Coolant leak on top of head

Sat Jan 04, 2014 10:11 am

Wondering if anyone has seen this and/or can provide guidance. I have coolant seeping from top of the head at the round button (plug?) next to the #4 spark plug at the rear of head. Is this thing a plug that can be removed or resealed or is it just part of the casting? If it's a plug I was thinking I could grind it off, tap the hole with a pipe treads and reseal. Or do I just have a cracked head.

cub head leak.JPG


This is on a '71 Int'l cub. Compression on #4 is good.
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Re: Coolant leak on top of head

Sat Jan 04, 2014 10:25 am

Paul I'm not sure but I think that is a casting sprue used to get the molton metal into the form. Don't check my spelling on this one.LOL

Re: Coolant leak on top of head

Sat Jan 04, 2014 10:59 am

Cecil wrote:Paul I'm not sure but I think that is a casting sprue used to get the molten metal into the form.
Agree.

Repair. Silver solder or brazing, think either can be accomplished without removing the head from block.

Re: Coolant leak on top of head

Mon Jan 06, 2014 1:04 am

Drain about 1/2 gal of coolant, then use a dremel tool clean out the crack with a sanding disc. Mix up some J.B weld ( not the J.B weld quick weld)
apply it neatly wait. 12hours sand to smooth finish touch up with IH red paint, refill radator should be good to go. I had a hair line crack around a head bolt on my 48 cub did this repair 13 years ago so far no leak. Dave F.

Re: Coolant leak on top of head

Mon Jan 06, 2014 11:47 am

I like Dave's suggestion, but I would add that after grinding/sanding, to warm the area for the repair very well with a heat gun to ensure a dry surface on which the JB Weld will adhere. Give us an update (with photos) of your progress.

Re: Coolant leak on top of head

Mon Jan 06, 2014 12:11 pm

http://www.amazon.com/Permatex-26346-Te ... 12-6064046

Might try an epoxy similar to the one above. Product advertisement says for exhaust manifolds, should hold up for Cub's head.

Didn't initially recommend an epoxy because several years after purchasing my Cub, a leak developed on top of the head. Turned out to be a crack that had been epoxy patched. Patch had been in place for a long time, well before I purchased the Cub.

Re: Coolant leak on top of head

Sat Jan 11, 2014 6:54 am

Thanks for all the suggestions. I'm going to grind/clean and give it a braise. Will report back on results!