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1.8t (AUM) Coolant Leak, Fixed (inc pics)




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#1 Pat

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Posted 24 September 2007 - 04:33 PM

62xxx miles. Jumped in the car, let it idle for 20 seconds and then the old 'STOP! Check Coolant' appeared. My first thought was the sensor in the coolant bottle, so checked and realised I was actually quite low (below the minimum mark, but not entirely empty). Topped off with water and went on my way wondering what might it have been. The waterpump and thermostat were done about 9 months ago so hoped it wouldn't be either of those...


Did about 20 miles with no more apparent loss and no odd symptons but thought I'd have a snoop anyway and found this:


Posted Image


Looked like G12 Coolant on top of the gearbox and it looked like it was coming from the coolant temp sensor housing on the side of the head


Posted Image


So I bought a replacement - part number 06A 121 132 J and also marked 06A 121 132 AP - this comes complete with the necessary seal and is 8.27 + VAT


You can now see where the leak was coming from


Posted Image


and here's a view from the passenger side (airbox & MAF removed for easier access. The water & coolant was dropped before I started and replaced with G12+ 50/50 mix with water.


When removing the old housing I removed the 3 water pipes that are on it as well as the coolant temp sensor and O-ring. Then, I took the pipe from the SA pump to combi valve out for a bit easier access to one of the bolts that holds it onto the head.


Posted Image


Also, after doing a bit of research on vwvortex 1.8t forums I found that a possible cause for this leak would be worn lower radiator mounts. When my car was cold I grabbed the base of the radiator near the bottom hose and was able to rock it a good way back. So I got 2 new mounts and did these at the same time.


Posted Image


Part number 1J0 806 157F at 4.61 ea + VAT


Bit of a mare to get in without removing lots (bumper has to come off plus the bolt that holds the old mount to the car) but my radiator's solid now and doesn't rock.


Big thank you [b] to Lee Ingham at VW Blackburn for getting me the parts double quick style [y]



It also appears that SDobbs and Patch are having the same problems with their cars - we all have X reg AUMs so it might be worth a look if you're slowing loosing coolant. Hope it helps someone



#2 Patch

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Posted 25 September 2007 - 12:49 PM

Your a good un Pat.

#3 tylerama

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Posted 27 September 2007 - 07:34 PM

Your a good un Pat.


Spot on as always with great advice, pics and part numbers and how to's ! [Y] [*]



#4 Pat

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Posted 28 September 2007 - 12:00 PM

thank you chaps [:$] hopefully this will help others with those elusive coolant leaks

#5 junglisteve

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Posted 10 April 2010 - 10:07 AM

was about to leave for Elemental5 Essex Show  and discovered i had coolant leaking for last few days since i serviced it and i needed to top it up more often than ever before!

using Pats great post (did a search for coolant leak)

i quickly picked up the part/s from VW and just finished fixing it myself, yay! (usually wouldnt attempt it)

the crack in the housing was impossible to see since it was facing the other side, and it was too small to even feel, but soon as i dried it, it literally seeped through so assumed/guest it must be a tiny crack.

it was only until i took the housing off i notice the hairline crack, i had to clean thouroughly to even find it...

SPOT the CRACK !

 Posted Image

its just perpendicular to the flat of the screw driver

so, thanks PAT !

saved me a few quid at least, not too mention not ruining the rest of my weekend and drive to work this week

why do VW bond these parts together instead of a better way?  must be cheaper?



#6 Deeply_dippy

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Posted 10 April 2010 - 10:40 AM

I had similar on my Mk4 (also an X reg AUM) but managed to get away with just replacing the seal and cleaning up the side of the head. Will check my rad now to make sure it isn't loose but if it is i shall be getting some of those new mounts



#7 robvw

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Posted 26 May 2010 - 12:31 PM

i had a leak from the same area, this really helped me out, so thanks Pat. 


its a slightly easier fix on the agu as theres no secondary air pump or combi valve stuff in the way.


for the agu the coolant temp sensor housing on the side of the head, or simply 'flange' as vw call it, is p/n 06A 121 113 2A. £9.84 +vat. it is different from the aum part as i asked the parts guy to confirm if it was or not.


the radiator mounts which Pat listed above have gone up a bit also, £5.65 +vat each. mine were really bad, radiator moved 1-2 inches! thanks for pointing this out too Pat. G12 plus was £7.17 +vat for 1.5 litres.



#8 bbewekim1

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Posted 20 November 2010 - 04:48 PM



#9 calimori

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Posted 10 December 2010 - 01:09 PM

Another good post Pat. Your symptoms match what I am seeing on my 51 AUM. I was searching the part number on the net and got directed back to this forum.

I was close to buy a more expensive hose connected to this part, I will be ordering this part tomorrow as at that price it is worth replacing. [B]



#10 tercitano

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Posted 08 May 2011 - 03:00 PM


Hi Pat,


I'm having the same problem like yours, i got a Golf IV GTI 1.8T 20v
AUM 150PS ( automatic tiptronic gearbox ) witha coolant leak. i think it
use the same parts...so could you please tell me were you bought the
replacement - part number 06A 121 132 J ; also marked
06A 121 132 AP ( complete with the necessary seal ) and the coolant temp
sensor and O-ring ? I saw in your post   "
http://uk-mkivs.net/...42/1029860.aspx"


please send a web page link to VW Blackburn ( if they have )


Any help will be appreciated


 


George



#11 Chris.

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Posted 08 May 2011 - 05:12 PM

My 20v did this the other month....decked it coming out of a carpark and all of a sudden water exploded up covering the windscreen followed by copius amounts of steam.


Rubber 'o' ring has been somehow forced out and the bolt had fell out aswell.


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#12 tercitano

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Posted 11 May 2011 - 02:06 PM

Hi there, where can i get GTI IV parts? Any link will be appreciated...


 


 


 



#13 Pat

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Posted 11 May 2011 - 02:20 PM

George, just go to any VW dealer and ask to buy the above part number [y]



#14 SULLYG

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Posted 11 May 2011 - 02:51 PM

 Had the same problem on mine a few months back ..  Used to notice a little damp patch of coolant under the car after been parked for a while. Also coolant traces on top of the gearbox. I wet to my local vw dealer and ordered the parts (housing and seals). With your reg or chasis Number they will bring up all the details to your car so they know what engine & gearbox etc..  so they know exactly what to order. I think it cost less than £15. Replaced a couple of days later in less than an hour...


Also make sure you clean the surface so it makes a good seal.


Hope this helps.



#15 Bow999

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Posted 19 April 2012 - 11:22 AM

Hi guys quite new to forum and was out checking my temp sensor for replacement as osted in other topic, then I noticed water slowly dripping from that area above pictured, mines is a 99 1.8 gti AGN anyone know if its the same part number for mine or the name of the part to ask for?


this should solve my OT problems my temp gauge is on bottom until traffic then moves up and need to replace water every 2 days or so.


 


next up my ruff idle [:S]



#16 dan_b

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Posted 19 April 2012 - 11:48 AM

 bow999 i replaced mine 2 days ago as it was slowly leaking a bit. ring tps give them the chassis number and will sort you out. the one at nottingham had 2 in and cost £11.66 including vat with the new o ring. put mine on 2 days ago and doesnt move like the old one and no more dripping.



#17 Bow999

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Posted 23 April 2012 - 02:22 PM

Nice one cheers, just checked my temp sensor its a blue square one so that mean i cant fit the green one? sry for noob question



#18 dan_b

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Posted 23 April 2012 - 02:36 PM

sorry mate not sure about that one as mine already had the green sensor.



#19 Bow999

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Posted 28 April 2012 - 09:45 AM

Got my flange pipe & temp sensor fitted today, no more water leak, temp gauge still lowers while driving - does that mean I need a thermostat also then?



#20 dan_b

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Posted 28 April 2012 - 10:46 AM

i would say thermostat yes mate. since i changed my coolant flange i have noticed mine drops from 90 slightly then back to 90 when put me foot down. but never did it before i changed it.



#21 Bow999

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Posted 28 April 2012 - 02:32 PM

Anyone any idea were the thermostat is located in the 1.8 agn.is it in beside alt



#22 dan_b

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Posted 28 April 2012 - 05:48 PM

yeh it is mate follow the hose to it.



#23 rickygti

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Posted 08 May 2012 - 04:03 PM

just broke down on the a12 today bec of this part not happy have to pick up a new on 2moz







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