Thanks in advance for any advice. I have a barn find Stihl 026 that is hard to pull with the plug inserted. With the plug removed it is much easier but not exactly free wheeling. I thought maybe it would be exhaust blockage so I pulled the muffler cover off and it is clear. Also verified the piston is not scored on the exhaust side at least. It does have good compression but I have not measured it. I removed the pull start assembly and it too works adequately. The sprocket spins when the cord is pulled. Can the intake side cause a compression lock issue? The chain break is not engaged and even if it were, should not cause this condition. Putting a squirt of oil in the cylinder and pulling the cord several times did not help. I want to restore the saw but not sure crank bearing replacement would be worth it. Is there anything I have forgotten to check before I toss this one back in the barn? Thanks,
Barn find Stihl 026 really difficult to pull with plug in.
- Thread starter Zknumero1
- Start date
I don’t know I would continue with removing parts till I narrowed it down but sounds like you have an idea that it’s the crank bearing's.
Okay. lets think about things for a wee bit.
Removing the plug eliminates compression- did we check for spark whilst the plug was out?
Seems the recoil starter side of the saw has "checked out"- so what does that leave us with?
What happens if you remove the bar and chain?
My number 1 suspect would be a frozen needle bearing under the clutch drum/bell- locking the clutch drum to the crankshaft and adding that resistance to the starting action.
Broken or missing clutch springs can cause the same symptoms- permanent engagement of the clutch shoes to the drum.
Barn find though- so could be main crank bearings and dried out oil seals as well.
Then rule out hydro locking from excessive fuel mix sitting in the crankcase from repeated rope pulling and no fire.
Removing the plug eliminates compression- did we check for spark whilst the plug was out?
Seems the recoil starter side of the saw has "checked out"- so what does that leave us with?
What happens if you remove the bar and chain?
My number 1 suspect would be a frozen needle bearing under the clutch drum/bell- locking the clutch drum to the crankshaft and adding that resistance to the starting action.
Broken or missing clutch springs can cause the same symptoms- permanent engagement of the clutch shoes to the drum.
Barn find though- so could be main crank bearings and dried out oil seals as well.
Then rule out hydro locking from excessive fuel mix sitting in the crankcase from repeated rope pulling and no fire.
The bar was removed before other test were performed. I did make sure the chain rolled freely in both directions before removal though. I did just check for spark and seems to be lacking. Could it really be hydro locked after sitting for years without being touched? Thanks,
I will clean it up some more and keep thinking about it. I need to know what model carb is on it and the chain and bar are so worn I cant trust the caliper measurements so that will be replaced. If the core engine is good, I want to get it running. Just not excited about taking the case apart especially since the rings and piston look good.
Yeah no spark won't help much- any fuel pumped in per rotation is just going to sit below the piston in the crankcase if the spark is not igniting the vapours on entry through the transfers. More likely dry or rusted main bearings from having sat a good long while. The clutch drum needle is usually the first to lock up with corrosion from sitting as they often are forgotten about and never lubed- the main crank bearings have an oil coating while the saw is being run.
Doesnt so much matter that the chain rotated- does the clutch drum move independent and freely from the crank shaft- ie: spin easily by light finger pressure?
Poured some oil on top of the piston. Hopefully, it will loosen up some. Gonna get the number off the carb and check out/clean the oil pump. It the crank starts to turn then I will have a shopping list ready to go. If it doesn’t, I have to decide how far to go with it. Thanks,