Change to Dolmar side chain tensioner

[TonyM]

All right, anyone working for Dolmar listen up. The last two PS7900s I have gotten in have a pathetic excuse for a chain tensioner. The first one I sold was brought back by the customer because he couldn't tension the chain, and his complaint was legitimate. Upon investigation we discovered that the tensioner was changed to a coarser pitch worm and pinion. The pitch is so coarse that the slightest amount of load on the tensioning pin, and the tensioner locks right up. Brilliant! I never have had a problem with my older style chain tensioner. Anyone out there know what is going on?

 

[bwalker]

I concure with the chain tensioner on the Dolamr 7900 lacking. The updated one was a little better, but Stihl has Husky and Dolmar beat in this regard. Have the done anyhitng to the bogus oiler yet?

 

[TonyM]

I'm still not sure how many iterations the chain tenioner design has been through. These last saws have been serial numbers 04#######, and my demo, with a functioning tensioner was serial number 02#######. This latest change is a bad thing IMO.

 

[bwalker]

I dunno Tony. the first one I had was plastic, the second was metal, both with fine threads. Another thing that is lasking with this design and huskys as seen on the 372 is the floating pin. The pin should be located on the saw like a Stihl.

 

[TonyM]

I went out to the shop, put the new tensioner back into the saw I stole an old tensioner out of to put in the customer's saw. You can tension the chain, but wow, does it take a lot of force. You really have to torque on the screw. I suppose you wouldn't notice it unless you had used a Stihl or Husqvarna or previous Dolmar tensioner that works much easier. It feels like you are going to break something as hard as you have to turn it. It shouldn't be that way IMO. The pin in the sprocket cover has advantages and disadvantages. I can live with that, but not with a screw requiring so much force to use.

 

[njforestfire]

TM - even with the bar nuts loose and the tip of the bar suspended it takes THAT much force to tension the chain?? If so, IMO sounds like something else is either hanging up or bent.

 

[TonyM]

No, it is in the tensioner. Even with the sprocket cover removed from the saw, you can make the tensioner almost lock right up just with your pressure on the pin from your finger. I have two of them, and they both act the same. It does work on the saw, just a lot harder than it should, and a lot harder than the previous design.

 

[Sparkkky]

Had the same problem with a 346CS Echo.

 

[ozflea]

Is there a mismatch in threads between the tang and adjusting screw ??

Mc Bob.

http://www.users.bigpond.com/ozflea/saws.html

 

[TonyM]

No, it's a friction thing. The tensioner works just fine, as long as there is no load whatsoever on the pin. As soon as you load the pin, it becomes very difficult to turn. It's kind of like there is a contact angle in the gears somewhere that is approaching a locking angle, where no matter how much torque you put in, the friction that results is as large as the input torque.

 

[Swannie]

I noticed the tensioner on my 7900 was rough and dry feeling when new. Before putting it in service I gave it a good coating of some grey antiseize compound. Smoothed up the feel of it and so far seems to be working OK.

 

[Lobo]

Have you tried spraying 100% silicone on it to see if it does not make it freer wheeling.

 

[TonyM]

Well, I took one apart and applied a liberal amount of grease to everything. Then I ran it back and forth several times with pressure on the pin, and it did improve. Maybe this new design is a little tight and needs some wear in time to really work well. I guess I have one more thing to do to brand new saws before they go out the door

 

[Lobo]

Tony the reason I mentioned 100% silicone instead of grease is that the silicone won't hold dust, dirt, wood chips etc. like grease will. It will probably be much cleaner.

 

[Sparkkky]

No, it's a friction thing. The tensioner works just fine, as long as there is no load whatsoever on the pin. As soon as you load the pin, it becomes very difficult to turn. It's kind of like there is a contact angle in the gears somewhere that is approaching a locking angle, where no matter how much torque you put in, the friction that results is as large as the input torque.

Thats how that CS-346 Echo was to a tee, I complained and dealer greased it and it was some better.