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problem with Stihl 038 AV Super

Started by Ejdb, February 08, 2016, 07:07:23 AM

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Ejdb

Hi there! a quick note from the Netherlands here:

About a year ago I have bought a Stihl 038  AV Super chainsaw that had been sitting on the shelf for a couple of years doing nothing. After changing the old fuel and replacing the old oil i'd managed to get it up and running quite easily. At first it was a bit difficult to get it up and running but after i replaced the old fule for new Aspen fuel it fired up nicely.

Anyway it worked fine and i have been able to cut a couple of logs into pieces when all of a sudden  i noticed  power-decrease, smoke coming from the muffler and then it stopped. No way to get it back up and running.

I suspected a ruined piston and/or cilinder but when i inspected them via the muffler side and the sparkplug side they seemed to look nice and clean and no real wear and tear. The piston also moves nicely in  the cilinder.

Not having enough time to spend on it i let it sit for a couple of months but yesterday i tried firing it up again but nogo.

I removed the plug to check the spark which was okayish, not the brightest blue spark but stil decent. What i thought was strange is that the plug was completely dry! So i suspect a fuel issue here. What i tried is to pour some fuel into the cilinder via the sparkplug hole. installed the plug and tried to fire it up. It did give some reaction and it sounded like it tried to start but only a couple of puffs and that was it (which isn't strange with only a bit of fuel in the cilinder)

Now my question is......where to start? is this a carb issue? and if so should i just replace it or rebuild it. or is there something else im not seeing?

Just to be complete...i did notice just a little bit of oil leackage on the bottom of the saw....but nothing a piced of newspaper cant handle.

Hope you guys can give a some tips and tricks on where to start with this machine as it would be a shame to leave it unused!.......and besides that i must say i really like to dig in to these kind of issues and thats why im glad i found this forum, beacuse surprisingly i could hardly find any info here in the Netherlands that  would give a proper direction.

Looking forward to hear from you guys!

Evert
Ill try to fix antything myself first......why? cuz i keep on learning by making foolish mistakes

old2stroke

Sounds like you have a fuel starvation issue.  Since it stopped suddenly while running, it is not likely the carb.  With a saw that has been sitting around for a long time, the first thing to look for is a cracked or broken fuel line.  If that saw has a separate impulse line for the carb, that would be another thing to check. If these items are good then it would time to check the function of the fuel tank vent and other less likely things. These fuel starvation faults are very important to find and fix, running a saw with leaned out air/fuel mix can quickly cause serious damage.
A bit of oil drooling from the base of the bar is normal.
Not too many saws.  Not enough storage space.

RIDE-RED 350r

Agree with old2stroke...

I just recently did some work on an 038 Super AV for a friend. These saws are getting pretty long in the tooth and the rubber parts are sure to be getting quite aged as well.

Get yourself a new fuel line, fuel filter, and tank vent to start. Now the fuel tank vent is a little strange. If you remove the air filter cover and air filter, you will see a small line fitting to the left of the kill switch as viewed from the operators position, protruding straight up. There should be a small length of vent line fitted to it, (about 2 inches or so). Inside this vent line should be 2 little threaded inserts. The threaded inserts allow just enough air to pass to allow the fuel tank to vent, but not open enough to allow fuel to seep or splash out during use. The 038 Super I worked on, this vent line disintegrated when I touched it to check it.

This saw does not use an external pulse line. There is a pulse port in the carb boot that mates with the pulse port on the engine side of the carb face.

As with the fuel line and tank vent line, the rubber intake boot may very well be badly rotted too. Check it carefully for cracks, dry-rot, or other damage that could cause an air leak. If questionable at all, I would replace it. This can/will cost you a top end if neglected when it requires replacement.

So I picked up a new fuel line, filter, and tank vent with both inserts from my local dealer for about $15 US total. The saw I worked on did not need the intake. But I suspect that it won't be too costly either.

And of course if you haven't already, it would be a good idea to disassemble that carb for a good cleaning/inspection/rebuild as needed.

If the situation is not remedied after servicing the fuel system, and being that you say the top end is still in god shape, I would then check for a sheared flywheel key. Also, make sure and clean the coil armature and verify proper coil/flywheel gap which is usually about .010-.015".
Swedish, you know, like the chef.

joe_indi

Sudden stop with smoke from the exhaust is a very bad sign. Usually the sign of con rod big end failure.
In such cases the spark plug would be dry and black. Fuel poured through the carb into the crankcase would be blackish when it flows out with the saw is inverted and the engine is turned over.
Try this and then you could confirm by lifting the cylinder.
Joe

HolmenTree

Before you do all that check the choke shutter in the air filter.
These 038's were notorious for faulty chokes. The spring in the air filter that tensions the shutter may have popped loose or weakened to allow it close the choke stopping the saw with smoke and all.
I have cleaned these air filters by taken them apart as their designed to be split in half. Sometimes if you're not careful you can stretch the spring or dislodging it for proper operation.
Making a living with a saw since age 16.

Ejdb

OK, thank you all....I've got something to work on now.

The fuel doesn't come out black as Joe_Indi mentioned.....so ive got my hopes on a bad fuel supply


Tried it again today.....nothing, the plug is still dry....colour is whiteish...not black.

Just to be sure i'll get myself a new plug....

and other then that I ordered a new Fuel line, Fuel tank vent, Fuel fliter, Rubber intake boot and a rebuild set for my carb.

I wil go from there and if nogo i'll remove the top end to check that too.....need to get myself some long torx tools first.

My hopes are still up as it does tend to start when i pour fuel in directly.

Thanks for now and i'll post an update when done.


Ill try to fix antything myself first......why? cuz i keep on learning by making foolish mistakes

HolmenTree

Quote from: Ejdb on February 11, 2016, 08:57:40 AM

My hopes are still up as it does tend to start when i pour fuel in directly.

Like I said earlier check the choke shutter in the air filter .
It may be not functioning properly. Not closing fully when the master control switch is on the choke position. ...causing it not to draw fuel and start.
And also at high rpm the choke shutter is closing due to a weak or damaged tension spring......causing the saw to smoke and stop.
Making a living with a saw since age 16.

Ejdb

@Holmentree: i checked the choke shutter and that seems to work fine.

The fuelline and filter and tank vent seem to be fine to. I still have to check the intake for damage.

I removed the carburator and its a Tillotson HK42Awhich seems to be quite rare as i can hardly find any inof on that carb.  I did look for a replacement but the only ones that come close have an extra intake connection on the bottom of the carb which the Original doesnt have.

So thats why i will first go for a replacement of gaskets and membranes.

Wen i took the carb out i noticed that the gasket between the airfiler and carb was sort of damaged on the outside.

The carb itself: the gaskets and membranes stille seemto be in pretty good shape. The onl thing i found was some dirt in one part of the carb. that was collected in one seperate section of a gasket.

so i gave it a good clean and will now wait to receive my ordered parts somewhere this week. I hate waiting for these things :)  i want it fixed!  haha

anyway ill keep you posted on the progress. i will post some pics of the carb. maybe you see something i didn't.

The thing that worried me a bit is the last picture where you can see the throttle doesnt completely close......



 


 


 


 


 


 


 


 


  


 


 


 


 


 


 


 


 


 
Ill try to fix antything myself first......why? cuz i keep on learning by making foolish mistakes

Ejdb

Another question: I keep on reading that i could use this carb to replace my Original one.





 


However this has an extra connection that my Original doesnt have. I gues that is for a so called pulse line?

Can someone tell me if i could indeed use this one to replce my Original and what should i connect to tha pulse connector?

Thanks!
Ill try to fix antything myself first......why? cuz i keep on learning by making foolish mistakes

joe_indi

Quote from: Ejdb on February 15, 2016, 02:17:54 AM
Another question: I keep on reading that i could use this carb to replace my Original one.





 


However this has an extra connection that my Original doesnt have. I gues that is for a so called pulse line?

Can someone tell me if i could indeed use this one to replce my Original and what should i connect to tha pulse connector?

Thanks!
Yes you can use this carb. That is not a pulse line. It is only an air compensator line which comes on the MS381. If you need to use that air compensator, you will have to replace the air filter and carb  grommet also.
Simpler would be to get hold of a suitable 4 screw cover of the earlier version and replace the compensator cover.

Logger RK

I have a question on a Sthil 044. I had carb problems on & off for about a year. I put a carb  kit /impulse hose & gas line & checked vent when it first started acting like it was starving for gas. Ran good for probly 5 hours? Brought it to a repair shop. Ran good for about another 5. Mechanic told me if it started running bad again he would have to change the carb. So I did put a new carb on & it's been about a year & still runs great. Guess my question is. What wears out on a carb? Been logging for 35 years & haven't had a carb wear out before.

joe_indi

Quote from: logger RK on February 15, 2016, 06:37:13 AM
...........What wears out on a carb?......

The metering needle for one. Wear out will cause flooding
Low and high speed check valve diaphragms. Wear out would cause leak in of air into the metering chamber, which results in leaning out of fuel supply.
Wear out of throttle shaft would cause lean fuel:air mixture.
Pump diaphragm wear out too will cause leaning out of fuel.
Most are curable except the low speed check valve (to my knowledge)
Joe

Ejdb

i did the carb rebuild and that looks good now. unfortunately the repair set i ordered has a wrong size gasket in it that needs to go between the airfilter and carb. the diameter of the large hole in that gasket is too small.....so i am searching for one with a bigger diameter or i need to alter the gasket i have myself with a shapr knife....

well other then that ....i started to further take apart the saw and when i wanted to remove the handlebar/tank i had to take the screws out of the rubber anti vibration pads....when i did that i noticed they were soaked in oil....thats probably not 'a good sign' >:( >:(

i suspect/hope it just the oilpump oil line....or could it be a seal or something?

ill continue my search by opening up the clutch side of the saw this afternoon and see what i find there...

I have figured out a lot myself by reading the forum and the entire internet ;) but i was wondering if anyone could help me getting a copy of the workshop manual for my 038AV saw? I have the 038 av super but i expect it to be the same as the magnum and/or the ms380 saws.

Hope someone can help me out
Ill try to fix antything myself first......why? cuz i keep on learning by making foolish mistakes

Ejdb

Doesn't look to good does it?  whats the first thing to check for?



 
Ill try to fix antything myself first......why? cuz i keep on learning by making foolish mistakes

joe_indi

Quote from: Ejdb on February 20, 2016, 09:31:24 AM
..... but i was wondering if anyone could help me getting a copy of the workshop manual for my 038AV saw? I have the 038 av super but i expect it to be the same as the magnum and/or the ms380 saws..
If I am not mistaken the manual you have should be fine for you needs because main difference isonly piston and cylinder dimensions .
The worm gear of that oil pump needs to be replaced.
Either you have loose screws on the oil pump or a worn out pump body.
Joe

Al_Smith

Just get some solvent, kerosine or diesel fuel perhaps and clean the thing up .Make certain the oil pump screws are tight and run it .Most oil pumps no matter who made them leak at least a little bit given an amount of usage .

Ejdb

OK, i removed the oilpump, gave it a good clean and that seems to be fine. Have to order a new gasket to reinstall it again.

But in my quest i discovered something else.....i removed the clutch and i was not really happy with what i saw there....a big thick sticky oily mess.....all the holes are clogged up by old oil and even more troublesome i saw a piece of broken plastic out there.........



 



 

What would this be? the remainders of the oilseal?? And more important...what would it mean for my next steps...
The cranckshaft still moves smoothly when i turn the flywheel. I dont feel any clearance there.

Would this be a matter of cleaning out all the old oil and place a new oilseal, or would this mean i have to open up the cranckhouse completely? I mean can i expect the same oily mess inside the cranckhouse?

I am learning a lot and i dont think there was a whole lot wrong with my carb(where i started this story) but i could really use some expert advice here....... Thanks!!



Ill try to fix antything myself first......why? cuz i keep on learning by making foolish mistakes

joe_indi

It is called a sealing washer and is from the brake.
See the diagram

Correction
:-[ My mistake, that looks like a portion of the oil seal.
Joe

Ejdb

That's what I figured. ...the break break seal is still there.

But my big question here is: should I open it up completely  (housing) or just clean thoroughly and fit a new oilseal?

Not that I would be happy to open it up but I don't want to put it all together and find out that it still won't run because of glogged up oil inside....

Or are those holes underneath the clutch just airgaps or something?
Ill try to fix antything myself first......why? cuz i keep on learning by making foolish mistakes

limbwood

I would just clean it and put new seal in, would do the other side to. Those hole are for the screws to hold case together.

Ejdb

Thanks but these holes can't hold screws....they are rectangular and too big for screws.

The seal on the other side is still fine.....I'm just not sure if I should worry about the inside of the engine
Ill try to fix antything myself first......why? cuz i keep on learning by making foolish mistakes

limbwood

the inside is always clean, fuel mix is going through all the time keeping it clean, make sure you clean out bearing and lube before putting in new seal.

smmyb123

I think that you have discovered most of the problems with your saw by removing the clutch and cleaning in there. I suspect that the oil debris around there is from you flooding the crankcase while trying to start it and that fuel was passed out of the failed main seal (which blew out during use, causing a lean running condition which explains the white ash on your S/P). While you have the saw apart this far, it would be a good idea to replace those (the saw will not run with a massive air leak in the crankcase). Make sure you check the crankshaft end play before going any farther with this repair. If you can wiggle the end of the crank shaft up/ down, left/right you may want to replace the bearings as this will effect your new seals (ruin them). Also, check the hoses/ grommet that attach to the oil pump just to be sure those arent leaking.

smmyb123

Also, unless you suspect crankshaft bearing issues, dont crack open the crankcase.

Al_Smith

Another common problem nobody mentioned .For some reason these models or rather the models of the 038 have a tendency to tear the rubber loose off the left hand upper shock mount allowing some extra movement which often goes over looked .This in turn will lead to tearing the intake boot on the lower portion where it's nearly impossible to locate unless you remove the boot .I've replaced at least 3 boots with this problem.

Under normal conditions the tear might not even open up enough to cause problem but in a hard leaned on up or down cut it will open up and suck air .

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