So this evening, my wife asked what the pool of fluid on the garage floor under the front drivers side of the engine bay was.

Air con water, I confidently replied. Then she pointed out it was red!

Lifted the bonnet and this (upside down ipad picture) shows what I found. Much lost coolant, well below the range fill markers and on inspection, there was indeed a pool of red (pink) fluid on the garage floor. The coolant tank bleed screw had water droplets coming from it too.

No dashboard coolant warning though.

1. What would cause such coolant loss after months of no apparent issues?

2. Could this be connected to the recent SC water pump replacement?

3. Could any damage have been caused by this (I'll top it up with the correct mixture and proper coolant later this evening once the engine has cooled down and see what happens at it sits idle overnight!)?

So this morning, into a cold engine and cold coolant tank, I topped up the coolant within the range fill markers. It took about 400ml of 50/50 water coolant mix (Picture 1).

Then left the engine running in the garage for 1 hour and with a bone dry floor underneath the car.

Upon return, there was a pink pool of water on the floor under the engine bay (Picture 2)... And at that time, the coolant tank/ contents looked as per picture 3.

It does appear that all of this coolant is escaping via the coolant tank bleed screw which was wet and with fluid obviously having dripped down the outside of the coolant tank. After switching the engine off, I carefully turned (closed) the bleed screw which needed about a quarter turn before it seemed to be in a more closed position. Hopefully that is all that is going on and hopefully, when the SC water pump was recently fitted, the garage inadvertently left the bleed screw more open than it should have been left.

Still no low coolant warnings on the dash.

Fingers crossed!

Apologies for upside down ipad images.

Picture 1 (correct coolant level after top up):

It could be a crack in the tank/hose that opens up when the tank cools. Other option (and that happened to me) is that your engine oil / coolant heat exchanger has ruptured !!!

That is a bit more serious and will show up soon with oil / coolant sludge in the expansion tank (by that time there is a lot in the cooling system already). With me it didn't show up in the engine oil at all (I did have the engine oil changed after the new exchanger was in).

The early coolers (Baer, German make) of the gearbox (happened to other cars with the ZF 6HP26 as well) and engine oil were prone to corrosion failure due to internal corrosion and too thin material.

On my car the gearbox one went first, followed by the engine one a month later. Cause, pure water instead of coolant in the cooling system BLOODY MUPPETS.

The other option is air bubbles in your system but that should reduce the coolant and not force it out.

Another option is head gasket blown (white vapour from the exhaust) or an internal coolant leak that hasn't shown up yet but they don't explain why it is pushed out of the system on cool down. At least I can't think of a reason why at the moment.

Also check if the coolant sensor (bottom of the tank) is still properly seated. MY 2010 5.0 SC Galway green and sand interior!!
Have the Faultmate MSV2 Extreme to be tinkering with the settings etc. !!

Gazellio @ Prestige Cars wrote:

Gazellio @ Prestige Cars wrote:

^ Yes as I said 2005+ White Tank is PINK and 2002-2005 BMW Black Tank is BLUE.

My post was quite clear

WHITE TANK - PINK COOLANT ONLY

BLACK TANK - BLUE COOLANT (Could have been replaced with Pink)

This is based on experience only I am not a LR Service Agent

I'm not 100% clear on what you're saying here, do you mean I can't have green with a lemon twist?  09 TDV8 Westminster, Mariana Black, Rear seat entertainment, hatch bag and 2 slobbery mutts

The green coolant is suitable for aluminium engines, however, the orange is supposed to be bio-degradable and the green one is not. Or at least that is one explanation I heard.

So since I couldn't get the orange coolant in Nigeria (well for a decent price that is) I had them fill the system with the green coolant after the oil/coolant mix was flushed out completely !!! This is on the 4.2. The current one should be original orange (I hope)  MY 2010 5.0 SC Galway green and sand interior!!
Have the Faultmate MSV2 Extreme to be tinkering with the settings etc. !!

Thanks Eugene,

I'm sticking with the loose bleed screw theory at the minute because of the fact that:

A. The bleed screw was loose/ open and when the engine was running I could clearly see coolant discharge from that and also fluid trace lines from where the fluid had come out of the bleed hole and had been pouring down the outside of the expansion tank.

B. The garage recently did work involving the cooling system and that might explain why the bleed screw was open.

C. If it's not a simple DIY top up and bleed screw closure, Mrs pld will kill me if this car has got to back to the garage after only 3 weeks back with her (her reaction when I told her I was having 'keeping on top of things' new rear calipers, brakesdiscs and pads fitted was challenging enough to address)!

Ah, that makes more sense and sounds less sinister !!! Hope that is the case.

By the way, how does the back look ??  MY 2010 5.0 SC Galway green and sand interior!!
Have the Faultmate MSV2 Extreme to be tinkering with the settings etc. !!

Cheers Eugene... Hope I'm right!

The back? New. Very nice to be fair

 MY 2010 5.0 SC Galway green and sand interior!!
Have the Faultmate MSV2 Extreme to be tinkering with the settings etc. !!

As above; if the system is not very well flushed. the mix of coolant will create a brown sludge that clogs galleys in the water jacket and will give major headaches!

Thanks happym... Okay. Assuming I've got more than a [bleed] screw loose with this car

What should I be checking for the presence of brown sludge please (though I'll say it again, the pink on my garage floor is so clean it looks like I've just poured it out of the bottle and the car has new rads, new water pump, new pipes/ hoses, you name it, it's all new!) ?

If it's clean I'd say

The sludge is pretty grim and can be seen sometimes as dirty specks in the coolant.

Hmm I'd put it in offroad mode and have a good look and feel around with a torch and fingers to look for damp.

I'm inclined to wonder if its the tank istelf as even with a clean regularly swapped coolant the bottom parts would proably have some kind of gunk. If it's really clean it may be from high up.

Good luck!

Steve

coolant colour?

if its a 'boy' engine it takes blue, if its a 'girl' engine, it takes pink!

when you don't know what your going to get, you play safe, and get some yellow!

 MY 2010 5.0 SC Galway green and sand interior!!
Have the Faultmate MSV2 Extreme to be tinkering with the settings etc. !!

Well, it seemed (although the jury was still out) to have stabilised from the point of not depositing pink coolant all over the garage floor overnight. Was hopefulnmost of the ongoing deposits up to midday yesterday were remnants of coolant fluid that had poured out of the bleed screw hole and had dripped down the external of pipes, down the engine bay and escaped out via various under tray holes.

Despite sitting cold overnight,the range fill markers were still bereft of pink coolant this morning (pictured) although the top of the tank had coolant in it as pictured.

Put about 300ml coolant in a short while ago and ran the engine for 2 minutes to try and release any air locks via the bleed screw. Despite towelling round the bleed screw and then opening it with the engine running, then found a small pool of coolant on the floor via the under tray holes so don't know if it's this morning's deliberate bleed screw discharge or coolant leaking from somewhere else when the engine is running. Now out if coolant!

Tank looked like this after sitting cold overnight: