Bolt Thread sealant/locker

[Beemer]

Looking for suggestions on a thread sealer/locker that would be heat and fuel resistant and seal against bolt thread vacuum leaks in an intake system.
I am dealing with a steel bolt in an aluminum manifold in an air cooled engine, so it gets hot. Through the years the bolt has worked the aluminum a bit so it's not a really snug fit anymore.

The main focus is sealing but I need it to stay put against engine vibrations in an old Brit bike.
I wasn't sure if thread locker sealed the thread space to the needed degree.

 

[Firebrick43]

While thread locker works to seal the threads themselves, it isn't going to do much under the bolt head flange.

You want to use soft (annealed) metal washers. McMaster Carr has both copper and aluminum washers. Aluminum are one time use and throw away. I really don't like them even then because they age harden and how old are they when they get to you?

Copper is superior and can be reused if you anneal them. Place them on a piece of steel wire and heat them up in the burner of your stove or a propane plumbing torch until dull red in low light and dunk them in water. They will be dead soft then.

https://www.mcmaster.com/products/washers/metal-sealing-washers/

 

[Rusted Nut]

Triumph intake manifold? The proper fix would be to tap the holes slightly larger, then use a tabbed retaining washer.

 

[Leaflessshadetree]

Loctite 2422 is high temp. Maybe a bearing retaining compound would fill better Loctite 620 or vibratite 567 maybe?

 

[The Cobbler]

ge harden and how old are they when they get to you?

Copper is superior and can be reused if you anneal them. Place them on a piece of steel wire and heat them up in the burner of your stove or a propane plumbing torch until dull red in low light and dunk them in water. They will be dead soft then.

don't you mean "cool them slowly"?

 

[Firebrick43]

don't you mean "cool them slowly"?

No. It’s copper not carbon steel. Reacts to quenching completely different.

If you bring copper to a dull red and quench you anneal copper.

Another plus is quenching knocks the scale off.

Now you can harden copper by heating to 600 degrees for several hours and quenching but that is a long way from dull red and a lot more time.

Copper also age hardens and work hardens which is why you need to anneal if you want to reuse the sealing washers.

 

[Beemer]

While thread locker works to seal the threads themselves, it isn't going to do much under the bolt head flange.

You want to use soft (annealed) metal washers. McMaster Carr has both copper and aluminum washers. Aluminum are one time use and throw away. I really don't like them even then because they age harden and how old are they when they get to you?

Copper is superior and can be reused if you anneal them. Place them on a piece of steel wire and heat them up in the burner of your stove or a propane plumbing torch until dull red in low light and dunk them in water. They will be dead soft then.

https://www.mcmaster.com/products/washers/metal-sealing-washers/

I suspect that if the threads are sealed the concern may be addressed, but I do see your point.
Oil drain bolts make the seal with the crush washer under the bolt/plug head.

Actually it's a bit more complicated though because there is a bracket sandwiched between the manifold and the bolt head. The bolt goes through the bracket to secure it and then into the manifold. The bracket needs good contact area to be stable and that might not occur with a round washer behind it.

In the picture, the vertical bolt seen with a washer and bracket is in a threaded thru-hole into the intake manifold. A better design would have been to make the bolt hole blind and not through into the intact tract. There is plenty of meat there to accommodate that.
As you can see there are many parts there at the bolt head that could allow a vacuum leak so I saw sealing the threads as the most direct approach.

 

[Beemer]

Loctite 2422 is high temp.

"LOCTITE® 2422 is a blue, thixotropic, medium strength, dual cure, dimethacrylate ester acrylic threadlocking paste".
Wow that's a mouth full. I laughed at the word "blue" in the string of technical words.

The 620 sounds too permanent (high strength)because it will need to come apart at some time in the future and the 567 notes that it's for tapered pipe threads which this is not.

Thanks for the input.

 

[Firebrick43]

545 is the sealant for hydraulic fittings which can be straight or tapered. But I don’t know if it’s a high enough temp

2422 would be high enough(650 degrees F) but none of the thread lockers are very thick and the don’t cure/fill gaps well at all.

 

[jonesg]

teflon tape or green loctite for stud mounting in engine block.

 

[wssix99]

Looking for suggestions on a thread sealer/locker that would be heat and fuel resistant and seal against bolt thread vacuum leaks in an intake system.

For this, you need to use a proper thread sealant. (Thread locker is NOT thread sealant.) https://www.permatex.com/products/t...ermatex-high-temperature-thread-sealant-6-ml/

I am dealing with a steel bolt in an aluminum manifold in an air cooled engine, so it gets hot. Through the years the bolt has worked the aluminum a bit so it's not a really snug fit anymore.

For this, you should repair the damage with a Helicoil.

I need it to stay put against engine vibrations in an old Brit bike.

This is what thread locker is for, but you can't use it with tread sealant. Time for a Nord-Lock! https://www.nord-lock.com/en-us/


If you use a Nord-Lock, Helicoil, and sealant, you should be proper and solid forever. Anything else is going to be a compromise given your issues and I expect that you'll be coming back to this for future repairs, otherwise.

 

[scooby074]

Timeserts are better than helicoil if you can find them. Plus they seal. And are regularly used for sparkplug repair (heat and pressure resistANT).

Id timesert it with some high temp loctite 272 red for extra security, then install a normal bolt with same HT loctite for the bracket. Do it right and it will be better than when it left the factory.

 

[Blueshound_GJ]

For this, you need to use a proper thread sealant. (Thread locker is NOT thread sealant.) https://www.permatex.com/products/t...ermatex-high-temperature-thread-sealant-6-ml/


For this, you should repair the damage with a Helicoil.


This is what thread locker is for, but you can't use it with tread sealant. Time for a Nord-Lock! https://www.nord-lock.com/en-us/


If you use a Nord-Lock, Helicoil, and sealant, you should be proper and solid forever. Anything else is going to be a compromise given your issues and I expect that you'll be coming back to this for future repairs, otherwise.

This sounds promising. OP, can you also use a stud instead of the bolt, and make it a more permanent install?

 

[gizardlizard]

At work, we have high pressure, high temp water heaters that we run upwards of 365 degrees Fahrenheit. We need thread locker and thread sealer and have been using loctite tight 51604 for years with great results. Great stuff.

 

[CraigStu]

This sounds promising. OP, can you also use a stud instead of the bolt, and make it a more permanent install?

I will second the idea of a stud and nut. One of the loctite or permatex products will set the stud into the manifold so the damaged threads are no longer a concern. I do this in a lot of instances w/ aluminum because tightening a steel nut onto a steel stud is so much better than a bolt into aluminum.