4.8l e70 small amount of coolant on the ground when backing out the garage
 

Twice as I backed out of my garage and saw a small trail of coolant on the ground. Looked under the car but it’s no longer leaking, but there’s a drop hanging from underneath the cover on the passenger side, which is where it came from. Then I take it out for a good drive and it doesn’t leak anymore. Any ideas?

sounds like the valley pan. Leaks around the front wheel area left or right

Probably need to take all the lower pans off, rinse everything off with water and then take it for a drive then inspect. Be careful though, I did this exact thing and wiggled a hose and a plastic fitting crumbled and it sprayed hot coolant everywhere. Luckily I didn't get burned too badly.

So this might be a silly suggestion....are you sure it's coolant? I've noticed our E70 really dumps out condensation from the AC. If it's soon after we drove it we'll notice the puddle under the car, and next morning it's common to see trails of drips down the driveway as we back out. Really stressed me out first time I saw it as I just assumed it was coolant.

True but if you havent done valley pan....

Lol.., yes, haven’t done valley pan. At least not that I’m aware of but the truck’s only got 50k miles on it.

And good point by nanniepoo, but. O, it’s deffinitely blue antifreeze.

I’m jus wondering, other than the valley pan, could there be a coolant connection somewhere around the right side of the engine that’s causing the leak. I was working down there a month ago while replacing the alternator.

Being a 4.8 it could be the internal coolant tube too. Leaks out a weep hole in front of the engine then down. When it first starts happening, no idea until low coolant warning. Then gets progressively worse until you finally see a drop on the ground on the passenger side of the car.

This internal coolant tube is visible after removing the valley pan, no?

Yes, it is but you can't tell it's leaking by looking at it there. The vulcanized o-ring attached to the OE tube starts coming off and that is what causes the leak.

Being that the tube is 1 piece you need to cut it out. Then use an expandable replacement like the one from All German Auto in Escondido, CA. That's what I installed and not an issue since. A bit of work but not too drastic. They even have a good video and instructions on their site. 11-14-1-439-975 BMW N62 Coolant Pipe | AGA Tools

Might as well kill 2 birds with one stone then, right? A new gasket for the VP and the expandable pipe put in. Just not as pleasant of a situation when trying to fix an ongoing problem then another one pops up. I barely even drive much on the truck after inheriting it.

forgot to point out, I think my expansion tank is leaking too.

Obviously, make sure you check all your hoses and connections too. Would be a shame to do the pipe and valley pan, just to find out it was your upper radiator hose all along (or coolant tank/hose). Of course, changing the pipe and pan gasket isn't a bad thing. :D

If you get the kit from AGA it comes with a new valley pan.

Guess I lucked out tonight as I found out the leak was coming from the sensor of the lower radiator hose.

A lot less work and money to fix that one. :D

Yes sir it is.. There's a lot of corrosion on the electrical connector as well as the sensor itself, which leads me to believe that this is an ongoing issue. I've been seeing from time to time, this puddle of water usually behind the front passenger wheel, but just never thought much of it. And someone has pointed out to me that this problem could very well be the reason for the existing problem on the truck, the multiple faults and hesitation that doesn't seem to go away even after replacing the negative cable from BMW or installing a brand new Valeo alternator. This has been a battle for months to find the cause of. I sure hope this is the culprit and I will find out this weekend when the factory sensor arrives in the mail. Wish me luck guys.