High Quality Chainsaw Bars Husqvarna Toys Hockfire Saws

HELP! Did fuel dissolve my Threebond gasket?

Huskyvarnya Saws

Well-Known OPE Member
Local time
10:31 AM
User ID
16213
Joined
Apr 12, 2021
Messages
26
Reaction score
27
Location
Alabama
Country flag
I rebuilt this Husqvarna 350 around 4 years ago using Threebond 1184 as a sealer. It has been a very reliable saw up until recently, when it developed a vacuum leak on the rear right corner of the bearing cap. When I disassembled the saw to reseal it, I noticed that there was almost no threebond left between the bottom clamshell and the bearing cap, as well as the top of the bearing cap and the cylinder.

I know that I used a good bit more than what is left on the mating surfaces, if anything I thought maybe I was using too much at the time. Has anyone else experienced this? I have rebuilt a hand full of saws using the same sealant so its a bit concerning. Any insight would be appreciated. Thanks!
 

Huskyvarnya Saws

Well-Known OPE Member
Local time
10:31 AM
User ID
16213
Joined
Apr 12, 2021
Messages
26
Reaction score
27
Location
Alabama
Country flag
I forgot to snap a pic of the paper base gasket, but there was almost no trace of threebond left on it either.
0704241842.jpg
0704241842a.jpg
 

cuinrearview

Unskilled Hammer Donkey
Local time
11:31 AM
User ID
9248
Joined
Apr 16, 2019
Messages
10,462
Reaction score
72,090
Location
Dowling, MI
Country flag
In my opinion, nothing in your pics suggests that there was ever "a lot" of sealant. Did you take a before pic?

I'm not up on 1184, but I believe some of these sealants are anaerobic, so if there is oxygen present they won't set up and can disappear as time goes on. The Hylomar seems to be different than the others in my experience.
 

Huskyvarnya Saws

Well-Known OPE Member
Local time
10:31 AM
User ID
16213
Joined
Apr 12, 2021
Messages
26
Reaction score
27
Location
Alabama
Country flag
In my opinion, nothing in your pics suggests that there was ever "a lot" of sealant. Did you take a before pic?

I'm not up on 1184, but I believe some of these sealants are anaerobic, so if there is oxygen present they won't set up and can disappear as time goes on. The Hylomar seems to be different than the others in my experience.
I can see how one may come to that conclusion based on the pictures, but I know for a fact there was. There is still plenty of excess sealant left on the bearing cap screw threads. I would wager there is more sealant left in the screw holes/threads than on the entire mating surface.
I have always applied a thin layer over the entire mating surface with a q-tip, that has never changed. You would never believe that by looking at the pics though, I get it. Unfortunately, I don't have any assembly pics. This saw was built a few years back.

Have you used the Hylomar stuff that you speak of with good results? I appreciate the input.
 

EFSM

Super OPE Member
Local time
10:31 AM
User ID
29079
Joined
Apr 30, 2024
Messages
314
Reaction score
673
Location
Extreme southern IL
Country flag
I have used Right Stuff sealant by Permatex quite a few times and have never had a problem. I smear only enough to cover the mating surfaces, because I'm OCD about having extra sealant obstruct the transfer flow. After torquing the cylinder down a bead of sealant 1/16" or less will be left around the base. Lots of extra sealant doesn't prove much in my opinion, but with your situation it probably won't hurt anything.

Anerobic sealant may work for some people, but it failed on the one and only saw I used it on.
 

cuinrearview

Unskilled Hammer Donkey
Local time
11:31 AM
User ID
9248
Joined
Apr 16, 2019
Messages
10,462
Reaction score
72,090
Location
Dowling, MI
Country flag
1/16" of sealant squeezed out would be a shît ton, imho.

I have used Hylomar. I didn't care for the way it never seemed to set up. It was useful for porting practice, when you may have a saw apart a half dozen or more times.

I always end up going back to the tube of Yamabond, which looks a lot like the 1184 in the pics. It could even be the same stuff. Did you true the flat surface on the bearing cup? They are notoriously "un-flat".
 

EFSM

Super OPE Member
Local time
10:31 AM
User ID
29079
Joined
Apr 30, 2024
Messages
314
Reaction score
673
Location
Extreme southern IL
Country flag

Huskyvarnya Saws

Well-Known OPE Member
Local time
10:31 AM
User ID
16213
Joined
Apr 12, 2021
Messages
26
Reaction score
27
Location
Alabama
Country flag
1/16" of sealant squeezed out would be a shît ton, imho.

I have used Hylomar. I didn't care for the way it never seemed to set up. It was useful for porting practice, when you may have a saw apart a half dozen or more times.

I always end up going back to the tube of Yamabond, which looks a lot like the 1184 in the pics. It could even be the same stuff. Did you true the flat surface on the bearing cup? They are notoriously "un-flat".
Yes sir, I did "true" the surface of the bearing cap before assembly. If anything, I used too much sealant when assembling this saw. It was my first full rebuild. The saw was very reliable with no issues at all for 4-5 years, until recently when it was suddenly out of tune, and wouldn't hold one. Thats when I discovered the leak through a pressure test.

This ordeal has me second guessing all of my rebuilds now. I have only ever used threebond 1184 from the start, and this was my first saw, so I can't help but wonder if the others are a ticking time bomb with the same issue. Makes me want to pull the cylinder on one of my other saws to see what it looks like.
 
Last edited:

Huskyvarnya Saws

Well-Known OPE Member
Local time
10:31 AM
User ID
16213
Joined
Apr 12, 2021
Messages
26
Reaction score
27
Location
Alabama
Country flag
If you look closely, you can still see the bead of threebond that was left after torquing down the cylinder. There is hardly any left on the paper gasket, or mating surface though. It peels right off with no effort.
 

Attachments

  • 0705241436b.jpg
    0705241436b.jpg
    244.7 KB · Views: 6
  • 0705241435.jpg
    0705241435.jpg
    189.6 KB · Views: 6

Moparmyway

Its just a saw
GoldMember
Local time
11:31 AM
User ID
21
Joined
Dec 4, 2015
Messages
5,336
Reaction score
28,465
Location
In a meeting
Country flag
A “skin” layer is all that’s needed if both surfaces are true. Remember, the manufacturers have tolerances, and any sealant used is designed to work with these tolerances, so a thin skin layer left is perfect and will do the job.

Dissovling sealant is another thing
 

EFSM

Super OPE Member
Local time
10:31 AM
User ID
29079
Joined
Apr 30, 2024
Messages
314
Reaction score
673
Location
Extreme southern IL
Country flag
I can see sealant dissolving if the crankcase was flooded with gas due to a leaking carb or primer bulb, but under normal circumstances the fuel in the crankcase is almost entirely vapor.
 

Moparmyway

Its just a saw
GoldMember
Local time
11:31 AM
User ID
21
Joined
Dec 4, 2015
Messages
5,336
Reaction score
28,465
Location
In a meeting
Country flag
There’s still a cloud of fuel entering the crankcase, atomizing as it moves up into the transferrs. In the transferrs is where it’s entirely vaporized, but that crankcase is usually wet with enough raw fuel to look foggy
 

Moparmyway

Its just a saw
GoldMember
Local time
11:31 AM
User ID
21
Joined
Dec 4, 2015
Messages
5,336
Reaction score
28,465
Location
In a meeting
Country flag
Fuel or oil? The oil shouldn't atomize since it is not volatile.
Both

It takes time to change state, even with the pressure difference, the fuel DRIES out as it travels through the crankcase, eventually all vapor as it enters the cylinder. The oil falls out of suspension with the liquid fuel drops as they atomize, leaving the oil in the crankcase.
 

lehman live edge slab

Live Action
Local time
10:31 AM
User ID
3953
Joined
Sep 2, 2017
Messages
3,736
Reaction score
12,973
Location
Mn
Country flag
I know none of the ones I’ve tried will survive raw mix gas in full contact. I tried to seal the two halves of an 075 tank once and it held gas for about 6 hours
 

Ketchup

Epoxy member
Local time
9:31 AM
User ID
5594
Joined
Mar 12, 2018
Messages
2,076
Reaction score
6,560
Location
Colorado
Country flag
I’ve used several tubes of 1184 now. I have rarely had an issue with it but I’ve seen a few base gasket deletes that looked bad. I think if the surfaces have true, tight tolerances the sealant will last quite a long time. If the surface contact is irregular or the parts have movement, 4 years is about the best you can hope for.

Holymar Blue is a little harder to work with but some people swear by it.
 

EFSM

Super OPE Member
Local time
10:31 AM
User ID
29079
Joined
Apr 30, 2024
Messages
314
Reaction score
673
Location
Extreme southern IL
Country flag
It takes time to change state, even with the pressure difference, the fuel DRIES out as it travels through the crankcase, eventually all vapor as it enters the cylinder. The oil falls out of suspension with the liquid fuel drops as they atomize, leaving the oil in the crankcase.
You're right. I don't think there should be enough liquid fuel in the crankcase to damage sealant, though.
 

Moparmyway

Its just a saw
GoldMember
Local time
11:31 AM
User ID
21
Joined
Dec 4, 2015
Messages
5,336
Reaction score
28,465
Location
In a meeting
Country flag
You're right. I don't think there should be enough liquid fuel in the crankcase to damage sealant, though.
More like very tiny droplets, atomizing as they go ……. the crankshaft/connecting rod area are pretty much operating in a fuel/oil fog
 
Top