[Sracs]

Hi,

Wondering if anyone's had this similar problem. It's a 2006 4-dr 325i with around 177,000 km.

I've tracked my car several times with no issues until last spring. We were doing 20 minute sessions when around 15 mins into my first, I got a yellow temperature warning that quickly went to red. I got the car off the track just as it began steaming from under the hood.

With the hood open, I could see it had sprayed coolant from around the coolant cap all over the engine bay. It was easy to see that's where the leak was from a perfect spray impression on the inside of the hood. There didn't seem to be any other leak, so I cleaned the car up, topped up the coolant, tightened the cap and carefully took it back out next session.

Same thing. 15 mins into the session I got the warning again and took the car off the track to see exactly the same spray from the coolant cap under the hood. I again topped up the coolant and drove 7-minute sessions the rest of the day without incident.

After the track day, the car was fine under normal driving conditions. No leaks, no warnings, nothing out of the ordinary.

With another track day approaching, I read up about the problem here and elsewhere and figured it was likely the coolant tank cap failing - so I bought a brand new OEM cap from a local BMW dealer.

Only the exact same problem happened again on my first track session. The car's fine for about 15 mins of lapping, then BLORP - it vomits up a mess of coolant from around the coolant cap. Every time. But under normal driving, nothing.

Any ideas? Should I replace the coolant tank now if I want to keep on doing track days? Or could this be a water pump problem? I'm still on my original.

Thanks,

S.

[Bamaben]

Since replacing the cap didn't solve the problem it's likely an over pressure issue which could be head gasket or WP starting to fail. Get a peake research scan tool to be able to read and clear codes yourself. The WP codes won't show on a standard reader. At least you could rule out the WP and start diag the HG. At 177km I'd replace the WP asap especially if tracking it

[Efthreeoh]

Sounds like the water pump doesn't like track days. Scan the car with a BMW scan tool and look for the water pump trouble codes. The codes will tell you at what KMs the pump intermitantly failed. If the codes are present, the repair is replacement of the water pump.

[Sracs]

Ok, great. Thanks for the info. I'll either pick up a reader or get my independent to do it.

S.