had an overheat , does this need work?

[fishfeatures]

1990 60hp johnson

Had it out today 2nd time this year, alarm must be bad as it barely sounded and i couldn't really hear it over the motor, it was a murmur at best. Anyway let it cool down and limped 1 mile home. :mad-new:
Pulled the head and slight scoring on no.3, i can feel it ever so slightly but it is scored. Compression reads 110-105-101.....
It starts and idles ok in gear. I didn't see any problem with water pressure gauge on my trip in or out and it never sounded out of whack.

Do i have to strip it and sort this or can I keep going for another month or two and then look into sorting it... will i do more damage by running it....?ray:

 

[fishfeatures]

Re: had an overheat , does this need work?

ok 70 views and no opinions..... so i have gone ahead with the theory that i'd be better to get it fixed then taking a chance and inviting trouble to happen later on when i'm out the water.

I stripped the motor down and am just in from doing it.
I can't see too much but 1+3 pistons have chards of metal embedded in them but their rings are still intact.The head too has tiny peices embedded in it and I'll get this milled down.

There is def a scoring in no.3 very slight so maybe a good hone might take it out? how do i tell if the rings are worn?? whole i've it tore down i'll guess i'll replace them , but won't do all bearings as i just don't have the cash for them all.

which leads me to the crux of my issue, maybe it's nothing but it looks suspect to me..... the bottom crankcase seal has a milky white substance in and around it, i'm guessing water intrusion.... if so how ????? spark plug or head doesn't seem steam cleaned at all.

 

[emdsapmgr]

Re: had an overheat , does this need work?

I would not reuse any ringsets. If they are old, there is a chance one of them could break the day after the overhaul. Go with 3 new ringsets and one new piston. The 2 strokes rely on good compression to run-and it's the rings that make the comression in a 2 stroke. You'll need to rehone all 3 cyl liners. Once you do the cyl with the scuffing, see how it cleans up. You'll want it perfect or it should be bored oversize and you will need one oversize piston. You can get water into the block a couple of ways: from water in the bottom of the oil tank, from the fuel tank and from a leaky/loose exhaust cover on the block. When you have the engine down, you can pull the exhaust covers off and install new gaskets. Pump some oil out of the oil line into a clear glass. Let it sit and see if there is any water at the bottom. Ditto for a fuel tank sample. It's unusual to get water in the oil tank, but rain water can get in if the cap is missing or damaged/cracked.

 

[fishfeatures]

Re: had an overheat , does this need work?

thanks for that emdsapmgr, no vro so i'll check the fuel for the prob. Will go and get new rings and 1 os piston

 

[fishfeatures]

Re: had an overheat , does this need work?

Just a quick update and question.....

I brought the parts to the machine shop and he will bore the damaged hole. Only thing is that they are already 0.030 each , so can i bore the damaged one to 0.040 without it being out of balance? 0.040 will clear the damage but i am worried that with it already bored , just boring one now may cause problems.

ALso the fuel is clean no water whatsoever, my only other reckoning is that i fitted smart tabs and had a bit of a prob with water spray coming up into my splashwell, also to add to the prob my rear latch is broken so I think water may have got in under the hood and sucked in through the rear of the sliencer into the carbs......would this explain the water intrusion ?? it's all i can think of...

 

[emdsapmgr]

Re: had an overheat , does this need work?

The factory makes oversize in .020 for some engines, .030 for most engines. The only factory .040 over pistons are for the V4 and (small bore) V6 crossflow engines. If you find .040 oversize from another supplier, it's best to replace all 3 at the same time (you can still mix sizes) so that all are from the same manufacturer. (same weight and thermal expansion rates.) Hard to figure that any stray water would get sucked up into the airbox through the drain hole at the bottom. It is possible spray (water mist) could get ingested through the intakes of the airbox and into the carbs. However-if you had that much water, I'd think you'd have experienced engine running issues. An exhaust leak might let water back into the combustion chambers, but seems unlikely it would migrate past the rings back into the crankase (onto the seal you have in the picture.)

 

[fishfeatures]

Re: had an overheat , does this need work?

It is possible spray (water mist) could get ingested through the intakes of the airbox and into the carbs.

what i meant to say...

thanks again Emdsapmgr

 

[steelespike]

Re: had an overheat , does this need work?

Isn't it possible water from the leg could get into a bad bottom crank seal.
I know on some of the little motors they often warn to replace the bottom crank seal
while apart.

 

[Grub54891]

Re: had an overheat , does this need work?

That bottom seal could be the problem but....is that orange stuff on the gasket/o-ring surface silicone? I don't think it should be there.possible someone was in there i the past and just slapped it together with old seal's/ gaskets?
Just something to check.

 

[fishfeatures]

Re: had an overheat , does this need work?

That bottom seal could be the problem but....is that orange stuff on the gasket/o-ring surface silicone? I don't think it should be there.possible someone was in there i the past and just slapped it together with old seal's/ gaskets?
Just something to check.

I was considering that , it looks like a sealant that is thicker that the crankcase sealant, and with the opistons being .030 over, i reckon it was rebored and put back together with inferior sealants. I have a spare seal in a box of spares i have , so may reuse that one.

 

[fishfeatures]

Re: had an overheat , does this need work?

tops of my pistons 1&3 have slight dents and nicks ...no, 2 is fine so i'm thinking that there was shoddy rebore job done somewhere along the lines, and that a piece of a ring wasn't discovered and ended being bounced about the place on the new pistons as all 6 rings on the ones i extracted are still intact right now.

are these pistons still ok to use?
i know no.3 is getting bored to 0.40 but i don't really want to spend more on no.1 , can i file or sand down these marks without repercussions one no.1 piston?

top pic is no.1

 

[boobie]

Re: had an overheat , does this need work?

If you want to use them it's your decesion. I'd replace them. But!! When you get all done find out the real cause of the problem.

 

[fishfeatures]

Re: had an overheat , does this need work?

If you want to use them it's your decesion. I'd replace them. But!! When you get all done find out the real cause of the problem.

That boobie is still puzzling me. Carbs were cleaned about 6 mths ago, and even looked at them the other day and they were spotless inside. Can't see another reason for the overheat except for the theory I pointed out on previous post