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GWGAllisfan

Briggs head gasket (Repaired)

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GWGAllisfan
Ok today I was staying home with a sick child, so while they slept I actually had some time to work on something. Here's my neat and orderly shop area:D

Pulled the head to change the gasket. This is what it looked like:

The gasket was not stuck to either block or head and lifted right off.

In these two the leak is clearly visible

The gasket wasn't burned away completely in that area, but was partially damaged. I couldn't get a clear picture of that. Questions: 1.How should the mating surfaces be prepped for the new gasket? 2.Should they be sanded or filed, or just brake cleaner cleaned and wiped with a rag? 3.I think I may have caught it in time, what do you all think? 4. Should I get new head bolts? here's why I ask The engine has 3 different markings on the head bolts. I can't tell which is right so I thought that might have contributed to the problem. also the one on it are very rusty headed and might not torque well. If I need new ones, I know new briggs ones are available, but are they really that special? Is there a hardware store or perhaps Granger, Fastenal or Napa equal? I get to take another turn at home Thursday, so I was hoping to pick up the bolts tomorrow and try to put it together then. Thanks for the help.

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Roy
Take a straight edge (steel ruler) and check the head and block for flatness. If either is warped more than a few thousandths (0.003" to 0.005" maximum, I don't have my Briggs Manual handy) they should be trued before assembly. On a Briggs the block is usually pretty flat except for around the bolt holes. A countersink can be used to chamfer the edges of the holes to remove the raised area (if any). If the head is slightly warped it can be hand milled (e.g. sanded) with a piece of sandpaper on a flat true surface (piece of glass or table saw for example). Put the sandpaper on the flat surface and move the head around in circular motions on the paper. Go slowly and carefully until the entire gasket surface is flat. Check periodically to see if it is flat as you go. Do not remove more material than necessary else you will raise the compression ratio. Hopefully your head and block will check OK and you will not have to do any of the above. Good luck,

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D-17_Dave
Agree with Roy. As for removeing the old gasket, just use a regular gasket scraper. The Aluminized gaskets ussually don't stick to bad so whats left should come right off. As for the head bolts, I think the shank on the bolts might be a touch smaller than a regular bolt. I'm failr certain it's a better grade of steel. I wouldn't be concerned with some head rust as long as a 6 point socket will grip them well and the shanks are still fairly rust free I'd use them.

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GWGAllisfan
Thanks for the replies. I'll check the head flatness and bolt it back up. I was surprised the gasket wasn't stuck to either surface. It I do need to sand it, what grit should I use? emory paper or regular sandpaper? This tractor will stay with me. It was brought home right after I was and has been with me ever since. My father traded a B1 for it.

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Al
Hi, We as a matter of policy always surface a head on a flat plate as described above. If it is OK it will show contact all over the machined surface. If it doesn't sand until it does. We stroke, turn 1/4 turn, stroke, another 1/4 turn etc. This keeps it flat Roys cirular motion will accomplish the same thing. If you shot blast it, IT IS IMPERATIVE TO WASH IT WITH SOAP AND WATER WHEN FINISHED. Silica or glass shot will stay in the metal until it gets a soap and hot water wash. When we shot blast alternator housings, you can blow the screw holes out and the screws will seize when installing them. A solvent like spray carb cleaner only makes it worse. Wash them in soap and hot water and blow them out they are fine. If you don't the abrasive residue will damage your cylinders and rings. It is the same as the need to scrub cylinders with soap and water after honing. If you shot blast put an old spark plug in the head to protect the threads. While on the subject Briggs put out a service bulletin years ago about abrasive spark plug cleaning. They listed the residue they removed from sand blasted plugs. If you blast clean plugs, blow them out and then put soapy water in them and blow again, you will be amazed at the abrasive residue you capture. Do it 2 more times , 3 total and you will see that this is the minimum to clean them out. One more point. If you shot blast the combution chamber in a head to clean the carbon out, you MUST get every trace out. A tiny spot will hold abrasive like a sponge and washing it will NOT get it out, unless the whole carbon spot is removed with the detergent. This abrasive will come out and imbed in the piston skirts, or rings and cause undo wear on the cylinder. Al Eden

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BLT
Also, it would be wise to run a 5/16-24 NC bottoming tap in the thread holes to clean out the junk along with cleaning off the bolt threads. The use a thread lubricant on the bolts only, then tighten up to the correct torque. Don't lube the thread holes before installing the head bolts as this will cause incorrect bolt torquing.

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B.Ikard
Randy, There is an automotive machine shop down in Cartersville that has a flat plate and can true that head for you. He's done some work for me and I was very impressed with his skills and attention to detail, not to mention his personality and fair prices...and I don't impress real easy :) I don't have his name in front of me but he is across from the NAPA store on Tennessee street in an unmarked brown building.....I believe the name is Performance Machine. Brent

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Wishin2BMowin
Must be common for these heads to leak out the front of the engine. My 3212H head must have leaked for a while before I got the tractor as the head was melted. I bought a nice used one from one of the members here. All I did was take a medium grade flat file and holding it as flat as I could, cleaned both the head and the block. I did see that the threaded holes for the head bolts in the block were slightly raised but the file took care of that problem. Got a new gasket and put it all back together making sure I did not over torque the bolts. After running it for a while I checked the torque again and they did need a little tweeking. So far I've had no problems with it leaking again. From the looks of your head you caught it just in time to avoid it from melting. As for your shop, don't feel too bad, mine gets that way and sometimes you just have to stop everything and spend some time cleaning up. I usually do this when I can't find a tool or something I've been looking for! Best of luck...

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GWGAllisfan
My Cold I caught from the kids finally got better enough I was able to put the head back on and start this tractor. You can really tell the difference in the compression with the new gasket. Strangely it only started when I changed the plug from the RJ19 that the book says it should have to a J8C. I wouldn't have expected that to make that much difference but it did. I wasn't able to run it too long in the enclosed garage, but it did run. I'm having a little trouble with it running for a while then quitting, but then it will start right back. I lowered the idle speed screw to give the governor more room to adjust the speed and that seemed to help. Does that make sense? I just decided to end the tinkering on a happy note and not mess with it for a while.

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