DOLMAR/MAKITA The Official Sachs Dolmar Dolmar Makita Dolmar Chainsaws Thread

[eric4]

Never really had an issue with dust ingress on that series of saws, I always slip an rubber 'o' ring over the air filter snout anyway on any saw that has just a slip fit. I also had a 5105 that somebody had over tightened the plastic elbow between the air filter and carb and distorted it, just put a slither of RTV or make a gasket. To check for any leaks just spray with brake cleaner around the inlet when running, it will drop revs if leaking. Also check that the air filter either has the foam gasket ring on top of the carb or no hole in the air filter where it touches the carb.

Looks like mine has the foam gasket on top of the carb, and the hole in the air filter. The foam ring has deteriorated quite a bit though, and doesn't seem like it'd be a tight fit.

How would you resolve this?

Also, here's a shot of the intake side of the piston...


Cheers!

 

[Powerstroke Cowboy]

Looks like mine has the foam gasket on top of the carb, and the hole in the air filter. The foam ring has deteriorated quite a bit though, and doesn't seem like it'd be a tight fit.

How would you resolve this?

Also, here's a shot of the intake side of the piston...
View attachment 413395

Cheers!

Ouch, that's not what I was expecting.

 

[eric4]

Ouch, that's not what I was expecting.

Yes it seemed a strange location to have deep wear. The exhaust side of the piston still had machining marks on it!

 

[Powerstroke Cowboy]

Yes it seemed a strange location to have deep wear. The exhaust side of the piston still had machining marks on it!

Do you have a picture of the top of the piston?

 

[Wilhelm]

Ouch, that's not what I was expecting.

Could water ingestion have done that?

 

[old_sir_henry]

A fourtnite ago I found a DOLMAR 116si nearby at a 20 minutes driving distance.
The saw was offered extremely cheap for 25 €, was dirty like never having received any maintenance during the last 30 years but she was a runner.



Brake band was broken to pieces as expected, piston looks chafed thru outlet. Huge loads aof debris underneath the muffler and between tank and motor.

 

[Wilhelm]

A fourtnite ago I found a DOLMAR 116si nearby at a 20 minutes driving distance.
The saw was offered extremely cheap for 25 €, was dirty like never having received any maintenance during the last 30 years but she was a runner.
View attachment 413470View attachment 413471View attachment 413472View attachment 413473

View attachment 413474
Brake band was broken to pieces as expected, piston looks chafes thru outlet. Huge loads aof debris underneath the muffler and between tank and motor.

You'll get her shiny again!

 

[old_sir_henry]

The chafings on the piston turned out to be a seizure on the intake side:



Hard to believe she was still running with this rupture but she was and must have done so for quite some time since the impact craters are all covered with carbon.



Frotunately and IMHO absolutely surprising: No damage on the cylinder's ports only corresponding craters in the ceiling.

 

[old_sir_henry]

@Wilhelm: She's making progess !

 

[Wilhelm]

I felt the need for more power but didn't wanna go overkill - pulled my Dolmar PS-6100 CE out of storage.


One doesn't even notice the amount of work done running proper equipment.
I just couldn't stop cutting, started stepping onto the rounds on the ground, neglected moving the tarp.

 

[Wilhelm]

Quack!

 

[Powerstroke Cowboy]

Could water ingestion have done that?

That, I do not know. I bought a couple saws off fleabay that had almost no run time. The machine marks were still clear as day on the piston, almost no carbon anywhere, exhaust ports still clean. But, both the pistons had wear starting in the exact spot as that piston. I tool apart an older saw that I have had for 14ish years, machine marks were gone on the piston it was kind of clean inside yet.

The only difference is the two that had wear starting with transfer happening were dry, mine had a nice coat of oil in it.

EDIT: All three saws are the same model.

 

[Wilhelm]

That, I do not know. I bought a couple saws off fleabay that had almost no run time. The machine marks were still clear as day on the piston, almost no carbon anywhere, exhaust ports still clean. But, both the pistons had wear starting in the exact spot as that piston. I tool apart an older saw that I have had for 14ish years, machine marks were gone on the piston it was kind of clean inside yet.

The only difference is the two that had wear starting with transfer happening were dry, mine had a nice coat of oil in it.

EDIT: All three saws are the same model.

I believe the PS-5000's had cylinder hot spots issues that would cause scoring & seizing.
I could be wrong though.

 

[Powerstroke Cowboy]

I believe the PS-5000's had cylinder hot spots issues that would cause scoring & seizing.
I could be wrong though.

Okay, on the intake side though?

The saws I mentioned were 79xx saws.

 

[Wilhelm]

Okay, on the intake side though?

The saws I mentioned were 79xx saws.

The first 5k's had cylinder cooling issues causing scoring on odd spots.

I have 5 big girls, 2 of the 79's - I have yet to encounter issues like You have described.

 

[Powerstroke Cowboy]

The first 5k's had cylinder cooling issues causing scoring on odd spots.

I have 5 big girls, 2 of the 79's - I have yet to encounter issues like You have described.

Here a dolmar ps-510 on the work bench now. I just bought it as a parts saw. Take a look at this piston. This is the intake side. This is an open transfer port saw. I wonder if there's any correlation?

 

[eric4]

Here a dolmar ps-510 on the work bench now. I just bought it as a parts saw. Take a look at this piston. This is the intake side. This is an open transfer port saw. I wonder if there's any correlation?

View attachment 413509

My piston looked identical. Are you also missing the metal ring inside the intake boot, that presses against the carb?

 

[Powerstroke Cowboy]

My piston looked identical. Are you also missing the metal ring inside the intake boot, that presses against the carb?

Yes, that ring was still inplace. The ring as there to keep the boot from squishing the intake closed when the carb is tightend against it. It real does nothing for the seal. The worst thing that could happen with the ring out as the boot closes in a little and you loose airflow, robing you of have some power.

 

[Powerstroke Cowboy]

This engine was also filthy inside.

 

[eric4]

Two new Dolkitas to pair with the 510. The 4300 is waiting on an oiler hose, fuel cap, bar tensioner mounting screw, and the parts to swap to a .325 rim sprocket. I've already cut the cat out of the muffler, so she should be ready to run soon!

The 7900 big bore arrived today and runs well, but my Stihl adapted SugiHara doesn't seem to be oiling sufficiently, so I'm going to have to investigate that further. Hopefully it's just a little grinding on the oil inlet hole for the bar...

I haven't looked into the muffler yet, to see how restricted it is. I recall reading that the horizontal lined 7900 mufflers don't have a cat, but we'll find out. Has anyone on this forum played around with adapting a Stihl 046/460 muffler to the 7900? I've seen a couple youtube videos on the mod, and it looks fairly straight forward.

My last 7900 inquiry... when the air filter cover is removed, is the HD filter supposed to sit somewhat freely on the inlet? It doesn't seem like my spring clamp is really holding down the filter tightly, but maybe that's the job of the plastic cover?