gasket advice

[robbie]

The injector pump on my backhoe is giving me trouble. There's a part on top that covers the throttle and fuel cutoff controls. It's about 5 inches long, and the design is very poor. As you can see in the photos it's held on by two bolts, but they are not arranged with one on each end, which would be the smart way. They're not even side by side in the middle. They're side by side, slightly off center, which means there is very little pressure on the gasket at the far end. The standard gasket is of the thin white paper type.

The problem is that in a relatively short amount of running time the internal pressure will blow the gasket out of the end farthest from the bolts that hold the cover on. I can't over tighten the bolts because they tend to break off. I've already done that twice.

I'm looking for a good sealant that will be OK with diesel fuel and will not leak.

 

[Doc Sprocket]

I'd be looking at an RTV silicone if I were you. With both surfaces impeccably clean, adhesion should be excellent. Flexibility is excellent, as is heat and chemical resistance.

 

[Rustydog2010]

I would use Permatex blue RTV. That stuff sticks like glue, I was really surprised at how well it worked. It supposedly fills 20mm gaps, which I don't recommend!

But, like Toystory says any RTV should be suitable.

 

[robbie]

I suppose that means you don't have any reservations about its durability in the presence of diesel fuel. That's what I'm most concerned about. I didn't see anything on the label telling me not to use it to seal against slightly pressurized diesel, but I thought I should ask if any of you have experience with it before charging ahead.

 

[Doc Sprocket]

My advice is to very thoroughly clean both mating surfaces, and finish them off with a wipe with a high grade solvent like acetone. I do not advise the use of Varsol, Mineral Spirits, Paint thinner etc. They tend to leave a residue. This is not what you want.

 

[robbie]

I stuck it together with Permatex 2, because the label says it's resistant to gasoline and kerosene. That's the brown gooey stuff, not the blue silicone.

It also says 24 hours to full cure. I'm waiting 2 or 3 days, then I'll start it up and see if it leaks.

 

[HellSpawn]

I would use Permatex blue RTV. That stuff sticks like glue, I was really surprised at how well it worked. It supposedly fills 20mm gaps, which I don't recommend!

But, like Toystory says any RTV should be suitable.

True story, I once had to fix a small gash/hole in the front hull of my fishing boat with Permatex blue RTV... It was probably a little over 20mm in diameter. Anyhow, We had just gotten to the lake without noticing it (my brother had borrowed it a week or 2 before... *******) and I definitely didn't want to drive all the way home without going fishing on such a nice day, so it was the first thing I could find that might work. and it did! Let the stuff cure for a bit while we fished off the dock, and surprisingly it held up for that trip.

 

[robbie]

True story, I once had to fix a small gash/hole in the front hull of my fishing boat with Permatex blue RTV... It was probably a little over 20mm in diameter. Anyhow, We had just gotten to the lake without noticing it (my brother had borrowed it a week or 2 before... *******) and I definitely didn't want to drive all the way home without going fishing on such a nice day, so it was the first thing I could find that might work. and it did! Let the stuff cure for a bit while we fished off the dock, and surprisingly it held up for that trip.

Did you patch over it with anything, or did you just use the goop to bridge the gap?

 

[HellSpawn]

Did you patch over it with anything, or did you just use the goop to bridge the gap?

I flattened out the gash so it would close up a bit first, was still pretty big after that, just slapped a couple layers of it on there for good measure and that was it. I was so amazed it held. And I guess damp air/moisture really helps that stuff set in and cure. so that might be why it held so well so quickly.

Got a legit patch on it now though.