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HTHM

Is my motor shot?

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I had to fix the recoil on my 20 HP 1983??? johnson seahorse, minor repair, loose retaining bolt. I decised to check my plugs, as I had not done that since I got it last May. I pulled out the top plug and find that whoever had installed it crossthreaded it when installing it. The recieving thread is essentially gone. Is there a way to fix this? I was careful to collect all shavings before I turned it over to blow out the cylinder.

Needless to say I am less than pleased. The people that I bought it from will be getting a request to look into the matter. However the motor was quite inexpensive, and really had no warrantee.

Thanks for your help.

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if you don't want to put any money into it, the engine obviously got good compression and ran the whole time you had it so you might just put the plug back in if you can find the thread/path it turned out on.

 

taping for a helicoil is the proper fix, but you might also luck out and find a used replacement head somewhere.

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well a helicoil isint excatly the right way

What is the right way to do it in your opinion? I am open to suggestions from all corners.

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theres GAZZILLIONS of those engines around get a new headgasket 15.00 probably could use it anyhow,and a used clean head and away ya go

well theres this way But I took notice to the yr of the engine yeah cheapers better on a 25 + yr ole engine ,a replacement head with proper plug threads is the right way to fix it ,helicoils is a backyard hack fix in my book,to each there own

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Funny thing I have used Helicoils for years in the autmotive industry, and have never had a problem with them. We have used them in sparkplug holes , brake caliper hold down brackets, oilpans , pretty much anywhere you use a fastener. So yes I guess they aren't the way to go in fixing things, "Hack Job " I believe the term was.

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Funny thing I have used Helicoils for years in the autmotive industry, and have never had a problem with them. We have used them in sparkplug holes , brake caliper hold down brackets, oilpans , pretty much anywhere you use a fastener. So yes I guess they aren't the way to go in fixing things, "hack fix" I believe the term was.

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well theres this way But I took notice to the yr of the engine yeah cheapers better on a 25 + yr ole engine ,a replacement head with proper plug threads is the right way to fix it ,helicoils is a backyard hack fix in my book,to each there own

 

Maybe not a backyard fix... but I do agree that a new head would be a better and proper fix!

Edited by GCD

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Depending on the heads heli-coils are not always the best choice of insert. Fine in an aluminum head of basically same material; heli-coils are even used on aluminum heads of NHRA top fuel dragsters.

 

Keenserts made of carbon steel are a better choice for most heads, not ever going to 'turn out' if someone torques down a plug too much. Heli coils can make your plugs run hotter too, saw an engineering vid comparing the 2 in a cast iron head-makes a dif.

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I agree on the plug heat issue but should not be a problem unless the engine was borderline. If repairing the head make sure to do both plug holes and you might as well pull the head to check it's condition before repair, clean inspect for cracks and warpage. If you can find a cheap replacement head then why not go that route.

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A helicoil is a totally proper and acceptable fix for your problem. Personally, I'd look for a replacement head. You will need a new head gasket regardless. Even though you can install a helicoil without removing the head I don't suggest it. You risk getting metal shavings in the cylinder. Remove the head and do it right. If you get a used head (like I would) you will need to plane it. You can do this by placing a piece of 400grit wet/dry sandpaper on a plate of glass or the like and rubbing the head in a figure 8 pattern until the high spots are gone.

 

Also, that model may require a new water jacket cover gasket if you replace the head.

Edited by boatman

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A helicoil is a totally proper and acceptable fix for your problem. Personally, I'd look for a replacement head. You will need a new head gasket regardless. Even though you can install a helicoil without removing the head I don't suggest it. You risk getting metal shavings in the cylinder. Remove the head and do it right. If you get a used head (like I would) you will need to plane it. You can do this by placing a piece of 400grit wet/dry sandpaper on a plate of glass or the like and rubbing the head in a figure 8 pattern until the high spots are gone.

 

Also, that model may require a new water jacket cover gasket if you replace the head.

 

The Master has spoken!! :thumbsup_anim:

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Helicoils are actually stronger than original. Absolutely a proper repair.

Years ago some British machinery was made with inserts in cast iron.

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I've done a dozen or so heads with heli coils. It is a good way to fix your problem. Do take the head off to fix. A new gasket is a must do. Most engine guys will do the coil for about 20-30 bucks. Any worries just PM me.

CX

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The head has been done with a helicoil, the initial torque is complete, all that remains is to torque after temp.

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