Coolant Leak- Flange or Hose?

[biketsai]

1.8T AWM. I noticed some slow coolant loss in the past 2 weeks. I looked around and noticed that my gloves would get covered in coolant (and I also saw it dripping onto the trans) when I would shake the hose that runs to rear coolant flange. It looks like it is leaking right where the hose meets the end of the coolant flange. This hose comes from the bottom of the coolant flange and then goes to the firewall towards the heater core.

I recently replaced both the hose and the coolant flange about 8 months ago. Thoughts? Bad seal? Bad parts?

[Seerlah]

Bad o ring.

[MetalMan]

Bad o ring.

Coolant flange O-ring, or heater hose connector O-ring?

[biketsai]

Coolant flange O-ring, or heater hose connector O-ring?

Mitch, did you mean the heater hose connector O-ring?

[Seerlah]

Si. Replace that and make sure the plastic washer is placed properly.

[biketsai]

Plastic Washer? Where is that?

Happen to know where you can find one O-ring without buying the whole thing?

[Seerlah]

I buy my o rings from fcp in bulk (should have a couple more laying around). Can't recall size off hand but they are all the same in that area. Same size as the cooling sensor o rings. Place cooling flange o ring and it kay pop up, in the fcp product listing. Or search by part number. But most places will sell it separately, including the stealership.

There is a tapered plastic washer (not used as a washer, but looks like one) that is contoured with a hole through to seal. The o ring sits between the cooling flange and this washer stop thong, shaped as the male end of the cooling flange that goes into the female heater hose connection.

PSA: Misinformation in this post, but corrected couple posts down.

[RagtagXMASTER]

when i removed my flange and the stopper wsher came out of my line i was a little nervouse thinking i broke the housing. it just slides in. a little tough just push it in evenly.

[walky_talky20]

...they are all the same in that area. Same size as the cooling sensor o rings.

Mitch, have you had success using a CTS o-ring in the heater core hose? It was my understanding that these were different sizes. The CTS o-ring is 19.6 x 3.6, and the heater core hose o-ring is larger. About 22 x 3 or so. Here is a picture that shows both side by side (CTS o-ring on Left, Heater Core o-ring on Right):



These heater core hose o-rings are not offered as a separate part from Audi/VW. I know of just a few options for replacement:

- Buy a standard "211" size o-ring from a parts store. This is supposedly 'close enough' and people have good success. (Info here). 212 also seems close. Finding (read: ordering) an exact metric sized replacement would be ideal.
- Buy a heater core fitting, either a straight one that will fit directly, or the cheaper, more common angled version for the Jetta. You can either install the entire fitting, or just "harvest" the o-ring from inside.
- Buy an entire heater core hose. ($$)

[biketsai]

I am totally lost on this stop washer. Any pics? I do not recall this when I installed a new flange earlier this year. Is it possible to even run the car without it and maybe now I am seeing leaks?

Does this washer come with flange or the hose?

Chris- I might just get a new hose, an OEM replacement online is about $30 for a Rein piece. Unless having the best quality connector is most important?

[Seerlah]

Keith, you are right. But it is the same size as a different o ring used and I def picked it up separate. It's late and I don't feel like finding the right one, but it is somewhere in this line up.

https://www.fcpeuro.com/Audi-parts/A...words=O%20ring

[walky_talky20]

Nifty. This is pretty interesting information, Mitch. Nobody has a part number on this o-ring, so if you can confirm at some point - that would be great.

So far I see this:
N90365302 (the coolant hard pipe o-ring on an AWM. Also the o-ring used on the B6 1.8T "J-plug") - 20 x 3mm
or
N90380002 (coolant crossover pipe o-ring on 2.8 30v, under intake, behind the t-stat area) - 24 x 3mm

Not sure if it might be one of those...

@Chris:

The plastic washer they are referring to is an internal piece of the quick connector itself. It is not really meant to be removed, but it can be. It is just how they put the things together at the factory. They have the connector, they push the o-ring in there, then push the little tapered plastic disc or "washer" in there after it. It is a fairly tight friction fit. Sometimes they really do NOT want to come out. Sometimes they come out easily. With a decent pick tool, you can get in there and pick the o-ring out easily without disassembling the quick connector at all. That's the way I like to do it. I use a small 90 degree pick tool. Craftsman brand, I think.

Anyway, here is a picture of a disassembled quick connector: connector/o-ring/tapered plastic washer

[Seerlah]

Ill search when i get home. May not also have been the same exact size, but very much could have been. It's just an o ring. Picked a bunch up in different sizes before and one fit perfect. No leaks yet for me.

[biketsai]

Assuming I'm fine just replacing the connector, I'm going to order one of the ones that Walky posted. $10 on Amazon for a Dorman replacement and I'll just cut the hose that is currently installed.

[Seerlah]

Keith, there is no way I can know which one in the list in the link it is (sorry). When I ordered, I ordered a bunch in different sizes to have around (have a bunch of stuff like this laying around). I simply went to my box-o-shit when I changed my flange and one fit perfectly (may not be exact OEM spec, but still fit perfect).

Chris, you can easily just run to any Auto parts store and get the assorted box of o rings (make sure the box has ones that looks like it would fit). One of them will fit. Those o rings can looks like pure mush after years of heat/coolant and being sandwiched.

[Articus]

Not sure why I didn't see this earlier but hope this helps. I did my coolant flange 3 or 4 weeks ago.

This is the Oring I bought for mystery part that is inside the heater core hose that no dealer seems to recognize: http://www.amazon.com/gp/product/B00...ilpage_o03_s00

It's a 7/8" ID and 1-1/8" OD. The silicone is chemically compatible with the propylene glycol based G13. I got the spec from an article on Passatworld where I found the AWM diy. This O-ring fit perfect and I don't have any leaks back there. (Its leaking at the other mystery o-ring in the hose which connects to the Themorstat housing)....

[walky_talky20]

I figured the "212" size would be a closer fit. The Jetta guys were saying "211", but I thought that was a bit small. Either would probably work.

I would also be concerned with the material a bit. Just because its a black o-ring, doesn't mean that particular material is going to be happy about being heat cycled between 0 and 95F all the time. Even some of the wholesale supposedly "VW Supplier" o-rings I get from our import parts supplier are all cracked and broken after just 30k miles. Terrible quality compared to the factory o-ring that lasted 150k+.

[biketsai]

Not sure why I didn't see this earlier but hope this helps. I did my coolant flange 3 or 4 weeks ago.

This is the Oring I bought for mystery part that is inside the heater core hose that no dealer seems to recognize: http://www.amazon.com/gp/product/B00...ilpage_o03_s00

It's a 7/8" ID and 1-1/8" OD. The silicone is chemically compatible with the propylene glycol based G13. I got the spec from an article on Passatworld where I found the AWM diy. This O-ring fit perfect and I don't have any leaks back there. (Its leaking at the other mystery o-ring in the hose which connects to the Themorstat housing)....

Thanks, I actually decided to just order the linked O-ring you sent. I figure it will be much easier to replace the O-ring than to replace the connector.