Loctite question

Joined
Jan 3, 2006
Messages
1,958
Location
Ohio
Haven't had much experience with threadlockers. The MG decided to part ways with a couple of machine screws holding the auto choke on the the carburetor. It was suggested to me to add a dab of blue Loctite to them. Only wrinkle is that the hole for one of them is tapped into the side of the float bowl; I figured out something was wrong when I got a whiff of gas fumes as it was dribbling out of the hole. I put them all back in with a dab of it, made sure they were tight, but does it hold up to gas? I'm letting it cure for the recommended 24 hours before I try to start it.

Lock washers aren't an option since these are flathead screws.
 
Should be OK, IF you can get the surfaces clean and actually get a cure.

Even gasoline can leave behind hydrocarbons and oils that will influence the cure.

You should use 243, which is a bit more resistant to that, and use the loctite primer. The primer cleans and leaves some additional metal ions to help speed the cure. The ions arent always necessary (really there for more stable metals like stainless, to help speed the cure), but the cleaning is.

IIRC, the long term strength tests assume a well prepared, fully clean and properly cured connection.

So tell us how you cleaned and prepared it???
 
Originally Posted by JHZR2
Should be OK, IF you can get the surfaces clean and actually get a cure.

Even gasoline can leave behind hydrocarbons and oils that will influence the cure.

You should use 243, which is a bit more resistant to that, and use the loctite primer. The primer cleans and leaves some additional metal ions to help speed the cure. The ions arent always necessary (really there for more stable metals like stainless, to help speed the cure), but the cleaning is.

IIRC, the long term strength tests assume a well prepared, fully clean and properly cured connection.

So tell us how you cleaned and prepared it???


Thanks, I used a Q-tip that I wet with some carb cleaner in the holes, and even though the replacement screws were new in the bag I sprayed them with some carb cleaner and wiped them off. Made sure they were dry before I put the stuff on and put them in.
 
Originally Posted by CT8
maybe this? Permatex sealant


That's interesting stuff, but still needs cleaning and prep.

Quote


DIRECTIONS FOR USE
For assembly
1. For best performance, clean all threads with a cleaning
solvent such as Permatex Brake and Parts Cleaner and
allow to dry.
2. Determine if the threads to be bonded are Active or
Inactive Metals (Ref: Cure Speed vs. Substrate on the second page). If material is an Inactive Metal, spray all threads with Permatex Surface Prep and allow 30 seconds to dry. Priming is not required if the material is an Active Metal. If unknown, it is always best to use the activator.
 
I think you'll be fine. Surely you are planning to keep an eye on those screws for a while, right?
Mark the screw heads and flange with something (white out, marker, etc) so you'll notice if they start backing out.
 
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