94 Explorer Transmission / Engine Problem

[rbinnslbg]

I have a '94 Explorer with a leaking transmission. The vehicle has 190k miles on it (amazing but it usually runs great).

I first noticed the problem last summer that the engine will run very hot (as shown on dashboard gage) and when this happens the transmission leaks fluid. In the winter the problem goes away with no leaking. I had the trans rebuilt 2 years ago. There are no problems with the transmission shifting as long as the fluid is kept full.

I'm not a mechanic and obviously with a vehicle this old I would like to keep costs down.

From reading the other posts I'm wondering if there might be a thermostat problem causing the engine / trans fluid to overheat??? Does this sound logical. I would obivously think a seal might be going but then wouldn't it leak in the winter when the engine runs cooler as well????

I would love to get some feedback on this issue before taking it into the shop and getting killed because of lack of knowledge.

Also, how complicated is it to change the thermostat. I have some mechanical ability and can do some simple maintenance myself.

Any feedback would be appreicated.

[Opera House]

It's a bigger problem than that. Your fluid loss is likeky the front seal leaking on the transmission. The transmission must be pulled to change that. This seal normally doesn't have any pressure on it. When it leaks is is usually because an alignment problem has worn out the bushings and excess fluid is leaking through them. There is a drain hole back to the pan that many drill out to a larger size to reduce this pressure. Bottom line is the last guys probably didn't do a good job rebuilding it. That is why you should always get a three year guarantee (or do it yourself).

You might want to try an extra cooler and an oversize pan. www.yourcovers.com has one for the A4LD with 2 extra quarts. The extra quarts might get you back home. Just replacing the seal is unlikely to fix it.

[rbinnslbg]

Thanks for the input. Can you help me understand why it would only leak when the engine warms up. Even in the summer it doesn't leak except when the engine warms up?? Could it be a combination of a bad seal and broken thermostat??

Or is the engine overheating just a coincidence??

[Opera House]

Well, is the engine really overheating? The problem usually happens when the engine is heavily loaded. It may seem connected because the engine will run hotter under load. TC will also unlock. The higher RPM will increase pump pressure. You never identified the location of the leak. If overflow tube, it could be water in the transmission from the radiator cooler. Many people report being able to live with it, but it is basically an alignment problem.

[rbinnslbg]

I really appreciate the feedback and would like to really try to understand most of the problem because like I said I'm not a mechanic and since I have just moved to a new area I will be dealing with a new mechanic who hasn't built up my trust as of yet. (So please bear with my questions even if they sound simple.)

I will try to explain the symptoms I see and if you could help me on where to look even closer that would be great.

When I start up the engine cold it runs fine. After driving in warmer weather I see the temperature gauge increase and even go into the red if I let it. (I usually turn on the heat which cools it down.) I guess that would be one question. Can a bad seal cause the engine to overheat???When the temperature gauge has raised I notice the leak coming from the front of the transmission (which would match your suggestion of a bad seal / alignment).

Is there something I'm missing that would cause the leak to come and go with the weather?? (actually I guess I mean the engine temp.)

Can you clarify what you mean by engine running hotter "under load"?? Does the leaking transmission cause the engine to work harder?? I don't pull a trailer or carrying heavy weight in the vehicle so the weight is not changing.

Also what are you referring to by "TC"??

Again thanks for all your help.

[Opera House]

Time for a new thermostat at least. Thermostats are a very common problem with Explorers. The TC is the transmissions torque converter that also has an internal clutch. It normally has a slip of around 300-500 rpm, but can lock up to incrase efficiency in third and overdrive. If the engine is overheating, I think it unlocks to increase engine rpm for better cooling. This is probably causing increased pump pressure in the transmission and causing it to leak more. At higher rpm slip (it can keep slipping up to about 2,000 rpm stall speed), the TC actually multiplies the torque of the engine. That is why you see higher towing capacity with an automatic with the same engine vs manual.

There are other things that can cause overheating like the fluid clutch for the fan. With the engine off, try spinning the fan. Should be fairly stiff. There are also clogged radiators. This is something you should take care of. These heads don't like to be overheated.

[RexNfx400]

Just want to add one thing, well, maybe two...There was, about 2 years ago, a bad run of front seals for many automatics, produce by National Seal.

Care to ask how many I had to eat? A4LDs, AX4Ss, E4ODs don't

(Its not a safety issue) nobody cares.

Anyways, this rig needs to run cool. Or at least at a respectable temp. The front seals in any Ford(nothing personal ok) will soften up and leak.
There is plenty of alingment issues too. As you said Opera.

The Front bushing is finished/machined while in the bell housing. Don't forget the crank spacer that is always broke and chipped too.

Keep it cool...Find the reason for running hot

[srercrcr]

Re: the 94 EXPL....
I think there are two separate problems. Solve the overheating first. Always go for the most obvious, least costly remedy first...that would be the thermostat.
Once the temp is brought under control, see how the leak is going. It could be a seal expanding from warming up.

[bmckay]

The Transmission fluid is cooled by fluid lines that circulate out of the transmission, through your radiator, and back to the transmission. When your engine is overheating your not only running the risk of damaging your engine but your transmission also! Fix the overheating problem! The transmission leak is most likely a mater of fluid and seals being overheated.

[homie774899]

it wouldnt hurt to change the thermostat i had that problem if i floored it the temperature would rise then when i slow down the temperature would decrease thats a symptom of the thermostat going bad. nothing that 5 bucks and 3 bolts cant fix.