MS310 air leaks afte Jar replacement.

[Chuck Spitler]

I had posted earlier that I had been asked to work on a MS310 that will only run in choke mode. Turns out the owner had attempted a 'jar' cylinder replacement. I have a few questions. I can see an excess of a blue sealant that has oozed from some seams etc. looks like what was done was not done very precisely.

I have taken the handle off and I have a lot of the saw apart, but I am not sure what I should do to get the top cover off. . there are some wires that connect to the frame of the saw that need to be removed. Do I need to pull the flywheel to see what I need to in order to disconnect them. I think I still need to remove more of the saw to get to the cylinder

Does anyone have any guidance for me on what to look for. Are the crank seals being improperly set a likely suspect? or is it more likely that some of the sealant didn't take somewhere? I would appreciate any and all suggestions from folks who have done this type of repair before. I assume that I will have to take it all apart, clean away all old sealer, and reseal it. What is the recommended sealer? How will I know that the shaft seals are correctly placed? etc.

I have done a lot of small engine work over the years but I never done this before. I assume that if I take my time and advantage of the insights you can offer me I can do it.

Thanks

Spit

 

[HarleyT]

You need to stop now and look closer at the fuel system first. Look closely at the fuel line for cracks, and correctly go through the carb.

 

[HarleyT]

HARLEY,

Yes?

 

[Chuck Spitler]

Harley, I cleaned the heck out of it and put a carb kit in the carb...it still will still shut off if taken off of full choke...in fact even if it is 3/4's choke it dies. I also used a very fine guitar string and probed the orifices in carb throat and they are open/not clogged. I do not see any cracks or leakage around the gas line. it is still anchored in the tank. The impulse line is easier to remove and it seems to be air tight too. Is one of the 2 lines more likely to be cracked? I would like to pressure test the engine, but I have never done that either, and of course I don't have the correct equipment to do it...maybe I could jerry rig it. I do have a MightyVac for vacuum and an air compressor for pressure testing, just nor sure how to seal the intake and exhaust ports, and how to add positive or negative air pressue. If I seal it with duct tape and use the mighty vac on the impulse port will that work? Can I pressurize the impulse port with 15-20 psi or would it be better to seal the port and try to add air pressure through the spark plug hole?

I appreciate your input.. let me know what you are suggesting that I do to check the fuel line for cracks? I have a lot to learn.. I hope I don't sound like I have the answers because for sure I don't. if you can share some more knowledge with me that would be awesome


Spit

 

[HarleyT]

When you had the carb apart, did you remove the needle/lever/spring, and clean the passage underneath?
The fuel line usually cracks above the tank. Can you put up some pics and show us the saw?

 

[lwn9186]

Check the impulse nipple on the engine. He may have put so much silicone in the pan that it is plugged.

 

[motorman1]

All they've stated, plus check intake boot carefully. The way the pan is mated to the cylinder pretty much rules out an air leak at the seals. Could happen, but I've never seen that series of saws have seal leaks that affected the saw running. My guess is torn impulse line, intake boot and/or fuel line hole/split.

 

[Chuck Spitler]

Thanks for all the attention to my problem. I was able to hook up the mighty vac to the impulse nipple and it seems to hold vacuum... I have not figured out a good way to check if for positive pressure. Can I pressurize a small hose hooked to the impulse nipple? I guess I would need to have a gauge some where in line to measure pressure and watch for a drop?

I do not think that the gas line leaks, I pressurized the gas line (it is still in the tank) with my air compressor, held my finger over the tank vent outlet and it held pressure until I took my finger off of the tank vent out let nipple. Also the gas line looks very sound, shiny black rubber no signs of an fatigue or wear, it makes me wonder if it is new.

Motorman I can check the impulse line for leaks and I will look at the intake boot. The boot is the rubber tube that the carb hooks up to correct? Looks like it attached with a screw down clamp. How tightly should that clamp be attached, seems like it was not so tight that the clamp wouldn't move it pushed.

Harley, Yes I did remove and replace the inlet needle, and sprayed cleaner into the passage below the needle, not to say that I did it perfectly. If there was excess sealant in the pan that got into the impulse nipple what should I do? I can insert a small wire or probe and try to verify it is open?


Thanks again for all of your help

Spit

 

[lwn9186]

Did you have the muffler and carburetor blocked off when you checked the impulse for vacuum? If not it should not hold a vacuum.

 

[motorman1]

When in doubt, pull all of the hoses off the saw, including the the intake boot, fuel line, impulse line, and thoroughly inspect / blow air/suck air into. Easy saw series to check for leaks. if none of the mentioned, double check carb. Is there a decompression valve on this saw?

 

[Chuck Spitler]

I checked the intake boot and both the impulse and fuel line they are air tight..no leaks No I do not have the carb and muffler ports blocked off and it does hold a vacuum. So maybe some sealant got into the impulse line? No I do not think there is a compression release, just appears to be a bolt with a bunch of sealer under it where the decompression release would go. I was thinking (incorrectly no doubt) that if I positioned the piston so it was blocking the 2 ports I would get something close to air tight. But this is holding very tight. I noticed that when I first started pumping away on the mighty vac that is seemed like it was leaking down and fairly quickly then I thought I would try to pressurize it with some compressed air and I tried dripping a little oil along some of the seams to see if I saw any bubbles etc. So I rotated the saw around a littler bit, the when I hooked the mightvac back up after, it seemed to hold. vacuum, which I thought was kind of funny. Also I turned the flywheel by hand and the vacuum still did not break...Duh! I guess this means the impulse port is plugged up doesn't it. I suppose this will require a tear down to get what ever is in there out? Is there anymore to the impulse port than just a tube? Is there anything that I can try short of disassembly to clear it? I know it's a guess but if anyone has any ideas. If the piston skirt goes up high enough maybe I can insert the tip of a air gun and try to blow any crap out?

Again thanks for all the help You guys are AWESOME

Spit

 

[lwn9186]

Stick a drill bit by hand down the impulse hole and see if you can get it through. Should be able to get a little piece silicon out of the cylinder.

 

[Chuck Spitler]

I will give it a go with a drill bit.

thanks
Spit

 

[ironman_gq]

Poke it out with a piece of wire and see if you can get it to fall out the intake port, I'm not too fond of the idea of having a piece of silicone magically disappear into the crank and hope that it finds its way out without gumming something up. I'd be worried about the rings and bearings with that much shmoo in there.

 

[lwn9186]

Run the piston up to TDC and dump it out of the intake port if you can't get most of it out by turning the drill bit and pulling pieces out. Might be worth pulling the whole engine it out and getting all the sealant out. You don't say the sealant is silicone but if it is I would for sure take it out and use a better sealant.