[CarGuy954]

So I have received a low coolant warning this morning. I have been smelling coolant ever since I removed the pump to install the charge pipe. I did have some coolant spill during the installation and hosed down the area. I just figured the smell was coming from the spillage and kept checking for leaks but, could not find any.

At this point I am not sure if I should take it to BMW or an outside shop. I have seen plenty of videos that BMW will not warranty any work unless the car has been put back to stock, even if the problem is unrelated to the modifications.

My second option is to add some coolant and see if I can locate the leak. Then determine if I can fix it myself or if I will need to have a shop repair it. However, looking at some CSF heat exchanger videos from Kies Motorsports there seems to be a process when adding coolant. Can I just add coolant to the reservior?

[CarGuy954]

So after watching a few videos, we can add coolant to the reservoir. I will top it off and try to see if I can locate a leak this weekend. I did see some white spots at the bottom of the engine, which looks to be under the water pump. There is a strong possibility the water pump seal is bad, which has a chamber to capture the blow by. Once it fills to capacity it is design to flow out. The reservoir cap did not have any residue, so I dont believe there is an issue there. I also dont smell any coolant or see any white smoke in the exhaust. So I dont believe there is a turbo or head gasket issue. If it does happen to be the water pump I would be shocked as I only have 21000 miles on it and I am not out racing it every weekend. Maybe a few spirited pulls from time to time.

[CarGuy954]

The pic below shows a leak and it is just below the water pump drain. I did run my finger over the drain plug and it had a small amount of crystalized residue. I did get the engine up to temp and ran up the rpm's but could not get it to leak again. I believe its happening after a long drive. I will investigate further this weekend.

When I picked the coolant from BMW, I spoke with the guys in the parts department. There first answer was its very common to burn a little coolant and I should check the reservoirs every 4 to 5months. When I told them my findings they believed it could be the pump as well. When I told them my mods and asked how service would handle the warranty, they rolled there eyes and said the will try to void you warranty with a spoiler install if they could. So I will either do it myself or source it out to a licensed BMW shop near me.

[TheSalmon]

My 2020 M340i with 35k on the clock just recently had a similar problem. BMW technicians diagnosed the issue as a defective water pump. This was replaced under warranty, but just barely.

[CarGuy954]

Stock or modified

[TheSalmon]

Only modification is a Dinan exhaust.

[Seba77W]

Same issue. 2021 M440i 19k miles. Stock. Leaky water pump replaced under warranty.

[Fudz]

Just noticed my engine coolant was low last night. Dealer has topped it off and asked me to watch it to see how long it takes to fall and report back.

This was an image from last night. Turbo circuit is OK. The indicator is quite low in the bottle but no warning given.

2023 M340i 8k miles.