Replacing coolant reservoir in 3.0

[PersonaNonGrata]

I recently replaced the coolant reservoir, or tank, in my 3.0. I had been losing coolant for some time and suspected the cause was the typical cracked leaky reservoir and that is what it was. After looking for information specific to the 3.0 I wanted to post some observations.

I bought the replacement tank from Bavauto. It was about $55 which is great but it was not OEM. I also bought a new cap and bleed screw in case they were worn and potentially leaking. I also ordered a new level sensor which sits at the bottom of the reservoir and in my case, appeared to be a potential source of the leak. That was about $17. The non-OEM cap was $12.

I confirmed the leak in a few ways including seeing small pools of coolant on the driveway and under the X5 when parked. I removed the under tray and poured out accumulated coolant. I observed quite a bit of congealed coolant right under the reservoir and with no evidence of a leak up top, the leak was from the bottom. There appeared to be coolant leaking out around the level sensor.

Removing the coolant tank was not difficult but more of a pain. I had to undo the air intake and MAF and push it as far out of the way as possible to get clearance to pull the reservoir out. On the bottom end, there is a large hose that is held by a sliding clip. That needs to be unclipped and the wire leading to the level sensor needs to be disconnected. This hose on the bottom will be disconnected when the reservoir is pulled out from the top.

There is a hose about midway down on the right side that needs to be disconnected. That hose is also clipped on and will be disconnected. This is the first hose I disconnected. This hose will spew coolant so have a container to catch it.

There are two hoses on top of the reservoir that need to be disconnected. The bigger of the two is a bit tricky because there isn't much room to work. It just takes some patience.

To get the reservoir out I got a good angle from above and wiggled the reservoir until it popped out and disengaged from the bottom hose. With the reservoir free it was a matter of maneuvering it out around the air intake rubber boot and hoses.

Replacement was just the reverse. I just made sure that there was a solid pop when it went connected with the bottom hoses and that all other hoses were fully connected.

I inspected my old coolant reservoir and expected to see a crack or other obvious defect but there was nothing obvious. It may well have been leaking from the level sensor connection but there could also have been a crack because the quantity of coolant loss was pretty significant. The reservoir doesn't really hold that much but when you are refilling it everyday it seems like a lot.

Sorry but I didn't bother taking pictures. I just wanted to get the job done.

[mywidebody02]

On the V8 the level sensor is sealed and doesn't have anywhere to leak. It's just a tube no the expansion tank that the sensor slides into. So if you took out the sensor out nothing would come out.