Expansion tank crack (not HGF - phew)

H

Hayesnmb

Member
Hey Guys,

Owned a 3.0l z4 2005 for just over a month now, About 2 weeks ago near the end of a long journey from North Wales to Yorkshire and back, noticed my 1st symptom of cooling system failing;

Towards the end of my journey, re-gaining the motorway pretty spirited I admit (hey only had the car 2 weeks at that point). I noticed the coolant low yellow light appear on dash. Went off after about 2 minutes only to reappear on and off again. Just as I got home the water temp shot up to max and red warning light sounded.

Next morning checked the coolant level and was just above the minimum so topped up.

Throughout that week the problem persisted and the low coolant level would appear more frequent. Checked the coolant level and all was still above minimum and no obvious loss of coolant on floor.

The water temp would behave perfectly when driving but as soon as I stood idle for 5 mins or more the water temp would creep up to max. As soon as I started driving the water temp returned to normal.

At this point I turned to the forum and searched for the below occurring symptoms;

Coolant light coming on and off
No heating in cabin
Slight loss of coolant but no wet patches
Engine over heating.

All the above brought up posts with the dreaded Head Gasket Failure. Having only owned the car for less than a month and bought private, I feared the worse!

The car went into a local Indy BMW specialist today and they found a crack in the expansion tank, they had originally thought it could be the water pump but all seemed ok after testing.

New expansion tank arrives tomorrow so can't wait to pick her up after the repairs.

Here's hoping
 
paulgs1000 said:
Phew indeed - glad it was a comparatively straight-forward fix. :thumbsup:

:driving: :thumbsup:
Click to expand...

Straight forward but a PITA to do. Good choice getting the Indy to do it. Getting the old one off the bottom bracket worried me!!
 
Expansion tank and thermostat are common weak points on the Z4.

Replaced both on mine, runs perfect now.
 
Happened to me. Exact same scenarios and I was puzzled.

Finally I saw a tiny crack spraying a mist of antifreeze out of the expansion tank.

Replaced the expansion tank, thermostat and water pump. Problem was fixed.

Note: had to unbolt the driver side engine mount in order to jack up the engine to allow the water pump to slide out. Otherwise the metal T frame gets in the way. Wear mechanics gloves when removing thermostat and water pump. That T frame cut the s**t out if my hands.

Don't even think about going to BMW. Unless you have your arm and leg on ice when arriving. Lol.

I make great money but don't give it away.
 
Yeah all sorted now, just picked up today from local Indy in North Wales.

New BMW expansion tank fitted, topped up with recommended coolant. £200 all in.

Just drove to Manchester and all is good, warm air in cabin and no coolant warning lights.

Here's to a nice run back home to North Wales on Sat evening, maybe a detour via the back roads rather than the dull M56/ A55.
 
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