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Discussion Starter · #1 ·
Hi guys , hoping you can help me with a real weird problem.

So a few weeks ago I noticed my coolant was disappearing and there was gunk on the coolant cap (pic attached). There were no visible leaks so my local indy had a look and told me the water pump was faulty and there was a leak near it.

I decided to change the water pump and replace the thermostat too.

However the problem was still there , revisited the indy as the oil on the coolant cap was getting worse and he told me the oil was red in colour indicating transmission oil. He diagnosed it as the Transmission oil cooler and I got that changed . Apparently this is a common issue ?

Good news is that the oil in the coolant is no longer there however the coolant still seems to be disappearing every week or so ( again no visible leaks and no cracks to the coolant bottle housing ).

Does anyone have any advice or know what this could be.
I've spent over 900 quid on the car in the last month and am really at my wits end.

Ps there's no coolant in the oil and the oil cap is clear so I'm assuming it's not the head gasket. There's also no excessive white smoke from the exhaust etc

Would really appreciate any help

The car is a 2006 525d e60 (m57) with 170k on the clock
 

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Has it been pressure tested to see if pressure drops and reveal any tricky to see leaks? Any signs of moisture in cabin?
If there are 100% no external leaks,not going in to oil or transmission then it only leaves 1 possible place for it to go and that’s through the combustion process
 

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Discussion Starter · #3 ·
Has it been pressure tested to see if pressure drops and reveal any tricky to see leaks? Any signs of moisture in cabin?
If there are 100% no external leaks,not going in to oil or transmission then it only leaves 1 possible place for it to go and that’s through the combustion process
Hi mate , we did pressure test but there was nothing. It does take about a week before it needs a top up so I'm not sure a small leak would be visible.

No moisture in the cabin etc ,
 

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Would a pressure test show a hot leak? Just wondering as there's quite a bit of anecdote about expansion tanks with hairlines only leaking when hot and it it was pressure tested cold, it might hold. Likewise the expansion tank caps can do similar. I had one on my E46 that was a real pain to track down - turned out to be the plastic manifold where it goes into the cylinder head (roughly round cyl 3 under the intake manifold). It was leaking very slightly and running down the side of the block but only when running and hot - so it was evaporating on the way down and not generating a helpful puddle anywhere to help find it. Very bright torch and a lot of patience caught it in the end.

You can also get UV die for the coolant which can help.
 

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Discussion Starter · #5 ·
Would a pressure test show a hot leak? Just wondering as there's quite a bit of anecdote about expansion tanks with hairlines only leaking when hot and it it was pressure tested cold, it might hold. Likewise the expansion tank caps can do similar. I had one on my E46 that was a real pain to track down - turned out to be the plastic manifold where it goes into the cylinder head (roughly round cyl 3 under the intake manifold). It was leaking very slightly and running down the side of the block but only when running and hot - so it was evaporating on the way down and not generating a helpful puddle anywhere to help find it. Very bright torch and a lot of patience caught it in the end.

You can also get UV die for the coolant which can help.
Hi mate thanks for the response, I think the uv die for the coolant might be the easiest option. Any recommendations on which one to use ?

The indy has suggested I use stop leak in the coolant to see if this helps , any thoughts on that ?
 

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I'd try as hard as you can to find the leak before resorting to stop leak type stuff.

Any of the uv additives should be ok - as you'll be draining and flushing when you find the leak anyway!
 

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As Evog said.
Them leak stop additives just clog the rest of the cooling system up.
+1 any uv kit will show up.
 

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Hi guys , hoping you can help me with a real weird problem.

So a few weeks ago I noticed my coolant was disappearing and there was gunk on the coolant cap (pic attached). There were no visible leaks so my local indy had a look and told me the water pump was faulty and there was a leak near it.

I decided to change the water pump and replace the thermostat too.

However the problem was still there , revisited the indy as the oil on the coolant cap was getting worse and he told me the oil was red in colour indicating transmission oil. He diagnosed it as the Transmission oil cooler and I got that changed . Apparently this is a common issue ?

Good news is that the oil in the coolant is no longer there however the coolant still seems to be disappearing every week or so ( again no visible leaks and no cracks to the coolant bottle housing ).

Does anyone have any advice or know what this could be.
I've spent over 900 quid on the car in the last month and am really at my wits end.

Ps there's no coolant in the oil and the oil cap is clear so I'm assuming it's not the head gasket. There's also no excessive white smoke from the exhaust etc

Would really appreciate any help

The car is a 2006 525d e60 (m57) with 170k on the clock
Try changing the coolant cap, it does not cost much and it sorted out the same problems I had with my 530D.
 

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Discussion Starter · #10 ·
Would a pressure test show a hot leak? Just wondering as there's quite a bit of anecdote about expansion tanks with hairlines only leaking when hot and it it was pressure tested cold, it might hold. Likewise the expansion tank caps can do similar. I had one on my E46 that was a real pain to track down - turned out to be the plastic manifold where it goes into the cylinder head (roughly round cyl 3 under the intake manifold). It was leaking very slightly and running down the side of the block but only when running and hot - so it was evaporating on the way down and not generating a helpful puddle anywhere to help find it. Very bright torch and a lot of patience caught it in the end.

You can also get UV die for the coolant which can help.

Something like that, complete with torch, then one dark night after running for a few days....
Hi both , just wanted to say a huge thanks for your help , you're both legends !!!
I used the uv dye kit and it turns out the area with a slight leak is the plastic manifold near cylinder 3 !!!!

Really appreciate your help chaps !!
 

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Discussion Starter · #12 ·
Has it been pressure tested to see if pressure drops and reveal any tricky to see leaks? Any signs of moisture in cabin?
If there are 100% no external leaks,not going in to oil or transmission then it only leaves 1 possible place for it to go and that’s through the combustion process
Would a pressure test show a hot leak? Just wondering as there's quite a bit of anecdote about expansion tanks with hairlines only leaking when hot and it it was pressure tested cold, it might hold. Likewise the expansion tank caps can do similar. I had one on my E46 that was a real pain to track down - turned out to be the plastic manifold where it goes into the cylinder head (roughly round cyl 3 under the intake manifold). It was leaking very slightly and running down the side of the block but only when running and hot - so it was evaporating on the way down and not generating a helpful puddle anywhere to help find it. Very bright torch and a lot of patience caught it in the end.

You can also get UV die for the coolant which can help.

Something like that, complete with torch, then one dark night after running for a few days....


Hi guys so took the car to the garage today to replace the coolant flange however I need the hose that comes off it too. Not the main hose but the little one that comes off the side of the flange housing.
Any ideas where I can get one from?

Even bm are struggling to find the part number or hose on their diagrams !!!

Any help you can provide chaps ?
 

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realoem.com and your VIN - might be able to drill down in that area.

But good to know the UV dye helped, never needed to use it myself, just came across it a while ago and thought 'what a good idea' ;-)
 

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Discussion Starter · #14 ·
realoem.com and your VIN - might be able to drill down in that area.

But good to know the UV dye helped, never needed to use it myself, just came across it a while ago and thought 'what a good idea' ;-)
Hi bud , there's not much on realoem, the actual flange is on there but no indication of part numbers for the hoses ☹
 

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Such diagrams as there are will be hiding under the 'Radiator' section:


On mine, the pipe in question is actually an assembly with integral connectors to the expansion tank and the manifold, but yours looks like it might be a bit different?
 

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Discussion Starter · #16 ·
Slight update the part number for the flange was 11122247744 and appears on real oem as part of the waterpump assembly, but there's nothing I can find for the hose that comes off the side (circled on the pic ) . Any help would be appreciated
Bicycle part Cable Wire Auto part Electrical supply
 

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Discussion Starter · #18 ·
Not knowing where the other end of the hose goes to makes it a bit more difficult to locate but number 12 in this link could be a possibility.


is other end of hose on the oil/water heat exchanger by any chance?
Thanks for the response bud , the mechanic said the other end is apparently on the auxiliary water pump ?
 

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Discussion Starter · #20 ·
Morning all , all resolved now (thank god) and thanks so much for all your help lads.


Just to help anyone who comes across this thread (as bmw were useless with the part number of the hose) it's 64216917697.

The hose in question is on the pic below and comes off the coolant flange


Thanks guys
 

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