When to pressure check a saw?

[backhoelover]

sorry guess i forgot to remove the last quote lol before i quoted this thread lol

 

[backhoelover]

also if you look at my avatar that is a collection of my block off plates, pic is old have bought alot more

 

[brandonstclair20]

have you check to make sure its not leaking where the bar oil goes? i has one that was leaking, it was not burning the bar oil one of them weird ones! also when you doing a vac test you need to rotate the crank. i had a echo 280e that would only leak when i put the drill to it i think my drill was set on the number 3 speed setting

I've had 5-6 completely rebuilt saws all do the same thing but run and idle great.


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[exSW]

I have tried to vacuum test and pressure test many saws and I cannot get a single one to pass and cannot find any leaks with soapy water. Could something be wrong with my mityvac?


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I'm a little Neanderthal in my pressure testing. I dunk the whole thing in the stock tank. Remember it's pressure,your forcing the water away. I find the bubbles,blow it off and let it hang till the next day to dry

 

[backhoelover]

I'm a little Neanderthal in my pressure testing. I dunk the whole thing in the stock tank. Remember it's pressure,your forcing the water away. I find the bubbles,blow it off and let it hang till the next day to dry

thats a good idea

 

[exSW]

I often have trouble getting the intake sealed well.

.

I have a collection of those plastic plugs that come in new hydraulic lines. One usually fits.

 

[huskihl]

IMO, gorilla tape works better for Vac than Pressure, but is not reliable enough. Usually bolting something over a tire tube over the exhaust works best (and is easy). I often use a 034 muffler spacer, easy to work with.

I often have trouble getting the intake sealed well.

If the leak is too big to ID with the MityVac, I hook up the bicycle pump to it, jut don't let presser go over 10 lbs. The addl volume helps you find leaks easier. I also sometimes use an automotive stethoscope to hear leaks in hard to reach areas.

Was the only way to ID an intake manifold leak on a MS 250. No other way to access where it was leaking with that stupid cover plate on those saws.

Clean the surfaces first. Gorilla tape over the exhaust, muffler bolted on. Gorilla tape over the block or manifold, carburetor bolted on. You've had this setup leak? If you start clean, you can remove the muffler and carb and it'll usually still hold vacuum.

Now I use the rubber pieces that Nate sells. Theyre tapered and just slide in till they're snug. It's a little quicker

 

[MustangMike]

I wasn't bolting anything over the G Tape. If I'm gonna bolt something over, I'll stick to the tube rubber.

 

[Homemade]

I use electrical tape that is 3in wide. I put the sticky side in and bolt the carb and muff back on. I'll start with pressure and spray soapy water to find a leak. If I don't see any bubbles and I know it's leaking on vac, it's most likely seals.


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[merc_man]

I have a collection of those plastic plugs that come in new hydraulic lines. One usually fits.

Can you get a pic of the plugs.

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[PA Dan]

I have tried to vacuum test and pressure test many saws and I cannot get a single one to pass and cannot find any leaks with soapy water. Could something be wrong with my mityvac?


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Hose connections leak fairly often! I cut and reinstall the hose. I actually now have a rubber hose on the mityvac and no more leaks!

 

[mnmdad]

I know if you have a saw with a burnt piston you should run a pressure check to make sure the seals are still good but what other symptoms would also lead you to run a pressure check?

Anytime you forget use RED AMOR oil a full tear down and inspection with vac/pres test is a must or it will self destruct

 

[PogoInTheWoods]

I never check pressure or vacuum until I'm done reassembling. I think it's a waste of time on a burnt saw because all the parts that can possibly leak should be getting replaced anyways.

Bearings leak around the bore, oil pumps leak, case gaskets leak...

I always test the case after doing seals before putting a saw back together. Saves having to take it all back apart again to re-seat a bearing or replace an oil pump 'o' ring or case gasket that was leaking all along but not enough to be obvious with a larger leak getting all the attention. Matter of fact a MS361 I'm rebuilding had what appeared to be a leaking PTO side oil seal by all accounts. Turned out to be the bearing bore. Glad I was paying attention to detail.

 

[Lone Wolf]

I have tried to vacuum test and pressure test many saws and I cannot get a single one to pass and cannot find any leaks with soapy water. Could something be wrong with my mityvac?


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Dunk it under water.

 

[psuiewalsh]

For the carb side , I like to use an old carb body that I filled the throat with epoxy. I usually connect through the impulse if possible or block off the whole carb and the modified spark plug with epoxied hose barb for intake block saws

 

[Chainsaw Jim]

Bearings leak around the bore, oil pumps leak, case gaskets leak...

I always test the case after doing seals before putting a saw back together. Saves having to take it all back apart again to re-seat a bearing or replace an oil pump 'o' ring or case gasket that was leaking all along but not enough to be obvious with a larger leak getting all the attention. Matter of fact a MS361 I'm rebuilding had what appeared to be a leaking PTO side oil seal by all accounts. Turned out to be the bearing bore. Glad I was paying attention to detail.

Are you having trouble seating bearings?

 

[PogoInTheWoods]

Nope.

 

[Chainsaw Jim]

Nope.

Had you asked me how far I go on reassembly I would have told you it's before I put the tank/handle back on if I'm putting case halves together. I wasn't trying to one up anyone.

 

[drf256]

Hose connections leak fairly often! I cut and reinstall the hose. I actually now have a rubber hose on the mityvac and no more leaks!

I'm with you Dan. The plastic hoses that come with the vac absolutely suck balls.

 

[Simondo]

Carb pop off pressure and re-seat pressure is a useful thing to do as well as ...fuel line.. when going through a machine . I do it when i rebuild a carb as a matter of corse.