Stihl 088 just died

[farmguywithasaw]

If they have an impulse Oiler they can leak there but I’m pretty sure they are worm drive Oiler. I have a Mac 610 that has a line that comes off the bottom of the crank case to the Oiler inside the oil tank. I think it’s more of a McCullough thing but it shouldn’t leak anyhow unless cracked line or bad diaphragm

 

[garjess]

I had a second today to work on the saw. I pulled the flywheel off and unfortunately the woodruff key looked fine. I was really hopeful that was the problem as it would be a simple fix. I'm still planning to pressure test it when I get time. Maybe the pressure test will show a bad impulse line or intake boot, but as noodlewalker said, I would have expected it to over rev if it was an air problem. I'm just hoping for something simple.

The confusing part for me, the last time I got it started I let it idle for at least 30 seconds. It sat on the ground idling fine, sounded perfect, I picked it up (still idling fine) but the instant I moved the trigger it died. It made no attempt to speed up from idle, it didn't spit and sputter, it didn't sound like it bogged down, it just sounded like I turned the switch off.

 

[chilipeppermaniac]

Garjess, I can't help but file my own symptoms from my various saw troubles and the eventual causes in my memory banks. When I discovered running issues in el cheapo Poulans to Pro level Stihl saws, I knew enough issues with fuel were likely number one cause of most saw failures.

What I would do, is drain the gas from your tank, then take a visual look at your fuel filter and the fuel line attached to it. Ethanol gas has a detrimental way of making fuel lines mushy and then when calls for increased fuel falls below what the carb needs to rev u up. My fuel line in one saw looked like it had shriveled in the middle, essentially like hardening of the arteries.

At minimum, I would 100% verify the cylinder and bore were not all scratched up and take compression readings. Next I would inspect, test and replace any bad fuel lines and filter. ( cheap insurance) Then, go about the other vac and pressure tests to eliminate negative effects if air leaks are happening anywhere in your saw

 

[noodlewalker]

I had a second today to work on the saw. I pulled the flywheel off and unfortunately the woodruff key looked fine. I was really hopeful that was the problem as it would be a simple fix. I'm still planning to pressure test it when I get time. Maybe the pressure test will show a bad impulse line or intake boot, but as noodlewalker said, I would have expected it to over rev if it was an air problem. I'm just hoping for something simple.

The confusing part for me, the last time I got it started I let it idle for at least 30 seconds. It sat on the ground idling fine, sounded perfect, I picked it up (still idling fine) but the instant I moved the trigger it died. It made no attempt to speed up from idle, it didn't spit and sputter, it didn't sound like it bogged down, it just sounded like I turned the switch off.

That sucks!! I was really hoping the key would be sheared off and it would be an easy fix for you. Keep us posted, we are all curious about what is going on. We all gain a little knowledge from each other's experiences. Best of luck!

 

[SteveSr]

The confusing part for me, the last time I got it started I let it idle for at least 30 seconds. It sat on the ground idling fine, sounded perfect, I picked it up (still idling fine) but the instant I moved the trigger it died. It made no attempt to speed up from idle, it didn't spit and sputter, it didn't sound like it bogged down, it just sounded like I turned the switch off.

This sounds like it could still be electrical. Wires chafe and rub, usually NOT in readily visible places! I would pull, clean, and inspect your kill switch (and spark plug) wiring harnesses. I rebuild saws regularly and find a surprising number of wiring harness issues... that I wouldn't have found had I not disassembled and cleaned everything. These saws go to trail volunteers across the state where I won't be around to fix it later!

If the plug harness looks good you can also pull the kill wire terminal off of the coil and see if it runs then. To get the terminal off you'll need a jewler's screwdriver or small pick to release the catch on the terminal. You'll probably have to spray it off with brake cleaner to see it!

 

[Wood Doctor]

This saw cost this man or the guy that he bought it from about $2000 when new. You have to wonder why a dealer would not offer to at least help take care of the non-running situation. Regardless, I have always realized that any used chain saw that I buy is my responsibility to repair and keep running. Anyone who buys a used chain saw should accept that. Just MHO.

 

[SEAM]

...might be a failed rod bearing. Everything feels fine with no load and symptoms show up under load. If the spark is OK (steady) the next step might be pulling the jug to have a look inside...

 

[garjess]

So here's the recap.
Before I used it I replaced the gas with fresh mix
Had problem in original post
checked spark
visual check of fuel line, fuel filter, impulse line
cleaned carb
tried to start with same problem as original post
rebuilt carb
tried to start with same problem as original post
Scratched head and said several choice words
pulled flywheel to check woodruff key
pressure tested crankcase. Held 7 psi for 4 minutes with NO drop in pressure. Thanks for the Duct tape suggestion. I used Gorilla tape on the exhaust and reinstalled the muffler and it worked great. When I first pressurized the crankcase it dropped a little but it was just the tape expanding. I pumped it back up to 7 psi and it didn't drop any
vacuum tested crankcase. Held 7 in.Hg for 4 minutes with NO drop
pressure tested carb needle
Pressure/Vacuum tested fuel line.
Inspected wiring, all wiring looked good. Since it died when I touched the trigger, I inspected to make sure linkage wasn't touching/moving/grounding any wires. Of course all the wires are on the opposite side of the carb from the linkage

At this point I haven't found anything wrong, I'm quickly running out of things to check. I put the saw back together. Pulled it four times and it cranked and ran great.
I scratched my head and said some more words.
I'm going to put the bar on it and try it out today, I'll let you know how it goes.
If it dies again I'm going to pay particular attention to the electric side of things because it died so quickly
Any particular thing or way of checking something I should do? Any suggestions would be appreciated!

Thanks for all the help! I love this site!
Gary

 

[noodlewalker]

Tank vent clogged???? I would be interested in how many similar cuts you are going to be able to do before it dies again.... If it dies again. Has that idea been investigated or suggested yet??

 

[noodlewalker]

Tank vent clogged???? I would be interested in how many similar cuts you are going to be able to do before it dies again.... If it dies again. Has that idea been investigated or suggested yet??

I just re read through the posts, and realize it was already suggested... And inspected, sorry guys!

 

[CausticUC]

Does the 088 have the same stacked intake gasket problem as the 041 that causes a similar type of issue?

 

[chilipeppermaniac]

So here's the recap.
Before I used it I replaced the gas with fresh mix
Had problem in original post
checked spark
visual check of fuel line, fuel filter, impulse line
cleaned carb
tried to start with same problem as original post
rebuilt carb
tried to start with same problem as original post
Scratched head and said several choice words
pulled flywheel to check woodruff key
pressure tested crankcase. Held 7 psi for 4 minutes with NO drop in pressure. Thanks for the Duct tape suggestion. I used Gorilla tape on the exhaust and reinstalled the muffler and it worked great. When I first pressurized the crankcase it dropped a little but it was just the tape expanding. I pumped it back up to 7 psi and it didn't drop any
vacuum tested crankcase. Held 7 in.Hg for 4 minutes with NO drop
pressure tested carb needle
Pressure/Vacuum tested fuel line.
Inspected wiring, all wiring looked good. Since it died when I touched the trigger, I inspected to make sure linkage wasn't touching/moving/grounding any wires. Of course all the wires are on the opposite side of the carb from the linkage

At this point I haven't found anything wrong, I'm quickly running out of things to check. I put the saw back together. Pulled it four times and it cranked and ran great.
I scratched my head and said some more words.
I'm going to put the bar on it and try it out today, I'll let you know how it goes.
If it dies again I'm going to pay particular attention to the electric side of things because it died so quickly
Any particular thing or way of checking something I should do? Any suggestions would be appreciated!

Thanks for all the help! I love this site!
Gary

Gary, did u put soapy water on your cranks seals as you pressure tested? Also, I was wondering if your little wire that goes down to your ground might not be doing it's job? As in is it grounding out when not supposed to?

 

[farmguywithasaw]

How did you check for spark? Try a different spark plug. My grandpa told me once that just because a plug will spark out of the engine doesn’t mean that it will spark when it it is warm and under compression. He used to have a dragster and could fix just about anything

 

[garjess]

If it happens again, which I don't see why it wont, I'll take a close look at the grounding. I'm still think its a fuel problem because it idled fine until I hit the trigger.
As for the spark plug, in the field I did the ole "yeah its firing" test and replaced it just to be sure, but I did a more thorough test on the bench. It would jump a 6mm gap with a blueish spark so the coil is good. Thats always a good thing to check, even if the plug fires when pulled out, it takes a lot more voltage to fire when under compression.

 

[noodlewalker]

If it happens again, which I don't see why it wont, I'll take a close look at the grounding. I'm still think its a fuel problem because it idled fine until I hit the trigger.
As for the spark plug, in the field I did the ole "yeah its firing" test and replaced it just to be sure, but I did a more thorough test on the bench. It would jump a 6mm gap with a blueish spark so the coil is good. Thats always a good thing to check, even if the plug fires when pulled out, it takes a lot more voltage to fire when under compression.

It sounds like you have a pretty good feel for what is going on, and have the knowledge and skills to be able to troubleshoot it thoroughly, the problem now is the repeatability of the symptoms. Now that you know there may be an issue the next time you run it, you will be more "in tune" to what it does just before the symptoms arise (if they do, of course). I'm starting to lean towards the fuel delivery side of the discussion. Maybe it's a combination of circumstances... Possibly flooding on the high side as you suggested.... But I just can't see that happening suddenly as you described..... Here's a question I would like to introduce to everybody-- is it possible for the cylinder to expand from the heat enough to come in to contact with the flywheel?? I have dealt with flywheels in the past that have had "flashing" or "overcast" on the casting line, and it did in fact come into contact with the cylinder and caused the coil to ground out and eliminate the spark. I just took some Emery cloth to the casting line and the problem was fixed.

 

[Wood Doctor]

It sounds like you have a pretty good feel for what is going on, and have the knowledge and skills to be able to troubleshoot it thoroughly, the problem now is the repeatability of the symptoms. Now that you know there may be an issue the next time you run it, you will be more "in tune" to what it does just before the symptoms arise (if they do, of course). I'm starting to lean towards the fuel delivery side of the discussion. Maybe it's a combination of circumstances... Possibly flooding on the high side as you suggested.... But I just can't see that happening suddenly as you described..... Here's a question I would like to introduce to everybody-- is it possible for the cylinder to expand from the heat enough to come in to contact with the flywheel?? I have dealt with flywheels in the past that have had "flashing" or "overcast" on the casting line, and it did in fact come into contact with the cylinder and caused the coil to ground out and eliminate the spark. I just took some Emery cloth to the casting line and the problem was fixed.

More likely might be the gap between the flywheel and the ignition module might be too small, and the heat from the running engine expands both to reduce the gap even further. Recommended gap is between .009" and 0.01". That's worth checking.

 

[garjess]

Well I guess this is good. I ran it for a little bit today and it did fine. Started easily, (which it hasn't done since the incident) idled fine, and ran wide open fine. I made 5 cuts in a 30 inch hemlock and it did great.
The only thing I can think of that changed between not running to running great was carb related. I rebuilt the carb and it still wouldn't run right but I didn't do one thing inside the carb. I didn't remove the welsh plug because my carb kit didn't come with a replacement. It had a welsh plug in the kit but it was obviously too small. While I had the carb off the last time I was cleaning off my work bench and threw away the little plastic bag the carb kit came in. When I grabbed the little plastic bag I happened to grab it in just the right spot and felt something inside the bag. Turns out the correct welsh plug (the kit came with two different sizes) was stuck to the inside of the bag behind the sticker. Looking at the bag from the front I couldn't see it for the sticker and from the back, the back of the sticker is the same color as the welsh plug. I don't know how it got stuck, but it felt like it was glued to the inside of the bag. Since I already had the carb off I pulled the plug out and cleaned the ports and replaced the plug.
That's the only thing that changed, so if its actually fixed that had to be it. I felt like it was a carb problem from the start but I'm surprised that fixed it. The chamber behind the plug was spotless and all the ports seemed clear but maybe I got lucky.
I guess I'll chock all the questions and head scratching up to piss poor repair work! I shouldn't have half assed the rebuild on day one!!!
Thanks for all the help!
I learned a couple of things to look out for in the future even though they weren't my problem
Don't worry, If it lays down again I'll be right back on here
Thanks,
Gary

 

[garjess]

 

[SteveSr]

Good to hear! Leave the welch plugs alone! the odds of replacing one and getting a leak free seal are about ZERO.

Here is another thought... Fuel pooling in the intake at idle can also cause sudden "switch off" stalling when the saw is picked up and especially pointed nose down to release the chain brake. Stihl 026/MS260 are notorious for this with this the WT-403B carburetor.

 

[CausticUC]

That is great to hear! As before, if the intake gasket stack on the 088 is the same silly setup as the 041, if one is leaking or the stack is loose, you will have carb issues.