Black RTV to patch plastic carb parts?

Bantou · Sep 21, 2024

Any reason I couldn’t use black rtv to seal this crack on my nozzle well? It doesn’t appear to run very deep and the brass tube runs all the way through. Best I can tell, it’s just for support and the tube is still very solid. My big concern is that it sits down in the fuel bowl and will be constantly exposed.

They are considered an obsolete part now and difficult as all get out to find without paying an insane amount.

DaleH · Sep 21, 2024

I’d probably clean well w/ alcohol & would use this sealant MADE for fuel systems.

And could a small zip-tie (or SS wire, twisted tight) go all the way around the body/housing shown (between thumb & finger) to give added support, to at least stop that ‘wall’ where cracked from breaking out??

airshot · Sep 21, 2024

I believe "goop" is also gas resistant, I can say that it gas always held on my projects..

Bantou · Sep 22, 2024

DaleH said:
I’d probably clean well w/ alcohol & would use this sealant MADE for fuel systems.

And could a small zip-tie (or SS wire, twisted tight) go all the way around the body/housing shown (between thumb & finger) to give added support, to at least stop that ‘wall’ where cracked from breaking out??
View attachment 122855

I was planning on using permatex black. I’ve had mixed luck with loctite stuff.

Using the SS wire is a good idea though. Just have to be careful that I don’t twist it TOO tight. I suspect that the plastic is brittle given the crack and how it feels in hand.

lckstckn2smknbrls · Sep 22, 2024

Bantou said:
Any reason I couldn’t use black rtv to seal this crack on my nozzle well? It doesn’t appear to run very deep and the brass tube runs all the way through. Best I can tell, it’s just for support and the tube is still very solid. My big concern is that it sits down in the fuel bowl and will be constantly exposed.

They are considered an obsolete part now and difficult as all get out to find without paying an insane amount.

Could a new part be 3D printed?

Stand Up · Sep 22, 2024

RTV sealant is basically a heat resistant silicone. I would use something else. I think the Loctite will work.

DaleH · Sep 22, 2024

Regardless of brand … the goop used should be fuel rated …

airshot · Sep 22, 2024

Never had any sucess with silicone based products...do not use silicone for anything.

OldSailor85 · Sep 22, 2024

Good Luck.

FWIW, I haven't found anything that works submerged in fuel, long term (I was modifying a carburetor).

JB Weld was the most successful.

This product wasn't available at the time. Give it a look.

https://www.jbweld.com/product/j-b-weld-tankweld

thill · Sep 23, 2024

I have used a plastic welder with success. You cut a piece of the stainless reinforcement screen to the right shape and size and use the heat to imbed it into the plastic, and then add more plastic as needed.

The trick is using the RIGHT type of plastic to do the repair. The wrong stuff won't stick or worse. The right stuff will become one with the part, and then you can use a Dremel tool to hone it to perfection. Worth doing for something really expensive or hard to find.

OldSailor85 · Sep 23, 2024

airshot said:
Never had any sucess with silicone based products...do not use silicone for anything.

I've seen a water pump installed without a gasket, just silicone. This was on a 2600 hp diesel.

It worked, although I would always recommend a gasket.

I coat some gaskets with a thin layer of silicone before installation, especially if the gasket surface isn't perfect. Makes removal and cleaning a lot easier. Pretty much just Super Blue or Ultra Copper.

Just be careful and use as little as possible. People have ruined engines with silicone (gobs of it blocking oil/water passages).

LDUBS · Sep 23, 2024

Is this the same part?

Bantou · Sep 23, 2024

LDUBS said:
Is this the same part?

View attachment 122868

It certainly looks like it. Where in the world did you find it? I thought I had scoured every corner of the net already.

LDUBS · Sep 23, 2024

Bantou said:
It certainly looks like it. Where in the world did you find it? I thought I had scoured every corner of the net already.

That is a screen shot from eBay.

Bantou · Sep 23, 2024

LDUBS said:
That is a screen shot from eBay.

Part numbers don’t match up. Mine is a 0396605.

I’m guessing the 7189 is for a different size motor.

airshot · Sep 23, 2024

OldSailor85 said:
I've seen a water pump installed without a gasket, just silicone. This was on a 2600 hp diesel.

It worked, although I would always recommend a gasket.

I coat some gaskets with a thin layer of silicone before installation, especially if the gasket surface isn't perfect. Makes removal and cleaning a lot easier. Pretty much just Super Blue or Ultra Copper.

Just be careful and use as little as possible. People have ruined engines with silicone (gobs of it blocking oil/water passages).

As a gasket, silicone might work, but as a self supporting repair material, never had it last. Living in a popular boating and fishing area, no reputable mechanic uses silicone for anything, far to many better products on the market. Once silicone is applied, nothing else will stick to that area has been my experience.

lckstckn2smknbrls · Sep 23, 2024

Bantou said:
Part numbers don’t match up. Mine is a 0396605.

I’m guessing the 7189 is for a different size motor.

But can it be made to work?

Bantou · Sep 23, 2024

lckstckn2smknbrls said:
Could a new part be 3D printed?

That’s an option but I’ll have to do some research. 3D printing might as well be wizardry to me right now.

Bantou · Sep 23, 2024

lckstckn2smknbrls said:
But can it be made to work?

Hard to tell from a picture. I’ll have to figure out which motor it goes to before I know for sure.

Edit: It looks like the 7819s were used from 93 on in the 15hp and under motors. I wonder if they just made a minor change and updated the part number... I didn't not expect this project to turn in to a research project as well.

Bantou · Sep 23, 2024

OldSailor85 said:
Good Luck.

FWIW, I haven't found anything that works submerged in fuel, long term (I was modifying a carburetor).

JB Weld was the most successful.

This product wasn't available at the time. Give it a look.

https://www.jbweld.com/product/j-b-weld-tankweld

From what I’ve been able to find, tank weld does not bond well to plastic. Plastweld seems to do ok on exterior repairs but I haven’t been able to find anyone that used it for an internal repair.

Black RTV to patch plastic carb parts?

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