I have a 2010 535i that has a coolant leak. I found it several days ago and when I opened up my hood, there was coolant on my reservoir tank. It seems like it is leaking out of my expansion hose. My issue is that the hose and the tank were replaced in Feb of 2020. Before I go any start replacing anything else I would like to see if anyone here has experienced the same problem and what they did to fix it. I am a brand new BMW owner who likes to do their own repairs and I really don't want to take it to a dealer to figure it out

Thanks

MD

 

Either too much coolant and it bleed out or seal on cap. If you have a pressure tester you can pressurize the system to see where it leaked from. Since there was no pic uploaded I can only guess. You can also check to see if there is a crack in it also. Some manufacturers products don't last long. Also there is no hose on top so the cap area is where I would pay attention.

 

I had the same exact thing happen when my water pump was failing. It should be throwing codes if it is.

 

Here are the pictures. It started leaking three weeks ago and I had to fill the reservoir tank with new coolant. It does not happen all of the time however when it leaks, it is quite a bit.

This is one of the most recent puddles

Here is where the coolant pools on the tank after I found the leak

This is the back side of the hose where I have seen coolant could be leaking out of

 

I assume it only happens when hot and under pressure. When you look around while engine is running and is hot do you see any steam coming out of those hoses?

 

Looks like a bad hose. Check at operating temp if you see a leak or steam. You may have to pump the hose (use your hand to force pressure) to see if it is the hose itself that's bad

 

It never leaks when it has been sitting for a long period. No steam comes out of the hoses when it runs and it is not. It does not leak when it is running. I have checked many times. The only time it leaks is after I have driven it for some time and I park it in the garage. Basically it leaks when the car cools down.

I have bled the system several times to make sure the air is out of it. I have also not seen any steam out of any of the hoses when it is running.

I purchased it off of a friend of mine and he said that a dealer did the work. The water pump was replaced in 2019 by the same dealer. The only thing that is different on my car then in the videos I have seen on YouTube is the cap on the reservoir tank does not "click" or have arrows

My thought is that it is a bad hose however I don't want to spend the money to replace something that is not the problem . I also have a hard time believing a hose that was replaced in Feb of 2020 would go bad.

 

Yep mine looked exactly like that and leaked only when running as well. Its the pressure from the heat. It'll release out of the top. Check the codes.

 

I might be color blind, but that coolant in the picture looks green.

Our synthetic Pentofrost NF coolant is always blue.

Are you running the right coolant in your car?

 

That's what I was thinking just didn't say anything.