Engine Block Crack Problem

E

Ed in Maine

Well-known member
We have a fellow club member who brought his Model A to our club garage for a tune-up (points and condenser). While working on the car we noticed that there was a water stain down the side of the valve cover. We pulled back the exhaust manifold and there was a puddle of water sitting in the two exhaust ports on either side of the distributer shaft. It appeared that we had dripping, about 3 drops per minute. We pulled the cylinder head, removed the gasket and cleaned up the top of the block. We found two cracks from the exhaust valves to #2 and #3 cylinders. The crack (so very fine as to be hard to see) does go down the cylinder about an 1 inch.

Up to now, the car runs perfectly, good compression and the water loss is very little, almost being a normal evaporation. My feeling is that this car is still performing satisfactorily and it is worth trying a stop-leak attempt but which brand has proven to be the best in Ford Barn's opinion. I'm thinking that maybe we should isolate the engine from the radiator and pore a sealer into the engine and let it soak for a few days. Let me have your thoughts on how to proceed. Thank you for your help, Ed
 
Ed,
Just a question - did the car have a thermostat in the upper radiator hose?

If so, had the thermostat drifted up the hose to the neck of the radiator?

How many holes were drilled if any in the thermostat to allow water to flow by until the thermostat opens?

I had a similar engine issue as this and think the thermostat was the cause.

Jerry
 
KW Block Seal is an excellent product. Used it on my daughter's Honda, saved her $1500 on and engine job, drove the car for another 30,000 miles and then junked the car. Follow the directions to the letter.
 
IMO, a good crack sealer is a very cheap option and well worth a try before you go to greater trouble and expense. If it fails, then by all means go the extra. That said, I have discarded a block with exactly the same problem you describe.
By the way, many of the crack sealers instructions tell you to drain and refill the cooling system after following the earlier instructions. I leave it in there.
 
I have heard that a product called Water Glaze works well. Years ago, I heard you could get it at the plumbing supply store. That was before the WWW though.
 
Ed in Maine said:
We have a fellow club member who brought his Model A to our club garage for a tune-up (points and condenser). While working on the car we noticed that there was a water stain down the side of the valve cover. We pulled back the exhaust manifold and there was a puddle of water sitting in the two exhaust ports on either side of the distributer shaft. It appeared that we had dripping, about 3 drops per minute. We pulled the cylinder head, removed the gasket and cleaned up the top of the block. We found two cracks from the exhaust valves to #2 and #3 cylinders. The crack (so very fine as to be hard to see) does go down the cylinder about an 1 inch.

Up to now, the car runs perfectly, good compression and the water loss is very little, almost being a normal evaporation. My feeling is that this car is still performing satisfactorily and it is worth trying a stop-leak attempt but which brand has proven to be the best in Ford Barn's opinion. I'm thinking that maybe we should isolate the engine from the radiator and pore a sealer into the engine and let it soak for a few days. Let me have your thoughts on how to proceed. Thank you for your help, Ed
Click to expand...

You could try that but with so much heat focused on the valve seat crack it'll only get worse. It's a common area on Model A engines to crack, caused by overheating.
We can repair it permanently but the engine would have to come apart for us to fix the crack and install hardened valve seats.
http://www.jandm-machine.com/crack_repair.html
 

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Hello ,
From personal experience I can highly recommend J & M as the best engine builders in the business.
I had the same problem with a block that they rebuilt for me. The engine has 10000 miles on it now . I only top the radiator up probably once a year to make up for any evaporation loss. The Engine is a cool running engine. It never exceeds 180 F on a 90 F day.

To do a permanent fix on your block metal stitching is the only way to go as J & M have stated.

Mark. A
 
I would go with what J & M said in post #8. Any temporary fix is just that.

I was interested in the Model A engine built for a speed record where they made a clamp that mounted just below the head. It compressed the engine at that point. The guy who built the engine, over 200 horsepower if I remember correctly, said that it was typical for the engine to come apart at the top of the block because of minimal material there.

Regarding the thermostat, I have a winter thermostat that has a larger hole drilled at the top where it comes with a smaller hole. I have a coolant heated heater so there is always coolant flowing through the engine. In the summer I use a thermostat that has 6 holes drilled in the flange and have the coolant to the heater turned off with a ball valve. The thermostat is kept from moving up the hose with a hose clamp.
 
nkaminar said:
The thermostat is kept from moving up the hose with a hose clamp.
Click to expand...

I have seen written here many times that the thermostat should be held at the bottom of the top hose but does it really make any difference?
If there are extra holes drilled in it (and who doesn't do that), then coolant will flow through it regardless of where in the hose it is. The coolant won't cool over the 3 inches or so difference while inside an insulating rubber hose.
Is this another case of something being repeated so often that it becomes fact or is there a genuine reason? I'm ready for them.
 
"I have seen written here many times that the thermostat should be held at the bottom of the top hose but does it really make any difference?
If there are extra holes drilled in it (and who doesn't do that), then coolant will flow through it regardless of where in the hose it is. The coolant won't cool over the 3 inches or so difference while inside an insulating rubber hose.
Is this another case of something being repeated so often that it becomes fact or is there a genuine reason? I'm ready for them."

Synchro,
The thermostats only come with 1 small or no hole at all. I think if they drift up the hose and are driven in cold Fall/Winter temps when the thermostat finally opens the rush of cold water up the middle possibly causes these kinds of cracks. Since this car has this condition it would be good to know if they had said thermostat, where it was and how many holes...If we can get data we can help out others from avoiding an expensive repair possibly. I have not purchased a thermostat from any of the vendors in a while, but am curious what the install instructions are for them.

Jerry
 
Thank you all for your pictures and comments. As further information, this car did not have a thermostat. The car did have machined valve seats and inserts installed. I understand the benefits of the permanent repair. I would be nice but the work to get the engine out and the expense of delivery and repair by a rebuilder I think suggests a try at sealing. This car isn't driven every day to work and if we could get another 5000 miles out of it, it may meet the needs of a guy who wants to use the car for club events. Ed
 
"If we could get another 5000 miles out of it, it may meet the needs"

In that case just use the block sealer.

Did I ever relate my experience trying to seal the radiator in my 54 Packard? I tried oatmeal. I put in the oatmeal in the sealed coolant system and let it get hot. I tried to check the coolant level and took of the cap. Cooked oatmeal exploded out the radiator and got all over me and the engine compartment.
 
Did I ever relate my experience trying to seal the radiator in my 54 Packard? I tried oatmeal. I put in the oatmeal in the sealed coolant system and let it get hot. I tried to check the coolant level and took of the cap. Cooked oatmeal exploded out the radiator and got all over me and the engine compartment.[/QUOTE]

Sounds like a "little" too much of a good thing :D
 
Jerry Kzoo said:
"I have seen written here many times that the thermostat should be held at the bottom of the top hose but does it really make any difference?
If there are extra holes drilled in it (and who doesn't do that), then coolant will flow through it regardless of where in the hose it is. The coolant won't cool over the 3 inches or so difference while inside an insulating rubber hose.
Is this another case of something being repeated so often that it becomes fact or is there a genuine reason? I'm ready for them."

Synchro,
The thermostats only come with 1 small or no hole at all. I think if they drift up the hose and are driven in cold Fall/Winter temps when the thermostat finally opens the rush of cold water up the middle possibly causes these kinds of cracks. Since this car has this condition it would be good to know if they had said thermostat, where it was and how many holes...If we can get data we can help out others from avoiding an expensive repair possibly. I have not purchased a thermostat from any of the vendors in a while, but am curious what the install instructions are for them.

Jerry
Click to expand...

Jerry, I assumed everybody drills a couple of extra holes in the T/stat. As for a rush of cold water, a thermostat opens slowly and would therefore not allow a rush of water anywhere. It would be a gradual change of temperature preceded by warm water that has come through the holes drilled in it.
That said, I've never been inside there when all of this is happening so I haven't seen it, just observed what happens when a T/stat is put in hot water on the stove.
 
I have some experience with the stock thermostat that has the small hole. It was retained in the bottom of the top radiator hose with a hose clamp. This was in the summer and the temperature was in the 90's. I was driving hard up a grade. My temperature gauge showed the water temperature steadily climbing towards the 200 degrees. The thermostat opened and a slug of hot coolant entered the radiator causing the motometer to register at the top and some coolant to escape out the cap. The temperature gauge then went down to the 160 range and the motometer went back to not registering. After a while the process repeated. It was after that that I drilled the extra holes in the flange.
 
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