Finding air leak

[merc_man]

Working on a smaller stihl. Think its 023?
Got the intake and exhaust all blocked off and it definatly is leaking some where but i cant seem to locate it with soap and water poured on it.
Is it a good idea to dunk it in a bucket of water to find leak?

Thanks

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[Glennmac]

As a last resort yes. As long as you have some pressure water will stay out for the most part. I have had to do that a few times.


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[merc_man]

Was just out trying again and still no luck.
I will drop pressure on air compressor and give it a try i guess.

Should I remove the coil?

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[deye223]

Yep remove all electrics

 

[Vintage Engine Repairs]

Take your time, you’ll find it. If you are confident it’s not the seals, intake manifold or impulse, It’s probably around plug or your dams you made to block the ports or connections from them. It’s a clamshell, that alone makes it a heap easier good luck mate

 

[Yukon Stihl]

I use a spray bottle with liquid laundry soap for leak finding.
I found it worked great for finding tiny leaks in tires that were hiding from normal procedures. Spray it down and wait. Soon a patch of tiny bubbles form into a visible foam.
Worked as good on saws

 

[Creaky limb tree care]

I had one, took ages to find the leak, it was between the clamshell halves, it would only leak when saw was warmed up!!!!

 

[countryhog]

I’ve done several by dunking. Totally strip everything from the carcass and keep pressure above atmosphere. Leaks cannot hide in a tub of water. Any water trying to intrude into the carcass has to overcome pressure; not scientifically possible. Keep pressure in the carcass until it is removed from tub and blown off with compressed air. Even if water could intrude, which it can’t, the amount of water that could overcome the physical laws would be exceedingly minimal. As an added, extra precaution, because I am always overly cautious with machinery, I rinse the carcass with fuel and shake it up before pouring it out. Follow all precautions. Just saying.

 

[drf256]

How much of a leak are we talking about? Can you hold any vacuum or pressure at all, or does it slowly drop?

Is the impulse capped off or being used as test barb? Does the model have a decomp? Did you spray around the plug threads? Lastly, did you check your tubing from your tester-I’ve had then leak at the tester barb.

 

[merc_man]

Its a big leak somewhere. Cant build presure. I am putting presure through the spark plug hole.
I have never had an isue finding the bubbles till this saw.
Iv sprayed seals. All rubbers. Around the clam part. And around my block off rubbers.
Think i will hook up to air compressor so i have a constant flow of air.

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[stretch5881]

5 psi from compressor and dunk it. You'll find it fast.

 

[lehman live edge slab]

Pretty funny this is here, I have a ms 250 about 3 year old and is loosing tune when warm go’s into a lean bog. Tried 3 different carbs on it and runs for awhile most times but every now and then it will be boggy right away. Has done this will all 3 carbs so I’m assuming the carbs are ok fuel line holds vacuum and not collapsing when checked. New Stihl fuel filter new line and tank vent but also tried other vents same issues. Saw has held pressure and vacuum every time I’ve tried it but does change idle when layed on side but may be puddles of fuel dropping rpm. But didn’t get better after leaning carb a touch. I’m to the point I’m thinking I just need to strip it check everything including the bearings. Put new seals in and seal the clamshell up well and see what happens. Only thing that hasn’t been changed is the coil, I guess I could give that a try but never seen a coil make the saw act like it is.

 

[Basher]

Spray bottle and dish soap concoction has found every leak I ever had but one. I had just built a crank up 026 and had tested it several times before running it, it held solid so I mounted a bar and went out to the test log to get the tune just right. Once tuned I bring them back in and wash/clean them back to near perfect, then check compression, note numbers and pull a vac and pressure test. Well it wouldn`t hold either, tried and tried with soap, then light bulb idea, check the trusty hose I had used for years, yup, it had developes a pinhole sized tiny crack ,it was a piece of vacuum line from a 1964 Chevy, guess its time was up. Severe leaks can only come from so many places on a saw, spray it down with soapy water and keep the pressure on it, the bubbles will soon amass.

 

[kneedeepinsaws]

As a last resort yes. As long as you have some pressure water will stay out for the most part. I have had to do that a few times.


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I had to do this with a 372, it worked very well and was a good way to pinpoint a leak.

good advice glenmac

 

[drf256]

Not able to build any pressure at all may be pointing to an unblocked impulse line or a totally blown out seal.

When they fail that bad, it can be tough to find the issue. There’s little to no time to see what’s actually happening.

Make sure your block off plates are sealed well, I’ve owner tightened and crimped the rubber seal at times also, creating a leak. How did you seal the intake?

Cleaning the intake snout and ex port with acetone and using gorilla tape works great for vac testing. Harder with pressure, cause it will pop right off. I’d try that, put a plug in, and test through the impulse barb. Just for shíts and giggles.

Any pics?

 

[5000+]

Hook it to 5 or so #'s of regulated air. Should be easy to find, if not, hold a piece of hose to your ear and go over the saw

 

[merc_man]

Hooked it to the air compressor and could hear where it was coming from. Impulse line is almost split in half. I guess hole was to big to make bubbles when i sprayed soapy water on it.

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[stretch5881]

 

[RipRap]

Just went through the same thing on a friend's MS250, had a new impulse line and the manifold looked new but it had a small hole in it that would disappear at times.

 

[Al Smith]

That sinking the engine in a tub of water is kind of a last resort and is old school but it works .E. Copsey did that on a saw engine some very good mechanics had scratched their heads on .Usually you can find it with a spritz of starting fluid if it's on the clutch side which is normally the leaky seal .You can run without a clutch but it would be rather difficult to run without a flywheel . As for me I just change both sides and be done with it .