The Mystery missing coolant and Tranny O/D - shift problem.

[Dash Riprock]

A few days back there was a thread with someone who had found that their coolant was gone and was having shifting problems. I just wanted to confirm this problem and state my experience for others so far.

My wife's 95 XLT started having shifting problems a month ago. Same problem that is described on this site a 100 times over:

O/D light blinking, no O/D shifting. Clunking into Reverse hard. Other difficulties in the 1-2, 2-3 shifts...etc.

A check of the dipstick showed two things, both bad:
1. The tranny no longer contained Mercon V, in its place was some form of black coffee
2. The fluid level was nearly 2 inches above the fill line

The wife used to take this thing to a tune-up place while I was too busy with various other hobbies, but no longer.

I changed the fluid and filter. At this time I also found, to my amazement, that the radiator and catch tank were bone dry, or nearly so. I kept adding coolant and water til it finally topped off. Because I have spent my life working on motorcycles and manual transmission autos, it really didnt click about the radiator cooling the tranny fluid. However, when all the symptoms returned last week, and after readng this website, I was preparing to do the valve body overhaul described on this site or , gulp, shelling out 2-3K for a new tranny, when the light finally came on and I went and checked the radiator.

Sure enough, I couldnt see any coolant. I had to add 48oz to top it off and then fill up the overflow tank. I disconnected the battery to clear the fault, reconnected and drove around for a while. No O/D light flashing, good shifting. I was relieved, but now I have to find a coolant leak. Its not going into hte engine, no steam, no milky oil. Its not going into the tranny, fluid looks good. Where the hell did it go??

First thing I will do is replace the radiator cap. From there I will just have to keep watching for leaks, maybe associated with the heater??

So for anyone with the shifting problems, check your coolant. Apparently overheated tranny fluid will cause the fault described by so many.

If anyone can offer any advice as to the coolant leak, it would be appreciated.

By the way great site!

 

[Eneurb]

It's not too common for a radiator tank trans. cooler to fail. But when it does happen, a vicious cycle of transferring fluid occurs. When the engine is running, the trans. makes more pressure than the cooling system, so it pumps trans. fluid into the radiator. Then, when the engine is not running, the pressure in the cooling system is now higher than the in the trans. cooler, so it will push coolant into the trans. A few tell tale signs are rust on the trans dipstick, and a film of oil in the coolant degas bottle.

 

[Dash Riprock]

No rust on the dipstick and no oil in the overflow bottle. (Im assuming by "degas" bottle you mean the radiator overflow?)

I have looked for signs of leakage and the only thing I can find is a small area with some white residue. This is located beneath a hose connection that I believe is for the heater system.

The connection is located (described as you are standing at the front of hte car looking at the engine) just to the left of hte oil filler cap. There are two ~3/4" (~20mm) hoses that are connected and then lead to the firewall. At this plastic connection near the filler cap, is a small bell housing looking thing with a small mechanical arm below it. This is the only place I can find evidence of what *may* be a leak.

 

[Eneurb]

That sounds like the heater valve. Definately a very common leak area.

 

[Dash Riprock]

That sounds like the heater valve. Definately a very common leak area.

Bingo! I had the wife turn on the heater for the last 15 minutes of her drive home from work. When she pulled up I found moisture on the heater valve, right at the mechanical arm. I had her cycle the heat on and off and sure enough, when the arm moved, out dripped coolant.

Im so relieved its not the transmission.

Anyone know how much this valve should cost or if I can get it aftermarket??

 

[Eneurb]

In Canadian dollars it's 25.22... buy it from the dealer, part no. YG-350. Pretty simple to replace.