Water loss / useage

1

1972nail

Member
Our 43K 3.0L is using or loosing some water. I know of all the probable leak sites from reading the forum threads and possible head gasket problems but none of these seem to apply in my case. It seems to be using about 300ml between weekly checks. I haven't let it get so far down that the warning light comes on.

I assume that a new rad cap would be the first port of call? Could inadequate bleeding cause this too?
 
When you say 'would inadequate bleeding cause this' .............has any part of the cooling system been worked on?
 
vester86 said:
Where does the water go? On the plate under the engine, or into the motor & burnt??
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Hard to say where it goes. The tray has some oil spill on it and was a bit wet today from washing. There are no tell tale white marks in any of the usual places so I'm assuming it's just a weak cap. The oil is clear and there is no 'steam' from the exhaust.
 
Toe-side said:
When you say 'would inadequate bleeding cause this' .............has any part of the cooling system been worked on?
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Service book says it had an oil and coolant change at about 40K. We've just owned it for a couple of weeks (private purchase) so can't say any more than that.
 
I'd put money on it bing a cracked expansion tank. There won't be any evidence as it tends to steam out.
 
There may be a period when the system drops level but that should complete quickly. Look for signs of leakage as you already have.
Smell for hot coolant after runs by lifting bonnet.
cj10jeeper has a good point on the expansion tank split or leak. You should be able to smell it if you have antifreeze/inhibitor added.
 
You don't specify the age of your car OP, but my 2002 325ti with the M54 engine had a cooling system refresh a year ago due to a bowed radiator. :cry:

Had the radiator, thermostat, "radiator cap", expansion tank and auxiliary drive belt done while I was at it. No problems now though!

Not sure if Z4s suffer from radiator issues, but I wouldn't be surprised if the expansion tank was worth looking at.

Hope you get it sorted painlessly! :thumbsup:
 
Mr Tidy said:
You don't specify the age of your car:
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It's an 03 with 43K on the clock.....registered on 20 December 03 so was a nice Christmas present for someone.. :) Haven't noticed any smell of coolant after a run but must check more thoroughly when hot.
 
Thanks OP, my 52 plate E46 needed it's refresh in April 2015 so I would guess your Z4 may be due a similar workover by now - but it will give you many more years of fun once done. :driving:
 
Took a 5 mile run this morning and lifted the bonnet with the engine running and then switched it off to allow pressure to build further. No coolant smell or obvious leaks, under tray still wet though. Must take the radiator cover off next time for a better look.
 
You could put some 'Bars leak' into the coolant and see whether that makes any difference. Before anyone starts questioning pour in solutions, some car manufacturers put the product in on the production line.
 
Thanks for the suggestion. I've used Barr's leaks before as well as other products on old copper rads but I'm not a fan of using it on narrow tube aluminium radiators. Their fins are crimped to the tubes which caused ripples inside the already marrow tubes, these trap the leak sealer and block up. :(

Any more thoughts on bleeding?
 
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