Oil Leaking/Burning in the Exhaust

[hoosier122]

I have a Mcculloch MS1635 (16" 2 Stroke, self lubricating)...don't make fun, it fits my needs right now. Anyway I recently started it and noticed and extreme amount of smoke. So I opened it up and saw that the exhaust manifold was covered in burned oil (and also unburned). I checked the oil tank, but don't see any leaks.

Any ideas on where it could be coming from?

Thanks for your help!

 

[ericjeeper]

sounds like a rich fuel to oil mixture

And possibly a rich fuel to air mixture.
Welcome to the site btw.
There is an Indiana GTG in two weeks. You are welcome to bring the saw here and run it a bit.
Or you can come run some good saws. LOL

 

[HiOctane]

Probably too rich mix ratio or could be that your saw is running with the hi speed adjustment too rich too.You could lean it with the H screw until the exhaust sound almost stop burbling at wide open throttle.

 

[Austin1]

I am not familar with that mac, how old is it? but I run 40-1 fuel mix in all my older saws and keep a close Eye on the plug condition to make sure they are not running lean. But as stated before just Try and lean it out a bit listen for the burble or stumble then smooth then go back to the burble, Dam this is hard to explain on line!

 

[Austin1]

Probably too rich mix ratio or could be that your saw is running with the hi speed adjustment too rich too.You could lean it with the H screw until the exhaust sound almost stop burbling at wide open throttle.

Thats a better way to explain it!

 

[hoosier122]

Thanks for helping me out I'll play with it once I get my replacement throttle trigger release...dang thing broke in two .

One other thing; What does part 26 do in this diagram (the one I drew an arrow to)?

 

[Al Smith]

Must be a little bitty saw and relatively new because I've never heard of this model nor do I have anything in my library of Mac stuff about it.

That said,it most likely is burning chain lube .Most McCullochs used some form of an impulse operated lube pump.Some were diapragm and some were piston operated.If they develop leaks in the pumps it will suck chain lube into the crankcase and smoke like it is burning soft coal.If they get bad enough it will oil foul the sparkplug to the point it won't run.The mini series were especially bad about this.

 

[hoosier122]

Must be a little bitty saw and relatively new because I've never heard of this model nor do I have anything in my library of Mac stuff about it.

That said,it most likely is burning chain lube .Most McCullochs used some form of an impulse operated lube pump.Some were diapragm and some were piston operated.If they develop leaks in the pumps it will suck chain lube into the crankcase and smoke like it is burning soft coal.If they get bad enough it will oil foul the sparkplug to the point it won't run.The mini series were especially bad about this.

Yes it is new only about 3-4 years old...Walmart

Yes, I believe you have given the closest diagnosis. It is most likely chain oil, not a mix issue.

I posted the diagram because the saw is missing that pin (part 26). Does this have anything to do with the flow of chain/bar oil?

 

[hoosier122]

Thanks for helping me out I'll play with it once I get my replacement throttle trigger release...dang thing broke in two .

One other thing; What does part 26 do in this diagram (the one I drew an arrow to)?

Part 26 is a Pin, Roll 1/4 x 1.0L which fits in Housing/Pin Asy, Right...

But what does it do?

 

[sugarbush]

Part 26 is a Pin, Roll 1/4 x 1.0L which fits in Housing/Pin Asy, Right...

But what does it do?

i think it's an aignment pin when mating the two halves.

 

[hoosier122]

Here are some more specific pics (sorry for the crappy photo)...camera phone is all i have

What is this cavity for and what does the pin do?

 

[Scooterbum]

That's part of your chain adjuster.It screws into a piece that fits into that cavity and has a pin on it that protrudes into a hole in you bar.
Also has nothing to do with your oil pump.

I know some of the smaller homelites had a duckbill valve that would cause the bar oil to get in the crankcase and smoke like a train.It was used to pressurize the oil tank instead of using a seperate oil pump.
See if you IPL list such a part.

Maybe one of the techs that are more familiar with the newer MAC's will post.

Good Luck.

 

[Al Smith]

Maybe one of the techs that are more familiar with the newer MAC's will post.

Good Luck.

Wishfull thinking ! Since big Mac circled the drain in about '98 and became part of Sen Fen or whatever it is,most Mac affectionatos don't claim them to be honest to goodness Macs.Sorry but true.

Anyway that gizmo is the bar tightener.The part that moves the bar is AWOL.I don't have a clue where you might find one for that model.You might have luck by doing an on line search for Mac parts or perhaps their web site might list a source.

 

[PES+]

Hoosier

Can you post a link to where you got the IPL from?

I have the chain tensioner in the last batch of NOS Mac stuff I got but I do not have and IPLs or service lit on the very last macs.

It looks identical to the mac 3216 which was a Mexi mac but I have never been inside one.

I have one here and if you get stuck we can investigate where the chain oil is finding it's way into the crank case.

I am pretty sure I also have most of the oiler parts in that last batch of stuff as well.

 

[joecool85]

Yeah, thats the chain adjuster. If you don't know what that is you might want to figure it out soon, I can only imagine your chain must be real slack at this point and that's dangerous.

 

[PES+]

Found the IPL

I did work on a 3816 years ago and it is the same.

The only place for chain oil to get into the crankcase on these style saws is if you have a leaky oiler and a bad mag seal.

The oil pump is on the flywheel side of the crank.

 

[hoosier122]

Probably too rich mix ratio or could be that your saw is running with the hi speed adjustment too rich too.You could lean it with the H screw until the exhaust sound almost stop burbling at wide open throttle.

Is there some kind of special tool I have to have to adjust H and L? The throttle adjustment I can do with a screw driver, but H and L appear to require a special tool...

 

[Al Smith]

That little saw most likely has adjustment limiters installed .For some reason or another a lot of newer equipment came that way.As a normal rule they are just little plastic caps that are over the metal hi and low speed needles.Most have a screw driver slot in the needles but some have slotted fittings for the plastic limiters.I have no clue what is on that saw, I have never seen that model.

 

[joecool85]

If it is a slip on cap they will pull off with pliers, if not you can modify the cap with a dremel to make it adjustable with a screwdriver.