Stripped Out Treads On Exhaust Port

[polarisgold]

I bought this Dynamark 12hp B&S used. It was made in '95.

The original muffler bolts broke off one and the other came out without threads.

Is there any type of epoxy that I could glue to the cylinder head? Sounds stupid but trying to drill out the threads to repair the bolts is nearly impossible, same with exhaust port.

There has got to be some sort of high temp epoxy.....right??

Any ideas would be much appreciated.

 

[reynoldston]

The problem is the high temperature. The highest silicone sealant is only good to 700 degrees. I don't know how hot exhaust temperature runs but I find anything I have ever tryed just burns up. What I have done with broken exhaust studs is drill them out and retread them. If it is beyond that I would try going to the next size bigger bolt and retread the head and drill out the exhaust flange for the bigger bolt. Just be careful if you have to go oversize because they don't give you much material to work with. They also make thread repair inserts but with the high temperatures and small areas to work with I don't know how that would work?

 

[polarisgold]

The problem is the high temperature. The highest silicone sealant is only good to 700 degrees. I don't know how hot exhaust temperature runs but I find anything I have ever tryed just burns up. What I have done with broken exhaust studs is drill them out and retread them. If it is beyond that I would try going to the next size bigger bolt and retread the head and drill out the exhaust flange for the bigger bolt. Just be careful if you have to go oversize because they don't give you much material to work with. They also make thread repair inserts but with the high temperatures and small areas to work with I don't know how that would work?

Thanks for your input.

 

[hitmanharleyk]

Look at companies online like Lawson Products. I know they carry a repair product that is good for 2000 degrees, but it is going to be costly.

The cheapest repair would be to tap it out to the next size bolt if you have enough "meat" between the port and stripped hole.

 

[motoman]

The guys are right, however it is very common to weld fill in aluminum. I am not familiar with the engine head you have . If aluminum and if another cannot be found take the head to a "good" welder who can heliarc or possibly wire weld the eshaust flange bolt holes. You can probably finish them your self by machining ( careful hand filing ) the filled holes level , using the manifold to scribe hole outline, center punch and drill and tap. Make sure the drilling is perpendicular and also the tap. This can be done on a small drill press. The welder should not charge you more than about $5-$10.

 

[reynoldston]

The guys are right, however it is very common to weld fill in aluminum. I am not familiar with the engine head you have . If aluminum and if another cannot be found take the head to a "good" welder who can heliarc or possibly wire weld the eshaust flange bolt holes. You can probably finish them your self by machining ( careful hand filing ) the filled holes level , using the manifold to scribe hole outline, center punch and drill and tap. Make sure the drilling is perpidicular and also the tap. This can be done on a small drill press. The welder should not charge you more than about $5-$10.

I agree with every thing you are saying till you get to the 5-10 dollar part. The last time I went to a shop and had aluminum welded it was more into the 40-50 dollar range. Which still isn't a bad price if you had to replace the head.

 

[motoman]

Well it's been a while but look around for a home based welder. Seems like $50 is excessive. Perhaps a school based weld program if there are any. Again , alulminum weld repair is very common for cracked heads, loose valve seats etc. I would like to think a home based welder could be found in Idaho. There's a sign just down the road from me in rural Wasington. Maybe I'll inquire.

 

[polarisgold]

Well it's been a while but look around for a home based welder. Seems like $50 is excessive. Perhaps a school based weld program if there are any. Again , alulminum weld repair is very common for cracked heads, loose valve seats etc. I would like to think a home based welder could be found in Idaho. There's a sign just down the road from me in rural Wasington. Maybe I'll inquire.

Thanks for the reply to my post. Please do inquire I'd love to know........

 

[reynoldston]

Frist of all I am doing this as a repair job. I am not going to someones house that may or may not know what they are doing unless I know them and the type of work they do. But I don't and I have to guarantee my work. I am going to a business that does welding and that is all they do. I know what it just cost me to have a 1in. long crack welded in a aluminum engine case. Even at that its cheaper then new parts. This is why on older equipment it is cheaper for me to go for used parts.

 

[Rivets]

Listen to reynoldston, he's got it right. The welder we use for aluminum charges $40/in. That includes the cleaning which it is not done right will ruin the component.