Can you guess what did this?

[TJ the Chainsaw Mechanic]

Let's play a guessing game. Winner gets bragging rights. No cash payout.

What caused this?
View attachment 47775

Didn't have the spark plug torqued right.

 

[Marshy]

@Chainsaw Jim was on the right path, it's a snowmobile engine, liquid cooled. This was a result of the engine digesting some coolant. The guys saying water or snow in the intake are right.

 

[Marshy]

That concludes this week's "Guess What Did This" game show. Come back next week when we take a look at some abstract porcelain painting.

 

[malk315]

I was going to say anti freeze got in since it's milky and used to happen on my chevy v8 when one of the two head gaskets failed and you get that milky crap under the valve cover and no oil pressure as more and more coolant mixes w/ the oil. Once time when one side failed I would start cold w/ 40 lbs oil pressure and once I go to work it would be down towards 5 lbs I would shut it off and let it cool off and oil thicken til I could get home and take the heads off for new gasket and get all of the milky crud out of the engine... I sure don't miss that. Saws much smaller, cheaper, and simpler to deal with!

I wouldn't have guessed looking at the picture w/o reading the rest of the thread -- once someone said what is that milky stuff and your picture of the lower half I immediately thought anti freeze in oil.

 

[exSW]

I didn't even pay any mind to the milky stuff,thought it was blowby. The scores on that piston looked nearly identical to the scores on an undersized piston I took out of my 757 Shindaiwa.

 

[Marshy]

I have to measure the slugs. One was reused and is known good OEM slug. The other came used and they are NLA. There were no other options so they got installed without checking clearance. When I took it apart they seemed to have more clearance than I would expect.

Size is stamped on the top.


Not sure what the cause of the leak is. I suspect the base gasket where the flow comes up through the transfers. The head has Orings and none are pinched or show a leak path. Base gasket didn't show any obvious leak paths either. I do know the reassembly process from the manual was not followed properly last time and that could explain the coolant leak.

 

[Philbert]

. . . it's a snowmobile engine, liquid cooled . . .

? I didn't know that other stuff used pistons and jugs too! Learn something new every day!

Philbert

 

[smokey7]

No cracks in the jug or liner?

 

[danimal]

If it's not a gasket, then is probably a hairline crack.

 

[Marshy]

No cracks in the jug or liner?

None that I could see. It's worth a second look with a magnifier though. The one cylinder did have a hot seize from a defective piston. Transfer was cleaned and cylinder was reused.

Assembly procedure has you set the cylinders on the case, snug the head bolts and exhaust manifold to help locate the cylinders then snug the cylinder bolts, take the head off, torque the cylinder and reinstall the head. That was not followed last assembly and is believed to be the cause of the leak.

 

[DrewUth]

It looks like it has an ELKO cast piston on one side and a Wiseco forged on the other...with how differently forged and cast pistons weigh and react to heat, I would never consider mixing them.

 

[Marshy]

It looks like it has an ELKO cast piston on one side and a Wiseco forged on the other...with how differently forged and cast pistons weigh and react to heat, I would never consider mixing them.

There were no other options, its that or park the sled at the time. The ELKO is an OEM and the Wiseco was a known good one before they re-engineered their product for that motor. The re-engineered piston they produced after that installed one had an error in the manufacturing process code and caused all the pistons to expand too much and hot seize. I had two of their pistons do it in 2 brand new cylinders that had the required clearances. There was another snowmobile forum member that had 4 do it and there were 2 other members that all had the same results with them. Wiseco finally admitted the error they made and said they changed them. Im not sure I believe them because they did not rev the part number like they did between the one I have installed vs the ones that seized. They comp'ed us all a set of pistons but were left with wrecked cylinders. I cleaned one cylinder up and have it installed. The other new cylinder was cracked near the transfer bridge. *f-word Wiseco., Im still pissed at them.
Later we learned Polaris changed the part number but kept the part the same and used it in a sled 2 generations newer.

 

[tickbitintn]

check the cyl heads for warpage. had a few sea-doo-doos do the same thing... o-rings looked fine but when it got up to temp it would start drinking from the cooling sys..(lake water)

i nick-named wiseco "seize-co".... had a few in a row that would cold seize before they ever got to temp.... Polaris 2-stk 400l, polaris watercraft, and a yamaha watercraft... all about 15 yrs ago though

 

[Marshy]

Yep, plan to check the head for flatness.

Good old seizeco.

I was in it 3 sessions ago. Got it back together and ride the season until I busted a drive shaft. Session after that I didn't ride much but went through both clutches. Last year I didn't ride at all. Pulled it out this year and had no coolant in the resivour. Pulled into the garage and took it apart. It must have been burning a little without me knowing in the previous seasons.

 

[DrewUth]

I avoid Wisecos at all costs when building bikes. I would rather put in a Pro-X or Athena cast piston.

Check out Pro-X, by the way- they make LOTS of pistons. You may be pleasantly surprised. They are great.

 

[BigRed96]

Flippy Caps?