TS700 investigation

[belgian]

I got this cutter back into the workshop again. Wouldn't idle, bogging at rev up and shutting unctrolled off. I suspected a fuel delivery problem, but checking the entire fuel route out, still the same problem.
Next possibility was a massive air leak somewhere, so decided to take everything apart.

To my disbelief, I noticed that the crank seal on the drive side had completely come out of the housing, and was freewheeling on the shaft. Original Stihl seal. I have never seen that happen before on any chainsaw. Manufacturing tolerance problem ? What do you guys think ?

 

[farmhard]

To my disbelief, I noticed that the crank seal on the drive side had completely come out of the housing, and was freewheeling on the shaft. Original Stihl seal. I have never seen that happen before on any chainsaw.
I had that happen last week.
First off you could use a vernier to measure up the faulty seal against a new one and see if there is a tolerance issue. Then you could check the saw case. I suspect the interference on that should be 0.003".
It also depends on how you installed it (hammer vs press). I use a press so it goes in square. Some guys use aircraft sealer, some silicone, some loctite and occaisionally I see pipe dope.
Depends on type of seal.
Also make sure you installed in the right direction. The side with the spring goes towards the higher pressure side.

Now....my issue which will prob get me banned form this site.....I worked on a 55hp Johnson and used OMC seals. I coated it and went to install and it pushed in with my thumb pressure. I do not use Sierra products as the quality has issues. Same with Stihl. The Chinese seals will waffle as you press them.

Try a new seal. Let us know.

 

[farmhard]

I got this cutter back into the workshop again. Wouldn't idle, bogging at rev up and shutting unctrolled off. I suspected a fuel delivery problem, but checking the entire fuel route out, still the same problem.
Next possibility was a massive air leak somewhere, so decided to take everything apart.

To my disbelief, I noticed that the crank seal on the drive side had completely come out of the housing, and was freewheeling on the shaft. Original Stihl seal. I have never seen that happen before on any chainsaw. Manufacturing tolerance problem ? What do you guys think ?

Was this a model where you have to press the bearings and seals in then the crank? I'd have to drive to shop to see one.

 

[belgian]

Was this a model where you have to press the bearings and seals in then the crank? I'd have to drive to shop to see one.

I never replaced the oil seal before on this machine. It is separate from the bearing. the oil seal that came out was the original one from Stihl (metal outer ring/rubber inner ring) that was pressed in. I have ordered a new one of course since the old one was quite worn anyway. I have never witnessed a seal completely letting loose of the housing.

 

[farmhard]

I never replaced the oil seal before on this machine. It is separate from the bearing. the oil seal that came out was the original one from Stihl (metal outer ring/rubber inner ring) that was pressed in. I have ordered a new one of course since the old one was quite worn anyway. I have never witnessed a seal completely letting loose of the housing.

Looks for signs of it spinning in the case. Completely possible if crankcase pressurizes and backfires from plugged exhaust or something like timing in an engine in general. I'd be splitting the case at this point and pressing in new bearings. Crud from them may be what took out the cylinder.

 

[belgian]

installed a new seal with snug fit, and the enigne started and ran flawlessly. When I adjusted the high rpm, and the engine ran down, I noted the same problem again. Turned out the new seal was blown out again, ggrrrrrr. I meant to hear a sigle misfire, so I am worried the coil may be turning bad and causing misfires, hence popping the seals. I am planning on reinstalling the new seal (yellow one) and using some loctite. Any suggestions ? .

 

[farmhard]

installed a new seal with snug fit, and the enigne started and ran flawlessly. When I adjusted the high rpm, and the engine ran down, I noted the same problem again. Turned out the new seal was blown out again, ggrrrrrr. I meant to hear a sigle misfire, so I am worried the coil may be turning bad and causing misfires, hence popping the seals. I am planning on reinstalling the new seal (yellow one) and using some loctite. Any suggestions ? .View attachment 849266View attachment 849267

 

[farmhard]

Yeah, check your timing and check your rings. If you didn't pull the saw down the first time grit could have trashed the piston and you now have blow by.

 

[belgian]

Yeah, check your timing and check your rings. If you didn't pull the saw down the first time grit could have trashed the piston and you now have blow by.

Farmhard was right on the money. Piston and rings turned out to be quite worn, and blowby caused the clutch seal to be kicked out. Ordered a new piston and rings. running fine now.

 

[farmhard]

Farmhard was right on the money. Piston and rings turned out to be quite worn, and blowby caused the clutch seal to be kicked out. Ordered a new piston and rings. running fine now.

Thanks for letting us know. I still have not been able to fix that TS700 spark issue plague.

 

[belgian]

Thanks for letting us know. I still have not been able to fix that TS700 spark issue plague.

make sure you have the right match for coil and flywheel. They have at least two different types, and do not intermix. I ordered an aftermarket coil and had to sent it back, for the same reason.