044 Vac Test Question

[MustangMike]

My 044 #1 acted very strange on me last week. It ran fine the first tank, but when I refilled it I also tried to adjust the idle a slight bit.

The saw ran fine for a minute or two, then when I let off the gas it started racing and I shut if off. It continued to diesel till I hit the chain break and did not use it any more.

I presumed it was a vac leak, torn boot or something, so I started taking it apart today, but do not see anything amiss with the boot.

So I quickly hooked up a vac tester (my first time using it). To save time, I sealed the exhaust port and intake boot with Gorilla duct tape. The exhaust seemed to seal well, but not the intake. So I put my finger over where it was leaking and I got the vac to hold from 10lbs to 9lbs for 40 seconds. I really think the only reason it declined is that the tape is still leaking a bit.

Does that rule out a vac leak as the problem, or do I need to seal that intake better?

I'm thinking if it is not a vac leak then it either must be the carb or a a timing jump.

Any thoughts? THANKS!!!

 

[MustangMike]

I put some rubber tire tube over both ports and used a piece of paint stirrer over the exhaust and a wine cork to press it into the intake and had the wife pump the meter up. Still not sure I had a perfect seal, but took a full minute to go from 10 to 9.5. Is this OK???

Would appreciate if it someone with knowledge would comment.

 

[Simondo]

I put some rubber tire tube over both ports and used a piece of paint stirrer over the exhaust and a wine cork to press it into the intake and had the wife pump the meter up. Still not sure I had a perfect seal, but took a full minute to go from 10 to 9.5. Is this OK???

Would appreciate if it someone with knowledge would comment.

That would be a pass according to most manuals Mike. Vac to 0.5 bar down to no lower than 0.3 in one min is a figure thats common .

 

[MustangMike]

Thank you very much for that response.

I think I got very paranoid about the saw reeving like that when I let off the throttle. Thinking about it some more, I was wearing a brand new pair of gloves, a little thicker than what I am used to wearing. I'm starting to think maybe it just got accidentally switched to high idle when I let off the trigger.

Gonna reassemble it and see how it runs. Compression is still great, and the P&C look just fine. The saw is over 23 years old and I can still clearly see the machine marks on the piston!

Will keep you posted, and thanks again, I'm much relieved with that response.

 

[Simondo]

Thank you very much for that response.

I think I got very paranoid about the saw reeving like that when I let off the throttle. Thinking about it some more, I was wearing a brand new pair of gloves, a little thicker than what I am used to wearing. I'm starting to think maybe it just got accidentally switched to high idle when I let off the trigger.

Gonna reassemble it and see how it runs. Compression is still great, and the P&C look just fine. The saw is over 23 years old and I can still clearly see the machine marks on the piston!

Will keep you posted, and thanks again, I'm much relieved with that response.

I think your wise to vac test ..Just..in case there was a rupture in the intake boot. A sudden full on air leak on a seal is less common but not unknown. Now you can pop things back together with some confidence its something (If at all) simple. Strong saw the 044 and made of good stuff .

 

[huskihl]

When I do it, if I don't see the gauge move, I call it good.
I've noticed recently some "run-on or dieseling" after a long cut and even after being turned off. I used up my gas in the lawn mower and bought new. Problem fixed

 

[MustangMike]

When I do it, if I don't see the gauge move, I call it good.
I've noticed recently some "run-on or dieseling" after a long cut and even after being turned off. I used up my gas in the lawn mower and bought new. Problem fixed

This one was obviously not on "regular" idle, but I think the problem is the control lever and not the vac leak I feared.

 

[Deets066]

Vac AND pressure test should hold the same for ten minutes, if it loses any pressure in 30 seconds then you have a leak

 

[panteliss]

Vac AND pressure test should hold the same for ten minutes, if it loses any pressure in 30 seconds then you have a leak

 

[Definitive Dave]

just doing a vac test doesn't eliminate the possibility of a leaking oil seal or intake Mike, give it the pressure test too
ol 44s need love

 

[panteliss]

And dont forget to check first if the pump work corectly , sometimes the pump maybe have problem and leak slow and you think that the leak come from the saw

 

[MustangMike]

I put the saw back together and it seems to be just fine. Had to lower the idle a bit, but that is about it.

I'll keep a close eye on it when I run it next to make sure it is acting properly, but I think it is good.

Thanks everyone for the comments. I think it was loosing pressure because I did not properly seal the ports. I will work on making things to do that.

 

[Deets066]

I like the Stihl kit that the techs use. Don't have to make anything

 

[MustangMike]

Except money!

 

[huskihl]

@MustangMike, I have rubber strips from nate, but sometimes when the strips are on a different saw, I use gorilla tape. If you wipe the intake boot and exhaust flange with carb cleaner, install tape between the bolts, and tighten the carb and muffler down, it won't leak. Or at least I've never had them leak

 

[Deets066]

Except money!

True

 

[MustangMike]

@MustangMike, I have rubber strips from nate, but sometimes when the strips are on a different saw, I use gorilla tape. If you wipe the intake boot and exhaust flange with carb cleaner, install tape between the bolts, and tighten the carb and muffler down, it won't leak. Or at least I've never had them leak

I think I will make some metal plates that will serve the same purpose, thanks for the advice. I'll also use either some carb cleaner or brake cleaner next time also.

 

[Simondo]

I think I will make some metal plates that will serve the same purpose, thanks for the advice. I'll also use either some carb cleaner or brake cleaner next time also.

Mike ...just so as you know...Sthils own workshop manual only looks for a 20 second time for the test. This is a picture out of the workshop manual for you .

 

[drf256]

Mike, sounds like yer all good.

I didn't know what to think either, until I had a saw with a vacuum leak fail the test. It was an 026 that ran fine, but the idle wandered. It couldn't hold 10 inches of vacuum for more than 5 seconds and it still ran ok, just with an idle issue.

If I can get a saw to hold vacuum for 1 minute, I call it good. I use gorilla tape too. Cheap and effective. AngeloC turned me on to it.

 

[CR888]

Does anyone turn the flywheel back & forth while doing press/vac testing 2 check crank seals? Well even if all checks out fine ya did the right thing Mike shutting down saw and checking it on the bench. After 23 years running a saw you know when it don't sound right.