cracked block

glenn in camino

glenn in camino

Well-known member
I'm working on a Model A that the owner thinks has a cracked block. I don't have the equiptment to magnaflux it. Is there any other way to find the crack?
 
If he's using plain water look for rust stains, or does he think it's an internal crack?

And, why does he think it has a crack?
 
Water in the oil could be caused just as well by a blown head gasket. Any indication of that? Maybe rust has make a hole from the water jacket through to the crankcase. That's fatal for the block.
These Model A engines have a habit of cracking around the exhaust valves on No 2 or 3. I just sent a block to scrap because the crack had gone right across to the cylinder and was heading down the bore. I only had a drop or two of water in the oil.
I suggest you inspect closely around the exhaust valves but the only way to be really sure is get it tested.
 
Hi Glenn,

There is a guy in town who I've used for magna-fluxing and other Model A engine work, he does great work and is very knowledgeable. He's been doing A's and flatheads for about 60+ years now and knows his way around these engines very well. He did an engine for me last summer. Let me know if you want his number.

-DAN
 
Synchro909 said:
Water in the oil could be caused just as well by a blown head gasket. Any indication of that? Maybe rust has make a hole from the water jacket through to the crankcase. That's fatal for the block.
These Model A engines have a habit of cracking around the exhaust valves on No 2 or 3. I just sent a block to scrap because the crack had gone right across to the cylinder and was heading down the bore. I only had a drop or two of water in the oil.
I suggest you inspect closely around the exhaust valves but the only way to be really sure is get it tested.
Click to expand...

Yes, I agree about rusting from the inside out...not good!
As for your cracked block, pinning and sleeveing the hole(s) works
well. Saves a matching number bock or one with good babbit.
 
glenn in camino said:
They suspect a crack because there was water in the oil.
Click to expand...

Check the easy stuff first, the head gasket. Take off the head, check the block for visible cracks, check the head for flatness, replace the gasket, bolt it down and see what happens. You are only out the cost of a head gasket if it still shows water in the oil.
 
Snyder has a pressure testing kit that Mr. Tom Endy kindly illustrated recently on this Forum; however, this test kit is $220.00 "plus" shipping cost.

Could you find someone who has one?

Best to find the very "exact" leak source(s), (without even the slightest doubt), "under pressure" rather than visual, prior to spending any time or money on an engine that leaks water in oil.
 
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Mike V. has a good approach. Consider a pressure check first. Most professional auto shops have a pressure tester. Hopefully the head gasket is the bugger.

Has it been overheated just prior to the water in the oil?
 
Hi Glenn, I don't know if its still available, but years ago there was a two-part, two spray can coating and developer which did a very good job revealing cracks in cast iron or steel. Spray on the coating, dry, and then spray on the developer. I used it and it did a very good job of revealing cracks. I think the best place to look for it if it still exists would be in a welding supply emporium. Good Luck with this!
 
Glenn,
I thought I had a cracked block myself no to long ago for the same reason, water in the oil pan. I talked with Rich at Antique Engine Rebuilders, 847-674-6716, and he turned me on to a modern composite style head gasket for my car. I had already changed it three times with a copper gasket and was pretty sure the block was done. After some conversation with him I got the gasket he recommended, installed it following his instructions and the car is back on the road and the oil and water are not mixing.

If you want to make sure the block isn't cracked I would do the pressure test also. There is a very detailed video on you tube that shows the process in pretty good detail too.

Good luck and I hope things work out as good for you as they did for me.
 
I have used my old armature growler to do magnaflux for many years, before I got the red powder I would collect the fine shavings from the final cut of turning rotors or cylinder boring ---they worked but not as easy to see as the real dyed powder
 

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I tried all options I could think of short of testing and finally pulled the head and stared at the crack in the cylinder. Amazing the motor ran as well as it did. Have you checked the head bolts? Bob
 
I have run antifreeze which runs thinner then water and the green becomes quite visible.

sometimes its that simple to see.
 
I just junked a block because of a crack from the distributor hole to in between cylinders 2 and 3. Was on the roof of the valve chamber.
 
If you have towing insurance . Flat bed it to a machine shop and have it magnifluxed
while it's on the truck and then take it back home while it's still on the truck.

May take a little planning but is do able.
 
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