Stihl 038 AV Magnum rebuild

[francky78]

Hello,

My name is Franck, and I'm new on this forum. I'm french so excuse me if I make some mistakes !

I have started to repair a Stihl 038 Magnum that I have bought for 50 euros (aprox 65$). The seller say me that the cylinder and the piston are dead.

I join some pictures and I will add others when i will progress.

If it helps someone, I'll be happy

 

[francky78]

When I start to dissassemble :

Problem wtih the piston :

And another with the oil !!!

 

[pioneerguy600]

Welcome to the site Franky, don`t worry about the language mistakes some of us including myself can barely master our own language online. You have chosen a great saw to do a rebuild on, they are tough as a tank so a new piston and cylinder will be an easy rebuild if that is all it needs. Keep up the good work and post lots of picts as you go. opcorn:
Pioneerguy600

 

[Mad Professor]

Welcome to AS

Check crank pressure before rebuild, if not, put in new crank seals after primary problem (if you don't need to do crank work anyway).

After you pull off the cylinder, examine cylinder for aluminum transfer and/or scoring. The former is piston material that can be removed, the latter is damage to the cylinder lining that may require a new cylinder.

With piston off rotate the crankshaft and feel for rough spots in both the upper and lower bearings. The crank will "grab" when each to the magnets line up in the flywheel , that is normal.

You can do a search to explain this, LOTS of reading with pictures here.

Report back on this and you will have lots of good advice.

 

[francky78]

Thank you for your advices.

I have tried to clean my cylinder. I think it is possible to not change it but just the piston. What's your mind ?

Before :

After :

I'm waiting for the parts that i ordered (piston, seals kit, clutch, intake pipe, kit for carburettor,...)

 

[pioneerguy600]

I think your cylinder will work fine with a new piston and rings, it cleaned up well.
Pioneerguy600

 

[madhatte]

Now would be a good time to switch from a spur to rim sprocket. Way cheaper in the long run.

Also, I'd put some pretty good odds on that cracked intake boot being a contributor to the original damage to the piston.

 

[sefh3]

The cylinder looks really good to me. I would run it. I would also replace the fuel line and impulse line while you are at it. They are cheap and it's a peace of mind. The carb boot is/was your problem I would say. I would assemble the saw and build yourself a vacuum pressure tester and test it.

 

[jockeydeuce]

Great project and a nice job cleaning up that cylinder!!! That will run fine with a new piston!

I agree with madhatte, Now is the time to change to a rim type sprocket!

Can you check the bore of your cylinder? Judging by your pics, there's a few things that point to that saw not being a Magnum. Maybe that's the way they were sold in the European market and I could be wrong.

 

[demographic]

I'm tagging onto this thread cos my 038 AV super is slappy sounding and I reckon it will be needing a strip down.

 

[adkranger]

Welcome aboard francky78. No worries on the language, we understand you just fine. There are some here with English as their first language that have more difficulty.

You picked a great saw to start on and will attract much attention to your thread. The xx8 series of Stihls are their all-time best in my book. They are like a rock..........:rockn: I have one of your saw's little brothers (028WB) tore down waiting on parts, that makes number five for me. Also have a 038M II and a 048 (though it isn't really related except by color and shape)

Oh yeah, that cylinder looks good enough to me. New piston/ring set and you should be good. I also recommend replacing the tubes (fuel & impulse) while your saw is tore down. I've tried to reuse what I thought were good impulse lines just to have it crack during re-assembly. Don't know about you, but when I get to re-assembly I don't like set backs.......

 

[francky78]

Thank you all !

To Jockeyduce, for my information, what are differences between US 038 Magnum ? exhaust ?
Do you think my saw is not a magnum ?

The bore of the cylinder is 52mm it's normal for a Magnum, no ?

I continue to clean the saw before the spare parts arrive, i will post more pictures in these days.

 

[francky78]

I have another question about the oil leak. Is it a common problem ?

I will change the seal under the oil pump of course but I have doubt about the gear of the oil pump because there is a hole in the center. When I disassembled it, the oil escaped through this hole.

I will try to make a picture to show you.

Do you think that the seal lips of the oil pump can be bad ?

Thank you !!

 

[jockeydeuce]

Hey Francky!

Yes, your saw is a "Magnum" if it's 52mm bore. It was the muffler that I thought looked odd for a Magnum. You've got the biggest 038 though!

 

[francky78]

Some news,

After some cleaning, I received the spare parts.

I took the new piston, intake pipe, sprocket,seals....

 

[francky78]

some more pictures....

I have always the problem with the oil, so I have ordered some seals for rebuilding the oil pump
http://www.arboristsite.com/showthread.php?t=137765

 

[Stihlofadeal64]

some more pictures....

I have always the problem with the oil, so I have ordered some seals for rebuilding the oil pump
http://www.arboristsite.com/showthread.php?t=137765

It is possible that you can buy an aftermarket oil pump if you are not able to rebuild what you have. It seems like I bought one recently for less than $50.00. but can't recall the exact amount. Work looks great thus far!