359/357 intake boot leak

[Eric Modell]

I have a old 359 saw bought brand new off the internet. It never ran very good,
I scored the piston running old gas and a dull chain. I put a new stock piston in it and scored it immediately. Met you guys and could not junk the saw. I bought a new 357 piston and jug, and the new style intake boot clamp. I built a pressure / vacuum tester, and it is leaking big time. It appears to be leaking around the boot some where. The boot looks good. Is there a trick to seal the intake boot or should i just buy a new boot. I am using cork gasket material to block the carb and muffler.


Thanks for the help
eric

 

[parrisw]

I have a old 359 saw bought brand new off the internet. It never ran very good,
I scored the piston running old gas and a dull chain. I put a new stock piston in it and scored it immediately. Met you guys and could not junk the saw. I bought a new 357 piston and jug, and the new style intake boot clamp. I built a pressure / vacuum tester, and it is leaking big time. It appears to be leaking around the boot some where. The boot looks good. Is there a trick to seal the intake boot or should i just buy a new boot. I am using cork gasket material to block the carb and muffler.


Thanks for the help
eric

Spray some windex around it, it will bubble where it is leaking, when you know for sure where it is excatly leaking, that will lead you in the right direction for repair.

Is the boot installed correctly? Not folded under or anything.

 

[stihl025]

I don't like cork for blocking off intake and exaust ports. I didn't feel that they sealed off all that good. I finally bought the real deal (sealing cover #502 54 11-02) from Jack's Small Engines. It was $3.64 and is made of thick rubber. If you choose not to go that route, try a piece of old rubber from an inner tube.

As far as a trick to sealing off the intake boot, none that I am aware of. Never had a problem with the intake boot, but did have a problem with the carb loosening up causing a lean condition. I was lucky to recognize it early with no damage.

 

[blsnelling]

Use a piece of inner tube rubber.

 

[Eric Modell]

Thanks
I will try rubber instead of cork. Is windex better then soap suds to pinpoint the leak.

 

[HiOctane]

Boot dont usually leak very often.Did you install "dry"?Use a bit of grease around the boot end to get a better seal on the cyl spigot.Or use Loctite 515,Permatex,Yamahabond,etc.When you take pressure,are you blocking the small pulse tube too? I cant see why it will leak if the boot is not damaged.

 

[Eric Modell]

Yes I did install it dry. It might have been leaking where i blocked the carb, but it sounded like it was the boot. First i tried to pressure test through the impulse line, then tried through the spark plug hole. Will grease soften the boot? Is there a down side to sealing it to the jug.

Thanks

Eric

 

[HiOctane]

. Will grease soften the boot? Is there a down side to sealing it to the jug.

Thanks

Eric

No,he wont soften the rubber with grease,not worst than gas flowing inside.Just use a bit to"wet' the rubber.You can pressure from anywhere,plug,intake.

 

[parrisw]

You could use dielectric grease, it wont harm rubber. I never use anything on the boot's though, I just put em on dry.

I find windex works well, bubbles pretty good.

 

[Lakeside53]

And.. it may not be the boot. The impulse line takes a sharp bend right beneath the boot, and it can wear a hole though the line.

 

[Eric Modell]

Thanks for tall the input, new impulse line.

 

[Eric Modell]

Still leaking a little

I put it back together with with silicone grease and inner tube rubber to seal carb and muffler, it still leaks but very slowly now. Every thing looks good. 160 PSI compression. It will leak from 12 psi to 5 psi in about 30 sec. I put fuel in it and it started in third pull with a prime. runs good but i think i still have a leak. should i spray case with carb cleaner and listen for rpm change

Thanks for the help

eric

 

[Lakeside53]

Does it leak on pressure or just vac?

Pressurize it, then dunk it in a bucket of water. You soon see the leak...

 

[blsnelling]

It will leak from 12 psi to 5 psi in about 30 sec.

eric

That's a significant leak. I would not use the saw until I found it.

 

[Eric Modell]

Lakeside it pumps down to 20 in HG and leaks to about 10 in HG and holds for a minute or two. it leaks slower with a vacuum.
So i should just put the saw in a bucket of water.

 

[blsnelling]

Either that or spray it with Windex or soapy water.

 

[Urbicide]

Is the clamp on the intake between the carb and the cylinder made out of plastic? There was a service bulletin awhile back on this subject.


**********************************************

Service Bulletin, 357 XP, 359, 353, 346 XP
Partition wall and clamp for intake system, 2006-03

The existing intake system on 357XP, 359,353 and 346XP currently consists of an integrated plastic clamp in the partition wall. As the clamp is made of plastic, there is a risk of deformation. This results in impaired clamping force against the cylinder, which in turn can result in leakage in the intake system. To prevent this from occurring, we have now introduced a metal clamp and a new partition wall.

The new partition wall is made up of polyamide with 30 % fibre glass. The new clamp is a hardened steel clamp. The new material and the design of the clamp reduce the risk of deformation and the subsequent risk of leakage.

Full replaceability prevails.

Introduced from serial number:

357XP 061100201
359 061100001
353 061100001
346XP 061100001

New part no. Description Excl. part. no. Remark
537 25 13-02 Partition wall, intake, complete New spare part

537 43 88-01 Clamp, intake New spare part

Spare part, partition wall, part number 537 25 13-01, has been discontinued and is replaced by part number 537 25 13-02.

 

[Eric Modell]

thanks for all the input, back to the barn and I will Use soap or water bucket to determine the point of leak. And yes urbicide I did put the new style partition wall and clamp on. I thought that was my problem., the old one was junk.

 

[Lakeside53]

BTW.. if you have a decomp valve and don't plug it, it will leak under vac.. and some times under pressure.

 

[Eric Modell]

I sprayed the saw with carb cleaner, compression release, intake boot, clutch and flywheel bearing, no noticeable rpm change.

I am done for today

Thanks for the help

Eric