transmission must be leaking.... but from where?

[iLoveMyExploder]

a couple months ago I posted about my transmission, thinking it had burned out. short and sweet story: I was about 15 or 20 miles away from home and started smelling something weird- for about 5 miles. stopped at a parts house and put a quart of fluid and a bottle of lucas transmission fix in the transmission, as it was a quart and a half low- I assumed it was leaking, but I did not see any leak underneath it in the parking lot..... then went on to towards the house. then there was smoking.... really bad smoking just got worse as I kept going- with a smell I still cant recognize- and a black cloud trailing behind me. really had to push the engine to try to maintain speed- even with the tranny topped off, it had trouble shifting properly and maintaining speed. So i got the truck to the house and hadn't really fooled with it since- I assumed I had burned up the transmission driving it like that....

yesterday I went out to start it up and let it run a few minutes, then decided to check the fluids. again, the transmission was low- by a quart. I had half a bottle of lucas transmission fix sitting around..... so I put that in the transmission- along with half a quart of transmission fluid. then for ***** and giggles, I thought I would drive it around a bit. took it around the neighborhood (3 miles) at low speeds (no more than 30mph)- then onto the farm road (one an a half mile) to see how it acted during highway speeds- it performed normally as if nothing was wrong with it.

then I parked it- with the engine still running, I actually crawled underneath it trying to find leaks.... I could not find any! .... but if it is losing fluid- then it must have a leak somewhere, right? I got to thinking, maybe a transmission line might be broken and leaking/spraying fluid out only while the truck is in motion? possibly spraying it onto a exhaust pipe, explaining the horrible smoking it did the previous time I drove it? I didn't see any evidence of this, but its difficult for me get underneath it to get a good look since im so damn fat.

where could it be leaking from? blown gasket? busted a line?

...but I did see something unusual- there was some kind of metal tube hanging down at the transmission and going upward toward the engine- this tube seems to be free standing underneath there- not too far from the transmission pan- on the left hand side between the transmission and the parts for the front wheel drive parts.... there are no other tubes around it from what I could see- so it does not appear to attach to anything else under there. also, the other two (2wd) explorers I had do not have this. is this metal tube part of the 4WD?

thanks in advance for answers and advice!

 

[larrydd999]

Does the metal tube connect to the transmission? There should be two small diameter metal lines, supply and return, filled with transmission fluid to be cooled. The circulation is to the driver's side of the radiator (to the transmission cooler tank attached to the radiator) then to a secondary heat exchanger in front of the radiator, and then back to the transmission. There are also a couple of hoses involved which are under the radiator support (as I recall). I wonder if you have a leaking hose or a break in the metal tube? If you had a missing or disconnected hose you'd be down more than a quart rather quickly. Anyway just a thought.

 

[Maniak]

The a4ld has a metal vent line that goes over the top of the transmission and has a hole over the top (good way to get water into the trans if you drive through deep water).. Is that what your seeing?

There is also a line that goes from the passenger side of the transmission's (vacuum modulator) to the vacuum tree on the engine. If the diaphram in the modulator goes bad it will suck up transmission fluid and burn it off in the engine. It will also make the vacuum hoses at the engine soft and pop off giving you vacuum leaks etc...

Here's a random video I found on youtube showing how to replace the vacuum modulator...

This is assuming you aren't leaking on a transmission cooler line (assuming you have one... but IIRC if you didn't have the tow package you won't have one stock).

~Mark

 

[OneofMany]

Failed vacuum modulator. Was an issue when I first got mine too. There is a metal vacuum line going from the modulator to the vacuum tree with just a short piece at the vacuum tree, pull that line off and see if it is oily inside. chances are it is. It will suck the trans fluid into the engine and part of it burns, the rest ends up in the engine oil. BAD! There is a write up on here somewhere on how to change the vac modulator on this forum. If not, I will tell you how. Fixing that will fix your shift point issue. As to the electrical issue, I suggest diagnosing the circuit.

 

[iLoveMyExploder]

thank you all for the replies! .... another explorer I had turned out to have a vacuum modulator issue, but I didn't find out what the problem was until after the truck was stolen- so I never got to fix that problem and learn how to do it. on THAT truck, it would not shift properly when the engine was cold and had been sitting for two or more hours.- I had to race the engine to make it shift, and after that- it would shift normally until the engine cooled down for a couple hours. it also did not suck up trans fluid into the engine. that was a 2wd transmission....

THIS truck seems to shift normally all the time- could it still be the vacuum modulator? when I researched this before, they said it was a common problem for these trucks. when the modulator fails, can it cause a number of symptoms, or just one?

is it possible the transmission would leak only when the transmission is working to move the truck... like maybe a weak gasket that opens up enough to leak when the pressure builds up?

could one of you possibly post a photo of the vacuum tree, pointing out exactly which line goes to the transmission? that would be most helpful!

I am planning to go out and do a little work on the daily driver car (pt cruiser)- I will also crawl underneath the truck and take a photo of that metal tube i was talking about- maybe one of you can identify it? this tube DOES go up along the firewall to somewhere around the engine, but I couldn't tell where exactly it goes to. the other end just sticks out- all by itself... no other tubes are near it- and it does not seem to connect to anything....

 

[iLoveMyExploder]

This is assuming you aren't leaking on a transmission cooler line (assuming you have one... but IIRC if you didn't have the tow package you won't have one stock).

~Mark

it does have a transmission cooler. I will start it up and see it theres any leaks coming from anywhere underneath the front end.

another transmission question: I have a parts truck, it is a 1992, which also has a transmission cooler. I was thinking about taking the cooler off of the parts truck and putting it on the 1993 4X4- so that it would have 2 transmission coolers. if I did this- I imagine it would be even better for keeping the fluid cool, but would it have a negative effect on performance?

 

[iLoveMyExploder]

Does the metal tube connect to the transmission?
........ There are also a couple of hoses involved which are under the radiator support (as I recall) .

the metal tube im talking about is not connected to anything on the transmission and there not any other tubes near it- as if it is supposed to be connected to anything else.

the transmission hoses you are talking about- that carry fluid, are they made of metal or rubber?

 

[Rhett]

the metal tube im talking about is not connected to anything on the transmission and there not any other tubes near it- as if it is supposed to be connected to anything else.

It needs to be connected. The hard line running along the side of the transmission, up into the tranny tunnel toward the engine, is the hard vac line providing vacuum from the manifold to the trans.

It needs to be connected on both ends. One end goes into the vacuum modulator on the side of the trans, and the other end connects to the upper intake manifold vacuum "tree". If it is not connected, get some vac line and connect both ends.

Hopefully that's what you are talking about there.

 

[Maniak]

it does have a transmission cooler. I will start it up and see it theres any leaks coming from anywhere underneath the front end.

another transmission question: I have a parts truck, it is a 1992, which also has a transmission cooler. I was thinking about taking the cooler off of the parts truck and putting it on the 1993 4X4- so that it would have 2 transmission coolers. if I did this- I imagine it would be even better for keeping the fluid cool, but would it have a negative effect on performance?

As long as you run the fluid through both the coolers AND the heat exchanger in the radiator you should be fine. The heat exchanger not only cools, but warms the fluid in winter.

You can fit 2 coolers up there but you may have to make your own mount. I'm running 2 coolers AND I put in a fan out of a Geo Prism (Toyota Corolla) that runs when the transmission is not in lockup.

Transmission-cooler-misc 003 by maniak_az, on Flickr

If you did find your transmission was over cooling (not likely) you can get bypass valves that will keep the fluid from going into the 2nd cooler until it is warmed up.

Another upgrade to the transmission is to put in an external filter. Basically, it's a remote oil filter mount (used the same filter as your engine) and you plumb it inline with your cooler lines. I change mine every 2 oil changes. This filter is much more fine than the screen in the pan and you are replacing 1 quart every time you change the filter.

~Mark

 

[iLoveMyExploder]

Another upgrade to the transmission is to put in an external filter. Basically, it's a remote oil filter mount (used the same filter as your engine) and you plumb it inline with your cooler lines.

yes, I saw "natenkiki" post about the external filter with success stories. I intend to do that project when the funds are available- as well as adding in that 2nd cooler from the parts truck. the fan blade on the 4X4 needs to be replaced as well, and I plan to replace it with the brand new one the parts truck.... make a weekend project out of it.

 

[iLoveMyExploder]

It needs to be connected. The hard line running along the side of the transmission, up into the tranny tunnel toward the engine, is the hard vac line providing vacuum from the manifold to the trans.

It needs to be connected on both ends. One end goes into the vacuum modulator on the side of the trans, and the other end connects to the upper intake manifold vacuum "tree". If it is not connected, get some vac line and connect both ends.

Hopefully that's what you are talking about there.

it really doesn't look like it connects to anything.... it just sticks out like a sore thumb with no other tubes or connections anywhere near it... I still haven't gotten around to getting up under there and taking photos of it- (haven't been doing too well lately)... but perhaps I will go do it tomorrow since we are supposed to have great weather the next couple days.
...then you guys can literally see exactly what I have been taking about. its weird since none of the other explorers I had don't have that tube there. this is my first 4x4 vehicle

 

[iLoveMyExploder]

..... when the transmission is not in lockup.....

what does that mean?

 

[Maniak]

what does that mean?

The torque converter has the ability to lock. Think of the torque converter as 2 fans facing each other and one powers the other by spinning the fluid. There is wasted power in the converter and when locked it is mechanicaly locked so power isn't lost in the converter.

~Mark

 

[iLoveMyExploder]

ok.... i finally was able to get all the way up underneath it. took photos of the tube I was talking about. pix of that tube here:

https://www.facebook.com/media/set/?set=a.1818896228361519.1073741836.100007234783548&type=3

while underneath there, I noticed transmission fluid all over the place. it was on the front half of the transmission pan. it was all over the back half of the oil pan, and all on the bottom side of the oil pan. it was all over the one side of the oil filter (the side facing the transmission)... and it was on pretty much everything between these areas... so it must be leaking in the areas between the transmission pan and the oil pan. I looked at all the hoses and lines, all the ones I could see seemed to not be the source of the leak.

I pulled off all of the vacuum lines from the vacuum tree on the intake manifold. none of them were oily inside- made sure of it using q-tips. ...

also- while I was under there- I had the engine running at least 5 minutes- still no sign of a leak. did the same thing again, only with the E-brake engaged, and in gear (R),..... still no visible leaks.... but there is evidence of a major leak of fluid spraying out all over the place under underneath there. any ideas where it could be coming from?

 

[iLoveMyExploder]

when the transmission is not in lockup.~Mark

is lock up a good thing? normal?..... I don't know much about engines.... and even less about transmissions.

 

[Maniak]

ok.... i finally was able to get all the way up underneath it. took photos of the tube I was talking about. pix of that tube here:

https://www.facebook.com/media/set/?set=a.1818896228361519.1073741836.100007234783548&type=3

while underneath there, I noticed transmission fluid all over the place. it was on the front half of the transmission pan. it was all over the back half of the oil pan, and all on the bottom side of the oil pan. it was all over the one side of the oil filter (the side facing the transmission)... and it was on pretty much everything between these areas... so it must be leaking in the areas between the transmission pan and the oil pan. I looked at all the hoses and lines, all the ones I could see seemed to not be the source of the leak.

I pulled off all of the vacuum lines from the vacuum tree on the intake manifold. none of them were oily inside- made sure of it using q-tips. ...

also- while I was under there- I had the engine running at least 5 minutes- still no sign of a leak. did the same thing again, only with the E-brake engaged, and in gear (R),..... still no visible leaks.... but there is evidence of a major leak of fluid spraying out all over the place under underneath there. any ideas where it could be coming from?

That hard line is part of the transmission vent. It goes up/over AND it has a hole in the top.

So, Either it's pressurizing the transmission and venting fluid out the vent line OR as you are describing it, I'd think it could be coming from the front pump in the transmission.

I haven't had an a4ld transmission in years so I can't remember if there is an inspection port/lower cover in front of the trans near the bottom. IF there is, you can open that and see if it's full of fluid. If it is, you have a bad front pump seal which means the transmission comes out to fix it.

Don't worry too much about the lockup. I described what it is in my previous post but in short it lets you get more power from the engine to the wheels (less wasted power) and creates less heat than when the torque converter is slipping.

~Mark

 

[natenkiki2004]

The only inspection port is where the starter goes in. Nothing in the bell housing or anywhere else unfortunately.

 

[iLoveMyExploder]

....If it is, you have a bad front pump seal which means the transmission comes out to fix it. ~Mark

...does that mean the transmission would have to be dismantled to replace the seal? ..the local transmission man says if he has to take a tranny apart- he will just rebuild it- not optional (at least with this guy)... but the plus side of that is it will be under a warranty.

so if it is venting fluid out from the line (assuming the top, since fluid is all over the place under there), what does that mean? is the problem still the front pump, or something else? if the seal is bad, does that mean the pump is also bad?

 

[iLoveMyExploder]

...does that mean the transmission would have to be dismantled to replace the seal? ..the local transmission man says if he has to take a tranny apart- he will just rebuild it- not optional (at least with this guy)... but the plus side of that is it will be under a warranty.

so if it is venting fluid out from the line (assuming the top, since fluid is all over the place under there), what does that mean? is the problem still the front pump, or something else? if the seal is bad, does that mean the pump is also bad?

 

[natenkiki2004]

Dismantled? No but it will need to be removed. The pump seal is in the bell housing and is visible once the torque converter is slid off the input shaft. However, the pump seal is something easily screwed up by someone not familiar with the A4LD. I certainly wouldn't pay someone to remove my transmission, replace the seal and re-install it. The vast majority of your money would be going towards labor time removing and installing the trans. If you remove and install it yourself, it can be a worthwhile gamble.