I topped up my water in the expansion tank yesterday,and today it the coolant low light came on whilst I was driving.When I got home a couple of miles later I checked and there was water pissing out of the top of the expansion bottle. It could just be the seal in the cap has gone ,or it could me more serious.The temp gauge wasn't rising and the car was running fine.There are rumours of the expansion bottles cracking but was wondering if maybe I've overfilled it resulting in splitting the bottle.Any ideas?.
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expansion tank leaking
- Thread starter bigshurv
- Start date
I might have done.I put in what I thought was the right amount,only a small amount to top it up.the next time I drove it it started pissing out of the top of the bottle.I'll have a look tomorrow when I get back from work and try to see what I've done,it's hard to do it right with a hot engine.But 3 times I got water coming out of the cap.
Kenwood732
Member
My 2003 Z4 2.5i. I had the smallest of leaks from the waterpump which I noticed during a chance inspection from under the car. No puddles, no noticeable loss of fluid, but a little droplet. I ran the engine while on the hoist and watched for 1/2 hour...the droplet remained but did not fall down.
Dealer quoted approx 300 canadian dollars to replace the water pump.
Next they call and tell me the reservoir has a leak and needs replacing, up goes the price. I Never had any fluid loss and with all my waiting for that elusive drip from the pump, there was NOTHING from the reservoir. I think they did the replacement as a pre-emptive measure, all the better while I was paying.
Next they call me and declare that the thermostat housing is leaking.
How convenient is that, three cooling related problems all at once?
Net result, over $1000 Can in repairs.
I should have gone with my first thought, a little bottle of "bars leak" in the rad would have fixed it for 5 dollars.
Dealer quoted approx 300 canadian dollars to replace the water pump.
Next they call and tell me the reservoir has a leak and needs replacing, up goes the price. I Never had any fluid loss and with all my waiting for that elusive drip from the pump, there was NOTHING from the reservoir. I think they did the replacement as a pre-emptive measure, all the better while I was paying.
Next they call me and declare that the thermostat housing is leaking.
How convenient is that, three cooling related problems all at once?
Net result, over $1000 Can in repairs.
I should have gone with my first thought, a little bottle of "bars leak" in the rad would have fixed it for 5 dollars.
Unfortunately these are common weak point in BMW's, due to them being plastic they tend to weak over time and eventually fail. I got a face full of coolant recently when my bleed screw decided to leak, i found out later that they often fail. The top breaks off the bleed screw allowing a fine jet of coolant to escape, the expansion tank can fail at the seam as can the radiator where the plastic joins the metal. Look for signs of white residue which signifies dried coolant. OP in your case you probably put too much water in, the cap is design to stop a high pressure build up and it releases if the pressure is too great. Don't know if anyone remembers all those E30s where people were being scalded in the passenger seat due to catastrophic coolant leaks, the fix bmw made was to put on a cap that can release the pressure.
I did see a really useful video explaining the weak points, i think someone on here posted it. I doubt bars leak will do anything to help plastic fatigue, a Z4 is worth more than that.
On a last note, I bought a spare Bleed screw if any fellow Z4 owners in Central Scotland get caught out like it did. The dealer was shut and i couldn't drive my car until i got a new bleed screw.
I did see a really useful video explaining the weak points, i think someone on here posted it. I doubt bars leak will do anything to help plastic fatigue, a Z4 is worth more than that.
On a last note, I bought a spare Bleed screw if any fellow Z4 owners in Central Scotland get caught out like it did. The dealer was shut and i couldn't drive my car until i got a new bleed screw.
bigshurv said:All fixed now. New cap.Easy really.
.....and did you top it up with the appropriate 'mix' or just plain tap water....?
A
Anonymous
Guest
Allright listen, I have a 2005 BMW E85 Z4 3.0i Sport Package and it runs like a clock. It first began with a radiator light on the odometer. On the next morning, I loosened the small screw to free it from air while filling it with OEM anti-freeze. After then no more air was coming out and the anti-freeze has began to leak so I tightened the small screw and closed the radiator cap.
P.S. You have to SLOWLY keep filling the expansion tank to the maximum with anti-freeze in order for the air to fully escape from the small screw. Once done, tighten the small screw and close the radiator gap. IF air is kept inside, the electric fan might not work properly due to the vapor gas that are preventing water from circulating. And thus, you might notice a temperature overheat.
P.S. You have to SLOWLY keep filling the expansion tank to the maximum with anti-freeze in order for the air to fully escape from the small screw. Once done, tighten the small screw and close the radiator gap. IF air is kept inside, the electric fan might not work properly due to the vapor gas that are preventing water from circulating. And thus, you might notice a temperature overheat.