Rear diff thread sealant?

[subyboy]

Hey all, just a quick one.

 

How important is it to use thread selant/Teflon tape when re-installing the rear diff plugs? Is it absoltulety essential or will I be OK without it?

I've already done the oil change and drove the car a few miles and couldn't see any leaks. Will it be OK after a longer drive with the diff warming up?

 

Cheers,

 

Jean

 

PS: What's stopping the plugs to screw all the way in when they look straight, ie without a head to stop them going all the way in?

[porcupine73]

Subaru calls for Threebond 1105 (can find here though I see you're in Australia...), or alternatively 3M T-3 silicone which is probably available at the parts stores.

 

I have used sealant (permtex ultra grey) and have not used sealant and haven't had any leaks either way.

 

You should use a sealant because the threads are tapered, sort of like threaded pipe. The taper is what keeps the plug from being driven all the way into the diff. It's not a straight thread like on a bolt. So even when in at the ideal number of threads of engagement there is still a potential leak path between the thread crest and roots.

 

[kevinsUBARU]

I have never never ever ever used a sealant on differential plugs. Differential oil is what...75w90? That stuff is H E A V Y !!!!

 

You'll be fine...just clean the threads before you put it back together.

[idosubaru]

i've never used sealant on the plugs either, i did not know you were supposed to. hmmm, talk about learning something new....that's almost funny. how in the heck do you clean the old threads out without getting debris in the diff then? that sounds annoying.

[Rooster2]

I have checked the rear diff fluid level, and replaced the bolt with no leakage afterwards. Like said earlier, the lube is really thick stuff, and very unlikely to leak out past the bolt threads.

[82glsw]

I never used sealants either. If you look at the chart it says impreza only not sure what makes them different though.

[idosubaru]

If you look at the chart it says impreza only

i think that's only for the "bearing cap", not the diff plugs.

[fnlyfnd]

I've never used sealant either

[srs_49]

I just did both my diffs. Didn't use anything on the front drain plug, but used some Permatex Thread Sealant, P/N 59214 on both the drain and fill plugs on the rear. Will let you know in another 100,000 miles which plugs come out easier:).

[porcupine73]

You don't need any sealant on the front diff plug because that is straight threaded with a sealing washer; it does not rely on leaktight threads.

[srs_49]

You don't need any sealant on the front diff plug because that is straight threaded with a sealing washer; it does not rely on leaktight threads.

 

Ahhh, right! I knew there was a good reason I didn't use the sealant on the front diff:rolleyes:.