coolant leak question

cattlerepairman

Veteran Member
Joined
Jan 22, 2003
Location
Ottawa
TDI
none
I have a coolant leak. I tracked coolant loss due to no time to work on the car; it did not get worse and it does not leak from a "dangerous" location where subsequent damage would be likely, so I just topped up (about one pint per week-10 days).

It drove me nuts to find the exact location. It will not leak at idle, it will not leak with the a/c on (to drive temps up). I could see residue on the block underneath the thermostat housing, so I figured that was it and replaced it. Nope.

Higher rpm and wiggling of hoses finally revealed the location - O-ring #11, where the coolant pipe enters the block: ******WRONG PICTURE!!!! THIS IS THE 1.8 T**** CHECK PIC LOWER IN THE THREAD!****




Now my questions, mainly to figure out how much time I have to set aside to fix it:

  • how is the pipe attached to the block? Is it just pressed in there/snapped in?
  • can I just pull it out (by pulling it to the right side) with the other hoses still attached, or do I have to disassemble everything else that is attached to it? (I have a Beetle, so that is a PITA in that location).
  • ETKA part # for the darn O-ring and the coolant pipe (in case it tuns out to be rusted or leaking at a seam).
Many thanks!
 
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paramedick

TDIClub Enthusiast, Vendor
Joined
Jul 29, 2001
Location
Versailles, Kentucky
TDI
2015 Audi Q5 TDI, 2000 New Beetle
The sealing ring is 037 121 688.

The ring is relatively easy to replace. Drain the coolant. Unplug the coolant temp sensor. There are two bolts that hold the flange in place. If a manual tranny, you will need to remove the vacuum line bracket first. Pull it away from the head, and clean the head area well with scotch brite. Put the O ring in place, and resecure. If it won't pull away far enough, just remove the hose on the front to give you more room. I never remove all the hoses when I remove these for head replacements.

If you need a new flange, there are two different ones for the manual vs auto tranny. You will need a new O ring to bolt the coolant glow plug flange to the coolant flange.

038 121 133A Flange with coolant glowplug
038 121 132C Flange with sealing washer (won't need the sealing ring above)

037 121 687 Sealing washer for glowplug housing

Per ETKA, I can't find out whether the flange for the coolant glowplugs come with the coolant flange. I haven't had to buy one.

Obviously, if you haven't replaced the coolant temp sensor, now would be an excellent time to replace it.

Good luck, Bruce
 
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cattlerepairman

Veteran Member
Joined
Jan 22, 2003
Location
Ottawa
TDI
none
I still did not find out the part number for the #11 o-ring; after I had wiggled the coolant pipe enthusiastically to make it leak, it has almost stopped leaking. Currently, I lose maybe a pint in three weeks (down from a pint a week or quicker).
I will eventually get around to it....on the positive side, I have become an expert in judging the coolant level in the reservoir by evaluating the strength of coolant smell upon exiting the car and I am usually ready to top up before the red warning light honks at me.
 
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copilot

Veteran Member
Joined
Jan 16, 2005
Location
Northern IL
TDI
2001 Jetta
My car is an 01 Jetta automatic, are the part numbers in this thread correct for my application? I have a leak but I can't take the car apart until I have the replacement parts here. Should I replace the flange and o-ring just to be safe? Sorry to threadjack but I didn't think I should start another for the same problem. :)
 

Herm TDI

Vendor
Joined
Nov 21, 2001
Location
Richmond, Maine...The far side of Witsend
TDI
2002 Golf GLS Malone Stage 3, P+520 nozzles, 11MM Inj pump, Sachs VR6 clutch, Stelth Race Pipe, Immo Deleat, EGR Deleat
cooling sys

copilot said:
My car is an 01 Jetta automatic, are the part numbers in this thread correct for my application? I have a leak but I can't take the car apart until I have the replacement parts here. Should I replace the flange and o-ring just to be safe? Sorry to threadjack but I didn't think I should start another for the same problem. :)
For your TDI (2k1 ALH w/auto trans)
coolant flange P/N: 038-121-132-C
O-ring P/N: 037-121-688
 

cattlerepairman

Veteran Member
Joined
Jan 22, 2003
Location
Ottawa
TDI
none
Correction

I inadvertently scanned the wrong picture; the pic above is the 1.8T engine.

My leak is where the coolant pipe (#10) is connected to the block; the O-ring in question is #11. It requires a cross-eyed look to place the O-ring into context with the coolant pipe!



The O-ring has the part number N-903-653-02 SEAL and cost $1.40.
 

cattlerepairman

Veteran Member
Joined
Jan 22, 2003
Location
Ottawa
TDI
none
cattlerepairman said:
I

My leak is where the coolant pipe (#10) is connected to the block; the O-ring in question is #11. It requires a cross-eyed look to place the O-ring into context with the coolant pipe!
The O-ring has the part number N-903-653-02 SEAL and cost $1.40.
......and putting it in is a %§$%% P.I.T.A.
In order to be able to pull the coolant pipe out of the block far enough to actually get the old O-ring off and the new one on, I had to remove the intake air hose, the coolant flange (with the coolant glow plugs), the turbo oil supply line and brackets (bolted to the coolant pipe and crossing it in a way that makes moving the pipe almost impossible; I did not remove the fitting on the turbo, though), the dipstick tube and several coolant hoses attached to the pipe and the flange. Be very, very careful with the turbo oil supply line, do not twist it and do replace both copper washers at the banjo bolt!!

I used blue gasket maker on the end of the pipe as well, just to be sure.

Test drove, filled up with more 50:50 coolant - so far so good. I also had to replace the door lock module and a rear wheel bearing. When it rains, it pours!
 
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TOBarber

Veteran Member
Joined
Dec 20, 2002
Location
Toronto, Canada
TDI
Golf SportWagon, 2012, dark gray
I think I have the exact same leak. There is pink residual down there and I can't see an obvious leak, but the coolant level drops very gradually to the minimum mark. How did your repair work out?
 

wishin4atdi

Active member
Joined
Aug 11, 2006
Location
NE Wisconsin
TDI
2001 beetle
I've got the exact same problem. I posted an inquiry two days ago in the "tdi 101" forum entitled "possible coolant leak?" and in my impatience googled "coolant leak beetle" and found this thread. Amazing.

How did it work out?
 

copilot

Veteran Member
Joined
Jan 16, 2005
Location
Northern IL
TDI
2001 Jetta
I got my replacement flange a bit ago but haven't taken the time to install it yet. The cold is making the leak worse so I guess it's getting done this weekend.
 

GdB

Veteran Member
Joined
Sep 5, 2005
Location
Cypress, California, USA
TDI
Golf IV swap 2002
Bad Coolant Flange - GOOD OEM vs BAD

My coolant flange was damaged during my tranny swap, and so I bought another one for $6.20. Well $41 of G12 coolant later, I found out the new one is defective.

So I am posting these pics so maybe someone else can avoid my this by just looking at the part. I bought the part online, and it looks just like the OEM except for the little circles in the sealing groove. I would not be surprised if some of these also made there way to the dealers.



EDIT: You might notice some glue which is painted filler epoxy which I used to glue the OEM back together and reinforce the new part (before I new about the defect).
 
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GdB

Veteran Member
Joined
Sep 5, 2005
Location
Cypress, California, USA
TDI
Golf IV swap 2002
silicone copper sealant

I don't know about #10, but regarding the plastic hose flange, I ended up using silicone copper sealant also to make sure it does not leak.

I noticed my Jetta Wagon has the leak same problem, so I'll take it apart, clean it, and seal it...
 
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GdB

Veteran Member
Joined
Sep 5, 2005
Location
Cypress, California, USA
TDI
Golf IV swap 2002
I got the metal coolant flange installed to fix a leak. I also used the grey coolant specific RTV sealant to be double sure of no future leakage.

For reference, the hose that is unique to the manual coolant flange is

VW PN: 1J0 122 157 BF

That way if you want a new hose when you install it you can get it on worldimpex for $20 or maybe at Napa?
 

volmaniac

Veteran Member
Joined
Oct 20, 2003
Location
McFadden's Ford, Stones River NMP M'boro, TN
TDI
02 Golf GLS
Thanks for posting this question cattlerepairman (are you a vet?) and all the followups. I am having a slight intermittent coolant leak issue on our 2002 golf and thanks to this thread looks like I have a plan to figure it out. Search is good!
 

jeff eiber

New member
Joined
Feb 4, 2008
Location
Cleveland, Ohio
TDI
1999.5 jetta TDI
o-ring holder to make this job a little easier

I did this coolant pipe o-ring replacement on my ALH engine and as Cattlerepairman noted earlier moving the coolant pipe far enough to install the new o-ring on the coolant pipe is difficult.

To install the new o-ring I made a crude "o-ring holder" that allowed me to install the o-ring on the end of the coolant pipe while the coolant pipe was jammed against the side of the bracket that supports the fuel injection pump. Once the coolant pipe was "loose" I pulled the coolant pipe away from the fuel injection pump bracket, positioned the "o-ring holder" with new o-ring between the end of the bracket and coolant pipe and then let the coolant pipe squeeze the o-ring holder in place. Then it was simple to roll the o-ring in place over the end of the coolant pipe.





 

GdB

Veteran Member
Joined
Sep 5, 2005
Location
Cypress, California, USA
TDI
Golf IV swap 2002
That is one good macro lens. Whatever works, but that is one scrappy look tool! :D I have not had any more leaks since I replaced all the crappy plastic coolant manifolds with aluminum ones. Also I used the grey coolant sealant, not the orange stuff. I think the orange stuff does not like the coolant.
 

3turboz

Veteran Member
Joined
Jul 29, 2011
Location
Tempe AZ USA
TDI
2000 Golf GL Wolfsberg
I'm confused!

My 2000 Golf ALH calls for 06b121687 oring where the pipe goes into the enging, not N90365302. But the seal I removed did not look like either one. I have tried both of the above and cut them both on install. Tried silicone grease and still screwed it up. Any sugggestions?
 

abchilds

Member
Joined
Jan 21, 2013
Location
Battle Ground, WA
TDI
99 VW Beetle
7 years later...same problem exists

Reading this series of posts on fixing leak at flange/o-ring intersection on my 99 tdi beetle. I guess I should have fixed my leak when I was replacing the seals in the fuel inj pump! Does anyone have more specific step-by-step instructions or youtube video? or know of any? The leak is just below the F.I. pump. Yes, looks like a PITA. But, for sure I should buy a new flange in addition to the o-ring? Thanks for your help, all. -ac
 

abchilds

Member
Joined
Jan 21, 2013
Location
Battle Ground, WA
TDI
99 VW Beetle
So, this is the flange that has the thermostat or coolant sensor attached to it? Or is there a flange on the backside in addition to the o-ring? This is a tough fix. I am still struggling. I will attempt what cattleman and paramedix posted 7 years ago. I am not finding much else. So, using 'stop leak' in my coolant is not a good alternate? Thanks for your response, GdB.
 

abchilds

Member
Joined
Jan 21, 2013
Location
Battle Ground, WA
TDI
99 VW Beetle
Bonus, VolManiac! Thank you very much for sharing. I will read the entire thread. I also have one of those ****on maint books. The 1.9L TDI schematic for the coolant system doesn't seem to jive with what I observe on my car. Or I could have been extra sleepy last night when studying it.
 
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