Need help with Stihl 038 Super Pro

[kentucky_ young_buck]

I have a 038 super pro Stihl that I have been having trouble with. Two or three months ago it started and ran fine, but last week I got it out and it wouldn't do anything. I replaced the fuel line and filter and it started, but when I gave it gas it would die. So I ordered a carburetor rebuild kit and installed it today with a good cleaning. I have also replaced the spark plug (which has spark). Went to crank it and got nothing. One squirt of starter fluid and it turned over, but never ran continuously. Anyone have any ideas what it could be? I have checked the intake boot (looks good), and have cleaned the screen on the exhaust. Any help appreciated. Thanks.

[Al_Smith]

Check the clutch side crankcase seal .

[joe_indi]

Possibility #1.Impulse hose damaged or loose.
This is the hose you see connecting the engine to the tank housing. Looking down from top, near the spark plug, on the right side itsthe thin black hose connected to the angle connector.

Possibility #2. You have a stuck check valve which is not closing fully.
You will need to dismantle the carburetor and give the metering section a thorough cleaning.But you could also try setting L & H screws 2 turns out, initially and then closing them down once the engine runs smoothly.

Possibility #3.That is what Al has posted

Possibility #4. A blown cylinder gasket. 038s have M5X20(25) cylinder screws which tend to become loose, which results in the gasket blowing

Joe.

[kentucky_ young_buck]

Thanks for the responses guys. I always try to work on my own stuff, so trying to figure this out without a labor bill.

1) I checked the impulse hose when I was looking over the intake boot, and without taking anything apart it looks fine. But I will check it all again.

2) When I installed the carburetor kit it came with a new check valve. The old one looked a little worn, but not bad. I replaced it anyway, but installed the old spring. The kit did not come with a new spring. Could this be the issue? It seems to be opening and closing fine to me, but again this is my first time replacing one.

3) I'll check on this. Thanks to both of you.

4) I will check on this as well. Would this blown gasket cause it not to start at all?

Also, I can pull it about 10-15 times, remove the spark plug, and it is wet with fuel. Leads me to believe I'm flooding it. So, I cleaned the plug, pulled about 6-8 times without the plug installed, reinstalled the plug, pull another 10-15 times, still nothing, remove the plug and its wet again. Any thoughts on this? This is all with the choke ON.

Thanks again for your input. I appreciate the help,
Mike

[JohnG28]

Where did you set the H and L screws after the carb rebuild? Start them turned all the way in clockwise, then back out 1 to 1 1/4 turn. See if that helps. Possibly a stuck open or incorrectly set metering lever also?

[Mag Craft]

Since you rebuilt the carb I would get a diaghram of the carb and check the order of assembly.   It is common, and I have done it more than once to have things in the wrong order.  Especially the gaskets.

[joe_indi]

...........

2) When I installed the carburetor kit it came with a new check valve. The old one looked a little worn, but not bad. I replaced it anyway, but installed the old spring. The kit did not come with a new spring. Could this be the issue? It seems to be opening and closing fine to me, but again this is my first time replacing one............................................
This is all with the choke ON.

That is not the check valve. That is the inlet needle.The check valve (Jet valve) does not come in the repair kit.Its top is visible as a  circular bit of brass.
I would pass this for the time being because you seem to have flooded the engine by having the choke on during all your attempts.
Repeat the last bit again, but this time do not use the choke.
Better still do it without the air filter. That way the choke will not function, even accidently.

Joe

[kentucky_ young_buck]

Joe - I know what you are talking about now. I remember seeing the check valve during the carb rebuild. Thanks for the terminology lesson.

John - I did not adjust the H & L settings before I tried starting. I will set them before I try again. Where and what is the metering lever?

Mag - I double check my order again, you never know.

Thanks to all for the help. Going to work on it tonight and see where I get.

[bill m]

I have seen saws flooded so bad the bottom end was full of fuel. This may be your problem. Pull the plug out, stand the saw up on the bar end( with the muffler pointed down ) and pull the starter over about a dozen times. Then put the plug back in and try starting it without the choke.

[lumberjack48]

 When i had a saw flooded, i always used a match to clean the cylinder out. Pull the plug, then light a match, holding it partly in the plug hole pull the starter rope real slow. It might blow it out a few times, try again, when it goes Woofff, shes good to go, put the plug back in. Now it should start in one pull, with out the choke. If it doesn't try one time with choke pulled, it should fire, push choke in, 1 pull it should start.
If it didn't start, try the this one more time, evidently its still flooded.

[kentucky_ young_buck]

Okay guys, still not running. I removed the spark plug, pulled about 20 times (saw stood muffler down), and reinstalled spark plug. I turned the H & L screws all the way in and backed each of them out 1 full turn. Pulled about 30 times and nothing. Didn't even turn over. Removed the spark plug and it was dry. Reinstalled and pulled another 30 times. Still nothing. Spark plug still dry. I did all this with the air filter removed so the choke would't accidentally engage. Reinstalled the air filter, engaged choke pulled 10+ times, and still nothing, but spark plug is still dry. I'm at a loss, may have to bite the bullet, unless anyone has an idea.

Thanks,
Mike

[beenthere]

Remove the plug, and dribble some fuel into the cylinder. Replace the plug and pull to see if you get some action.

[lumberjack48]

Now your going the other way, you need gas, try what beenthere said or spray a little gas in the carb, if you have spark it'll fire.

Is the compression up where it belongs ?

[T Welsh]

Young Buck, Do what beenthere and lumberjack48 said! I just received an older 048 from a friend and did all you went through and still no fire in the hole! I pulled the muffler off to get a look at the piston and it was toasted. It had no compression. You need 3 things to make a 2 stroke run,compression,spark and fuel. Tim

[kentucky_ young_buck]

I have not checked compression, but I will. Anyone know what it should be for this model?

Mike

[Al_Smith]

Another one of my long posts probabley .First a little about the 038 which although one of Stihls finest it does have it's Achelles tendon .

They have tendency to rip intake boots reason being the annular buffer will tear loose .This is the upper anti vibe mount left side near the handle .Often you can't really tell it's torn unless you take it off .

So what this does is allow extra flexing which will tear the boot which tears on the underside where you can't see it .Looks good but has a tear .Unless it's torn completely into this will not stop it from starting though just runs bad .

What will stop it dead in it's tracks is a completley blown crankcase seal and 038's will blow seals .Why I have no idea but I've changed several .Now just a leaker will cause a lean run but blown out completely no go period even if you dump an ounce of gas down the carb .It cannot blow the fuel up through the transfers into the cylinder .

I've done at least three 038's two McCullochs and just recently have an s-25 Poulan with a blown out seal that drove me nuts before it ever dawned on me .

It's pretty easy to tell once the clutch is off .You'll see little blow patterns of oil around the seal usually .If not block off the carb and give it a little puff of air through the impulse .You can stick your thumb in the carb boot  if nothing else to block it off .

It probabley has enough compression .Should be pushing 140-150 but anything above 120 it should go I'd think .

A tell tale sign of a tattered seal is a whistling sound after you've jerked on the rope until your arm about falls off .

[kentucky_ young_buck]

Haha, well my arm was about to fall off earlier. Not doubt about that. Long post much appreciated. I'm learning quite a bit during this headache. I just tried messing with it again. This time I poured a little fuel down the spark plug hole. Pulled the rope and Vrroom. Turned over, then died instantly. Did it again, and same result.

So, this leads me to believe that I am not getting fuel. Possibly the intake boot as Al says. Without pouring the fuel in, it will not turn over at all. No matter how much you jerk on the rope. 

Question: Would it turn over (as it did when I poured the fuel in) if the crankcase seal was blown?

Im going to tear it down, take the boot off first and check it, then move to the crankcase seal.

Thanks again, Mike

[Al_Smith]

Terms my friend .Turning over is rotation .Firing off is running however short that might be .

FWIW it will fire by just pouring gas in the intake with no carb ,won't do more than a few putt putts though .

So yeah you might get a few putts from a crankcase full of fuel if it can get through the transfers into the cylinder .

So it's down to one of several but it's all about no fuel .Carb,impulse or badly blown seal .

Impulse is easy,use the old thumb again  and feel if the thing has any impulse through the line as soon as your arm gets better from jerking on the rope .It should suck and blow alternately as it's pulled over .You can remove the plug for that test to save the poor old sore arm if you want .

[fuzzybear]

   Do your self a favor and look REAL close at the manifold as Al has said. I use a small dental mirror and head lamp to look all around them. Twist the motor around on it's mounts, you may not feel any excessive movement, but it only takes a small amount over factory specs to stretch out and tear the manifold.
  Also look at the intake side of the piston. 038 are notorious for knocking off the skirt of the piston. This happens when the oil mixture is not correct. It will fire and run at wide open but will die as soon as you let off the gas. The quickest tell all, there will be fuel spraying out the carb as it's running. The air filter will be soaked with fuel. good luck
FB

[JohnG28]

Did you try to start the saw as you normally would after retuning the carb? Just wondering, as you said it had no fuel on the plug but you were also trying to start it with no choke or air filter. I'm just wondering if the original problem would come back if you tried to start it again as normal now or if it would still be fuel starved. 

[Al_Smith]

They're tough rascals .I have a mag that literally grenaded a piston but did not as much as leave a mark on the cylinder .That one I rebuilt twice and it spend over 20 years of extreme hard service for a tree service company .The previous owner gave it to me and replaced it with a 441 .

Since then it's came out of retirement twice as a back up and can still get-er-done in grand style ,old or not . ;)

[kentucky_ young_buck]

John - Yes, after everything yesterday I did try to start it normally with no success. Didn't fire at all.

FB - I did not notice any movement, but not 100% sure there isn't any. As you said it only takes a little. Took a look at the intake side. The piston had some dicoloration at the top of it, but no scratches. No sure what your referring to as the "skirt"?

Al - I completely tore down the saw. Checked the intake boot, looks good (bottom and all), checked the impulse line, looks good too. No visual cracks on either. They are working correctly as I pull the rope.

So, this evening Im going to start with the fly-wheel side and check the seal, then move on to the clutch side. Appreciate the comments and help.

-Mike

[Al_Smith]

Sounds like you have it peeled down to the bones already .You'd just as well give it a good pysical while it's that  far .Seldom does a flywheel side seal go out but nothing is impossible when it comes to a saw .

Be carefull pulling that flywheel and don't be beating on the threads with a ball peen hammer .Best is a flywheel puller but you can shake them with a block of  hard wood and a brisk  tap with a hammer .Use a dead blow,raw hide mallet  or something .No metal on metal now .

[martyinmi]

Use a dead blow,raw hide mallet  or something

Holy "old man" batman! You must be ancient, Al. At almost 51, I've never even heard of a raw hide mallet. ???

Did people use them before the invention of plastic? :D Have you made your own mallet from bison hide that you've hunted and tanned yourself? :D ;)

[Al_Smith]

You use them to thump on a wood chisel young man ,not to be confused with a 4 pound ball peen ,commonly known as a BFH.