[Jagaer]

Just under 160k kms on my E91 (N52), have not replaced the pump or thermostat. (Have both on-hand, as I expected them to go out)

It appears that the Thermostat Housing is Leaking. But before I dive in and replace the thermostat and pump, I wanted to ask for a second opinion from those that have already replaced theirs once - Just to make sure that it is in fact the Thermostat Housing and not one of the hoses (since I don't have all the hoses on-hand)



It appears to be a slow leak, so I think I've got a few days before it becomes an urgency, in case I do need to order a few more hoses etc...

[moantreal]

I recently did my thermostat and waterpump. After replacing them I still had coolant leaks from two of the hoses that connect to the thermostat. Those plastic connectors warp overtime and need to be replaced as they wont seat properly. I ended up having to replace the lower radiator to t-stat hose as well as the lower coolant tank hose cause it connects to the t-stat as well. Better safe then sorry. Order those hoses!

[Jagaer]

moantreal Thanks for the tip on the hoses, I'll take a look at them while I'm in there.

I believe the source of the leak is a cracked thermostat - Maybe the bolt expanded as it rusted, cracking the housing and creating a slow leak.



As an aside, the job isn't too difficult. It just takes a lot more time in the winter...(Garage is insulated but not heated, so it was only 3C in there... had to take a number of breaks since I kept getting my hands wet/cold with coolant)