head bolt leakage

B

bgalla

Member
I have rebuilt a 21 stud flathead now on the chassis of my 36. It has about 2hrs of engine time, just staring it up and running it periodically to keep things lubed etc while I work on the body. It runs great!. I noted today, however, a small water leak around the head bolt at the nut just below the spark wells of cylinders 7 & 8. It is a cast iron head torqued to 55lbs at the time I rebuilt it. What should I do? How do I make sure water is not leaking into the cylinder? Do I need to pull the head? Should I torque down the whole head more? Thanks for any advise-----Bruce
 
Bruce, you have a stud that runs through into the water jacket, which apparently was installed without sealant on the threads. Don't worry about water in the cylinder, as your head gasket prevents that, but water does have a direct path alongside the stud to the top of the head, making an ugly mess of things topside.

Correction of the problem can sometimes be as easy as loosening the headnut, winding a sealant impregnated string around the stud a couple or three turns, and torqueing it down again. If it fails the first time, you'll have that valuable experience to draw on for your next try.
 
if the car is where there is no danger of freezing fill the cooling system with water. it will seal it,s self. always better to run a rebuilt eng with water for a few thousand miles .this way if there is a leaking proulbem the water woun,t hert the eng like anti freez .but if you live were freezing is a proulbem you have no choice but to use anti freez . in the winther ware i live we would run the rebuilt eng in the shop with water make sure no leaks then drain & fill with 50/50 anti freez mix . this way we did not loose any expensive anti freez .also the cooling system got a finnel flush
 
It might seep for a little while, but it usually seals it's self over time. Unless it's really loosing a lot of water out of the stud. Have you only torqued the heads once since rebuild. Run it warm, let cool, re-torque. Do it 2-3 times over time. I wouldn't worry about it.
 
retorque and run with water will seal in a while, nothing unusual for a flathead. Kinda like a baby dribbling till it grows up. When it gets old it starts again!!! Grin getting older not always pleasent.
 
My '36 LB engine did this as well. I chased all the stud hole threads and applied some sealant to the threads, but had a few leakers anyways. Running pure water allowed them to rust over and all were dry after a couple of months or so.
 
Thanks for all the help guys. I have not retorqued the head after running it warm for a while and will do that. I have only water in the system now, so one did tell me to do that, so maybe in time rust will help. If not I will try sealing the threads and then perhaps some sealant in the coolant. Thanks gentleman Bruce
 
Put a bottle of Barrs heavy duty stop leak in and it will seal the leaks. Just about all of these engines have some small leaks, we put a bottle in every old Ford. G.M.
 
G.M. said:
Put a bottle of Barrs heavy duty stop leak in and it will seal the leaks. Just about all of these engines have some small leaks, we put a bottle in every old Ford. G.M.
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I agree done the same many times!:)
 
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