Dolmar PS-7300 oiling rate

[grits]

I've picked up a Dolmar PS-7300 in great condition that's only been used as a homeowner firewood saw. The oiling rate was very light, if you were being generous you could maybe say 1/4 of a tank of oil to one of fuel with the oil adjustment screw fully open and spray off the tip was very, very fine. It has a lightly used Tsumura 18" bar and everything looked clean in terms of the channels and holes but I've taken the covers off a few times and made sure. Running the saw without the bar resulted in a fairly steady rate of clean oil coming through the channel. The guide plate is very slightly dished but seems to clamp down fine with the bar on, the mating surface seems to be a fairly raw casting, not a mirror finish by any means but it doesn't seem like I'm losing much oil behind the plate. Today I worked the adjustment screw back and forth a fair bit and gave the saw a good while to run in without going into wood and it seems the rate has picked up. The tip was throwing a fair bit of stringy black globules and inside the sprocket cover is getting pretty oily, it was pushing a fairly steady trickle out the top which I'm assuming has come off the chain with that point being above the outlet. Going by this behaviour I think I can turn the rate down again but just wanted to check if my experience so far gels with others experience of the saw and their understanding of its function? What rate do you like to see in terms of oil usage to fuel on these saws?

 

[FederalQ]

I had to turn back the oiler on my 7910 as it would run out of chain oil before motor fuel. 28” bar. The photo looks normal to me! I find the oilers on Dolmars are much more generous than a comparable Stihl. The oil I use flows rather well in low temperatures, maybe a higher viscosity oil would make less mess?

 

[hacskaroly]

@Wilhelm the Dolmar King...what is your experience?

 

[Ketchup]

It should over oil a 18” easily. Did you check the oil pickup in the tank? Worm gear?

 

[Wilhelm]

A PS-6400/7300/7310/7900 will easily sufficiently oil a true 36" 3/8" B&C setup.
They will use oil to fuel nearly 1:1 (PS-7300/7310 are really close) , depending on the oil You are utilizing, and in my case what cc saw I am running.
My PS-7900's have their oilers maxed out and still run out of fuel first.
My PS-6400 has the oiler turned down a bit as she is noticeably more economic in terms of fuel consumption.

Maybe the previous owner used Bio or veggie oil, which will gum up.
If You are lucky the oiler system just needs to flush itself clean with mineral oil.
Run a tank of less viscous oil through it (clean engine oil) and observe whether oiling capacity will pick up.

Troubleshooting would include:
- check whether the oil appears to come out from under the clutch when the bar is mounted, if the saw is an early production it needs the oiler pressure line replaced with the current updated one
- checking that the pump driver has both wings, and that they are still long enough to fully engage the clutch drum
- check the bars oiler hole, if it is a fancy tiny pinhole grind it open
- check proper bar oiler alignment
- freshen up the pump with a repair kit

 

[Wilhelm]

I've picked up a Dolmar PS-7300 in great condition that's only been used as a homeowner firewood saw. The oiling rate was very light, if you were being generous you could maybe say 1/4 of a tank of oil to one of fuel with the oil adjustment screw fully open and spray off the tip was very, very fine. It has a lightly used Tsumura 18" bar and everything looked clean in terms of the channels and holes but I've taken the covers off a few times and made sure. Running the saw without the bar resulted in a fairly steady rate of clean oil coming through the channel. The guide plate is very slightly dished but seems to clamp down fine with the bar on, the mating surface seems to be a fairly raw casting, not a mirror finish by any means but it doesn't seem like I'm losing much oil behind the plate. Today I worked the adjustment screw back and forth a fair bit and gave the saw a good while to run in without going into wood and it seems the rate has picked up. The tip was throwing a fair bit of stringy black globules and inside the sprocket cover is getting pretty oily, it was pushing a fairly steady trickle out the top which I'm assuming has come off the chain with that point being above the outlet. Going by this behaviour I think I can turn the rate down again but just wanted to check if my experience so far gels with others experience of the saw and their understanding of its function? What rate do you like to see in terms of oil usage to fuel on these saws?

View attachment 459296

Judging from the picture the oil might be seeping from under the clutch and then gets flung around under the clutch cover.

I'd check the pressure line!

 

[Wilhelm]

@Wilhelm the Dolmar King...what is your experience?

Very kind of You, but there are members here with notably higher Dolmar seniority than my sorry self.

 

[Wilhelm]

BTW, I love Your saws spikes!

Aka.: Star Trek, Klingon, Bat'leth

 

[grits]

I had to turn back the oiler on my 7910 as it would run out of chain oil before motor fuel. 28” bar. The photo looks normal to me! I find the oilers on Dolmars are much more generous than a comparable Stihl. The oil I use flows rather well in low temperatures, maybe a higher viscosity oil would make less mess?

I'll check usage and behaviour on the next round of cutting and consider the viscosity, we're in a frost free temperate area, so no extremes of cold or heat.

It should over oil a 18” easily. Did you check the oil pickup in the tank? Worm gear?

The oil screen seems clean and the suction line supple. I haven't disassembled it the point of taking out the pump, would I be looking for wear on the worm gear or the oil pump piston?

A PS-6400/7300/7310/7900 will easily sufficiently oil a true 36" 3/8" B&C setup.
They will use oil to fuel nearly 1:1 (PS-7300/7310 are really close) , depending on the oil You are utilizing, and in my case what cc saw I am running.
My PS-7900's have their oilers maxed out and still run out of fuel first.
My PS-6400 has the oiler turned down a bit as she is noticeably more economic in terms of fuel consumption.

Maybe the previous owner used Bio or veggie oil, which will gum up.
If You are lucky the oiler system just needs to flush itself clean with mineral oil.
Run a tank of less viscous oil through it (clean engine oil) and observe whether oiling capacity will pick up.

Troubleshooting would include:
- check whether the oil appears to come out from under the clutch when the bar is mounted, if the saw is an early production it needs the oiler pressure line replaced with the current updated one
- checking that the pump driver has both wings, and that they are still long enough to fully engage the clutch drum
- check the bars oiler hole, if it is a fancy tiny pinhole grind it open
- check proper bar oiler alignment
- freshen up the pump with a repair kit

It doesn't seem very gummy at either end but can't say about the internal state of the lines. If looking for a leak under the clutch, would I see a drip in line with the clutch shaft? Or welling around the perimeter once I take the bar off again? I gave the oiler holes a bit of polish with the dremel but didn't want to remove too much material in case the delivery rate picked up. The alignment seems good through the adjustment range. How do I identify the different generations of pressure line? I'll keep an eye on the next round of cutting before tearing down to the point of checking the wings of the pump driver or considering a repair kit.

Judging from the picture the oil might be seeping from under the clutch and then gets flung around under the clutch cover.

I'd check the pressure line!

Would that be seeping from the back of the line when under additional pressure with the bar mounted vs freely flowing when open?

BTW, I love Your saws spikes!

Aka.: Star Trek, Klingon, Bat'leth

The spikes are great, providing a natural and positively engaged pivot and useful alignment guide.

---

Thanks all for your responses.

 

[Hulsty]

My 7901 consistently uses slightly more fuel than oil, which is how I like it, when it was a 6401 I turned the oiler down as it was more fuel efficient (smaller bar too).

 

[Wilhelm]

It doesn't seem very gummy at either end but can't say about the internal state of the lines. If looking for a leak under the clutch, would I see a drip in line with the clutch shaft? Or welling around the perimeter once I take the bar off again? I gave the oiler holes a bit of polish with the dremel but didn't want to remove too much material in case the delivery rate picked up. The alignment seems good through the adjustment range. How do I identify the different generations of pressure line? I'll keep an eye on the next round of cutting before tearing down to the point of checking the wings of the pump driver or considering a repair kit.

If Your saw is leaking oil under the clutch You will notice it best by checking the clutch drum.
If the drum is oily on the inside , its friction surface, even though You wiped it clean & dry on a previous checkup, You have an oil pump leak of sorts.

The oil pump driver wings can be checked by just taking off the clutch drum.
The drivers wings (orange/brownish plastic, about 1/2" wide symmetrically on opposite sides) must protrude further out than the clutch itself.
When spinning the drum over half a turn CW & CCW You should hear and feel the drum engaging the drivers wings.

The oil pressure lines changed color, that is how You know which one Your saw has.
On top of my head I think the pressure line changed from BLACK early production to GREEN later production & fix update.
Though I will check on this and correct myself if I have it head backwards.
I know the part number is
038 245 061

Would that be seeping from the back of the line when under additional pressure with the bar mounted vs freely flowing when open?

Yes, if Your saws oil delivery system has issues it will show more severe with the bar mounted as it will create a significant flow choke point.

 

[SOS Ridgerider]

Lots of good info up above here.
Wilhelm has pretty much covered everything.
I'd start with looking at the oiler hole in the bar. Some bars have a smaller oiler hole, and I've opened up a few myself. After that I'd look at the pump driver, the pressure line to make sure it's the green version, then the pump itself for a rebuild. The pump can be modified as well, to pump more per stroke, and there should be a thread on here for that mod.

I have a couple of these saws, and I am able to adjust them so I run out of fuel just before I run out of oil, which is how I prefer it.