# Stihl Chainsaw Mag Fails When Hot



## ccrider966 (Jul 8, 2006)

My 029 Stihl chainsaw runs fine until I shut if off and let it set for a while. It appears that the mag gets heat soaked and I get no spark until I let it set for a long time to cool off, then it starts and runs fine! Does this sound familiar to any of you guys? I dread tearing into it since these things are so compact and difficult to work on. Wish I had a step by step procedure to follow! Also I bet the mag is expensive from Stihl. 
If anybody has had any experience with this, I would like to hear from you. I am [email protected]. Thanks.


----------



## rotti1968 (Apr 26, 2009)

Ok heres a few things, if you are the original owner and your saw was registered at time of purchase or you have proof of purchase you may have a warranty option on this saw. If your saw was purchased before march of 2003 the coil should be covered under warranty repair . In the late 80's through the 90's the coils were covered under 2 different warranties. The dates at this very moment slip my mind and Im not at work to look them up but they were as follows: the 1st warranty was a lifetime coverage parts and labor the 2nd was a limited lifetime warranty, 2 years parts and labor, then lifetime part only for the coil. After march 2003 the coil is covered 2 years parts and labor and 5 years parts.
If you pm me your serial number of your saw I can run it and let you know if A: its registered and B: if it may be covered. Its not uncommon to get heat soak in a coil like that I see it often. The list price for the coil is 109.00 so if you can get this covered at least in parts it would be worth having a shop do the repair it should take them about 35 minutes with testing and replacement. yes this saw can be a little tricky to change the coil .


----------



## ccrider966 (Jul 8, 2006)

*Where is Stihl 029 Chainsaw Serial Number Located?*

Thanks for your very detailed reply. I cannot find the serial number on the saw. I bet you have to remove the housing to find it and that is a big job! Tell me how to find the serial number and I will get back to you.
I found used ignition modules on Ebay for $35. I wonder if they are ok? Thanks again for your input.


----------



## rotti1968 (Apr 26, 2009)

if you turn your saw so the muffler faces you and you look to the left of the muffler right around the area of the brake handle there should be a flat spot with the serial number etched into the saw.
the part # of the coil /module for the 029 is 0000 400 1300


----------



## ccrider966 (Jul 8, 2006)

*Stihl Serial Number*

Thanks for pointing out location of serial number....it is 0 238844581 I am not sure if the 0 in front is part of number or not. The saw is a 029 Super...whatever super means. What can you tell from the number?
Meanwhile, I have taken the cover off the mag and cleaned off all the sawdust and oil, etc. The air gap looked to be about .014 so I reduced it to about .007 or .008. I wonder if that could make a difference. I will try it out but it takes awhile to get it warmed up to see if it helps.
I sure wish you could just take the mag to a dealer and get a new one under warranty. If not, I might try a used one on Ebay for $40. I have a repair manual on CD and feel I can install it myself ok.
I am very thankful for guys like you who know a thing or two and will take time to help. This site is wonderful!


----------



## ccrider966 (Jul 8, 2006)

*Stihl Mag ON Ebay*

There is a guy selling New mags for this saw on Ebay for $41. I wonder if they are really made by Stihl or are some aftermarket mag. Any idea as to the quality of an aftermarket mag? There are a couple guys selling used mags for this saw also for $35. Of course you don't know how old they are or if they are any good either. Both these guys sell hundreds of things on Ebay and have very good history ratings....close to 99 %. Any thoughts or experiences?


----------



## rotti1968 (Apr 26, 2009)

ok ran your serial number and its registered 12/4/1998 are you lewis? since the date is before march of 2003 I suggest you take your saw to a Stihl dealer and have them replace your coil under warranty with an oem coil . The part is covered under the warranty but you will have to pay for labor , if you have any issue let me know and Ill see if I can help you in any way. As far as I know there are no aftermarket coils available for that saw, but I could be wrong.


----------



## ccrider966 (Jul 8, 2006)

*Serial Number*

Thanks for the info on my saw. I am not Lewis, I am the 2nd owner of the saw. Does that void the warranty?
I removed the cover and cleaned the mag and adjusted the air gap from .014 to .008. I ran the saw and it did start when hot this time. I don't know if it is fixed but since wood cutting season is over I will probably wait and see this fall.
Another problem has surfaced! I tried to adjust the oil pump screw and it just turned and did not hit a stop in either direction like my other .029 Stihl saw does. Now the oil flow has stopped and I don't know where I am on the adjustment screw. I looked at the parts diagram and it shows 2 o-rings on the screw but I saw no means to limit the adjustment on the drawing. I guess the oil pump body is plastic and hope I have not ruined the adjustment screw threads! I did not force it, it just kept on turning in both directions. I will remove the bar and try to adjust the oil flow again tomorrow. I will try to press in on the screw as I turn it to see if it will pick up the threads and turn on the oil flow. 
I sure am glad you are working with me on this, you must be a stihl mechanic. I don't want to wear out your patience either!


----------



## rotti1968 (Apr 26, 2009)

That oil pump is not plastic, it may have become overheated and damaged the o rings. I suggest that you just replace it, I have not had the best of luck trying to repair that part of the oil pump. Also your oil issues may not even be your pump. It could be the worm drive , they also overheat and become loose and no longer turn the drive for the pump or the gears strip. The worm runs off of the drive sprocket via a metal arm and it has a nylon worm gear. When it overheats the arm becomes loose on the worm , there is no repair for this other then replacing it. The oil pump part # is 1127 640 3204 I see them on eBay from 15.00 to 30.00 used,new is 55.00. the worm gear part # is 1125 640 7110 that is around 10.00 new , the ones on eBay are way over priced. make sure that if you do replace either the oil pump,worm drive or both that when you put the sprocket back on there is a little notch cut out and its marked with a line on the sprocket for the worm gear arm. If you don't get that in the notch you will burn up the sprocket bearing and may cause other damage .
That warranty is for the original owner of the saw, and stihl is very firm on that. The air gap on the that coil should be around .010. Yes I'm a gold certified stihl tech and its no problem helping you.


----------



## ccrider966 (Jul 8, 2006)

*Thanks Rotti1968*

Thanks Rotti, I got the saw oiling by moving the adjusting screw in further. My other Stihl saw adjusting screw seems to be limited in travel and this one was not for some reason. I really like the 029 Stihl saws and have 2 of them. I cut a lot of firewood in the fall and winter and heat my house with wood too. I picked up this saw at an auction and am getting it ready for fall cutting. 
I really appreciate your help and information. It and along with a CD I bought on Ebay for Stihl saws has got me up to speed. 
You certainly know your stuff on these and I would love to have your phone number for reference on future problems with them. You can email it to me privately to [email protected]. I am a retired engineer and have a small farm in Union, Mo where I collect antique tractors.


----------

