High mileage 4L80E oil leak

[seza]

Hi all,
I hope I can find some suggested solution to my issue,

my 1994 Chevy burban K1500 silverado with a 6.5TD and a 4L80E,
over the years she has been well used and now she is well into the high mileage club!

of late I noticed Trany oil coming mostly from the whole in the belly between engine and trany,
I replaced ATF oil and filter to no avail,
me thinks it could be the input shaft seal(s)?
absolutely - noway I can change the seal so I am looking at other options to somehow "renew" the seal chemically
without opening the unit?

.... or any other suggestions short a teardown?

 

[stutaeng]

Hi all,
I hope I can find some suggested solution to my issue,

my 1994 Chevy burban K1500 silverado with a 6.5TD and a 4L80E,
over the years she has been well used and now she is well into the high mileage club!

of late I noticed Trany oil coming mostly from the whole in the belly between engine and trany,
I replaced ATF oil and filter to no avail,
me thinks it could be the input shaft seal(s)?
absolutely - noway I can change the seal so I am looking at other options to somehow "renew" the seal chemically
without opening the unit?

.... or any other suggestions short a teardown?

Yes, could very well front main seal on the transmission if you know for sure it's ATF...or rear main seal of the engine? Transmission front main seal, unfortunately, does requires removal of the unit. Actually, either seal requires transmission and engine be separated to replace.

Let's see a picture of your truck. The CK/1500 with 6.5TD/4L80e are super rare here in the states. I actually forget these exist!

 

[seza]

Thanks Stutaeng, you right, 94 burban with 6.5TD is rare indeed, this one had an engine swap from gas to diesel by previous owner,
so far so good after nearly 15 years - 3 years with the original owner and the rest she has been with me.
Unfortunately - I am now in Algeria where I have no parts or knowhow to change the seals,
I was told one option is to try to make the ATF fluid bit thicker by adding some engine oil or hydraulic oil in the hope that it won't escape the seals as easily?

 

[stutaeng]

Thanks Stutaeng, you right, 94 burban with 6.5TD is rare indeed, this one had an engine swap from gas to diesel by previous owner,
so far so good after nearly 15 years - 3 years with the original owner and the rest she has been with me.
Unfortunately - I am now in Algeria where I have no parts or knowhow to change the seals,
I was told one option is to try to make the ATF fluid bit thicker by adding some engine oil or hydraulic oil in the hope that it won't escape the seals as easily?

Oh, I see. I wouldn't recommend trying to add additives to the ATF fluid to try to stop the leak. While it "may" help, there's passages and filter screens inside the valve body of these units that are very small. I feel like something is going to get clogged or reduce or cut off lubrication internally, causing a burnt up clutch.

So there's no mechanics in your area? With a transmission jack and a helper, you can probably remove unit, change seal and reinstall underneath the truck. The seal itself is only like $10 US dollars and can removed and replaced with a screwdriver and hammer.

Only complication is also having to remove the driveshafts and transfer case.

 

[seza]

There are mechanics but not many have seen this type of vehicles before let alone worked on it,
so what you are saying is that if I find someone who can:
1. remove rear drive shaft
2. remove transfer case
3. separate trany from engine
both seals (engine's and trany's) can be replaced?
all of that can be done from under the vehicle?

 

[stutaeng]

There are mechanics but not many have seen this type of vehicles before let alone worked on it,
so what you are saying is that if I find someone who can:
1. remove rear drive shaft
2. remove transfer case
3. separate trany from engine
both seals (engine's and trany's) can be replaced?
all of that can be done from under the vehicle?

Yes, essentially. I mean there's things like removing tranmission cross member, torque converter bolts, bell housing bolts, etc. But that's the general procedure, yes.

The vehicle just has to raised on ramps or jackstands to make room so you can work down there.

Do they have shops with lifts there? That would make it easier.

 

[stutaeng]

This is when I installed my transmission on my truck. It's on a transmission jack on a plywood sheet on my grass backyard. I installed it by myself (my 9 year old son helped a bit,) but it's better to have a helper. This is a heavy transmission.

This is a 2wd, so a bit easier. I don't know anything about the TD, but on most GM engines the rear main cover is right behind the flywheel. You can see it it on this gas engine.

Most critical step would be reinstalling the torque converter correctly. There's plenty of YT videos on that.

You can see on the second photo the seal. The transmission is upside down here.

 

[seza]

Thanks Stutaeng, you are giving me hope to keep this ol' gal going
The other issue I have is finding the right part (part number),
I just looked at Rockauto listings for crankshaft seals for the 6.5TD and I have a list of 7!

I know I might be asking too much of this great forum and of good people like yourself but
what I hope is that yourself someone else will point me to the right seals that are prone to going bad:

I have two oil leaks:

1. a preexisting one for many years where I noticed the dampness/occasional drip at the belly between engine and trany
2. and a more recent severe leak that comes from the same area but the oil looks/smells like trany oil

in your opinion what seals do I need to rectify both issues?

 

[stutaeng]

Thanks Stutaeng, you are giving me hope to keep this ol' gal going
The other issue I have is finding the right part (part number),
I just looked at Rockauto listings for crankshaft seals for the 6.5TD and I have a list of 7!

I know I might be asking too much of this great forum and of good people like yourself but
what I hope is that yourself someone else will point me to the right seals that are prone to going bad:

I have two oil leaks:

1. a preexisting one for many years where I noticed the dampness/occasional drip at the belly between engine and trany
2. and a more recent severe leak that comes from the same area but the oil looks/smells like trany oil

in your opinion what seals do I need to rectify both issues?

The front main seal are all the same as far as I know for all 4L80s. On RockAuto I think those 3 first seals look like they are the ones. The 4th item is for a different transmission, and the last item are the pump bolt seals. Gas and diesel show the same part (I was 100% sure they were the same part, just confirming.)

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Since you are removing the torque converter, go ahead and replace the o-ring on the input shaft, since those tend to flatten out and leak internally. I can't seem to find it here on RA though at the moment...I'll check later for you.

We do have some guys here running the TD. Maybe they can offer advice on the engine rear main seal... @smdk2500 @skylark @someotherguy have knowledge about them.

 

[seza]

you are a gentleman n scholar!