How often do you check cylinder bolts?

sevensandeights

sevensandeights

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Just wondering how often you check cylinder bolts? Do you do it routinely? Torque to spec or guesstimate? Threadlocker?

I upgraded to a 79cc p&c on my Makita 6421 about 20 tanks ago. Upgraded to the HD air filter about 2 tanks ago. After the air filter change, I noticed some intermittent lean conditions with erratic idle but saw was still running strong and plug looked good. Retuned the carb thinking the new filter changed something and ran another tank through and everything seemed OK. Went to use it a few days later and fired right up but was racing really fast - knew something wasn't right so I shut it down. Today I cleaned the carb, pressure/vacuum tested the tank and fuel filter. Saw wouldn't stay running for more than 5 seconds - seemed to be starving for fuel. When checking the spark plug I noticed the entire cylinder was rocking when I pulled the starter rope. All 4 cylinder bolts were really loose!!!

Suggestions so this won't happen again?
 
MacAttack

MacAttack

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Just for the sake of asking, did you torque them to the correct torque spec?
I've never had cylinder or head bolts loosen up. If you think about it, other than something like a race car engine, how often do head or cylinder bolts get re-torqued after the engine has been run?
 
Stihl99

Stihl99

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On the yearly cleaning if I can see a bolt / screw I check it, I do not pull up torque specs or anything I just check and snug it tight if need be.
Air filter cover on a trimmer and string guard on another is all I can remember actually finding loose on my stuff.
My FS 250 came with the wrong shaft screw from the factory, 4 years later after my complains of the head turning a little bit we found it at the dealer and it was warrantied.
 
sevensandeights

sevensandeights

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To be honest - I don't remember but I'm fairly certain I don't have a way to torque them - would need a long shank torx driver and a small torque wrench. I only have a 1/2" drive torque wrench and a FAT wrench. I do remember snugging them down incrementally in an "X" pattern with a Wera t27 screwdriver.

I vaguely remember searching for torque specs and most everyone said they just snug them down from the posts I saw.
 
heimannm

heimannm

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I recently worked on an MS880 with similar issues, Two of the screws had fallen out completely and two others were very loose. This saw had recently been put together (by someone else) who admitted to not having the correct tools to torque down the screws. I didn't actually use a torque wrench but did use a T handle T27 driver to make sure they were tight. That seemed to be all that was needed and he put the saw back to work.

That said I do not as a matter of any routine check the cylinder bolts on any of my saws and have not had any problems.

I have had two other saws through the shop with running issues and discovered loose screws holding the clamshells together. One was a 350 Husqvarna and the other was a Poulan Pro 295. The 350 only needed the screws tightened, I am still waiting on seal for the PP295, the ring has already arrived. I am not sure who had worked on the 350 before but the PP had never been touched as far as I know.

Mark
 
Vintage Engine Repairs

Vintage Engine Repairs

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I don’t re check bolts. Cylinder head bolts are the only ones I routinely use a torque wrench on.

Most other bolts I prefer doing by feel using a T wrench or scrench. Nuts and bolts are over tightened far more than under tightened.

in my experience with a t-wrench

Lightly snug = 3.5nm (Carb nuts)
Snug + 1/8 = 7nm (General hardware)
Very firm = 10nm (exhaust and cylinder bolts)



Every nut and bolt gets loctite 243
 
Dennisthemenace

Dennisthemenace

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Just wondering how often you check cylinder bolts? Do you do it routinely? Torque to spec or guesstimate? Threadlocker?

I upgraded to a 79cc p&c on my Makita 6421 about 20 tanks ago. Upgraded to the HD air filter about 2 tanks ago. After the air filter change, I noticed some intermittent lean conditions with erratic idle but saw was still running strong and plug looked good. Retuned the carb thinking the new filter changed something and ran another tank through and everything seemed OK. Went to use it a few days later and fired right up but was racing really fast - knew something wasn't right so I shut it down. Today I cleaned the carb, pressure/vacuum tested the tank and fuel filter. Saw wouldn't stay running for more than 5 seconds - seemed to be starving for fuel. When checking the spark plug I noticed the entire cylinder was rocking when I pulled the starter rope. All 4 cylinder bolts were really loose!!!

Suggestions so this won't happen again?
If the jug has been off I check em after a tank or 2 and always use loctite 242/3. Never found a loose one on anything I've been fiddling with. Found plenty of missing screws and bolts on other blokes saws though
 
ozziechainsaw

ozziechainsaw

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I recently did a Stihl 044 rebuild, after i went through the first full tank of fuel I did a re check of the cylinder head bolts just to make sure they were tight ( which they were ).

I think if you do it correctly the first time you shouldn't have a problem, but checking it after a few heat cycles isn't a bad thing either.

Justin
 
sevensandeights

sevensandeights

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Well I have a Blackhawk 3/8 torque wrench and VIM t27 long shank socket on the way. Will add the locktite as well.

Bought the saw used from a member here and it had an aftermarket big bore kit that leaked from day one (loose impulse line nipple). I bought an OEM 79cc p&c, mityvac tool, and a new carb. Seller offered no financial help but I've learned a ton in the process. Have close to a grand into this saw with Tsumura bar and 2 chains and all the extra parts/tools I've bought. This saw is awesome when running right though so I don't want to take any chances.
 

TBS

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Just wondering how often you check cylinder bolts? Do you do it routinely? Torque to spec or guesstimate? Threadlocker?

I upgraded to a 79cc p&c on my Makita 6421 about 20 tanks ago. Upgraded to the HD air filter about 2 tanks ago. After the air filter change, I noticed some intermittent lean conditions with erratic idle but saw was still running strong and plug looked good. Retuned the carb thinking the new filter changed something and ran another tank through and everything seemed OK. Went to use it a few days later and fired right up but was racing really fast - knew something wasn't right so I shut it down. Today I cleaned the carb, pressure/vacuum tested the tank and fuel filter. Saw wouldn't stay running for more than 5 seconds - seemed to be starving for fuel. When checking the spark plug I noticed the entire cylinder was rocking when I pulled the starter rope. All 4 cylinder bolts were really loose!!!

Suggestions so this won't happen again?

After the first real heat cycle - log cuts and setting up the carb, let it cool right down and recheck the cylinder bolts in a cross pattern.

Do what gord and everyone has suggested, you'll be fine all of these suggestions. Any time you have the covers off to clean recheck All the screws and bolts. I've had a couple cylinders come loose while cutting and luckily never caused issues other than not running good, but it's a good way to wreck an engine if a bolt gets between the piston and the case.
 
Wood Doctor

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An MS660 owner brought his saw into my shop and said it was running erratically. Two cylinder bolts were missing their heads (sheared off) and the other two were loose. I had never seen that in all my years. How it ran at all is a complete mystery.
 
Canyon Angler

Canyon Angler

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I bought a "new" 660 on ebay 2 or 3 years ago that was built using a combination of Chinese and OEM parts. Other than the builder doing a quick "test run" to make sure it ran right, and tune it (pig-rich when I got it, but after break-in I set it right) I don't believe the saw was even broken-in when I bought it.

Question: I've probably run 10 tanks or so through it since I got it, and it runs great. Should I check the cylinder bolts for proper torque spec? I haven't yet -- mainly because I didn't want to disassemble it enough even to check the bolts.
 

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