My 1999 U320 has been in storage for 4 months. I went yesterday for my monthly "running of the Aquahot" and noticed that there was red fluid in the back passenger area. It is not actively leaking. I did not see it last month when I was there (but I may have just been in a hurry and missed it).
See pictures below. It has an oily feel (as opposed to a watery feel ) so I don't think it is coolant. I checked all dipsticks and everything looked good.
I crawled under to look it over and it is leaking through that heavy felt/rubber cover. I couldn't see where it was coming from, so any help would be greatly appreciated.
If not coolant, Could be tranny fluid. Looks like area under the radiators from your pictures.
Blot some up with a paper napkin, see if it burns. Trans fluid will, coolant won't.
If it is tranny fluid, where do I look for the leak?
It is coolant, there is no red tranny fluid on a '99. Looks like the lower radiator hose clamp might be loose.
Just realized that the Allison tranny fluid is red so the trans cooler would have red but. not under the radiator.
What type of antifreeze are you running as that sure looks like the radiator end cap gasket could be bad. I know you said it feels oily but some of the new antifreeze has a strange feel and has a red cast.
Mike
Fleetguard ES Compleat OAT
It may have felt tacky/oily because is was sitting there for awhile/
Same as what we use. The concentrated version definitely feels oily on my fingers, and is bright red.
You could check your white plastic coolant overflow jug (engine compartment) and see if the level is lower than normal.
Kevin, as Mike states it's probably the radiator end tank that is bolted to the core. There is one on each end of the core. Many of us on here have experienced this. On mine the first time it started to leak I was told to add 4 bottles of Bars leak and that stopped it for a while. Then it started again and my SIL saw traces of moisture at a few of the bolt heads you can see from the rear if you look close. Tightened as many as I could get to with a 1/2" wobble socket. That stopped it again. I wanted to replace the radiator due to overheating. I ordered a new one from FOT witch took 6 months. Be aware that the Bars leak may clog the trans cooler, I had quit a bit of Bars leak residue in mine. I was able to replace the radiator myself witch saved about $3,000.00. Jim.
Also check your bedroom aquahot heater register. It can easily drip down through. I have had 2 AH registers develop leaks, and one was dripping in the back underneath like yours.