Stihl a38v magnum Problem

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keithh255

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HI All; Im new here and like what I see. A nice community.
I have a problem (original not rebuilt) stihl a38v magnum I inherited and have problems with it starting and running. I got it over to a repair depot and they put a carb kit on and a new filter , made adjusts etc.
The saw started fine the first time I got it back but after 10 minutes it stopped cold. The saw was letting off a bit of steam (hot indicator) when it stopped (0 celsius) but it was cold that day so I ignored that until it did the same thing next 2 times I got it going. I was cutting close to the ground where snow had built up so some moisture may have gotten pulled up by the chain. Now, It will not start at all unless you pull off the air filter.
I called the repair depot and they suggested a new spark plug and I did that and Im having the same problem.
I can fix things so my internet search has lead me to your forum.
Question, I hear the Stihl magnum a38v has a electronic shutoff in high heat conditions? If the saw is having internal problems then the high heat shut off could be happening due to scored piston wall or old bearings? This saw has never been rebuilt.

If anyone is handy at this sorta repair or problem diagnosis I would appreciate hearing from you.

Thanks Keith

PS As a foot note, I looked at husqvarna and stihl 441 as a replacement. Big bucks for a great saws Im sure. Any suggestions?
 
HI All; Im new here and like what I see. A nice community.
I have a problem (original not rebuilt) stihl a38v magnum I inherited and have problems with it starting and running. I got it over to a repair depot and they put a carb kit on and a new filter , made adjusts etc.
The saw started fine the first time I got it back but after 10 minutes it stopped cold. The saw was letting off a bit of steam (hot indicator) when it stopped (0 celsius) but it was cold that day so I ignored that until it did the same thing next 2 times I got it going. I was cutting close to the ground where snow had built up so some moisture may have gotten pulled up by the chain. Now, It will not start at all unless you pull off the air filter.
I called the repair depot and they suggested a new spark plug and I did that and Im having the same problem.
I can fix things so my internet search has lead me to your forum.
Question, I hear the Stihl magnum a38v has a electronic shutoff in high heat conditions? If the saw is having internal problems then the high heat shut off could be happening due to scored piston wall or old bearings? This saw has never been rebuilt.

If anyone is handy at this sorta repair or problem diagnosis I would appreciate hearing from you.

Thanks Keith

PS As a foot note, I looked at husqvarna and stihl 441 as a replacement. Big bucks for a great saws Im sure. Any suggestions?


Often times a failing coil will shut a machine down once it gets hot. I am not familiar with the nature of the 038, however many sing its praises. Pull the plug and look at it. If you are running rich, you may be fouling your plug after 10 minutes. Pulling the air filter to get it started would also indicate an overly rich condition requiring more air to 'lean' things out = dirty filter, improperly adjusted carb. A few ideas, but it is hard to troubleshoot over the WWW.
 
Changing the plug is a bogus suggestion to cure your ails...

There is nothing built into the saw that will make it shut down when hot. If it does, you have another problem...

In addition to the other suggestions..

-Reset the H screw to exactly 1 turn out.
-Take the carb apart again and see if you have a blocked inlet screen
 
Take a look at your fuel tank vent. Perhaps it is dirty, plugged, or otherwise not functioning properly. A malfunctioning fuel tank vent can cause the problems you describe. Also, a spark plug change wouldn't hurt. I'd use a Bosch WSR6F. A new fuel filter pickup body wouldn't hurt. Your carburator fuel inlet screen may be plugged, however, the saw should still run/idle but low power/poor accelertion. Resetting the carb needle screws wouldn't hurt. With the H nd L needles turned clockwise lightly into their seats, back out counter-clockwise 1 turn. Tune from there.

Turn L needle slowly counter-clockwise until engine starts to load up/slow and blubber with fuel, make note of screw driver position. Turn L needle slowly clockwise until engine starts to race and starve for fuel, make note of screwdriver position. Now turn the L needle half way between the rich and lean setting or where the engine idles and accerated the best. Check acceleration. Engine should accelerate without hesitation. Does the chain turn or creep at idle? If so turn the T/idle screw clockwise (faster), or counter-clockwise (slower).

H needle adjustment by ear. Place saw on ground in a clear area free of debris. Warm the saw up. Hold saw at WOT turn H needle counter-clockwise until engine slows, loads with fuel and blubbers. Now turn the H needle clockwise until the saw smooths out/almost screams, and turn the H needle counter-clockwise until the engine emits a slight, yet distict 4-cycle/flutter sound. Let the engine return to idle, and cool down a bit. Check acceleration and 4-cycle/flutter sound a few times. Now, saw some wood. If the saw is too lean it won't have any power in the cut, it will just kinda fall on its face. If the saw is too rich, the saw will have a heavy 4-cycle sound and sort of blubber through the cut. If the saw is tuned correctly into its power band, the saw should have a smooth sound and lots of power while in the cut.

If you have a tach, just tune the H needle to give you 12,000 rpm. That is the recommended rpm for a Stihl 038. However, the power band might not always be at 12,000 rpm. I could be at 12,200 rpm, or 11,800 rpm, or even 12,500 rpm. Every engine is slightly different.

Hope this helps,

Nick
 
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Yup the others hit the high points. I'd concentrate in the fuel delivery area. Fuel filter, inlet screen on carb, tank vent(notorious problem), carb adjustment and overall condition of carb (is it all crudded up?). The first few items are simple and easy to check.

As far as suggestions? The 038mag is a great saw, darn near bulletproof in durability department. Used 'em for many years, (though none were mine:( ) have nothing but respect. A little heavy by today's standards and some things are old school(like front chain tension) but I like old school sometimes and would love to an 038 in my stable. My suggestion is if you like the saw, get 'er fixed up and run it well, it'll probably outlast you if maintained properly. One more thing, do your own work that you feel comfortable doing and when over your head take it to a chainsaw tech, preferably Stihl, not some everything-under-the-sun repair shop. I have two 028s which are your saw's little brothers and have put many hard hours on them over 15+ years, they just keep cutting.:chainsaw:

Good luck with your great classic saw and welcome to AS.
 
reply about your stihl 038av magnum

HI All; Im new here and like what I see. A nice community.
I have a problem (original not rebuilt) stihl a38v magnum I inherited and have problems with it starting and running. I got it over to a repair depot and they put a carb kit on and a new filter , made adjusts etc.
The saw started fine the first time I got it back but after 10 minutes it stopped cold. The saw was letting off a bit of steam (hot indicator) when it stopped (0 celsius) but it was cold that day so I ignored that until it did the same thing next 2 times I got it going. I was cutting close to the ground where snow had built up so some moisture may have gotten pulled up by the chain. Now, It will not start at all unless you pull off the air filter.
I called the repair depot and they suggested a new spark plug and I did that and Im having the same problem.
I can fix things so my internet search has lead me to your forum.
Question, I hear the Stihl magnum a38v has a electronic shutoff in high heat conditions? If the saw is having internal problems then the high heat shut off could be happening due to scored piston wall or old bearings? This saw has never been rebuilt.

If anyone is handy at this sorta repair or problem diagnosis I would appreciate hearing from you.

Thanks Keith

PS As a foot note, I looked at husqvarna and stihl 441 as a replacement. Big bucks for a great saws Im sure. Any suggestions?
it defenitly acts like it at the very least sounds like it needs a set of rings. i know a couple of websites that might have the parts you need. cutters choice and baileys.i you could email me some pics of your saw i might have a better idea of whats wrong with it. i need pics of the carb,the jug from all four sides,and as much of the wiring as possible.bill howe huskys 51 and 141
 
Many thanks for the replies guys

Hi; I can see from the replies I need to consider getting a parts manual for the saw if I will have a go at it by myself.
I will try some ideas passed on by you guys this morning before work ,with the saw and see if it is a simple gas starving problem or something simple that I can see without taking it apart, like the fuel tank vent. It has a small screw in it and would let some air in but no gas out? Has anyone seen these vent tubes with a small screw?

I have confirmed the fuel filter was changed out when it was worked on by the repair depot also.

As for photos, I will get a camera from a friend if I go and get it apart. Since we all work and I take of the farm animals etc , short term work on this will be an issue but I'm game to handle as much as possible.

Question, how long will a saw of this size run with gas from the carb only. I mean, if this is a simple gas starve, will it run maybe 10 minutes before dying? It could be that gas leaks into the carb while sitting and runs until dry. I will check the plug again once it dies next time and see if it is dry or wet. Is this a sure method or clue or is it bound to be dry from evaporation once the saw is hot?

Thanks to everyone who replied. I really appreciate being welcomed and made to feel right at home. A real nice group!

Anyways, I will post an update as soon as I know more.

Many thanks guys,,,:popcorn:


Keith
 
Hi; I can see from the replies I need to consider getting a parts manual for the saw if I will have a go at it by myself.
I will try some ideas passed on by you guys this morning before work ,with the saw and see if it is a simple gas starving problem or something simple that I can see without taking it apart, like the fuel tank vent. It has a small screw in it and would let some air in but no gas out? Has anyone seen these vent tubes with a small screw?

I have confirmed the fuel filter was changed out when it was worked on by the repair depot also.

As for photos, I will get a camera from a friend if I go and get it apart. Since we all work and I take of the farm animals etc , short term work on this will be an issue but I'm game to handle as much as possible.

Question, how long will a saw of this size run with gas from the carb only. I mean, if this is a simple gas starve, will it run maybe 10 minutes before dying? It could be that gas leaks into the carb while sitting and runs until dry. I will check the plug again once it dies next time and see if it is dry or wet. Is this a sure method or clue or is it bound to be dry from evaporation once the saw is hot?

Thanks to everyone who replied. I really appreciate being welcomed and made to feel right at home. A real nice group!

Anyways, I will post an update as soon as I know more.

Many thanks guys,,,:popcorn:


Keith

I may be able to help you out with IPL, I'll PM ya if I've got it. As for the tube w/screw next to carb, yup that's your tank vent. The tubes harden over time and don't allow the tank to breath. You can sometimes play with the screw to get it breathing again, though likely it'll tend to pizz on itself when saw is held/lain sideways. Better just to replace it on a saw of that vintage, that's why Stihl got away from those.

If the fuel filter is new(in tank) I'd check the screen on in the carb on the inlet to see if it's clogged. If it had one of the older/cheaper filters on before you received the saw it could be clogged with junk. Lakeside had a good thread on filters awhile back(do a search).

That saw will not run long on carb only, certainly not 10 minutes. But how does it run in those 10 minutes? I'd check the impulse line as well as the metering diaphram. Where is your H metering valve set at? The fuel delivery issues are the quickest/easiest to check that's why I'd recommend starting here. A compression test would be adviseable when you can get your hands on a tester.

Let us know how you make out. I'll get ya an IPL so you can ID parts.
 
The easiest way to test the tank vent issue is just pull it off and run the saw with a half tank of gas. (not on its side obviously..). There should be two screws in the vent tube- one at the top and one at the bottom.


Rings? You can't really say that without a compresision test..
 
Vent tube missing bottom screw

HI guys; Short update. I checked over the vent tube and it was missing the screw at the bottom. Replaced it with another but still not starting yet. Im pretty sure the compression is good as it cuts well until it stops, meaning a possible heat problem or gas starve.

I will update as time permits. Thanks to Wil for the Ipls.

I could use a service manual for this saw if anyone knows of one please let me know.

Many thanks

Keith
 
The early mickey mouse vent tubes only had one screw in the line....there was a recall and they added a second set screw. They still leaked fuel.

Does the saw start easily with the sair cleaner cover removed?
 
Heh Pest

HI; I got the second screw in, took it back outside and rain came, being later in the evening I let it be. I have not taken off the filter yet this time around but will try that next ( we have rain again all day here) and Nick's directions on adjusting the carb settings.

The saw does start grudgingly without the air filter after maybe 15 pulls and continues to idle and accelerate well once replaced, for the average run time of ten minutes. It has good cutting power while it runs and then dies with a sudden duhhhhh.

Could be heat shutting the coil down?

Thanks for your reply..

Keith
 
yes, the coil could be going bad (not "shutting down") when it gets hot. Next time it fails, check the spark immediately. You may also have a seal that is marginal and gets worse as the engine heats up.

To answer one of your earlier questions... If it was just gas in the carb, it will only run for a few seconds.


There are many possibilites for what's wrong with your saw. A simple pressure/vac test will eliminate or confirm most..


BTW... the saw starting without the airfilter FROM COLD indicates an issue... maybe.. It needs the choke in the airfilter to get going...
 
Stihl a38 v update

Hi guys, Well , looks like the lower of 2 vent tube screws was out so I fixed that. That was right when the rain decided to arrive . Today, more rain but in between showers I went back out and pulled some more. This time I got it going in 4 pulls without pulling off the filter but before I could say Lickidysplit it died again. So she ain't dead yet.lol
I will dig up the spark tester as soon as I can remember where I put it, and put it to good use.
I have written all the carb adjustment methods down and will have another go tomorrow. I'm really beginning to be hopeful that I will get this going before long.

Thanks to all for the great info and support.

Keith
 
Got it done..thanks for all the help

Hi guys, got down to the adjustments and the saw ran fine for a couple hours. No dead stops.

Im have a go at a falling maple. Will try to post pics if camera arrives.

Have a great year...

Keith
 

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