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Thread: Blown head gasket or head?

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  1. #1
    Member Nemo von Klepper's Avatar
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    Blown head gasket or head?

    Blown head gasket or head?

    There must be something wrong, thereĎs water in the number 2 & 3 cylinders. Itís a pity too because I got the engine running evenly and well. Now I think the plugs are water fouled.

    Anyway Iím determined to do as much of the work as I can, but this is my first rodeo so to speak. I have had a head off before only to inspect the cylinder heads on a dead engine. Anyway I canít remember that it was that difficult and the manual makes it look straight forward. I imagine thereís an even chance the head is cracked. Is there anything I should know before getting into this?

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    Super Moderator LarrBeard's Avatar
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    Uh - oh ... That's not good!

    Quote Originally Posted by Nemo von Klepper View Post
    Blown head gasket or head? There must be something wrong, thereĎs water in the number 2 & 3 cylinders.
    F-134 or L-134 engine?

    If you have the L-134, you don't have that big of a job in front of you. Tape the plug wires out of the way, pull the plugs and start undoing head bolts around the perimeter toward the center of the head. Persuade the head to come off and give things a good looking over. I hope you have a blown head gasket, but in the long life of the '48 - it did have a cracked head when Dad drove it as a flathead.

    I would defer to gmwillys' opinion here, but if you do have a blown head gasket, it might be worth getting the head checked for flatness or warping before you put it back on. Warping could have been why the gasket failed.

    And, as always - a picture or two helps the rest of us know just what to look for when we have the problem.

  3. #3
    Member Nemo von Klepper's Avatar
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    Yes, it’s an F, and it could be warped. Simplest case I was going to hold a straight edge in it and check with a feeler gauge.

    I might not get around to this right away; next month maybe. Is there anything I can do to minimize rust or pitting? I’ve blown most of the water out and drained the cooling system.

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    Super Moderator gmwillys's Avatar
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    It would be well worth having the head magnafluxed. You can check the head yourself to get an idea if it is warped with a straight edge. Check the deck of the block as well to ensure it is flat.
    The F head is a bit more prone to cracking than the L head. In my opinion, if the water shows up after after running a while, then it would be a cracked head. If the water shows up after sitting overnight, then it would be a head gasket. A cast iron crack will open when heat is applied, while a gasket will deal more after being heated, then cooled back to ambient.
    To prevent any rust issues while waiting to get time to year into the head, use WD-40 to fog the cylinder. Then replace the plug.

  5. #5
    Member Nemo von Klepper's Avatar
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    WD40, that sounds right.

    Right now I’m weighing my options. This was a pretty big setback and I’m trying not to let it get me down.
    It seems to me the rebuilt head in the KW catalog is a “plug and play”.
    There are also NOS heads available that I could rebuild myself.
    Obviously if the head checks out, I’ll just put new gaskets on.

    Making lemonade out of lemons I’m thinking of making this one as bulletproof as possible. I’ve read someplace that valves or valve seats suffer from the higher combustion temperatures of modern gasoline. I imagine there are remedies one can build into a head, harder valves or seats.

  6. #6
    Super Moderator LarrBeard's Avatar
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    Uh - oh Rev A

    Quote Originally Posted by Nemo von Klepper View Post
    WD40, that sounds right.

    I imagine there are remedies one can build into a head, harder valves or seats.
    Pulling the head on the F-134 is a bit more of a job than an L-134. Don't forget that short head bolt that hides under the throat of the carburetor.
    The guy who rebuilt the F-134 for the '48 forgot to put that one back in - and it caused an unbelievable month long headache before we found it!

    Exhaust valves are the ones that take the real beating. Keep in mind that when the air-fuel mixture burns in the compressed combustion chamber, the intake valves are closed and the rim of the valve is seated up against the head - giving a good heat sink for the lip of the valve.

    But, after the air-fuel mixture has burned, the exhaust valve opens and the very hot exhaust gases flow out past the open valve. The top of the valve is washed in the hot exhaust gases and that makes the exhaust valve much hotter than the intake. Once hot gases erode a bit of the lip of the valve, hot combustion gases erode the cast iron of the seat area in the block unless hardened valve seats have been installed. Normally, hardened seats are installed during overhauls to keep erosion down.

    Tetraethyl lead, in addition to enhancing octane rating of gasoline, actually put a thin coat of a lead oxide on the surface of the valves which protected them from exhaust erosion. No lead, no coating, we get erosion. The good news is that our engines are low compression engines and they don't burn up "instantly" like the high compression V-8's did.

    Here's hoping for a bad head gasket!
    Attached Images Attached Images

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    Super Moderator gmwillys's Avatar
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    The issue with modern gasoline is that the lead acted as a cushion between the valve and seat. The original head can have hardened seats cut in by a machine shop, then stainless valves. Then you don't have to worry, except for running ethenol. Don't. Ethenol will just cause you headaches. There is additives that are supposed to neutralize the effects of the corn alcohol.
    One thing I find it important to add on the subject of valves. Remember that on an F head, the intake valves are in the head, but the exhaust are still housed in the block.

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    Member Nemo von Klepper's Avatar
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    I'll probably pull the head this weekend just to see what I'm up against. If the head is blown, I'll buy a new one this coming month. Any recommendations for sealing the top of the engine to keep out the debris while I'm rebuilding the head? I was thinking of cleaning it up with gasoline and then just duct taping the entire milled surface. A simpler solution would probably be just putting a garbage bag over it with a bungee cord around the block. What would you do?

  9. #9
    Super Moderator LarrBeard's Avatar
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    Simple works ...

    Quote Originally Posted by Nemo von Klepper View Post
    A simpler solution would probably be just putting a garbage bag over it with a bungee cord around the block. What would you do?
    Garbage bag and bungee work for me. A light coat of oil protects everything nicely.

  10. #10
    Member Nemo von Klepper's Avatar
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    So I got the darn thing off. Some of those head bolts were quite a bear and I was sure I was going to skin my knuckles in the very least.
    The last one I was sure I was going to have to go out and buy a breaker bar.. Visual inspection gives me no clues other than to confirm coolant in cylinders 2 & 3.
    EAD65C9D-32F2-4E2A-8392-DA16F27006AC.jpg
    I cleaned it up as much possible for this stage, getting the gaskets scraped off. I checked with a straight edge and 0.25 mm feeler gauge.
    75B84722-0647-4E79-BE96-18D4EA8DD8D2.jpg
    The gauge was consistently the highest point in any place I checked. I do not feel at this point the head is warped. I’m more inclined to think the gasket was faulty.

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