Husqvarna 435 Intake air leak

[Huskyvarnya Saws]

I have a Husky 435 that is on the verge of driving me nuts. First it was a transfer cover leak, so I disassembled the saw and fixed that. Then I found a leak between the carb and intake, which was causing some erratic running. So I ordered a new inlet pipe and insulation wall assembly thinking that would surely do the trick. Well today I installed those and nothing changed. The saw still dies almost instantly when I spray carb leaner around where the carb and inlet pipe connect. Has anyone else encountered this issue before? Yeah I know, I have already put more time into the saw than what it is worth without even taking the parts into consideration, but i'm stubborn and I don't like throwing in the towel. Any suggestions would be greatly appreciated.

P.S. All 3 carb screws are good and tight. Just in case anyone was wondering.
I have considered trying to seal it with some Threebond as a last ditch effort, but I would prefer to avoid that.

Here's a pic I took with the old Inlet pipe and insulation wall. Same situation with the new one.

 

[Vintage Engine Repairs]

Throttle shafts wear out over time: here is a video I made for you as an example. If this is your issue, you can 45 degree chamfer the shaft orifice and insert an o-ring with a small washer and spring each side, which I have successfully done before, however it can cause its own hoast of problems including the linkage sticking, not enough spring tension, butterfly catching on the venturi etc.

Use some really heavy grease on and around the throttle shaft to see, as proof of concept, if this is your issue - the grease will temporarily stop any air leak.

If you want to try this fix if it is your issue - The low and high screw washers and o ring sizes for the shaft are ideal. The smaller and thinner the better. You’ll need to enlarge the washer hole wjth a drill and remove any burrs everywhere or you’ll tear the o-ring. Silicone grease is your friend when you out it together.

 

[Huskyvarnya Saws]

Throttle shafts wear out over time: here is a video I made for you as an example. If this is your issue, you can 45 degree chamfer the shaft orifice and insert an o-ring with a small washer and spring each side, which I have successfully done before, however it can cause its own hoast of problems including the linkage sticking, not enough spring tension, butterfly catching on the venturi etc.

Use some really heavy grease on and around the throttle shaft to see, as proof of concept, if this is your issue - the grease will temporarily stop any air leak.

If you want to try this fix if it is your issue - The low and high screw washers and o ring sizes for the shaft are ideal. The smaller and thinner the better. You’ll need to enlarge the washer hole wjth a drill and remove any burrs everywhere or you’ll tear the o-ring. Silicone grease is your friend when you out it together.

I'll double check that tomorrow to make sure. I thought I was pretty sure that the leak is where the carb meets the intake, but I had not considered that some of the carb cleaner could be leaking past the throttle shaft if it's leaking. Luckily I haven't run across this issue yet with any of my saws. I'm sure it's just matter of time, especially with some of the older saws. I appreciate you bringing that to my attention. I'll take note of the possible fix you mentioned as well.

 

[Huskyvarnya Saws]

Short clip from earlier today

 

[cscltd]

have you tried putting in a gasket between carb and air boot even though not required. Very first versions of 034 I think had that?
and have done that on saws with similar issue that will not seal around air boot.

 

[Huskyvarnya Saws]

have you tried putting in a gasket between carb and air boot even though not required. Very first versions of 034 I think had that?
and have done that on saws with similar issue that will not seal around air boot.

I have not tried this, but it did cross my mind. I am going to double check the throttle shaft, if that checks out I will make a gasket and see if that works. I'm beginning to wonder if maybe this issue has something to do with the 3 bolts that hold the carb to the intake. It just doesn't seem like a very reliable design to me to hold an air tight seal, especially with no gasket. Good to know that other people have had this issue and the gasket worked. Thanks for the reply.

 

[Gomofast]

Did you ever resolve this? I have the same issue with my 435.

 

[Homer6679]

I had the same issue with a 435 as well, here is the link to the thread I started about it perhaps you may find some value in there.

https://www.arboristsite.com/threads/some-help-needed-with-carb-tuning.361704/page-2

The insulator wall fixed my issue, I don't recall there being a gap like that on the top of the carb on the one that I worked on.

 

[Gomofast]

I had the same issue with a 435 as well, here is the link to the thread I started about it perhaps you may find some value in there.

https://www.arboristsite.com/threads/some-help-needed-with-carb-tuning.361704/page-2

The insulator wall fixed my issue, I don't recall there being a gap like that on the top of the carb on the one that I worked on.

Thanks I ordered the insulator

 

[Huskyvarnya Saws]

Did you ever resolve this? I have the same issue with my 435.

I never did, I made a gasket and still had the same issue. I put the saw away and never got back to it. I planned on applying some threebond to the top of the carb where it meets the intake to get it to seal. I may do that tomorrow. I'll let you know how it goes.

 

[Huskyvarnya Saws]

I had the same issue with a 435 as well, here is the link to the thread I started about it perhaps you may find some value in there.

https://www.arboristsite.com/threads/some-help-needed-with-carb-tuning.361704/page-2

The insulator wall fixed my issue, I don't recall there being a gap like that on the top of the carb on the one that I worked on.

I'm pretty sure I did buy a new insulator wall and intake with no luck. It's been a while, I'll have to check.

 

[Huskyvarnya Saws]

Thanks I ordered the insulator

Let me know how it works out!