Dolmar 5105 carnage

[Aaron441]

The neighbor brought me over a 5105 that wasn't running right. I cleaned the carb and it ran better so I went back to the woods to try it out. Halfway through the second tank of gas the flywheel key sheared. When I got back to the garage I found out why. The rod snapped right below the wrist pin. Piston is junk, jug is junk, flywheel is junk crank is junk and the crankcase has a hole in the oil tank where the rod went through. Any ideas? I have never seen this before.

I am posting this on an iPhone. I have pictures on the phone. If someone can tell me how I will put them up here. Thanks.

 

[w8ye]

It's all junk now.

A something may have come loose and hung up the piston to cause the rod to break? Look for a broken piston ring or a missing wrist pin keeper ring?

 

[Aaron441]

It sure is junk. But I can't find anything out of place that would have caused it. Piston looks fine other than the chunk out of the bottom where it hit the rod.

 

[Aaron441]

View attachment 284960
See if this works.

 

[3000 FPS]

It looks like a break right at the wrist pin journal. This could have had previous damage from a piston stop and then once a crack or weak point is developed it becomes a ticking time bomb that goes off.

 

[Aaron441]

Could be. I don't know if anybody has ever had it apart. Ill see if I can find out.

 

[166]

How old is the saw?

Take it back to dealer. If it's under a year old it will probably be replaced under warranty.

We haven't had a single failure on a 5105.

 

[Aaron441]

It's probably 2-1/2 years old or so. We are going to take it to the dealer anyway and see what happens. Can't hurt to ask.

View attachment 284983

 

[166]

It's probably 2-1/2 years old or so. We are going to take it to the dealer anyway and see what happens. Can't hurt to ask.

Does the saw have a lot of time on it or is it low hours?

 

[Aaron441]

Pretty low houred. It has the original bar on it and the word Dolmar hasn't completely worn off yet.

 

[burnses]

not sure how this saw is built but looks like alot of oil in the crankcase...did the bar oil tank gasket get sucked in and hydraulic stop the engine? Or am i just seeing bar oil from the rod breaking though the oil tank?

sap can

 

[Aaron441]

Yeah the rod poked a hole in the oil tank.

 

[SawTroll]

Yeah the rod poked a hole in the oil tank.

i don't really understand how that could happen, as it should be inside the cylinder?

 

[Aaron441]

The rod went through the lower front part of the crankcase which is also the back of the oil tank.

 

[Adirondackstihl]

You made sure not to drop anything in the intake when you had the carb off......RIGHT opcorn:

 

[Aaron441]

Yeah. It ran too long after I had the carb off for that anyway.

 

[Adirondackstihl]

I guess you could look at it that way......but I would say it didnt run long enough.