Thread sealer on differential drain and fill plugs?

[HoosierDaddy]

I was checking fluid levels a few days ago and discovered my dealer put red loctite on the diff fill plug in January after they drained my Torsen diff because they thought it had failed when the wheels did not turn together on a lift.

Having no idea they put Loctite on it, it took a breaker bar to remove it.

I mentioned that to the service manager thinking it was a mistake and he emailed me to say the manual calls for that. I had replaced the fluid long before with BG and I am positive they didn't have any sealant from the factory nor did the plugs show any of the stuff they put on some new bolts that activates when compressed the first time.

Anyone else ever heard of this? I have what supposedly is the factory service manual and mine does not have ANY mention of Loctite other than one place where if says to make sure old blue Loctite is scraped off of some part before installing some other part. I'm not too happy with a manual that doesn't mention what Ford claims are critical steps. The Service manager says I just need to heat them to 550 degrees when removing. Again, back to my service manual, how the heck is someone supposed to know there is red Loctite that needs to be heated to 550 degrees?

Do you use sealant on these plugs? I'm 70 and don't think I have EVER used any.

If you DON'T, have you ever had one leak or loosen if properly torqued (25 ft/lb in this case)?

Here is what the Service Manager emailed me from their manual:

Here's what my plug looked like after I wire brushed most of the red Loctite off:

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[kent0464]

That’s crazy. I never loctite drain plugs, and certainly not with red.

 

[atomicpunk]

Just use Teflon thread sealant paste, it's a tapered pipe thread.

 

[JohnVallo]

I tend to agree @HoosierDaddy that the Retaining Compound (Red Loctite?) should NOT have been used on the threads of the plugs.

The service manual entry they emailed you appears in the "Specifications" part of the Rear Drive Axle/Differential section, (The Retaining Compound is just listed Along With the fluid specifications), If it were me, I would look to see where it was called for to be used. -Which I did-

The only reference to Actually Using the (WSK-M2G349-A8) Loctite is Here :

I have purchased new (Magnetic) Drain/Fill plugs from Ford and they have a reddish rubberized/Vinyl coating on the threads for sealing
It is not anything like Loctite

The only compound I have used on the Plugs after removing them is the Grey Motorcraft Gasket Sealer compound. It has never failed me and I have never had any leaks or a hard time removing them again.

 

[GT Pony]

Here's what my plug looked like after I wire brushed most of the red Loctite off:

Sure that red stuff isn't just the sealant that the plug comrs with, as shown in the post above? The shop could have just over torqued the plug.

I always just use Teflon tape and torque to manual specs.

 

[HoosierDaddy]

Sure that red stuff isn't just the sealant that the plug comrs with, as shown in the post above? The shop could have just over torqued the plug.

I always just use Teflon tape and torque to manual specs.

I was going to ask if anyone else found that on the factory plug or just replacements. When I changed to the BG fluid I do not recall any on the plug.

And as noted, the dealer confirmed the tech did use red sealer in January.

 

[HoosierDaddy]

I tend to agree @HoosierDaddy that the Retaining Compound (Red Loctite) should NOT have been used on the threads of the plugs.

The service manual entry they emailed you appears in the "Specifications" part of the Rear Drive Axle/Differential section, (The Retaining Compound is just listed Along With the fluid specifications), If it were me, I would look to see where it was called for to be used. -Which I did-

The only reference to Actually Using the (WSK-M2G349-A8) Loctite is Here :

I have purchased new Drain/Fill plugs from Ford and they have a reddish rubberized/Vinyl coating on the threads for sealing
It is not anything like Loctite

The only compound I have used on the Plugs after removing them is the Grey Motorcraft Gasket Sealer compound. It has never failed me and I have never had any leaks or a hard time removing them again.

Thanks. I'm beginning to think the Ford service manual isn't much help. Why doesn't the factory service manual NOT say to heat the plug to 550 degrees to remove it? And I sure didn't have any trouble removing the plug or drain when switching to BG before the dealer got involved.

And I discovered why I didn't see what the dealer sent me in my service manual. After I got that from him I was searching for the sealer. Guess what? My service manual has no reference to it. Armed with your name of the section, I went there in my copy and no mention of any sealer at all. I can only guess Ford added that later, probably after one fell out after just being put in finger tight. On the plus side, it not being in an earlier version of the manual tells me its NOT a must do.

I did a search thru my manual and "heat" must appear a bazillion times. So after wearing out the "next" on-screen button, I switched to "Heating". Never saw any references to heating a fastener.

 

[BlackandBlue]

What kind of idiot thinks it’s “ok” to put red locktite on drain bolt of any type?

A plug of that size could easily hold beyond the shear strength of the square used to remove it with red locktite on it.

Be glad they didn’t clean the oil off the threads or it most likely would not have come of without 482 degrees on it.

I would seriously question why someone of (hopeful) that experience level would think this is “ok”. I think the proper response is to understand red Loctite has almost no applications on a car in a thread locking capacity. Blue on the other hand I use on basically every bolt a mess with on a vehicle.

 

[HoosierDaddy]

This is getting more interesting. I looked up Loctite 638 as specified in my dealer's and @JohnVallo's service manual and..... Ready for it?

The TDS says it is a GREEN liquid. https://tdsna.henkel.com/americas/n...8836AB931A10882571870000D859/$File/638-EN.pdf

Also, it does not appear to be designed for threads. The characters "thread" never appear in the TDS.

Since the manual reference never says where or how it is used, I'm starting to think the manual may be referring to some other parts in the diff.

I need to figure this out before asking the dealer who confirmed they used it how it turned from green to red.

 

[TicTocTach]

^^^^ This right here. It doesn't seem like 638 is the right product at all, but does make sense for the ring gear application shown in the manual. It doesn't seem like there should be any sealant or locking compound used on a drain plug, and the rubberized coating on the replacement plug would be sufficient to prevent loosening by by vibration - as you'd expect.

 

[dguzzi]

I learned long ago (industrial mechanic) the color is not a good reference for Loctite products. Last time someone argued with me I showed him the yellow stuff. READ the label!
The dealer in this case is using general knowledge that is incorrect.

 

[HoosierDaddy]

As expected, reinstalled with no sealer and zero seepage at mid-point and end of 5k road trip.

Unrelated but after the trip car has much more front rise or rear squat on acceleration than before. Hope its from more power in the considerably colder air after the trip than some issue with springs/shocks.

 

[GT Pony]

Unrelated but after the trip car has much more front rise or rear squat on acceleration than before. Hope its from more power in the considerably colder air after the trip than some issue with springs/shocks.

Yep, cold dense air means more HP.

 

[Stang 19]

I was checking fluid levels a few days ago and discovered my dealer put red loctite on the diff fill plug in January after they drained my Torsen diff because they thought it had failed when the wheels did not turn together on a lift.

Having no idea they put Loctite on it, it took a breaker bar to remove it.

I mentioned that to the service manager thinking it was a mistake and he emailed me to say the manual calls for that. I had replaced the fluid long before with BG and I am positive they didn't have any sealant from the factory nor did the plugs show any of the stuff they put on some new bolts that activates when compressed the first time.

Anyone else ever heard of this? I have what supposedly is the factory service manual and mine does not have ANY mention of Loctite other than one place where if says to make sure old blue Loctite is scraped off of some part before installing some other part. I'm not too happy with a manual that doesn't mention what Ford claims are critical steps. The Service manager says I just need to heat them to 550 degrees when removing. Again, back to my service manual, how the heck is someone supposed to know there is red Loctite that needs to be heated to 550 degrees?

Do you use sealant on these plugs? I'm 70 and don't think I have EVER used any.

If you DON'T, have you ever had one leak or loosen if properly torqued (25 ft/lb in this case)?

Here is what the Service Manager emailed me from their manual:

Here's what my plug looked like after I wire brushed most of the red Loctite off:

Interesting...I took out my filler plug to check the oil level and the filler plug has Loctite on it.

 

[GT Pony]

Interesting...I took out my filler plug to check the oil level and the filler plug has Loctite on it.

I'd think it's thread sealer instead of Loctite. I see no reason for any kind of plug like this torqued to 25 ft-lbs (manual spec) to need Loctite. The manual shows no mention of using Loctite on the differential drain or fill plugs.

https://cardiagn.com/2015-18-ford-mustang-rear-drive-axle-differential/

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