Dirko is not fuel resistant

[Vintage Engine Repairs]

Did a little demo, I hear so many people saying it’s fuel resistant and that somehow this is some special silicone. It’s really not. It’s bog standard acetic cure silicone at an inflated price. Not fuel safe / fuel resistant by any stretch. Had a contact speak to Elring in Germany who confirmed this too.

 

[00wyk]

I asked for a side by side comparison with other sealants.
Most all sealants exposed to fuel will react, sooner or later. The whole idea about Dirko and a few other sealants is that they do not leave big chunks of silicon in your crank case. What touches your fuel dissolves and goes out the exhaust without harm.

I have dirko here, and just ordered some Curil T, which Elring clearly states is fuel resistant. I'll try and test the two side by side.

 

[Shibby]

The whole idea about Dirko and a few other sealants is that they do not leave big chunks of silicon in your crank case. What touches your fuel dissolves and goes out the exhaust without harm.

How does that work if the whole seal is this Dirko stuff? Would the fuel dissolve the whole seal and form a leak? Or does it need some air or a lot of surface area to dissolve?

 

[Vintage Engine Repairs]

I asked for a side by side comparison with other sealants.
Most all sealants exposed to fuel will react, sooner or later. The whole idea about Dirko and a few other sealants is that they do not leave big chunks of silicon in your crank case. What touches your fuel dissolves and goes out the exhaust without harm.

I have dirko here, and just ordered some Curil T, which Elring clearly states is fuel resistant. I'll try and test the two side by side.

Chemical cure synthetic rubber sealants like moto seal or theeebond 1104 will start to dissolve
After 24 hours in fuel then re harden after the fuel is removed, silicones like Dirko, hondabond Ht etc instantly reach losing elasticity and adhesion, but actually swell. Excess in the crank case gets blown out the muffler and most remains in between the mating surfaces.

They all work, silicones and synthetic rubber, I’m just tired of people saying you must use Dirko and not silicones from the shop because Dirko is fuel resistant. It’s nonsense. Any silicone sealant with the same shore hardness will work just fine.

 

[Motorka]

https://www.elring.com/en/products/sealing-compounds/

How about Curil™ T2

1. General product infomation
Chemical basis Polyurethane
Curing No curing
Components Single component
Colour Green
Consistency High viscosity
Temperature range -55°C to +250°C (for 24h up to +270°C)
Maximum sealing gap 0,2 mm
pH value neutral
Detachment Can be easily detached
Resistant to Mineral oils (including additives), synthetic oils, Lubricating
grease, Coolants, cold and hot water, salt
water , cleaning agents, weak acids and alkalis, fuel
Possible applications Oil pan , water pump , oil pump , differential housing
, gearbox, gear oil sump , thermostat housing ,
control housing , axle cover, flange connection
In general all application, which need an easy
removal

 

[00wyk]

How does that work if the whole seal is this Dirko stuff? Would the fuel dissolve the whole seal and form a leak? Or does it need some air or a lot of surface area to dissolve?

I really couldn't say. In any case, with chainsaws, it would mostly be oil that gets deposited into the area the sealant would be after it's first start up. It would very rarely see raw fuel, let alone fuel with oil since it will have a coating of oil. So dunno how that affects it as it is meant to be oil resistant....

Whereas if you maybe use the wrong 'fuel resistant' sealant and it leaves even tiny chunks of itself in your crankcase...and it doesn't dissolve...and maybe it gets sucked up into the piston and cylinder and rings... maybe that isn't the best?

I mean, you don't open up a cylinder and go 'look at all this fuel', do ya?
It's all oil.

 

[Stevetheboatguy]

You want fuel safe or max fuel resistance????? 3m super weatherstrip adhesive. Industry name of monkey snot. It's yellow, gets on everything and nothing takes it off. Try taking a crankcase apart someone's resealed with that stuff.

There has to be some degree of fuel safe, but totally fuel proof...... Well that just flat out sucks. Dont believe me try the monkey snot on your next build. I promise you will hate me if you do.


Steven

 

[67L36Driver]

You want fuel safe or max fuel resistance????? 3m super weatherstrip adhesive. Industry name of monkey snot. It's yellow, gets on everything and nothing takes it off. Try taking a crankcase apart someone's resealed with that stuff.

There has to be some degree of fuel safe, but totally fuel proof...... Well that just flat out sucks. Dont believe me try the monkey snot on your next build. I promise you will hate me if you do.


Steven

+1

Comes in black nowadays. [emoji106]

Been using it forever.

Give it 24 hours and one needs a razor knife to scrape it off

 

[Deets066]

You want fuel safe or max fuel resistance????? 3m super weatherstrip adhesive. Industry name of monkey snot. It's yellow, gets on everything and nothing takes it off. Try taking a crankcase apart someone's resealed with that stuff.

There has to be some degree of fuel safe, but totally fuel proof...... Well that just flat out sucks. Dont believe me try the monkey snot on your next build. I promise you will hate me if you do.


Steven

What’s not to hate????

 

[Stevetheboatguy]

What’s not to hate????

You musta been talking to my ............






Steven

 

[Vintage Engine Repairs]

You want fuel safe or max fuel resistance????? 3m super weatherstrip adhesive. Industry name of monkey snot. It's yellow, gets on everything and nothing takes it off. Try taking a crankcase apart someone's resealed with that stuff.

There has to be some degree of fuel safe, but totally fuel proof...... Well that just flat out sucks. Dont believe me try the monkey snot on your next build. I promise you will hate me if you do.


Steven

There is zero fuel resistance -

This is from the FAQ page of elring who make Dirko,

 

[Stump Shot]

"...but it works great."

 

[Stump Shot]

I've taken 40 year old Poulan and McCulluch cases apart that had nothing but clear silicone on them from the factory.
Dirko has been put on a blue million of saws and surely Stihl wouldn't use it in their shops if it didn't work.

 

[huskihl]

I've taken 40 year old Poulan and McCulluch cases apart that had nothing but clear silicone on them from the factory.
Dirko has been put on a blue million of saws and surely Stihl wouldn't use it in their shops if it didn't work.

I agree. Folks make way too big of a deal out of gasoline resistance

 

[Stump Shot]

I agree. Folks make way too big of a deal out of gasoline resistance

If you're trying to patch a gas tank then it's a different story...

 

[Ford3000]

I've taken 40 year old Poulan and McCulluch cases apart that had nothing but clear silicone on them from the factory.
Dirko has been put on a blue million of saws and surely Stihl wouldn't use it in their shops if it didn't work.

But was the fuel back then the same as today's gunk, I doubt it.
Did carbs not have their internal coatings melted off with the advent
of corn oil fuels, until the manufacturers updated their coatings, different times now.

 

[Ford3000]

I really couldn't say. In any case, with chainsaws, it would mostly be oil that gets deposited into the area the sealant would be after it's first start up. It would very rarely see raw fuel, let alone fuel with oil since it will have a coating of oil. So dunno how that affects it as it is meant to be oil resistant....

Whereas if you maybe use the wrong 'fuel resistant' sealant and it leaves even tiny chunks of itself in your crankcase...and it doesn't dissolve...and maybe it gets sucked up into the piston and cylinder and rings... maybe that isn't the best?

I mean, you don't open up a cylinder and go 'look at all this fuel', do ya?
It's all oil.

But fuel flows through the case continuously when the saw is running,
and only Two or Three percent of the volume is oil, so much more fuel is present while running.

But yes, Stihl use it, so it must be good enough, or maybe that's why so many clam shells develop leaks and burn up.

 

[rogue60]

Fuel development has out paced sealants IMHO modern fuel is some nasty chit.. If I didn't know any better I'd say it was close to paint thinners lol

 

[Duce]

That's why they make Motoseal.

 

[Ford3000]

Well were stuck with what we have, maybe there will be a breakthrough.
If the climate change brigade get their way we will all be swinging axes,
or trucking in loads of batteries to try and nibble
on a tree, that is if we get a permit to cut said tree.