Stihl 034AV WG "overhaul"

[bmwpowere36m3]

For a MS192T, different saw...

 

[bmwpowere36m3]

I got some parts today... turns out he did have some in stock.

Gasket Set ~$15
Fuel Filter ~$7
Fuel Cap ~$8
Impulse Hose ~$2

Still waiting on the fuel hose (he has the newer "s-shaped" in stock) and oil cap.

When I do the pres/vac test, if the seals are good... should I replace them? I know I probably should, but theres always the chance of messing them up R&Ring them. Just curious your guys opinion.

 

[BuckthornBonnie]

If seals are ok and pass pressure/vac, then naaa. Make sure you turn it over a few times during your test.

 

[bmwpowere36m3]

Got the fuel line: 1119 358 7701

Its "s-shaped", the flat portion on the grommet faces forwards? I wonder if I'll need to drill the hole in the housing. Heard a number of 9 mm, possibly...

 

[bmwpowere36m3]

^^^ Fuel line orientation?

Checked compression and vacuum tested... 150-160 psi after 15 pulls and held 15 inHG and 10 psi for 10 mins (dropped 1 inHG). There is a play/clicking when lightly rotating the flywheel back/forth. I'm thinking its either some wear in the rod bearings or the piston rocking.

On the piston, there are vertical marks coinciding with both side of the exhaust port. The horizontal striations are present on the portion I can see and both rings are free.

 

[HuckFinn]

I was getting ready to rebuild my 034 it was bogging and wouldn't rev in the cut until I found out the OEM air cleaner was plugged with oil, I guess from the fuel mixture misting up into the carburetor. I always brushed the air cleaner with a brush, thinking that was good enough so I took off and dissembled the two piece air cleaner and sprayed it with brake cleaner and blew it out with air. What a night and day difference that made. After 25 years of hard use it runs like a champ.

 

[RI Chevy]

Piston is a little scored there in photo #1. While saw is apart, you may want to pull the jug and check it too.

 

[bmwpowere36m3]

Piston is a little scored there in photo #1. While saw is apart, you may want to pull the jug and check it too.

That's the next step after I get the crankcase cleaned up first. Any comments on the flywheel "clicking"?

 

[RI Chevy]

Is it hitting the coil?

 

[bmwpowere36m3]

Nope

 

[Brewz]

Is the flywheel clamped on tight?
If it's loose the key can tick in the keyway as there will be a touch of clearance

Don't forget to pull the oil pump and replace the oil pickup hose that goes into the case

These are often behind oil leaks during storage

 

[drf256]

That's the next step after I get the crankcase cleaned up first. Any comments on the flywheel "clicking"?

It happens and isn't always a bad sign. Usually with the piston rotating near TDC. Pull the plug and see if the sound goes away. But I only accept this after knowing all inside was inspected and checked out OK.

You need a piston. That fuel line looks like the newer MS360 line to me, or maybe not-it does look thinner. The flat portion on the grommet goes forward. You may have to open the tank inlet for it.

 

[Brewz]

If it were my saw, I would be cracking the case and cleaning it up, changing the bearings, crank seals, case gasket, piston and rings, new OEM piston wrist pin bearing, new spark plug, new oil pump suction hose, new clutch, new clutch drum, new bar and chain and a serious muffler mod.

I only change the fuel line if its gone hard or soft and is leaking.

The muffler on these saws is one of the worst restrictive mufflers I have seen with a double baffle.
Either cut out the baffle, or remove the plate with the holes in it on the front cover to help flow.
If noise is not an issue, get rid of both. I can guarantee you will get a 10 to 20% power boost with just opening up this restrictive muffler.

I recently rebuilt an 034 super and with the stock muffler it felt strangled and cut like a saw 10cc less.
The guy who bought it wanted it left stock as he thinks if I get it breathing better it will blow up.

Its a great saw. half a job wont last another 30 years. If you leave one old part in there it will fail eventually

Just my opinion.

When I have a saw that's a keeper, I would rather spend a little bit extra on parts to do a full rebuild and know its completely overhauled than be using it thinking...... geez I hope that old case gasket I left in there holds out.

 

[bmwpowere36m3]

Is the flywheel clamped on tight?
If it's loose the key can tick in the keyway as there will be a touch of clearance

Don't forget to pull the oil pump and replace the oil pickup hose that goes into the case

These are often behind oil leaks during storage

No, nut was tight. Oil pump been pulled, cleaned and lubed. A new pickup hose is planned as well.

 

[bmwpowere36m3]

It happens and isn't always a bad sign. Usually with the piston rotating near TDC. Pull the plug and see if the sound goes away. But I only accept this after knowing all inside was inspected and checked out OK.

You need a piston. That fuel line looks like the newer MS360 line to me, or maybe not-it does look thinner. The flat portion on the grommet goes forward. You may have to open the tank inlet for it.

I was thinking either the piston rocking or cumulative play in the rod bearings. What if the sound goes away, but the play remains? Like I said, this is/was a "healthy" running saw... most probably wouldn't even take it apart.

I plan to pull the jug a least to replace the rings and have a look at those score marks. No the M360 and newer tank replacement for 034/036 is a different P/N. It "thin" like the old one, just s-shaped.

 

[bmwpowere36m3]

If it were my saw, I would be cracking the case and cleaning it up, changing the bearings, crank seals, case gasket, piston and rings, new OEM piston wrist pin bearing, new spark plug, new oil pump suction hose, new clutch, new clutch drum, new bar and chain and a serious muffler mod.

I only change the fuel line if its gone hard or soft and is leaking.

The muffler on these saws is one of the worst restrictive mufflers I have seen with a double baffle.
Either cut out the baffle, or remove the plate with the holes in it on the front cover to help flow.
If noise is not an issue, get rid of both. I can guarantee you will get a 10 to 20% power boost with just opening up this restrictive muffler.

I recently rebuilt an 034 super and with the stock muffler it felt strangled and cut like a saw 10cc less.
The guy who bought it wanted it left stock as he thinks if I get it breathing better it will blow up.

Its a great saw. half a job wont last another 30 years. If you leave one old part in there it will fail eventually

Just my opinion.

When I have a saw that's a keeper, I would rather spend a little bit extra on parts to do a full rebuild and know its completely overhauled than be using it thinking...... geez I hope that old case gasket I left in there holds out.

Honestly I don't want to take it that far... seals are holding pressure, I feel no play in the main bearings. When I pull the jug, maybe that'll change my mind.

The old fuel line has shrunk, barely get the filter out of the filler hole and the grommet around the tank is no longer sealing. The muffler, as compared to my CS-590 is very free flowing... The inner "cage" has very large holes, maybe the baffle on the front cover along the line of small holes. I'm not sure what I plan to do with it yet.

 

[bmwpowere36m3]

Cleaned the crankcase and pulled the jug....

piston crown:

exhaust side of piston:

intake side of piston:

The piston has 5 distinct vertical score marks. Either side of the exhaust skirt from top of crown to bottom of skirt. Either side and center of the intake skirt from top of crown to bottom of skirt.

 

[bmwpowere36m3]

Shots of cleaned up jug:


I only found one bit of transfer, centered below the intake port (scrapped off with a knife). Otherwise, vertical marks corresponding with those on the piston (line up with side edges of ports) that ran the length of the cylinder. I had a roloc backing disk the right diameter, shoved a bit of coarse scotch-brite (maroon) and ran it up/down with a cordless drill. Cleaned it up real nice.

I'm guessing a piston is in order... probably could be cleaned up a bit and save with new rings. No detectible radial play in the rod and the piston wrist pin seems "free".

 

[bmwpowere36m3]

What does the piston wear indicate?

 

[Onan18]

It definitely needs a new piston. I would personally get a Meteor from @Definitive Dave for it, and a new OEM wrist pin bearing and circlips. Flush the crankcase really well, with wear on the intake side of the piston like that it looks like it has ingested some dirt at some point, really should pull the seals out and flush the bearings at a minimum. Upgrade to the MS360 drum and bigger bearing, if the old one goes it can take out the crankshaft. Also that bar has had it, it would be OK for dirty wood/stumping but it is due for replacement, either with a Rollomatic ES or a Total Pro Series if you can get one. This is Dads' saw, do it up right for him.

Joe