So, that's two cracked 235 blocks that I have personal knowledge of. Anything old can break after years of heating and cooling cycles.

Hi Hot Rod Dad,

If you have a 52 GMC that was built in the USA, not Canada.

Put a 55-56 GMC 248, 270 or 302 in the pickup truck. It is a direct bolt in, except for the front motor mount which is easy to change. You get a much more powerful engine with full oil pressure fed crankshaft.

I just bought 2 55 GMC 248's running for $100.00 each. Yeah, I had to do some driving but, it is well worth it for the results. I have 2 1948 GMC's a 1/2t &1T.

Good Luck,