Ever seen a cylinder do this?

[Chris_In_VT]

This is off a 2159c I just got.
Was told it needed a piston, so I suspected the intake boot clamp+catalytic muffler. Surprisingly, someone must have updated the saw. It had the metal clamp and a non cat muffler. However, at some point this saw must have been subjected to some extreme heat. There is a lot of baked on crud on the fins, they are pretty dark. I've seen cylinder fins broken off, but never seen ones drooped like this. That side of the jug didn't look that bad either, although it's got a lot of transfer on the exhaust side.

 

[old-cat]

Shop wall decor!

 

[gulity1]

I sure have seen alum do that, was in a fire and either melted or caught fire and burned it self, like stated above wall décor. So whats the rest of the story

 

[Duane(Pa)]

I doubt it was heat. Likely dropped or hit. I can offer this suggestion, when you try to pry them straight, they will break off

 

[Chris_In_VT]

I don't know the rest of the story!
Guy responded to my cl ad, said he's got a 2159 that needs a piston, 50 bucks. Ok cool, don't even need to argue on the price, that's about what I like to pay for rebuild able pro saws (besides free!)
Tear it down when I get home and find the melted fins. I'm sure it's not the first jug to do that but I've never seen it and thought it was pretty interesting.

 

[Chris_In_VT]

Guess I won't try to pry them straight.
I would have thought if it was dropped or hit they would have just broken, not bent like that.

I'll see if the transfer cleans up, don't know if it will though.

 

[Chris-PA]

Well, since those are the cooling fins, if the heat was coming from inside the engine they would have to have been cooler than the cylinder walls. If they got slumpy then the cylinder should have been worse. Although they are less supported so I suppose.

If the heat source was external then there should not be much left outside by the time those fins got hot enough to droop.

So I'd have to guess mechanical damage - which might be consistent with someone having been in there messing with boots and clamps?

 

[RBurtcher]

We furnace braze everything we manufacture where I work. ( Aluminum components) At 1150 f ( hottest point in the ovens) the brazing takes place. We wind up having to hand braze many repairs post oven using propane and oxygen. I would say if one was to preheat the cylinder in an oven to about 450-500 and then using a map gas torch it would generate enough to soften up the outer tips of the fins enough to get them close to original position without fracturing them. If you think the cylinder walls are salvageable , it might be worth the experiment. I have an old clean scarred cylinder I will try it with today after the wife bakes something. I will do it on the rack, complete the process and let it cool inside the oven with the door shut for extra precaution. I have wondered if this would work having seen many bent fins on this site and the question being asked, (would you run it? )

How true the bore remains will have to be measured but I have a feeling it is easy to damage the fins while the bore remains true.

 

[Landmark]

My guess would be it was made for aero dynamics

 

[nk14zp]

My guess would be it was made for aero dynamics

40% better?

 

[wood4heat]

Well, since those are the cooling fins, if the heat was coming from inside the engine they would have to have been cooler than the cylinder walls. If they got slumpy then the cylinder should have been worse. Although they are less supported so I suppose.

If the heat source was external then there should not be much left outside by the time those fins got hot enough to droop.

So I'd have to guess mechanical damage - which might be consistent with someone having been in there messing with boots and clamps?

I agree. The piston would have failed before generating enough heat to melt the cooling find. Im going with mechanical damage.

 

[nmurph]

Something dropped on it.

Leave it be.

 

[Chris_In_VT]

I guess I didn't think something dropped on it would bend them, just break fins off.

If it's not scored through the plating I'll trim the edges of the fins to let it cool better.

 

[Duane(Pa)]

They tend to bend one way and not the other......SNAP! Think of what would have happened to the plastic cover above anything hot enough to melt aluminum. There would be a puddle of that goo stuck to the jug.

 

[Fubar]

yeah i have seen this before , that's what happens when a saw gets a tree dropped on it , if it runs just leave the fins alone or buy a new jug ...

 

[Chris_In_VT]

Started to sand the transfer off with emery cloth. Looks like there is one long line scored through the plating.
It was cleaning well, I thought it would be ok until I uncovered that scratch.

Above the exhaust port, to the left of the decompression hole.
Maybe not the best pics (phone camera) but it is scratched.

 

[cus_deluxe]

It appears that it will not buff out...

 

[HuskStihl]

It will fill with carbon and be fine. Don't bother messing with the fins, they will be fine.

 

[cus_deluxe]

So there ya go!

 

[Chris_In_VT]

It will fill with carbon and be fine. Don't bother messing with the fins, they will be fine.

Would you put a new piston in that jug and sell it? I'm not gonna keep this saw it will be sold.