1.9 tdi coolant leak fixed!


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Oct 7, 2013
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So after a long drive, starting the car up again showed the low coolant message on my dash. Couldn't see any pools of water, probably because the hot engine evaporated it all, so I topped up and ran the car. Initially it looked like it was coming from above the coolant temperature sensor, possibly a housing but on closer inspection a hose had bulged a lot and was the likely suspect.
The part number is 038121473 and it's a coolant breather hose from the rear of the engine around the right to a metal coolant pipe, and it's about £15.
changing it isn't too hard at all, 30 mins going slowly and carefully. I think the pipe perished over time because it goes right next to the engine and under the tandem pump, hot stuff! It did well to last 140k miles.


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Cheers for the pics at first i thought i had the wrong part cause it's a lot smaller than it looks. Mine had a massive split but it was hidden right underneath. I found removing the Airbox made it a lot easier to get to the metal clamp that holds it on underneath the pump.
i did mine a while ago, its caused by your tandem pump leaking diesel and it rots the rubber hose, might be worth changing your tandem pump gasket too before that one rots away too!
Evening! Glad this has helped someone, I seem to ask more questions than offer solutions on here so it makes a change for me!
I had my clutch replaced recently and noted quite a bit of leaking oil towards the rear of the engine, it's not the crank oil seal which is good but it is somewhere higher up that I need to investigate.
As soon as I get a minute I will check out this area - tandem pump, rocker cover and EGR valve, hopefully it's an easy cheap fix...

Oh if the tandem pump is leaking diesel is it the two rubber gaskets to replace that join it to the engine or do you split the pump and replace seals in the unit?
I've just checked and my tandem pump is leaking from the bottom. I'm hoping it just the gasket. How difficult is it to remove the tandem pump? Any tips as i'm gonna try and attempt it this morning..

They are very brittle things for what they do, also know as the Vac pump dude, check my thread as i had to replace mine due to been so ****e and snapping in 2 places!!
Ah ha, good point, yes I noticed a bit of play on the vacuum pipe on mine but have not done anything about it at the moment, it could probably do with some sealant and then self-emalgamating tape over it. The pump is only held on with three bolts as far as I am aware, so once you have access hopefully it won't be too bigger job. Let us know how you get on.
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Well, After buying a socket set and getting the metal gasket (part Number 038145215) Finally got all 4 bolts off, The bottom one is a pain:nightmare: Got the tandem pump off and..... It's the ****** rubber one's:audibash: So i thought i wonder if the metal one will fit.. In a word no after tighten them all up started the car will no mainfold (Big gust of black smoke form the the cylinder had removed the manofild with egr as replacing an o ring) was pretty funny:anbet::laugh: and it still leaks so gotta wait till tps is open. Hopefully bank holiday monday to get the rubber seals (038109293). Oh the joys of Audi:rockwoot:
Well got the rubber gasket from tps only comes with the large rubber gasket no figure of 8gasket. So fitted it car didn't start:banghead: got the jump leads after about 20 attempts it started:thrashi: was well chuffed! Until i checked and it's still leaking:( had a proper look and it's coming form the end plate of my Luk Tandem pump. Has anyone had any joy in using sealant gasket such as : Hylomar Hylosil Instant Gasket on it or would i just be better off buying the uprated bosch tandem pump off ebay??
When you say end plate, what do you mean?
Make sure you have a good hunt for a second one unless ya willing to buy new. Also the Allen bolts,as you know are a pain in the **** to get to and may not be tight