DOLMAR PS 5000 Air Leak?

[aaares]

Hi everybody,

I'm new here (long reading, not posting). I find this place absolutely fantastic -so much knowledge and fun that I cant even sleep some nights. opcorn:

I've already bought 2 saws - Husqvarna 372XP and Dolmar PS 5000 - CAD is coming really BAAAD :greenchainsaw:

SORRY for my bad English - Czech Republic (EU)

I would like to ask you whether you could me give some advice about my problem. It's with my DOLMAR 5000 (European version of US Dolmar PS 5100) - just rev-limited to 13.500

I bought it with scored piston and cylinder. Saw was quite new - I was said 30 hours running. Bought new piston, under-cylinder gasket, metal ring (thanks) to intake boot. I cleaned cylinder pretty well - not so nice but I tried it.

I fired it up and it idles just fine, but I had to richen H screw pretty enough. Now I have it set to 2 and 1/4 turns out (limitters cut away) and it still turns 13.300 (remember: 13.500 max limited coil). It just go down in revs when H screw set somewhere to 2 1/2 or 2 3/4. It cuts pretty well with this setting (2 1/4) but it seems fuel consumption is quite high (it could be just my feeling). On this setting Irun this saw for about 12 hours (I know, I know..........) and it has compression about 190 PSI.

Today I tried some test with starting fluid to find some intake boot air leak. I fired her up and sprayed some starting fluid around the intake boot. It changed revs and if I sprayed pretty much (fluid - from spray-can through some silicon tube) it died. I took the carb out and cleaned the contact surfaces between carb and intake boot. I couldn't find any disruption there, so I tried to give some plastic grease (vaseline) on the contact surface of the carb and assembled it together. It got little better but I dont know.................

Some advice guys??

Thanks aaaares

 

[SawTroll]

Sounds like you have an intake boot leak, as you more or less conclude yourself.

When was that saw made (look at the serial number)? There was a modification to that boot/intake in november 2006. You can find more info on the issue in threads about the 5100S.

 

[XLogger]

I find that my 5100 tends to drink a little fuel too. Then again, lately I've been cutting a lot with my strato saws so comparison may not be fair.

It sounds like you need to do a vac test. A long time ago, before I had the proper tools, I've done a vac test by sealing the carb with a slab of radiator hose and a make-shift plate. Pulled the muffler, bolted it back down with a slab of radiator hose to seal it. Then used a vacuum brake bleeder, some windshield washer hose and various other random items laying around in the shop. It's surprising what you can come up with when in a pinch. If you find you have a leak, try using (very low) pressure and a spray bottle of soap water. Watch for bubbles while spraying all connections. Good luck.

 

[aaares]

The saw was made in 2005 - so according to SawTroll there is the older intake boot. What was the change in the intake boot design in November/2006? What I found here - it was just the inserted metal ring (that I already bought). It should solve some problems with idle - if I'm right.

Does any of you guys know, what is the factory settings of the carburettor screws? I have been reading related topics here and I couldn't find any rock hard info. I have some materials from Dolmar here and it says that should be 1 1/2 turns for both screws. If anybody here has Dolmar 5000 or 5100, please write down some numbers of your carb-screws settings. I think that I have read here that somebody had to set the H screw somewhere to 2 turns out for Dolmar 5100 to run it rich enough.

When intake boot air leak occurs - doesn't it mean that saw idles pretty bad? I thought it was the case. But I don't know if it's any rule. Opinion here?

I was in the shopping of MITYVAC (Mityvac MV8500 Pressure/Vacuum Tester & Brake Bleeder) but it's some HELL money they want for it + shipment ($45). I don't have any brake fluid bleeder. Maybe I could ask around - some car mechanics ??

How long would you expect to run the saw (Dolmar 5100) for one tank (0,47 L - I think) in full load - bucking some 2' wood?


What spray or fluid is best (appropriate) for idle running intake leak test? Should it be gas or fluid (aerosol)? The saw shouldn't change revs at all?


Thank you for your ideas and answers guys. I go to search some inner tube etc.

aaares

 

[SawTroll]

Forgot to say; Welcome to the site!

Afaik, the change was just the metal insert - but I am no expert.

I had a similar leak on another saw (Husky 339xp). The Immediate symptoms was that it ran crappy generally (also at idle). When I richened it to run decently, it ran at way too high rpms, at both at idle and WOT. To slow it down, the carb limiters had to go, but I left the rest to the dealer (warranty).

 

[XLogger]

I've got 1 3/4 turns on the high and 1 turn on the low on my 5100. But I am running with no cylinder base gasket and a modded muffler (14,600 RPM's) 2 turns seems rich, If you're sucking air that might account for being heavy on your mixture. It is a little trickier to adjust your carb with a limiter.

Around here, a generic vac tester can be had for 20-25 bucks.

It's really tough to say as far as tank running time. I rarely buck stuff that large with the 5100 - I grab a bigger saw!. I wouldn't try to get too technical about running time - too many variables.

I use starting fluid for testing - with a hose, your not going to hurt your saw at idle with that. And there should be no change in revs at all (unless it's sucking it in the carb!).

 

[aaares]

Hi, I'm here again.

Thank you for welcome.

I've made some progress with my Dolmar PS 5000 - yesterday I accomplished some pressure test - 8 PSI of pressure and some soapy water - found an air leak (bubbles) where the intake boot connects to cylinder (= the place with the spring around). But I made the pressure test just without carburettor. So a question here: Is it possible to do the pressure test through the carburettor (=including the carb)??? I would't like to destroy the carb.

I also repeated running-idle air-leak test with the starting fluid (spray). I just suggest to everybody to be SURE that you give some material (boxboard, cardboard, list of paper,....) between the place you are spraying and sucking intake boot. (Ask me how I know :monkey: ) - The intake boot (under filter) is sucking the aerosol of staring fluid and you aren't able to see it at all - the saw is dying - any air leak???? NO !!!!

What is "welsh plug" supposed to be (in the carb)? Where can I find it? (just asking )

Thanks aaares

 

[XLogger]

I use a pressure test more for locating leaks, usually a vacuum test is done to see if there is a leak. The reason for this is the chainsaw operates under a vacuum and you will get leaks somewhere when you pressurize - that's the point. So step one is vacuum test (specific vacuum for specified duration - per manual). If it has been determined that there is a leak then proceed to step two. Step two, pressure and soapy water to determine where the leak is (Luckily, you were able to determine the case doesn't leak - that's great news). the boot may be leaking because 8 PSI is more pressure than it's designed to hold - remember, it was designed to operate under vacuum. The boot and spring may be expanding and just relieving the air. The carbs also have a pressure test. I think around 10 PSI, check that manual I sent you. Keep in mind, this is the proceedure that I use and it may differ some from the manual. And be careful with that starting fluid - use it very sparingly!

 

[XLogger]

One more thing, the carb pressure test is not done through the barrel. It is done through the fuel line so I'm not sure why you want to install the carb for the pressure test. The welch plug is usually under the diaphram in the carb

 

[XLogger]

Ok, did a little digging. Found in a Makita manual (5200i - different animal, same breed) it states a pressure test of the crankcase and carb not to exceed .5 Bar which is a hair over 7 PSI - which is less than the Stihls that I usually work on. C

Does anyone have a manual for the 5100/5000?

 

[aaares]

I wanted to proceed pressure test with the carb installed (I mean pressre through carb) because I would like to see if there is any leak in the connection between carb and the (green) rubber/plastic boot with metal ring installed - it seems to me to be the possible weak point. In the configuration I've made the pressure test I wasn't able to test this connection (carb off and metal plate with rubber(inner tube) screwed on).

I know I should do the vacuum test, but I don't have any manometer and brake bleeder for it. Thank you for numbers of pressure.

 

[XLogger]

Yeah, I saw that coming... Personally, if I were up against a wall I would do it. I can't see why that would rupture a diaphram - if you keep the pressure low. But I could be wrong, it's easy for me to say because I have quick access to carb kits here - you may not. I have never seen a leak there - however you said the saw had low hours and it ate up a P&C so there is a good chance you have a leak somewhere - not to mention the poor running. But... Then again, these models do tend to be a little hard on pistons...:jawdrop:

Just remember to take your time and be thorough, overlooking a little thing may bring you full circle after much time and frustration.