Hairline crack at spark plug holes in cylinder head

[titaniumneck]

Ok, another question. Replacing headgasket on M40C Tohatsu. Found each spark plug hole has about a half inch hairline crack, the cracks go up the threads and down the cylinder piston cup. Can't ignore it, have to bring it to machine shop to fix. Does anyone know about how much this should cost. I do not know anybody personally that does this, so I am looking for an idea of about how much it will cost so a stranger doesn't try to take advantage of me and charge way too much. Need some advice here please.

 

[Grub54891]

Show us a pic of the cracks. Never seen that happen myself.

 

[titaniumneck]

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[titaniumneck]

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[titaniumneck]

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That's the best pics I could get. I am thinking the previous owner tighten the spark plugs way to much.

 

[ondarvr]

I don't think that would be easily repaired. The entire crack needs to be opened up and the filled with new material, after that you need to redrill the spark plug hole and thread it again. Plus hope it holds up. I think a new head would be more cost effective.

 

[titaniumneck]

You are right, just got off the phone with a couple machine shops. They pricing $120 to 150, new head is 180. It's a no brainer, crap didn't want to have to spend all that, but such is life. It's true about a boat, it's a hole in the water that sucks up money. Lol.

 

[Sea Rider]

Install a new cylinder head specially if already warped due to overheats. Buying second hand "mint" condition generally turns out into real Pandora Boxes in which need to trow lot of cash into...boating is not a cheap sport.

Happy Boating

 

[Grub54891]

Well that stinks. I agree with replacing the head. Looks like the crack could migrate to the water jacket even if it looks repaired properly.

 

[Sea Rider]

If adjusting plugs extremely tight say with a big wrench, will surely pull out all threads instead.. Extreme cylinder head overheat can do strange things.

Happy Boating

 

[titaniumneck]

Yea, it does stink but what ya going to do. I tell you one thing, I will definitely live by the rule of changing my impeller every year now.

 

[Sea Rider]

You haven't answered if overheat was due to impeller failure being dried, hardened, rotten or lower water intakes picked a plastic bag, kelp, algae, even a banana peel ? If the latter a new impeller won't save your OB on that naughty one. Personally have fried several Evinrude's 15 HP impellers due to lower tail water intake obstructions while boating at kelpy areas. At WOT can fry an impeller in just 30 seconds while spinning dry inside liner, along overheating, melting adjacet powerhead cables, even warping cylinder head. Very bad music indeed.

Happy Boating

 

[titaniumneck]

Sorry about that, it was overheat because impeller dry rot. Back in November 2014 I had three disk collapsed inward on my spinal cord in the neck, surgery and all that. Anyway I finally got back on the water last month. It felt like heaven, I grew up on the water. But neglected to service engine first mostly because I can't do work like that no more and couldn't afford to pay someone to do it. Learned my lesson on that one.

 

[Sea Rider]

Sorry if being to picky with you on that matter, it's just that haven't had any Tohatsu impeller failures while buying OEM ones, those are rotten & bullet proof, can speak same for after market ones. Happy to read you're back on water again having good boating times, cheers for that, water is my daily element too.

Happy Boating

 

[titaniumneck]

Appreciate it, you really don't know how important it is until you go close to two years without it. There is nothing in this world like being on the water watching the sunrise, with the excitement of the upcoming day.