The Transmission Story

I have alluded to telling more about our transmission transgressions. Finally here is the story, which is probably too technically boring for some people. Right girls?

We always have to keep a diligent eye on the transmission fluid level. It seems to just disappear, more so after a tough uphill drive in the hills and mountains. I had examined the transmission and couldn't find where it was leaking. It was just not a big deal that would hold us back as long as we had lots of transmission fluid on hand. I would often have to a add quart or liter so I carry a couple of jugs to keep up. We got through last year's trip without problems but sooner or later this had to be addressed.

When time and inclination met, I got on the Internet and Googled for information. It seems that these transmissions (GM 4L80-E) can overheat and spew fluid out a vent on top of the transmission. Hah! That is why I couldn't see the leak, as I was always looking for drips from below.

Now...how to manage this situation.

See the vent pipe and notice the traces of fluid atop the tranny housing.

Add a line to the vent and a bottle to catch the overflow. Now we can be sure of how much fluid is being lost. Note: After the first drive, the bottle got deformed from the heat coming from the exhaust pipe so I had to re-position the bottle further aft. Good thing we didn't invest much in the bottle which was an empty dish soap bottle.

$23 7" electric fan in front of tranny rad.

Now we have to augment the cooling for the transmission fluid. While the transmission has it's own cooling radiator in front of the engine radiator, it has no fan to boost the cooling when driving slowly or while stopped in traffic. We could also have changed out the tranny rad and put in a larger one. We opted for the fan to avoid any plumbing issues with a new rad.

$30 adjustable thermostat

While we were staying in Benson AZ, I ordered an electric fan and thermostat from vendors on eBay. I got them installed prior to leaving for Tucson. The thermostat will turn on the fan when it reaches a preset temperature and turn it off when the temp drops back to normal. All I have to do now is set the thermostat to come on when the overheating condition starts.

Transmission temperature gauge.

Then I picked up a transmission temperature gauge at Pep Boys (cheaper than buying on eBay) and installed that in the dash. It won't help the cooling but will allow me to stay on top of the issue when it arises. I thought the installation of the temperature sensor was going to be a messy job. Thankfully, when I took out the plug on the side of the tranny, only a little dribble came out and I was able to get the sensor in without losing more than a few drops of fluid. I can now set the thermostat to come on when the temp rises above the normal operating temperature.



Hopefully the fan will be enough to solve this fluid loss problem but time will tell if a larger cooling rad is necessary. If so, it will have to wait until we get home in the spring.