Another coolant issue..

[Themoog]

Not long ago I had the thermostat replaced in my M62tu and last week I also had to pull off the main coolant hose going from the top of the water pump.
Today I was going to to put in a new timing chain tensioner so I removed the air box etc an noticed coolant all over the front of the engine.
The header tank was also empty.
I cleaned everything down, dried it all, topped up the coolant and have had it running for 30 min to pressurise the system.
As yet I cannot spot any leaks anywhere.
I thought it might be the seal on the water pump failed but it's dry.
Any ideas chaps?
I did notice that when I switched the motor off I could hear either air being pushed out of the filler cap but it's dry around that too.
Stumped. UK... 🤔

[Masospaghetti]

I would highly recommend getting a pressure test kit so you can pressurize the system without the engine running. I had a substantial leak that turned out to be a bad water pump (leaking from the weep hole) that would not show up when the engine was running because the coolant was evaporating on the hot surfaces. Here in the US, parts stores like Autozone will loan the kits out for free, but the kits aren't that expensive anyway.


It's much easier to chase leaks when you aren't worried about a hot engine or getting your arm turned to confetti by the cooling fan.

[Themoog]

Agreed. I'm going to the local garage in the morning so I can get them to take a look. It does need a radiator anyway as it's had a tiny leak for a few years right at the bottom corner.

[Themoog]

Found it. I think. Looks like the water pump seal and the pulley is chucking coolant across the front of the engine.

[Masospaghetti]

Awesome glad you found it!

[talljames]

This happened to me but it was the transfer coolant pipe which caused the issue. Of course I have had water pipe seal replacements. There is a kit you can get to fix the issue if it is that but there is a bit of work involved as you have to take off the inlet manafold. I had mine done by my trusty mechanic as I dont have all the tools.

The M62TU transfer coolant pipe in a BMW is located in the engine valley, specifically between the cylinder heads. It's a metal pipe that transfers coolant between the front and back of the engine. It's also known as the "water jacket" or "coolant transfer pipe"

Just thought I would let you know.

cheers