Blown head gasket- who has had it happen?

Jan 10, 2021
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Lost all power on my last ride. Thankfully only a couple miles from sno park, so it was easy to get back to the truck.

Pulled my motor open and one cylinder was full of coolant. Noticed even got pushed back into the reeds and intake. Head gaskets still look fine, but I know that doesn’t mean they are. Bringing in my head today to a machine shop for them to check for any warping. Pistons look fine. Cylinder is in good shape. It will be getting a complete new top end & head for rebuilt.

I’m just curious of a few things-
Has this happened to anyone else?
What could cause something like this to happen?
Taking my hood off I noticed my pipe sensor had come out, could that be a culprit?

Mainly just if there was a cause, I need to prevent it from happening again.
When I say the cylinder was full- it was full. And yes, coolant not water. The amount in there is kind of blowing my mind.
And no- the sled didn’t hydrolock.
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Jan 10, 2021
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What year, how many miles and has it ever overheated?

It’s a 17, so the bad year. It had 400 miles on it when I bought it so can’t speak of anything before that- but I do know the previous owner & he treats his belonging very very well so I doubt it. I can’t start it to check mileage, but I’d assume I’m somewhere around 1800 miles ballpark. I always pull over and let it cool down once I hit about 165 degrees. I usually run 110-120. When this happened it was running at 122.
 

Blk88GT

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I've had my pipe sensor come out as well, it didn't cause a sealing issue on the head.

I think you're doing everything right. Check the head, new O rings, if you can run a straightedge across the cylinders I'd check that too. Obviously get the coolant out of the combustion chamber and lower as soon as you can and flush with oil.

That's my 2 cents.
 
Jan 10, 2021
45
24
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I've had my pipe sensor come out as well, it didn't cause a sealing issue on the head.

I think you're doing everything right. Check the head, new O rings, if you can run a straightedge across the cylinders I'd check that too. Obviously get the coolant out of the combustion chamber and lower as soon as you can and flush with oil.

That's my 2 cents.

I didn’t think the pipe sensor would cause it but figure I’d mention it as an option. I know how to work on these things, but not super familiar with diagnosing issues. My thing is i haven’t heard of anyone else having a head gasket fail on these particular sleds. Searched different forums, google, nothing. At least not on a gen 4. Older sleds yes. Probably just a spontaneous thing but was curious if anyone else had this issue/discovered a cause.

Good idea to check the cylinder with straightedge as well, I wouldn’t have thought to do that.

I don’t recall if I mentioned it but sled will get full top end rebuild/head too just to be safe. There is one tiny tiny nick in the head, so very well could cause a repeat. I’ll see if I can get a pic of it, may be too small to see.
 
Jan 10, 2021
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Just left the machine shop and my head is NOT warped. But the machinist did point out a hairline crack on top of the head that I did not originally notice. See attached pic.

The machinist also suggested I come back with the head bolt so he can measure them & see if any stretched. Anyone happen to have what the head bolt measurements should be?
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Jan 10, 2021
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I’m sure that crack has nothing to do with it, but figured I’d mention it.

Another question- considering the coolant got pushed through my reeds, I’m assuming I’ll want to replace the reeds as well?
 
Sep 24, 2009
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Yakima Wa
If you haven't pulled the cyl's yet, put water in the coolant system until it fills back up to the top of the cyl's. If the crankcase fills back up again, then your leak is somewhere other than the head.
 
Jan 10, 2021
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If you haven't pulled the cyl's yet, put water in the coolant system until it fills back up to the top of the cyl's. If the crankcase fills back up again, then your leak is somewhere other than the head.

Good idea, I will do this today. Cylinders are still on . I’ll get back with the results.
 
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