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henroan

Blown head gasket

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henroan
Tryed starting 2012 motor(300421), wants to run but couldn'nt. Compression escaping out both sides of the head. Changing gasket is no problem. However I do have a question? Why do they blow? Should I be concerned of a greater problem that caused this? Rest of the motor seems fine. Put a straight edge on the head. No problem there. I did notice oil at the top of the cylinder on the valve side. Is that a concern? Well, please help me. TIA Patrick

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BLT
Bolts need to be checked periodically and I think it might be mentioned in OM. Also run a bottom tap in thread holes to make sure you get a true torque reading. I generally lube the bolt threads with Briggs anti seize compound. Also make sure you lube bolt threads and NOT bolt holes. You can crack castings stuffing the holes with anything.

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Willy
When I check a head for warp age I have a 12 in square of 1/4 in glass I lay a piece of sand paper on it and rub the head across it 4or 5 times and then look it over real good,if it's warped you can tell it real quick. If it isn't to bad apply an even pressure and rub until the sand paper makes contact over the whole head. But as Bob said running a tap in each bolt hole is always a good idea.

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HubbardRA
Don't forget to also run each of the head bolts through a die to clean up their threads also. I always do both the bolt and the hole to make sure their are no burrs or dings to mess up the torque readings. Once you have cleaned both, they should go together smoothly, like new ones.

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Storm7012
quote:
Originally posted by joshuaareed
Hey Willy what grit sandpaper do you use?
I've lapped a few and use the finest I have around. Seems like 600 was the last one but maybe finer. I use a little oil on the paper too. Don't be in a hurry, it takes a little time.

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Willy
quote:
Originally posted by joshuaareed
Hey Willy what grit sandpaper do you use?
I start with about 100 grit then when it make contact all around go with a finer like 350 or 400 wet dry.

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MrSteele
Any of you still have a babbitt file hanging around? They work fine on aluminum blocks and heads. A good sharp 12 or longer bastard file will do nicely on a cast iron block. Just be careful to use little pressure on the files, too much is not good. And remember, especially if using sandpaper or emery cloth, that cleanliness is next to Godliness. Clean the surfaces well, clean the bores, valve guides, any spot where parts move inside, and when you are certain you have cleaned well, use a clean rag soaked in (I use 10 wt) oil to wipe the surfaces one more time to assure yourself that everything is clean. If you pick up grunge on the oily rag, clean again, use the oily rag again...Emery or sandpaper grit works wonders on the inside of an engine, and engines wear out quickly if it is left inside them.

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