The Forestry Forum

General Forestry => Chainsaws => Topic started by: ashes on July 22, 2017, 01:29:13 AM

Title: ms280 overheating???
Post by: ashes on July 22, 2017, 01:29:13 AM
I would like to fix this saw, and not buy a new one, and I know it is out of production and you have to special order parts.

But, I like this saw and it has more than payed for it's self in firewood, and that's all it is used for. The problem is that the saw for the last year will only run for 10 minutes or so before it sputters out and won't start back up. It seems like it might be overheating. I recently took it to a saw shop and they put a new carb kit in, and air filter/sparkplug.

I was skeptical this would fix the symptoms, and it didn't, but I am not a small engine guy.

Anyone here have a saw that runs great for 10-15 minutes, and then just dies. I can only cut 3-5 rounds or madrone at this rate and my woodshed is not filling up at a rate that is acceptable.

I know, I know, Buy a new saw....
Title: Re: ms280 overheating???
Post by: Ianab on July 22, 2017, 02:14:18 AM
Check the breather / fuel tank cap (not sure it they are separate on that saw)

What can happen is that if the breather isn't working, as you drain the fuel you pull a part vacuum in the tank, until no more gas comes out, and the motor stops. Quick test is, when it stops, pop the cap and see it's still 1/2 full. Put the cap back and see if you can restart. If you can, and run for a few more minutes, than that may be the problem.

If that's not the problem, see if others have any better ideas.
Title: Re: ms280 overheating???
Post by: ashes on July 22, 2017, 03:20:15 AM
Ianab-
I thought that (and even tried exactly what you mentioned), and even bought a new gas cap to check.

That doesn't seem to be the problem.

The only thing that i can figure is that the fan isn't cooling it sufficiently. It is missing a few fins, but the shop said that shouldn't matter. It would eventually wear out the bearings for the fan though because it isn't in normal balance.

Title: Re: ms280 overheating???
Post by: blueberrymuzik on July 22, 2017, 07:14:37 AM
It is also possible that your coil is failing after it gets warmed up. This is not an uncommon problem.

You can pretty well tell whether the problem is fuel related or spark related by removing the air filter as soon as it has gotten warmed up and quit running. Then drizzle a few drops of fuel mix into the carburetor. If the saw fires up and tries to start, then your problem is fuel related. If it won't attempt to start, then the ignition is at fault.
Title: Re: ms280 overheating???
Post by: PNWRusty on July 22, 2017, 11:50:35 AM
Quote from: ashes on July 22, 2017, 03:20:15 AM
The only thing that i can figure is that the fan isn't cooling it sufficiently. It is missing a few fins, but the shop said that shouldn't matter. It would eventually wear out the bearings for the fan though because it isn't in normal balance.

What was the cause of the fins breaking off? I've never heard of such a thing.
Title: Re: ms280 overheating???
Post by: Ox on July 22, 2017, 12:00:32 PM
When you let it cool off it starts and runs normally until it heats up and dies again?  My money is on a bad ignition coil.
Title: Re: ms280 overheating???
Post by: ashes on July 22, 2017, 06:43:00 PM
Quote from: PNWRusty on July 22, 2017, 11:50:35 AM
Quote from: ashes on July 22, 2017, 03:20:15 AM
The only thing that i can figure is that the fan isn't cooling it sufficiently. It is missing a few fins, but the shop said that shouldn't matter. It would eventually wear out the bearings for the fan though because it isn't in normal balance.

What was the cause of the fins breaking off? I've never heard of such a thing.

There is a screw behind the fan that backed out. I didn't realize and ran it. Metal on metal sounds was all I needed to shut it down, but the damage was already done.
Title: Re: ms280 overheating???
Post by: Texas-Jim on July 24, 2017, 07:11:11 PM
Get a tester and run it till it dies and immediate try restart, it very well may lost spark. I use a zat tester that goes in line, you can easy see the spark. Actually over heating is very rare and its usually caused by that winter flap being closed.
Title: Re: ms280 overheating???
Post by: joe_indi on July 25, 2017, 08:30:23 AM
A partially blocked impulse hose could be a possible cause for leaning out, if the other possibilities have been covered.(Air vent, pickup body, carb diaphragms, carb jet valve)
If you suspect the ignition, if you can lay your hands on the coil of most any Stihl saw, the 028 coil is interchangeable with the  saws that would be most common on the ground in your area, 046/MS460/066/MS660/039/029/MS290/MS390/026/MS260/034/036/MS360.
The only difference is a couple of millimeter length of the ignition lead.
Speaking of which, how does the spark plug boot sit on the spark plug? If it is loose you could get over heating.
And finally, a cylinder gasket that is partially blown or a leaking exhaust gasket. The latter could be allowing hot exhaust to blow back through the cylinder fins.
Title: Re: ms280 overheating???
Post by: ashes on July 29, 2017, 12:30:11 AM
joe_indi
much appreciated, I sourced an ignition coil for the 280. It was not easy and I had to get it from the dealer. $$$

I was worried that the others may not work. I'll install that and hopefully be back in business.  If that fails I will look into the other thoughts you mentioned.
The spark plug boot fits very snug. This may be the last attempt to fix this saw, as the other things you mentioned are possibly out of my knowledge, and out of the money I'm willing to dump into an older out of production saw.
Title: Re: ms280 overheating???
Post by: Ox on July 29, 2017, 01:12:32 PM
I thought I remembered reading that Stihl's ignition coils are warrantied for life?  As in forever?  No questions ever?  Why did you have to pay for it?  Did I get bad information?  It was off this forum somewhere and not just once, but several different posts talking about it.
Title: Re: ms280 overheating???
Post by: ashes on August 02, 2017, 06:54:13 PM
Ox- I had not heard that. The Stihl dealer was happy to sell me the part. Maybe because they didn't diagnose it, and do the work?

OK-

I got the ignition coil, and installed it. Everything seemed to go pretty easy.

The problem is now I don't have any spark :'(
Is there something obvious that I am overlooking? (recap, the saw had spark prior to this)
Title: Re: ms280 overheating???
Post by: joe_indi on August 02, 2017, 09:33:37 PM
It could be a switch wire short circuit.
Disconnect the switch wire that is connected on the clip on the coil and try it once more.
Also check if you have fitted the coil with too wide a gap between the flywheel and the coil
Title: Re: ms280 overheating???
Post by: ashes on August 10, 2017, 10:49:30 PM
Thankyou Joe-Indi

Disconnecting the kill switch got me a spark, and the saw will start and run.

Problem is now, it runs like poop for a lack of a better term...

It runs like it is running too rich. fuel was fine before so I will rule that out. Carb was just recently redone, and it ran fine after (albeit for 10 minutes), so I can't imagine that has changed since. Air filter is newish, and clean.

It will run, but won't spin at correct RPM at full throttle.

Is there something that the ignition coil install could have tweaked or is this another separate issue that just happened coincidentally while I'm trying to fix this other thing.

I know, it is almost impossible to diagnose without seeing the saw, but I appreciate everyone's experience and kindness in trying to help.

Title: Re: ms280 overheating???
Post by: joe_indi on August 10, 2017, 11:23:25 PM
Ok! 'We have Ignition'!
But too much of fuel at high revs.
Well, if your 280 is a younger sibling of the 380, run it with the air filter removed and see if there is any difference.
If it improved matters, look no further the culprit is the choke shutter spring.
A weak spring or one with its free end out of its holding slot would cause the choke shutter to move forward in high air flow (accelerating engine), to cut off air into the carb.
Start the 'venture' with H and L set 1 1/4 turn out - this would be a richer setting than Standard, you can lean it out once you have the saw warmed up.
The idle screw should be turned out until it barely lifts the throttle, just enough to let in a tiny sliver of light when you view it against a light.
So, we know for sure that your black switch wire has lost some insulation. All we need to do now is confirm the choke is the culprit.
Title: Re: ms280 overheating???
Post by: ashes on August 12, 2017, 12:35:44 AM
Ok,
The "venture" is started, but, I will add that this is a ms280 so I have only two screws to work with. One reads L 1/4 turn. The other reads L A. After setting them both to 1 1/4 turns out from closed, it seems that the L 1/4 turn screw controls the idle. The other controls the gas air mixture. After tinkering a little the idle seems to need to be around 2 full turns to not spin the chain. The other L A adjustment seems to work best around 1 1/2 turn.

This still is not getting the saw to run well. The saw ran out of gas at the end of this session, and for a split second it hit full RPMs. I know that is too lean, but it gave me an idea of how much power I am losing.
Title: Re: ms280 overheating???
Post by: blueberrymuzik on August 12, 2017, 07:09:00 AM
When you installed the new coil, what did you set the air gap distance at?
Title: Re: ms280 overheating???
Post by: ashes on August 13, 2017, 12:35:48 AM
blueberrymuzik-

After watching some youtube videos it seemed that setting it by placing a business card in between the magnet and the coil body was close to right. Since that original business card spacing, I tinkered with it a little closer, and after that didn't work a little farther. The differences could be measured by a piece of paper or two. Now It is back to the original spacing with the business card.
Title: Re: ms280 overheating???
Post by: joe_indi on August 13, 2017, 01:16:44 AM
ashes,
First, I got to admit that I had your MS280 confused/mixed up with the old 028 :-[
Sorry for that.
The fact is we dont have the 280s here.
Could you please post a picture of the carb?
The only 2 screw carb (LA and L) for this saw shown, has a solenoid valve connected to the M-Tronic coil, probably to adjust the high speed fuel according to environmental (operating) conditions.
Is this how its on your saw?