I am going to say its transmission fluid. For a while now I have had this going on where there is a puddle on the driveway. Obviously it's a slow leak. So I took some pics to show how the fluid is all over everything on the bottom. However a bigger concern I have is there is a hose I am seeing that is open on the end and I saw that fluid had been coming out of it. Does anyone have any insight on this hose and if its supposed to be this way and what it is for.... thanks (After researching I realize this is most likely a vent tube. but i dont know if its the transfer case vent tube or transmission vent tube)

I also got the P0420 code which is Catalyst system efficiency below threshold. I hit on the middle catalytic converter and heard the metal moving around inside. I have ordered a new Catalytic converter.







HERE IS THE HOSE

 

I guess no one here has a clue either then.

 

I'm not sure it is, could be a vent tube. I would start by monitoring your fluid levels. It is obviously either transmission of transfer case fluid.

 

yes, when driving. esp at higher speeds on the interstate. I can hear the rpms going up and down a lot. and I can see it on the gauge at times too.

 

Ok. so that was from about 3.5 quarts of transmission fluid being low. However, I dont know why I have fluid coming out the vent hose. I assume thats why its all over my under carriage. I know its been getting pretty hot here and temp gauge has been going up more. I plan on getting an oil cooler too. maybe that will help.

 

I believe that is a breather line. It should have another hose connected to it which will be higher than the transmission it self.

 

someone said they end up on the firewall in a recent post?
idk.

 

That is the vent line. The transmission is getting too hot and puking out the fluid. Usually a sign of eminent transmission failure. Common on the 4L60E. Or you have been working the transmission hard. I have an external trans cooler installed on mine to help prevent overheating.

 

I just ordered an external trans cooler yesterday which is on the way. I have bigger tires and am doing about 80 on the interstate monday through friday... temps are high with index of 105 to 110.

 

Sounds like you are overworking the transmission. The cooler should fix the problem. My 2006 H3 is mostly stock. Up here in Canada it only hit 33 degrees (Celsius) and I usually only do 115 on the highway (kilometers per hour). So I can't compare.