Advice for leaky head stud!

[65Camp]

Well I ran the tractor last week for an hour let it cool and retorque the head. Everything appeared fine. So today I decided to let it in run for a while just for motivation. However, one of the head studs had a little moisture around the nut. So I shut the engine off and dried the stud. Problems is even with the engine off it leaks with just the water head pressure from radiator. So now what do I do? I used Felpro head gasket, new studs, washers, and nuts..used Permatex Aviation on stud threads…torqued with three step sequence…ran tractor for an hour…cooled and retorque the head. Tractor runs great and no water in the oil. So should I torque the head again…I doubt it?? Put some stop leak in it? Will it fix itself? Thanks.

 

[soaked]

Hi 65Camp, haven't had a early 8n with studs for a long time. I have had bolts weep a few times recently. Lifted just the weeper, and put some RTV around the top of the shank, then put it back in. Trying to seal the top off.
If you tried to wipe RTV around the stud, trying to push some down, it may succeed.
Are you using the "newer" torque chart?
Not sure it makes a big difference, but its what I go to.

It would likely seal itself over time....
John

 

[65Camp]

Hi 65Camp, haven't had a early 8n with studs for a long time. I have had bolts weep a few times recently. Lifted just the weeper, and put some RTV around the top of the shank, then put it back in. Trying to seal the top off.
If you tried to wipe RTV around the stud, trying to push some down, it may succeed.
Are you using the "newer" torque chart?
Not sure it makes a big difference, but its what I go to.
View attachment 154057
It would likely seal itself over time....
John

Hello Sir,
Might give that a try. It had bolts and when I changed the head gasket I went with studs in hopes of not having any leaks. Especially after the retorque. Yes I used the torque chart you show. Thanks Paul

 

[Hobo,NC]

Stop leak should take care of it. GM has some brown tabs as does parts stores. Crush'em up and put in the system in time it should seal up. I like GM's.

AI Overview




ACDelco GM Original Equipment Cooling System Sealing Tabs (Part #10-108 / GM #12378255) are specially formulated, 4-gram tablets designed to safely seal minor coolant leaks and porosity in radiators, heater cores, and engine blocks without clogging the system

 

[Ray,IN]

My experience with using cooling system stop-leak is not good with older tractors. IMO, don't use a band-aid on a fresh rebuild, do it right and it will last. Somewhere there is a leak in the new head gasket that shouldn't be.

 

[Jim L WA]

65Camp, did you put the head gasket on dry? An old trick from many years ago, that I still use today, is to just spray both sides of the head gasket with paint. Put the gasket and head on and torque it down before the paint has time to completely dry.
I don't know if you want to go through with all that in your case. Just something to file away.
I think I would opt. for stop leak.

 

[65Camp]

I have bigger problems now. I added the AC DELCO tablets and still have a small leak. So I pulled the spark plugs to see if any water was getting into any of the cylinders. Looking through the hole everything looks normal and don’t see any evidence of water intrusion. All cylinders grayish / black. However, all spark plugs were black and two have oil on them. Oh the engine runs great with no smoke or anything. The engine is not a fresh rebuild. Just new head gasket and studs for piece of mind. So I “now” decide to do a compression test and it’s not good…number 1 has 95…2 has 105…3 has 80 and 4 has 105. So is the compression off and plugs oily because of bad rings? Maybe but cylinders looked great and pistons were tight when inspected while changing head gasket. Could valve clearance adjustment be off causing low compression and intake valve guide seals bad letting oil inter combustion chamber…maybe? So in the morning I’ll do a wet compression test. Wet test should let me know if it’s rings or not. However, this thing runs very nice….strange! Oh and there isn’t any blow by coming out the breather. Paul

 

[Ray,IN]

Guesstamite; warped head, which can be planed/ground if not out of limits. Either way it's my guess the head has to come off for further inspection.
The cylinders can be roughly re-checked by adding a tsp of motor oil through the spark plug holes and repeating the compression test to check ring seal.

 

[65Camp]

Ok guys did another dry compression and wet compression test in the engine completely cool. I was careful and did everything the same for each cylinder to ensure a true test.
Number 1 dry is 115…..wet 165
Number 2 dry is 120…..wet 160
Number 3 dry is 90…..,wet. 110
Number 4 dry is 120….wet. 140
So what do you think? Thanks for your help! Paul

 

[soaked]

Hi Paul,
8n with stock, domed pistons, with a new rebuild are 120 - 125psi. On a mid life engine 110 ish. Carbon build up can raise the compression up some. Maybe up to 140? But you just had the head off, and removed the carbon, right ?
Im confused by the wide spread of yesterday's test, with today's.
Is your compression tester in good condition? Hose not restricted, or the shrader valve goofed up?
Wonder if the effects of not running a thermostat are involved here.

John

 

[Eman85]

The stop leak tablets aren't an instant fix, takes a little time for the water to circulate and seal. What was the compression before the work? Was the throtlle butterfly open for the compression test and air filter clear? How did the valves look and did you adjust them? After the oil in cyls. compression test readings I'd fire it up and run it and see how it does.
Why did you take the head off?

 

[65Camp]

The stop leak tablets aren't an instant fix, takes a little time for the water to circulate and seal. What was the compression before the work? Was the throtlle butterfly open for the compression test and air filter clear? How did the valves look and did you adjust them? After the oil in cyls. compression test readings I'd fire it up and run it and see how it does.
Why did you take the head off?

Tractor ran fine do I didn’t a compression test before changing the head gasket. Just changed the gasket as a safety net seeing how I was painting the tractor. Pistons, valves and cylinders all looked good. Seeing how good it ran I didn’t worry about checking valve adjustment and such. The tractor runs great now. Just a couple of oily looking plugs. I was very careful this morning when doing the compression. If the tablets work to fix the leak I’m considering leaving the engine alone. It runs great and it will not be a working tractor.

 

[Hobo,NC]

I said in time may be I should have said IN TIME!!!. It could take weeks are months give it time. This does happen give those tabs some time to do their thang.

 

[65Camp]

I said in time may be I should have said IN TIME!!!. It could take weeks are months give it time. This does happen give those tabs some time to do their thang.

Understood and thanks!