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R380 front cover assembly. Leaking

10K views 21 replies 8 participants last post by  LostChord 
#1 ·
So I fired up my motor for the first time, ran great but it was pissing trans oil from the bellhousing. Like streaming not just a drop

The trans is a rebuilt r380. I pulled it out this am and popped off the front cover. Once I took the bottom two bolts of the front cover order it started leaking and when I popped the cover off it really emptied

The input shaft seal is there and seems fine. The best I can tell the shaft is straight but I didn’t look overally in depth at it

It seems like the leak is from the bottom bearing. Is there supposed to be a gasket or RTV between the front cover and the face of the gearbox? Or is that bottom bearing supposed to have some sort of gasket. Here’s what it looks like as I took it off. There was just the slightest amount of rtv it seams like but really minimal. Almost like it was left over from before being rebuilt
 

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#5 ·
Yup - that what I was looking at. Put some RTV on it and bolted it back up.

Will let it dry and fill it up tomorrow, and try to put a drill on it to spin it and make sure it that was the issue before i put it back on. Also a good time to run the motor without the bell housing and make sure my rear main seal snt leaking at all

thanks guys

PS - sucks seeing $75 worth of brand new royal purple MTF on the floor!!!
 
#6 ·
Well. Cleaned the cover and mating surface. Put on generous amount of rtv, and spun it with my drill. Within a few seconds I had a steady drip from the input shaft. Must be the input shaft seal. This was with most of the trans fluid out too. So with it full I’m sure it would pour out

Guess I have to replace the input shaft oil seal
 

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#8 ·
I think I figured it out

The front seal looks fine and the spring around it is there. However the spacer that should have been used is a FTC2737. Which is “stepped” and i presume presses the seal against the front cover, preventingnoil from going around the seal on the outside. Instead what was used is, what looks to be the spacer from a lt77 that has a groove for an o ring, which mind you is not present and wouldn’t work here

New spacer in order from UK, along with new front seal just bc. Hopefully this is it

All this hassle over some $3 parts.

Starting to question the integretity of the rest of this rebuilt trans....
 

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#9 ·
FTC2737 is not in that location. It goes between the input shaft and the mainshaft. Pretty sure nothing should be there. The bearing goes into the race and that is it. You are holding the bearing race, not a spacer. The bearing is STC1628 and that looks correct.
 
#11 ·
OK- i was going off what rovers north told me and it kind of made sense. I thought FTC2737 was a race but the back side stepped


So what should the diameter of the pinon be and should there be an O ring in the groove aorund the outside of the race?
 
#12 · (Edited)
Two other things. Looking at the pic from when i took it off. The seal is facing with the metal ring side toward the gear box. That seams like it would be correct but can we confirm?

Also - should that seal be pushed ALL the way in or just left flush with the back face of the cover.

That same pic shows it was flush with the back face, and i think it should be pushed all the way in to help seal against the cover.

Looking at the manual i see this:

9. Fit oil seal to front cover. Ensure seal is fitted
down to shoulder. Apply Hylosil RTV 102 to
front cover as shown.

I think A there was no RTV applied and B it wasnt pushed all the way down.....
 
#13 ·
Oil seals face outward, the spring side inwards. Just think of it with pressure behind the seal the pressure pushing against the rubber making a seal.
 

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#14 ·
OK - that makes sense to me... and makes the spiral grooves on the inside of the seal push the oil BACK into the gearbox...

What doesnt make sense is A. what is maintain pressure on that seal to keep it firmly against the front cover? I presume just a friction fit from when its push in initially? Also the bevel on the inside diameter of the seal is then facing OUT towards the engine. You would think it would face toward the gear box but then the spirals would be going backwards.

New seal comes in tomorrow. I'll push it all the way down, bolt it back up, and give it another test.

Thanks all for the help guys
 
#15 · (Edited)
This is one thing that's kind of different between an LT77 and an R380 rebuild manuals - and it's something that confuses me a little. OK. A lot :)

On the LT77, I had to take great pains to make sure that the end float of the pinion shaft was correctly set.

I had to lap my own shims to get what is essentially zero end float.

The front cover on the LT77 looks virtually identical to the R380, but there _are_ shims in the LT77 gearbox and they serve a very important purpose.

The LT77 pinion/input shaft has two taper cone bearings - one supporting the pinion shaft on the cover side, and another supporting the pinion shaft and the main shaft simultaneously. There should basically be zero (or close to zero) end float and preload on those two bearings, the logic being that if there is preload, the bearings will heat up, and if there is end float, the input shaft will wobble about, causing bearing wear and input shaft seal leaks.

Why does the R380 not have this shimming step in the rebuild manual? How can it guarantee that the end float on the pinion shaft isn't so bad that it will wobble around?
 
#17 ·
Thanks John...I see that in the manual, but it still doesn't quite answer my question.

To me, this means that Land Rover is so confident in the manufacturing of the mainshaft, bearings, castings, and pinion shaft that simply by measuring end float at the mainshaft, you're guaranteed proper end float at the pinion shaft?

What changed between the LT77 and R380 that allowed this to happen?

Adrian, how much wobble/wiggle did your input shaft have when the front cover was bolted into place?
 
#20 ·
I put a new input shaft oil seal in, this time I coated it with rtv per the manual and made sure it is seated all the way into the front cover. As the manual explicitly says. Spun it with a drill and no leaks!


Kinda worried that who rebuilt this trans missed such an obvious and simple step. Now I just need a hand getting it back in the truck and the build can continue.
 
#21 ·
All gooda!
 
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