Teflon tape on differential drain plug

[matthewr87]

I am getting ready to change the fluid on my differential. I have seen a couple of videos on Youtube where the guys wrap teflon tape on the drain plug before reinstalling it. I looked into the procedure in the Ford shop manual and I did not see this mentioned. Is it necessary? Thanks

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[Mustang_Lou]

I've used Teflon tape whenever I need a tighter fit with some anti-seep properties so can't see it hurting at all.

In fact, when the gasket on my Krups espresso maker went and the steam started escaping out the lid, I was able to keep using it by wrapping teflon tape around the threads of the part the lid threads into. It's been a couple of years and still perfect.

And the location of the threads means there's no possible way of any teflon impurities getting into my coffee (in case someone points that out lol).

 

[matthewr87]

Anyone know if this is part of the official Ford procedure? I am just worried about the teflon tape bits getting into the differential fluid over time.

 

[03reptile]

Anyone know if this is part of the official Ford procedure? I am just worried about the teflon tape bits getting into the differential fluid over time.

I recall reading something that counseled against using Teflon tape in this application; just can't be remember where!

 

[bluebeastsrt]

Anyone know if this is part of the official Ford procedure? I am just worried about the teflon tape bits getting into the differential fluid over time.

An automotive manufacture will never recommend the use of it for that very reason.

 

[Point45]

If you're worried about it Teflon sealant is what you want. Just don't glob it on there, a small dab is all you need.

But I have never used sealant on any drain plug, just a new crush washer torqued to spec

 

[ctandc72]

Yeah, I wouldn't use tape. If you want to peace of mind, use some teflon paste. A new crush washer has always done the trick for me.

 

[ModularKid21]

I used it on mine without issue. I got the kit OP mustang sells and it comes with it. If you’re getting tape inside the diff, you’re doing something wrong.

There is no drain plug washer for the diff plugs btw

 

[NoXiDe]

Testing age of the removal plugs, remove the fill plug first to ensure it can be removed to prevent headaches down the road.

Remove drain plug and allow it to drain.

Reinstall drain plug (25 lb /ft of torque (34 Nm)) then remove the Fill plug
Caution: If the cooling line was used as the drain method, that is 17 lb\ft of torque when reinstalling the plug.

Fill with Material: Motorcraft® SAE 75W-85 Premium Synthetic Hypoid Gear Lubricant / XY-75W85-QL

Then fill with clean friction modifier
Material: Motorcraft® Additive Friction Modifier / XL-3 (EST-M2C118-A)

Install diff fill plug and torque to 25 lb ft. (34 Nm)



That's the gist of it. I encourage you to purchase the service manual especially for a bad ass car like this.

 

[Strokerswild]

Another vote for teflon sealant, as it's a pipe thread.

However, they usually have a dry sealant applied originally, and the remnants plus proper torque should do.

 

[jgruben1134]

Remove drain plug and allow it to drain.

Reinstall drain plug then remove the Fill plug

Fill with Material: Motorcraft® SAE 75W-85 Premium Synthetic Hypoid Gear Lubricant / XY-75W85-QL

Then fill with clean friction modifier
Material: Motorcraft® Additive Friction Modifier / XL-3 (EST-M2C118-A)

Install diff fill plug and torque to 25 lb ft. (34 Nm) & torque drain plug to the same or if it is the cooling line it's 17 lb ft (23 Nm)

That's the gist of it. I encourage you to purchase the service manual especially for a bad ass car like this.

I'd switch those first 2 steps if I were you. If you somehow can't get the fill plug out, better to still have fluid in the diff.

 

[CJJon]

Teflon tape is for toilets. I don't think I have ever used it on a car (in fact, I know I haven't)

 

[NoXiDe]

I'd switch those first 2 steps if I were you. If you somehow can't get the fill plug out, better to still have fluid in the diff.

I agree with this post. There is always opportunities to do things better and this is one great example. I've adjusted it.

 

[Hack]

I wouldn't use teflon tape for an automotive application. I once did that on an oil pressure sending unit on a Fox Mustang. Scared me to death when I was driving around a month or two later and the oil pressure started fluctuating all over. Luckily it was just a bit of tape blocking off the sending unit.

I use the paste.

 

[JAJ]

I am getting ready to change the fluid on my differential. I have seen a couple of videos on Youtube where the guys wrap teflon tape on the drain plug before reinstalling it. I looked into the procedure in the Ford shop manual and I did not see this mentioned. Is it necessary? Thanks

So, I've changed the diff fluid every year for the last four years on my 2016 GT350. My experience is that:

There is no drain plug on a GT350 diff - the drain plug hole is where Ford put the outlet line for the diff cooler system. The easiest way to drain the diff is by removing the snap ring on the lower pump line fitting and pulling the lower hose off. Don't bother with taking the fitting out of the diff (the service manual shows this, but It's not necessary).

The fill plug works just fine without any additional treatment. It has no tendency to leak because it's not submerged in oil like a drain plug would be. Take it out, fill the diff, put it back in and tighten it up. Personally, I WOULD NEVER use teflon tape on a steel plug going into aluminum. Teflon lowers the friction and you could crack the expensive and hard to replace housing if you snug it up too much. Besides, there's no benefit.

If you drained it as I described it above, then it takes 56 ounces of fluid to fill the diff - 4 ounces of XL3 and 52 ounces of Motorcraft 75w85. The correct level is 9mm below the bottom of the fill hole. DO NOT overfill it.

Forscan runs the diff pump just fine. The instructions that @NoXiDe posted above don't include this important step. You refill the diff, put the fill plug in loosely and run the pump for a minute or so to get air out of the cooler lines after the fluid change. After you've run the pump, use a piece of bent wire as a dipstick and check the level before you put the fill plug in for good.

As an aside, I advise everyone to take any YouTube advisors words with a grain of salt - a big one. I was looking yesterday at a video of how to flush the brakes on a BMW F26 chassis. The video I watched was great - everything I needed to know so I could do mine - except that if you do it his way, you only get about half the fluid changed.

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