Silicone(?) used to repair leaking head bolt

J

jscap99

New Member
#1
#1
Looking for an old post, someone had repaired a leaking head bolt with silicone. I need to know the info on this. What kind (product) silicone? Is it the stuff in caulk guns? I have some gasket cement I might use. Any and all info would help. Thanks, John
 
D

dobber

New Member
#2
#2
You could try the stuff in a brown bottle that they used on the heads of old Ford motors, I think it was a Shalk type of product. Not sure what it is called.
 
J

jscap99

New Member
#3
#3
Silicone/ used to repair leaking head bolt

Are you talking about gasket cement. I have something like that, it's a small brown bottle, and theres an applicater built into the cap. but it's really strong stuff, and thick. I'm a little afraid to use it. -John
 
D

dobber

New Member
#4
#4
Ya, that is the stuff. It smells like bad varnish, and if you do use it, it is some tuogh stuff to remove later. Question from you though, do you have a loss of compression through a head bolt? If that is the case, do you have a bad head gasket or a warped head?
 
J

jscap99

New Member
#5
#5
It's a new head gasket. The engine is running like theres an air leak when it reaches temperature. Theres oil bubbling around a bolt where the head gasket is, on the drive side of engine. I might seal it up with this strong stuff since I have no intensions of rebuilding it. I would seal it just in the area that appears to have the problem. I also need to check the intake gasket. I replaced it on this engine before. any ideas? -John
 
D

dobber

New Member
#6
#6
Does it have a cracked block from the valve to a head bolt? or maybe somebody put a to long of a bolt in one of the holes and cracked the block?

Do you have a lack of power? I had one that ran like crap from a bad Intake Gasket.

Also how many pounds of compression?
 
rudedog

rudedog

New Member
#8
#8
What are you working on?? Sometimes headbolts have a shoulder on them, and have to installed in a certain hole. Dobber nailed it, some of those old Fords had exactly that type of bolt, but they would leak coolant, because the bolt actually went through the water jacket in the head. Also because of that, the shoulder would corrode due to lack of maintenance and electrolysis, and the "easy fix" was to slather them all up with silicone.
 
bugman53

bugman53

New Member
#9
#9
I would check for a warped head and put another new gasket on it.

But for your question. You can use a liquid high temp thread sealer used in steam pipes made by loctite. I forget the # of the product though. works like a charm. and it will come back out pretty easy.
 
Strigoi

Strigoi

#10
#10
my buddy and i "fixed" a leaking head gasket (was leaking out of a head bolt) on a 3.5 tec with some silicone. we just siliconed the bolt and put it back in.
 
den35

den35

New Member
#13
#13
Wonder if automotive RTV sealant(the stuff used on the ends of a car engine intake manifold) would work.It's made for heat and pressure.
 
bugman53

bugman53

New Member
#14
#14
better idea get a copper washer used in banjo bolts and brake lines and put it under the leaking bolt and that will seal that leak.

But really silcone to fix a head bolt. I not trying to insult anyone but that suff might old 5psi not 150 psi in a cylinder head. If its just a oil leak then thats different but a head bolt.

If is leaking compression then have the head surfaced. and get a good gasket and there will not be a leak. Its a flat head, not a OHC watercooled race motor(and yes i build race motors for a living)

But the copper washer would hold. My concern is hot gases geting past the fire ring in the head and causing the gasket to burn up.

If a head gasket ever leakes for a few seconds then the gasket is toast.
 
bugman53

bugman53

New Member
#15
#15
I just read that you have a new head. What kind of gasket are you running?

We will get her fixed for you.

a quick trick to make sure the head is flat. Take a peice of glass and lay some 400grit sand papper on it and move the head in figure 8 patterns and look at the smooth parts on the bottom of the head. you will quickly see if there are any low spots. you can do this for a wile and get the head pretty flat. It is possable that the new head has warped if the casting was not aged before maching.
 
J

jscap99

New Member
#16
#16
leaking at the head

It's a new gasket on there, not a new head. The gasket is OEM and copper. I also used some copper spray sealant. still leaks.

When I get to it I want to try truing up the head with sandpaper, although I don't have any plate glass. I also heard you can use a file to do this, but I don't want to ruin it.
I would like to get this head surfaced but don't know where to look to have it done. any ideas on getting the head surfaced?
I guess using silicone as a sealant is not a good idea?
-John
 
J

jscap99

New Member
#18
#18
head leak

The bolt and threads appeared to be in good shape. I hear you about the sealers. The tecumseh book says not to use sealers. You just make sure the head is true and replace the gasket.

I'm going to take it apart soon. When I put it back I'm going to use a brass washer. I might want to get the head resurfaced but I don't want to spend that much. At a harbor freight near me they have the 6.5hp clone for $100.
John
 
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