Dirko HT Red is not fuel safe...

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Gaudaost said:
The two time’s I used it with gaskets it failed, I’m surprised that if it failed with gaskets it would hold without, but clearly you have had success.
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Yeah, lots of times.

Coat both surfaces, wait a couple minutes, stick em together.

I will say getting things back apart if you have to is a bit tougher than with gaskets or rtv.
 
For whatit's worth, untill recently, I couldnt have been bothered to use dirko ht. I had a friend that needed a rebuild on his ms390. I told him get the parts, and I'll show you how to put it together. He ran to stihl and said I'm rebuilding blah blah blah, cane back with a piston, ring, bearings, seals, amd a tube of dirko ht. I used it as he spent the money on it. It worked. Cant say any better or worse than threebond, or any other quality gasket maker/rtv on the market. He gave me the rest of the tube, and I've used it on a few other applications, with success. Dont know if I'd buy it again, but it does work...
 
Motoseal has worked fine on every clamshell, metal or plastic, that I’ve ever done. 15 to 20 possibly. It’s also worked as a cylinder to case sealant about 400 times for me without failure. I’ve never used Dirko HT, but that’s what came on every 029 through MS 390 and I’ve never seen one that was sucking air there. There are millions of chainsaws sealed together with Dirko and it works fine
 
I've used the gray Dirko quite a bit with good results. I have even used it exclusively to seal fuel tanks on Macs and Homelites.

Sent from my SM-G981U using Tapatalk
 
huskihl said:
Motoseal has worked fine on every clamshell, metal or plastic, that I’ve ever done. 15 to 20 possibly. It’s also worked as a cylinder to case sealant about 400 times for me without failure. I’ve never used Dirko HT, but that’s what came on every 029 through MS 390 and I’ve never seen one that was sucking air there. There are millions of chainsaws sealed together with Dirko and it works fine
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Because that area is not in a heavy wash of gasoline .
 
Gaudaost said:
Do you know if this happens to other sealants? Ones that state specifically that they are fuel safe?
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It will happen to any RTV that smells like acidic acid. You should think of this in terms of compromise among goals. Dirko is a fairly safe product to expose employees and the general public to, it is also fairly low in environmental impact. Even it’s cured state removal can be done without VOCs or any other type of chemical.

It works as described and generally exceeds the expected application’s requirements. While there are other products that a more stable when exposed to “fuel” they tend to be significantly more hazardous in all regards.

Dirko is an eye, mucus membrane, respiratory, skin irritant however compared to other products it seems fairly safe for liver, kidneys and pancreas. It is also cheaper(from Stihl, think about that) than many of the other products, especially when you include the needed clean up chemicals and safety supplies.
 
Justsaws said:
It will happen to any RTV that smells like acidic acid. You should think of this in terms of compromise among goals. Dirko is a fairly safe product to expose employees and the general public to, it is also fairly low in environmental impact. Even it’s cured state removal can be done without VOCs or any other type of chemical.

It works as described and generally exceeds the expected application’s requirements. While there are other products that a more stable when exposed to “fuel” they tend to be significantly more hazardous in all regards.

Dirko is an eye, mucus membrane, respiratory, skin irritant however compared to other products it seems fairly safe for liver, kidneys and pancreas. It is also cheaper(from Stihl, think about that) than many of the other products, especially when you include the needed clean up chemicals and safety supplies.
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Lots of very valid and important points thanks for taking the time to share, Justsaws
 
Chaps just to update this thread for future readers, I have a German friend who contacted Elring (the makers of Dirko HT Red) and they said very clearly, Dirko is NOT fuel resistant and should not be used on any surfaces that will come in contact with gasoline.

It’s worth noting that it actually expands when it contacts fuel and is probably why it does the job necessary. It exceeds necessary elasticity for movement even when submerged in fuel.

So there you go, it’s not fuel safe, though it still works.

Funnily enough, since this post I did lots of testing of Dirko, Motoseal, Permatex 3 and threebond. Dirko was so consistently good and never failed. I even made 3 holes in a gas can and patched each one with Dirko, threebond and Motoseal. Threebond failed within 8 hours, Motoseal lasted around 24 hours and the Dirko was still strong after 6 weeks. The fuel resistant sealers tend to go mushy and dissolve when submerged in fuel and it seems the change in pressure of the fuel tank depending on the temperature during the day and night meant it pushed the semi dissolved plugs out. The Dirko still hasn’t failed.

This isn’t real world chainsaw use of the product of course, but it was interesting none the less.

I also tested all 3 on a strimmer rebuild (clamshell). Dirko was the only sealer that worked and held pressure and vac. Both of the other two failed to seal. The mating surfaces of the two halves wasn’t perfectly flat and square with one and other from the factory and Dirko had no problem filling it, the other two did.

I’m sure I could just apply more threebond or motoseal and it may have worked. But it may have had trouble curing and excess squeezing out. I think these two sealers work better with closer fitting machined surfaces.
 

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