Head Gasket Leak - What Did I Do Wrong

R

RonLey

Member
Finished rebuilding my 1928 Roadster engine. I have a copper gasket and I sprayed it down twice with Perma Tex Copper Gasket Spray. Over the next week I tweeked the nuts to 55# several times.

I filled the radiator with antifreeze and got ready to start the engine. I cranked it by hand a number of times without the sparkplugs. I notices that antifreeze was coming up through the nut on the first center stud so pulled it and put on so sealant.

As a fluke I started to time it and put my finger down the #4 sparkplug and felt moisture. I pulled the head and the #4 cylinder had antifreeze in it. I pulled the head and the gasket came right off. It didn't stick at all. I have Perma Tex Copper Gasket Spray residue on all of the block and head indicating what should be a good seal.

I have taken off the side cover to check it and will now pull the oil pan and clean it out.

I am at a loss. I am going to check the deck and head again. I thought the gasket spray would be more sticky. Is it possible that I should have sprayed a heavier coat on it?

Ideas??

Thanks
Ron
 
First center stud? Which one is that?
Never remove a head nut with coolant in the block ... Always drain first as it can fill a cylinder very quickly...
Coolant coming up the studs is fairly common till the motor gets run in better they tend to seal up... You may have created your own problem and not needed to take it apart...
Some use technician in a can or dental floss to seal the studs, but I usually let it happen naturally
 
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RonLey said:
Finished rebuilding my 1928 Roadster engine. I have a copper gasket and I sprayed it down twice with Perma Tex Copper Gasket Spray. Over the next week I tweeked the nuts to 55# several times.

I filled the radiator with antifreeze and got ready to start the engine. I cranked it by hand a number of times without the sparkplugs. I notices that antifreeze was coming up through the nut on the first center stud so pulled it and put on so sealant.

As a fluke I started to time it and put my finger down the #4 sparkplug and felt moisture. I pulled the head and the #4 cylinder had antifreeze in it. I pulled the head and the gasket came right off. It didn't stick at all. I have Perma Tex Copper Gasket Spray residue on all of the block and head indicating what should be a good seal.

I have taken off the side cover to check it and will now pull the oil pan and clean it out.

I am at a loss. I am going to check the deck and head again. I thought the gasket spray would be more sticky. Is it possible that I should have sprayed a heavier coat on it?

Ideas??

Thanks
Ron
Click to expand...
Light spray not heavier-install while still tacky!
 
is the block a true surface?
has the head been trued?
Following the suggested torque sequence?
Coolant can easily leak by some of the studs up to the surface of the head. Happens all the time; there are no crimps on the water holes to get a good seal. When studs like that are discovered, you can do nothing and wait like Mitch, or drain coolant and wipe a layer of Permatex #2 non-hardening sealer around that stud or force it down between the stud and the head. Do you have any stud holes in the block that go clear thru into the water jacket? If so those need Permatex #2 on the stud threads right from the get go.

It is not as easy as ppl think to get a good seal on a Model A head gasket...Henry only gave 5 studs per chamber

As prev stated if you loosen even one nut on a Model A head you had better drain the coolant first; you will create your own leak for the reason just above
 
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Very informative and professional responses above.

Lots of lengthy details if a technical class were given on installing Model A head gaskets.

FWIW:

It may be helpful for us sometimes to not just ask ourselves, "What did I do wrong?"; but, also,

"What did I not do at all?"

For example:

a. "Correctly check head and block for "dead" flatness?"

b. "As mentioned above, because of so few studs for this head, use the most recommended vintage head gasket sealant used successfully by most vintage Model A professional mechanics since Model T days, i.e., Permatex No. 2 ?"

c. Tighten head nuts "gradually", in sequence, as opposed to applying 55 ft. lbs. to the very first nut?"

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And it is always beneficial to learn one way "how" to "successfully" warp a near-dead-flat Model A head:

1. Allow engine to attain operating temperature; check oil ...... looks milky with coolant therein, so;

2. Immediately drain coolant so head metal temperature can rise; and,

3. Completely loosen and remove one head nut at a time, not in reverse recommended sequence, in order to be able to cause the maximum warping stresses.

4. Reinstall head and over torque some nuts and under torque others to create more stress.

5. After 80+ years, this simple head warping procedure was successfully achieved often by many non-mechanical minded Model A owners.
 
I had a leaking head that a $70 trip to my local automotive machine shop fixed by resurfacing the head. I also followed proper head torquing per tbirdtbird's advise.
Good luck,
Hugh
 
forever4 said:
No wonder! I've been cheated!
I only have 14 studs per four cylinders instead of the 20 you apparently have! :D
Click to expand...

Some are shared, of course.

5 head bolts/studs per cylinder is pretty common. Here's probably the most popular motor of all times (small block Chevy)...

sbchvy_head_seq.gif


Some high compression new engines and blown/turbo charged engines have 6/cylinder.
 
You write that you finished rebuilding your engine. Does that mean YOU did everything, including checking for cracks in the block, or did a machine shop/rebuilder do all that? I ask because if you missed a crack in one of the valve seats in #4, coolant (ESPECIALLY anti-freeze) will leak into the cylinder, and depending upon the severity and location of the crack, it can fill a cylinder overnight, even if the piston is in its extreme downward travel location. This happened to a Model B engine I was running: a crack in #4 exhaust seat allowed coolant to fill the cylinder overnight and made starting in the morning difficult, with the engine hitting on three cylinders until all the coolant had been expelled. Lots of water droplets sprayed out of the exhaust pipe. RATS!!!
Another possibility for coolant leaking as you describe concerns boring the cylinders for oversized pistons. Once meat is taken away from a cylinder wall during the boring process, it is not uncommon in Model A engines to expose pin holes in the cylinders caused when the block was cast. These imperfections lie dormant in standard bores and in the smaller overbores, but are exposed when going to the bigger bores.
Check for these two conditions when you pull the cylinder head off to inspect the head gasket. It might not be the gasket after all!
Marshall
 
One question was: "Is it possible that I should have sprayed a heavier coat on it?"

There is a lot of pressure inside a combustion chamber when the spark plug ignites the fuel, so "if" the head gasket is not uniformly seated and compressed, the sealer in a loose joint can blow out.

Not trying to be funny .... but try to picture placing a wad of wet juicy Bubble Gum on the muzzle of a 12 gauge shotgun barrel, and pull the trigger ...... (but please do not try this) ..... even though the Bubble Gum is blown off, a very thin shotgun barrel can easily rupture with very little restriction like even soft mud.

Maybe a few simple answers to a few questions may help, like:

1. Did this engine run before with no water leakage prior to your rebuild?

2. Is it possible that this engine sat through freezing temperature with a marginal amount of anti-freeze and cracked?

3. In saying: "I noticed that antifreeze was coming up through the "nut" on the first center stud so pulled it and put on so sealant." ..... Did you use a gasket at the front water outlet, or possibly crack the water outlet when tightening this first center nut?

4. The source of this water leakage is of utmost importance ...... is there a Model A Club near you ..... if you state your address, help may be on the way.


 
One additional step in the procedure of replacing head gaskets must also be considered. Crud in the water jackets of the head can fall out onto the gasket, unseen, while wrestling the head down over the studs and get squashed in the sandwiching process. Always flush and blow out the head coolant passages before setting the head on the studs.
 
I like to fill a fresh engine with plain water the first time "just in case". That way, if there's any seeps or leaks, it's only water to deal with, not anti-freeze.
Don't ask how I figured this out.
 
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