Testing the seal between carb and manifold.

[Vintage Engine Repairs]

Do you guys test the seal here? Seeing as most place a rubber inner tube between the two. You’re not testing the seal between the carb and manifold. I only just thought about it when I noticed I had a bent washer and oring that wouldn’t seal so thought i’d ask what you guys do!

Thanks

 

[rupedoggy]

Most of us guys buy a factory manifold and ring and oring and do without the trouble

 

[Vintage Engine Repairs]

Most of us guys buy a factory manifold and ring and oring and do without the trouble

Hey, I do have factory OEM everything but the outer ring got bent (still not sure exactly how) and wouldn’t hold a seal. Replaced now, but curious for the future. I guess most don’t test it?

 

[rupedoggy]

If the ring got bent, put it on an anvil and hit it with a BFH

 

[Andyshine77]

You can spray some WD40 right at the seam with the saw at idle and if the saw slows down or speeds up and starts to smoke, you may have a leak. The problem is thin solvents will almost always get passed that type of seal, so it's not exactly accurate. If you use break parts cleaner, you will always get a change in idle, whether or not you actually have a real leak there, as the solvent is just too thin. Plus it's hard to prevent vapor from making it's way to the intake, but it can be another tool.

Mostly if the saw tunes correctly and everything else is sealed up tight you're good to go.

 

[Vintage Engine Repairs]

If the ring got bent, put it on an anvil and hit it with a BFH

Haha, I’m guessing that means Big F-ing Hammer? I straightened it but brought a new one and will keep it as spare

 

[Vintage Engine Repairs]

You can spray some WD40 right at the seam with the saw at idle and if the saw slows down or speeds up and starts to smoke, you may have a leak. The problem is thin solvents will almost always get passed that type of seal, so it's not exactly accurate. If you use break parts cleaner, you will always get a change in idle, whether or not you actually have a real leak there, as the solvent is just too thin. Plus it's hard to prevent vapor from making it's way to the intake, but it can be another tool.

Mostly if the saw tunes correctly and everything else is sealed up tight you're good to go.

Thanks for the reply! Yes that’s true, you’ll hear it in the tuning of the saw. No worries, just trying to learn as much as I can do I really appreciate it!

 

[drf255]

Tom,

There is a factory tool from Stihl that bolts in place of the carb and permits vac testing. That’s what I use and I Block the exhaust with a greased piece of plumbing rubber available in hardware stores.

It’s not too pricey and it seems like you’ve got the bug now, so it’s a worthwhile investment.

I do think you are worrying too much. Minor air leaks can be tuned out and major ones are generally quite apparent. The ones in between will give you issues with the idle. I’d personally just run your saw at this point. If it idles well and tunes correctly at the factory 1/1 settings (or close) call it a day.

I’ve never seen any saw run poorly with a minor leak at testing. You don’t know what a real leak looks like at testing till you actually see one. I’ve seen saws run fine except for some minor idle issues and upon testing They couldn’t hold any vacuum at all. My point is that when you get a saw that fails, there will be little doubt in your mind.

 

[Vintage Engine Repairs]

Tom,

There is a factory tool from Stihl that bolts in place of the carb and permits vac testing. That’s what I use and I Block the exhaust with a greased piece of plumbing rubber available in hardware stores.

It’s not too pricey and it seems like you’ve got the bug now, so it’s a worthwhile investment.

I do think you are worrying too much. Minor air leaks can be tuned out and major ones are generally quite apparent. The ones in between will give you issues with the idle. I’d personally just run your saw at this point. If it idles well and tunes correctly at the factory 1/1 settings (or close) call it a day.

I’ve never seen any saw run poorly with a minor leak at testing. You don’t know what a real leak looks like at testing till you actually see one. I’ve seen saws run fine except for some minor idle issues and upon testing They couldn’t hold any vacuum at all. My point is that when you get a saw that fails, there will be little doubt in your mind.

Thanks mate it should be fine now, just always good to know in the future just waiting for a cool day to test it. It’s 40+ degrees Celsius this whole week. Next week we have a day or two of 28c so will venture out then

 

[HarleyT]

How do you know that it is not sealing?

 

[Vintage Engine Repairs]

How do you know that it is not sealing?

I think it will be now with the new parts, it wasn’t sealing because it wouldn’t hold pressure there lol

 

[rupedoggy]

By god it is sealing!

 

[Vintage Engine Repairs]

By god it is sealing!

Wtf... no wonder it was leaking!! I’m using the wrong seals!

 

[SteveSr]

Do you guys test the seal here? Seeing as most place a rubber inner tube between the two. You’re not testing the seal between the carb and manifold. I only just thought about it when I noticed I had a bent washer and oring that wouldn’t seal so thought i’d ask what you guys do!

Thanks

Just make a blocking plate for the muffler and another in place of the carb and then test through the spark plug hole. This tests the WHOLE system. NO guessing involved. There should be LOTS of threads on leak testing here including one I did some years ago complete with photos.

 

[drf255]

Just make a blocking plate for the muffler and another in place of the carb and then test through the spark plug hole. This tests the WHOLE system. NO guessing involved. There should be LOTS of threads on leak testing here including one I did some years ago complete with photos.

Except the impulse line on this model of saw.

 

[Van462]

I find a light smear of thicker silicone (like spark plug grease) can solve many vacuum leaks. It doesn't take much to stop air at such a low pressure differential.

 

[SteveSr]

Except the impulse line on this model of saw.

Sure, just stick an appropriate sized drill bit shank in the impulse hose. Done!

 

[Cease232]

Sure, just stick an appropriate sized drill bit shank in the impulse hose. Done!

I prefer golf tees. Work great for plugging all manor of fuel and impulse lines.
Although I keep the plug in and vac test through the impulse.

Sent from my iPhone using Tapatalk Pro

 

[HarleyT]

By god it is sealing!

It passes the Walrus test!!

 

[Vintage Engine Repairs]

Now I understand why seals are so expensive! Here I was thinking it was a type of rubber...