3.Oi coolant leak - fan spray?

J

JSz4

Member
I noticed the coolant in my 2003 3.0i was lower than maximum so topped it up but after a drive spotted a small stain on the tarmac, about a foot back from the front of the bumper and in the centre, and drop of coolant hanging from undertray. From above the undertray looks damp in the centre and nearside and I noticed this dried spray on the side of the airbox:

https://www.dropbox.com/scl/fi/lghujjpemcbh38oyuc79z/IMG_1417.jpg?rlkey=bqqm8bz0ijpbnwumlghc61v71&st=dca8jqx2&dl=0

https://www.dropbox.com/scl/fi/htubdpz5mn7y8hlwwwexj/IMG_1419.jpg?rlkey=177s0akh3gs2jkkqw3wcmjb41&st=jex6frzk&dl=0


I cleaned the spray, went for a drive and noticed some wet specs again on the side of the airbox.

I had the thermostat housing and expansion tank replaced in 2018 (35k miles ago) due to leaks. Any ideas where this new leak could be coming from? I'm assuming the fan is blowing it back?

Thanks for any advice
 
Second picture is none too clear, but the first picture maybe fluid spinning off the aux belt rather than fan blowback so look for fluid dripping onto the belt.

I had a similar issue with my 2003 3.0i. Dried streaks of coolant all over the place, but after a drive wet/drips from the near side end of the radiator and also the near side splash guard. Absolutely no sign of where the leak was coming from. Anyhow, I took off the fan cowl to give a bit more visibility, made sure everything was bone dry then run the engine up from cold. As it started to get up to temperature, I could see a bead of fluid forming on the front wall of the reservoir, followed by a microscopic stream of fluid that looked just like a spider thread. I wouldn’t have been able to see it without a torch, but it was jetting water onto the radiator support and dripping down from there. I’ve now taken the reservoir off and there is no visible hole that I can see and it doesn’t leak when filled with cold water. Under pressure though, it’s obviously a different story.

If you can’t find a leak from an obvious joint or seal, this may be your problem.
 
Thank you both for the advice.

I think you're both right, having looked again it looks like coolant has perhaps dripped on to the belts and been sprayed nearside direction, over lower pipes and the side of the airbox. Guessing maybe the water pump is source.

Is it straightforward for a garage to replace a component, pressure test it, and guarantee they have definitely fixed the leak?

My worry is I have a track day in only 2 weeks time and I don't want the worry that the correct leak might not of been spotted.

Given it's on about 130k and I track it a couple of times a year, if the issue is the water pump, what are the other components that are worth refreshing at the same time as preventative work?
 
I would change the water pump and get them to pop a new temp sensor in as well as it’s two minutes work while they are in the area
 
Thanks, I asked them to. The garage said the water pump alone is £53 and the pump and fitting would be £240 including VAT.

Eurocarparts sell a Airtex water pump for my Z4 for £53 so assume this is the one they've ordered, is Airtex reasonable?
 
JSz4 said:
Thanks, I asked them to. The garage said the water pump alone is £53 and the pump and fitting would be £240 including VAT.

Eurocarparts sell a Airtex water pump for my Z4 for £53 so assume this is the one they've ordered, is Airtex reasonable?
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Never heard of them to be honest.
Whereabouts are you? Not too difficult a job really, just the need to jack the engine up a bit to clear the studs seems to scare people a bit.
 
enuff_zed said:
JSz4 said:
Thanks, I asked them to. The garage said the water pump alone is £53 and the pump and fitting would be £240 including VAT.

Eurocarparts sell a Airtex water pump for my Z4 for £53 so assume this is the one they've ordered, is Airtex reasonable?
Click to expand...
Never heard of them to be honest.
Whereabouts are you? Not too difficult a job really, just the need to jack the engine up a bit to clear the studs seems to scare people a bit.
Click to expand...

Thanks, I'm Dorset. I just let the garage fit it, I'd rather not of paid the labour and chosen the pump, but less than 2 weeks to track day and wanted time to be sure it was fixed. Can't see any dampness or puddles but just checked and marker well below minimum so hoping it's not still leaking and garage didn't fill it full enough
 
It’s likely the garage filled it full but there are some air pockets working their way through the system. Continue to check and top up after each drive until the level stops dropping. But obviously keep checking for leaks too.
 
Zedebee said:
It’s likely the garage filled it full but there are some air pockets working their way through the system. Continue to check and top up after each drive until the level stops dropping. But obviously keep checking for leaks too.
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Thanks Zebebee, that's reassuring, I will do. When I open the coolant cap there is a pressurised sucking sound which I didn't notice before so imagine linked to air pockets as you say. Will do some miles over the next week and keep an eye out for leaks.
 
That sucking sound will be vacuum in a pipe slurping coolant from the reservoir when the vacuum is released. It actually a good sign because it means you are unlikely to have a leak. Continue to top up until the level stops dropping. You can sometimes burp air out of the system by rhythmically squeezing the large top pipe, or the smaller bottom pipe that goes to the heater matrix.
 
I always fill the system with the front of the car raised to minimise air locks. Good chance the garage didn’t do this
 
enuff_zed said:
I always fill the system with the front of the car raised to minimise air locks. Good chance the garage didn’t do this
Click to expand...

That's annoying, will the air locks work their way through the system eventually?
 
JSz4 said:
enuff_zed said:
I always fill the system with the front of the car raised to minimise air locks. Good chance the garage didn’t do this
Click to expand...

That's annoying, will the air locks work their way through the system eventually?
Click to expand...
Should do, but you need to run it with the heat turned up too, to ensure the whole system can be purged
 
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