Dana 20 Leak

[d89don]

76 CJ5 w/ T-18 and Dana 20

Had the Jeep for a few years. Just started leaking one day from the top just above the rear output.

I've circled the part that is leaking in red in this pic here:



I'm not sure what this piece is. A vent? This is my first Jeep.

The fluid that is leaking out is coffee colored like when oil has a lot of moisture mixed with it.

Speedo also recently stopped working above 20mph but I'm not sure if they are related.

Have you guys seen this before?

Any help fixing this would be appreciated.

 

[Posi]

It's a vent
You have a mixer of water and oil
Dump the Transfer Case fluid and add some clean 80/90

 

[d89don]

alright will do man thanks for the quick reply

 

[Lumpy Grits]

Keep an I on the tranny oil level. Not unusual for the tranny oil to be pumped into the t'case. Make sure the vent on both are clear and you can spin the cap on the vent freely.

LG

 

[tarry99]

Its More than likely leaking because the TC is now overfull with the extra water volume that it has ingested...........sometime in it's recent past someone must have done a stream crossing and submerged that vent............if deep water is in your future you need to remove that vent and any others on your axles and extend them up to the frame above with some rubber hose............also check your vented axles for water.

 

[Hedgehog]

For a long time there were transmissions that routinely shared oil, the passage between the Transmission output gear/shaft and the Transfer Case input gear/shaft were open allowing a normal transfer between both cases. Not so with a T-18 , the cases are separate with a seal between. There might actually be a correlation between the speedometer and the oil leak. The speedometer gear is held in place by friction between the output shaft and the gear with assistance by the bearings and preload. With some speedometer gears being plastic it is possible to loose enough friction to run the speedometer. I'm not sure how that might load the Transfer Case output shaft housing enough to cause the oil to leak from the vent though. There is no question that there is water in your Transfer Case , how it got there is a mystery that you should try to solve. Especially is there is enough water to cause an over flow situation.

I suppose there is a possibility that the CJ is being parked on a steep slope where the Transfer Case oil is pooling in the back of the case. Are you parking any differently form the way you have in the past?

 

[hagar]

For a long time there were transmissions that routinely shared oil, the passage between the Transmission output gear/shaft and the Transfer Case input gear/shaft were open allowing a normal transfer between both cases. Not so with a T-18 , the cases are separate with a seal between.

I wonder what that seal does then?
Keep oil in the Transmission ?
And what would happen if that seal were to fail?
hmm....

 

[Lumpy Grits]

The seal is supposed to keep the 2 separate. But, it's not uncommon if pressure builds in the tranny for whatever reason. That the tranny oil get's pushed into the t'case.
That's why, when you see the t'case is overfilled, to ck the tranny oil level.

LG

 

[Hedgehog]

hagar you sure got me on that one. I defer to Lumpy's answer. Yes, the seal could fail, but how likely is that compared to excess water in the Transfer Case . Especially when to OP says that the oil is milky. Also with the T-18 being essentially open on the top, at the shifter mechanism, along with a vent I'm not sure how pressure of the type that could blow the seal in a T-18 could build up. I also believe that both the Transmission AND the Transfer Case should be changed.

The answer to your question seems simple to me, the T-15 and T-14 (I don't know about the T-150 ) are open to both D18 and Dana 20 transfer cases. The T-18 and T-98 is sealed between. You ask why, my answer is, "Ask the engineers that made that decision originally." I know a long time mechanic that fills his T-15 /T-14 transmissions and D18/Dana 20 Transfer Case combinations by filling the Transmission /transfer cases through the top of the Transmission with the proper volume of oil to fill both. Never lost one doing that.

It has been noticed that some CJ's parked on a very steep hill can and will leak out of the rear Transfer Case vent. Unless a tube has been added to raise the vent above the Transmission .

 

[d89don]

Thanks for the feedback guys I'll make sure to check both the vents and change out the tranny fluid as well since I have no idea the last time it was done.

To answer your questions, this CJ hasn't been through any deep water in many years if ever. No idea how the water got in there but I do drive in the rain and snow quite a bit so that's a possibility, the shift boots are pretty shot.

I always park it on a flat level surface in the parking lot so that shouldn't be an issue.

Had to shovel her out of 18 inches of snow today so tomorrow I'll get in there and have a look.

 

[Hedgehog]

A lot of water gets in transmissions that never get near high water in an open jeep by running down the shift lever, NOT being deflected by the shift boot and entering the T-18 through the top, but that isn't the Transfer Case . The mystery only continues.

I bet changing the fluids will largely cure the problem.

 

[Posi]

I know a long time mechanic that fills his T-15 /T-14 transmissions and D18/Dana 20 Transfer Case combinations by filling the Transmission /transfer cases through the top of the Transmission with the proper volume of oil to fill both. Never lost one doing that.

Is that the same mechanic that's been working on CJ's for 40 years that still thinks fuel caps on CJ's are not vented? If he could ask an engineer, or checked the factory service manual he would know better.

Anyways, I wouldn't recommend filling your Transfer Case by way of the Transmission . The factory designed a Transfer Case fill hole for that reason.
Also, the Transfer Case (18) takes over 3 pints, and the Transmission (14) takes a little over 1 pint. There are so many variables why filling a Transfer Case by way of the Transmission is not a good idea that I won't go into it.
Of course this is the internet so I guess one could fill the engine oil pan by way of the Transmission as well.

 

[Hedgehog]

Well Posi as always, by goodness you are so very right.


...... Unfortunately I will ALWAYS believe what he says about any CJ. Unfortunately I might have been wrong about the gas caps. There was a transition in the time frame we were discussing in that thread, I might have been on the wrong side of that transition with my answer. I do know and will always state that the emissions people always check my as cap. My gas tank breaths through the tank vent and the charcoal canister. Also if the breather is removed as in removing the roll over mechanisms, and simply looping the two breather vent hoses back to the tank (which was popular at one time) can create an over pressure problem in the tank.

With the specific Transmission /transfer cases combinations I wrote about it IS a FACT that the excess oil in the Transmission WILL flow into the Transfer Case finding an equilibrium between the two. The oil DOES flow regularly between the two, they are designed that way. The T-18 DOEN NOT work in that way, never did , never will. Originally I only mentioned this because I have a friend with a T-14 /D18 that took great pride in filling his Transmission and Transfer Case with different oil. The flaw in that was the FACT that both share their oil. Obviously mixing the two. Go ahead and troll me on that to.

However if it were me I'd always drain and fill each separately no matter what Transmission /Transfer Case I have.

 

[Lumpy Grits]

Also, the Transfer Case (18) takes over 3 pints, and the Transmission (14) takes a little over 1 pint.

That's quarts-NOT pints.
LG

 

[Posi]

That's quarts-NOT pints.
LG

You have been overfilling your case
3 1/4 pints, NOT quarts.

 

[Posi]

There was a transition in the time frame we were discussing in that thread, I might have been on the wrong side of that transition with my answer.

If you were on the right side of the transition would your non-vented cap answer be correct?

I know a long time mechanic that fills his T-15 /T-14 transmissions and D18/Dana 20 Transfer Case combinations by filling the Transmission /transfer cases through the top of the Transmission with the proper volume of oil to fill both. Never lost one doing that.

First time CJ owner reading the above quote,
says he was a long time mechanic...
he never lost a tranny or Transfer Case doing it....
seems much easier.......
I'll go for it



I believe most would agree this isn't the correct way.

 

[Lumpy Grits]

You have been overfilling your case
3 1/4 pints, NOT quarts.

As per the TSM.
"T-14 3 speed Transmission - 1.25 qts - Grade SAE 80 gear oil GL-4"

How could it be overfilled, if it ain't to the fill hole? LOL
LG

 

[Posi]

Haha,

Factory service manual
Dana 18 and Dana 20 = 3.2 pints
Dana 300 4 pints
T-14 2.5 pints

 

[Lumpy Grits]

The TSM I read was a '74 that was online. Be dang if I can find it now

What FSM are you using for reference?
I'll ck my FSM, MR-252 to see how it's shown for the D/300.

Also have read where folks have used 50W non-detergent engine oil for the T-14 /15 tranny. Have you ever come across that?
LG

 

[Hedgehog]

Hate to be the one to bring this up, but we (yes, me included) are getting WAY off topic here.

I hope the OP is able to change the fluids and everything works out for the best.