024/026 manifold boot woes

[Reesedlightning]

Converted an 024 super on an 026. Got everything together. Zero leaks from the case or cylinder. Sparked it up, turned it to the side and it dipped in idle. Grabed the brake clean and found a leak behind the carb. Confirmed it was not the fuel line or impulse line. I cannot, for the life of me figure out why the manifold boot is not sealing. The oem boot looked fine but just in case I pulled it out and put in an aftermarket boot. I made sure that the inner ring was installed correctly and the outer washer was installed correctly as well. I have tried about every combination of things. Adding a gasket, removing the inner ring, removing the outer washer and no matter what combination of things I try I cannot get it seal. I’m making sure the nuts are good and tight and everything. I have fixed this same issue on a lot of other saws and have never been stumped like this.

 

[Reesedlightning]

Also, it is an older model 024 super with the small fuel line. Did those happen to take a different manifold boot by chance? In this picture, I noticed some funky ridges behind the boot lip. I suspect this might be part of the issue.

 

[HarleyT]

A carb with a worn throttle shaft can fool you to thinking that it is the carb boot with the quickie test.

 

[Reesedlightning]

Glad you brought that up. Tested 2 different carbs on there with no avail

 

[pioneerguy600]

Do you have the metal sleeve/ring installed inside the manifold where it joins the carb? It`s #24 on the IPL, part number 1113 141 1805.

 

[Reesedlightning]

Yessir. I have the inner sleeve and outer washer. Both OEM

 

[HarleyT]

Put a thick smear of grease on the surfaces and see if it does any different.

 

[Reesedlightning]

Grease? Would something like Yamabond be a better candidate? I guess I’m looking for the reasoning. I’ll certainly try it though. Thank you!

 

[BrettS]

Grease? Would something like Yamabond be a better candidate? I guess I’m looking for the reasoning. I’ll certainly try it though. Thank you!

I can't see it hurting anything, I have put sealant on the manifold to get it to seal in the past.

 

[pioneerguy600]

Does the rubber flange sit nice and flat in the airbox bulkhead? If it is distorted or bunched /pinched then I could see it not sealing. The 026 and 024 have become the most common saws I work on these days and I have not encountered one that leaks at that junction.

 

[HarleyT]

Grease to find where it is leaking. It is designed well to not use sealant. If you can find out exactly where, then you can fix it.

 

[Reesedlightning]

Tried the grease trick. Didn’t find much in the way of clues. Had to put the saw down for a day or two. Was getting too frustrated. Like what HarleyT said. This usually isn’t a problem so I feel like there’s something right in front of me that I’m missing.

 

[Oletrapper]

Grease? Would something like Yamabond be a better candidate? I guess I’m looking for the reasoning. I’ll certainly try it though. Thank you!

It's not permanent, just a test to see if it makes a difference and to help locate a possible leak area. jmho OT

 

[Oletrapper]

Glad you brought that up. Tested 2 different carbs on there with no avail

Something you might check. Make sure you have the right gasket for carb to manifold. I have found that some have extra holes for other applications. ie: impulse, etc. jmho OT

 

[HarleyT]

Something you might check. Make sure you have the right gasket for carb to manifold. I have found that some have extra holes for other applications. ie: impulse, etc. jmho OT

Most of the newer stihls do not have a gasket there.

 

[Oletrapper]

Most of the newer stihls do not have a gasket there.

Hmm. I must be missing something. Thought the thread was about 024/026?
Just saying.

 

[HarleyT]

Hmm. I must be missing something. Thought the thread was about 024/026?
Just saying.

 

[HarleyT]

Many aftermarket kits come with a carb mount gasket, but most newer Stihls don't use them. The 021/025/ms250 uses a plate there that requires them.

 

[pioneerguy600]

Hmm. I must be missing something. Thought the thread was about 024/026?
Just saying.

The carb seals to the rubber manifold , it does not use a gasket on the 024 - 026 saws.

 

[Reesedlightning]

I eventually got it to seal using a thin layer of Yamabond. It’s temporary. But it’s been working so far. I’ll revisit it at some point