Heater core coolant line

[Matt2408]

So I was just driving in traffic and I looked over to the right and saw what seemed like smoke from the hood then saw it in my rear view mirror. I then got a notification saying stop engine and pull over. I popped the hood and smoke is coming from the back of the engine. It just so happened someone in a 2.0 A5 pulled over and used to be a mechanic and showed me that the coolant hose at the back of the engine head going to the heater core ripped off. So the coolant just leaked out onto the transmission and that’s what was smoking. I will attach a pic, can someone help me with a correct part number for the hose on the driver side.

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[bb-tt]

8K1-819-371-AB is the # for the one that connects to the head on the caeb i am confused by you saying drivers side as on my car there is a top and bottom line going thru the firewall not left/right or drivers/passengers

[Matt2408]

8K1-819-371-AB is the # for the one that connects to the head on the caeb i am confused by you saying drivers side as on my car there is a top and bottom line going thru the firewall not left/right or drivers/passengers

Yeah here it’s left and right. But I looked around more after getting home and it’s that part number. Should be like $80 at the dealer. I also looked at the pic more and the hose coming off the head looks normal, like it didn’t tear off, if you look at the pic. Maybe the clamp that’s on the hose just slipped off. I will check during the day tomorrow. If that’s the case I will probably just take off that piece that it goes onto and use a hose clamp and put it back on, the hose felt normal. I have a gallon of Audi coolant, not sure if it’s a concentrate, do I just put it in the expansion tank and run the car till the thermostat opens and wait for no bubbles in the tank? Sorry but never done anything around coolant in the car.


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[audrobotic]

Heres a video from FCP Euro that might help, with some of the info about the cooling system also.
https://m.youtube.com/watch?v=BKG4C4onReQ

[Matt2408]

Heres a video from FCP Euro that might help, with some of the info about the cooling system also.
https://m.youtube.com/watch?v=BKG4C4onReQ

Yeah similar because it’s a q5. It helped because now I know I can remove the air box to be able to check if the hose just slipped off or tore off the connector. I can skip the draining part because it’s empty in the tank.

I don’t have the tool they used for checking the system if sealed so would I just pour the coolant in the expansion tank and run the car till warm and would it just cycle it by itself till no air in the system?

I know on the cap it says g12 coolant, on the front of mine it doesn’t say but it’s own Audi coolant and I told them the car when I got it like 2-3 years ago so it’s probably good. I have right about a gallon because I only added it once and it’s a 50/50 mix, car takes like 7.8qt so I should be good. So going back do I just mix it up and keep adding it till it’s at correct level and let it cycle?


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[Matt2408]

Just to update this post, I was able to check today and it looked like the hose just fell off. The hose and clamp on hose feel good. When I was trying to remove it I noticed I’m able to crumble away the piece that the hose slips onto. I will add a pic, is it possible to just buy this piece without the hose.


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[Matt2408]

Just to update this post, I was able to check today and it looked like the hose just fell off. The hose and clamp on hose feel good. When I was trying to remove it I noticed I’m able to crumble away the piece that the hose slips onto. I will add a pic, is it possible to just buy this piece without the hose.


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Would this be a good replacement piece? Part number 3B0122291B.




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[Smac770]

https://audi.7zap.com/en/usa/audi+a4.../8/819-819045/

You mean part 4, 8K0 819 699 A? Visuals, https://www.ebay.com/itm/265531554836

[Matt2408]

https://audi.7zap.com/en/usa/audi+a4.../8/819-819045/

You mean part 4, 8K0 819 699 A? Visuals, https://www.ebay.com/itm/265531554836

No I meant the part that goes on the end of the hose, the end that connect to the flange on the behind the head, that quick connect fitting. On Amazon it’s URO Parts 3B0122291B, in the review people have use it on older a4’s and a ‘11 q5 so based on that and it looking really similar all around I would say it should fit. Should I just replace that hose clamp on the hose with a regular hose clamp when putting it on this.


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[Smac770]

Got cha. The hose separated from the integrated hose end, this being the hose that runs from the cylinder head coolant flange. So part 1 in that same diagram, 8K1819371AB.



So there exists the part number for the end piece, but it's only used as an independent part for VW and VW clone products. Or it's just an alternative people are using as a substitute. But then that leads to the question of the clamp.

Looks like it'll be some Oetiker clamp, I would expect. Usually there's some numbers on it to denote the sizing. Can you find any numbers imprinted on the one still on the hose?

If we look at the usage of that 3B0 part on the CBFA engine in the A3, it's used with spring clamp N 906 870 01, 27x12. That's the connection to the manual transmission; no idea why they bother with breaking out that coupling on only that one single hose.

[Theiceman]

wow i have never seen that .. looks like the hose fitting had some type of stress fracture .. that is in such a strange spot you almost have to think that is a manufacturing defect..

But also what is that inside ? almost looks like engine suffered an intermix at some point. I took my 130k mile engine completely apart and nothing looked like that .. Does this car/ engine have any interesting history ?

[Matt2408]

wow i have never seen that .. looks like the hose fitting had some type of stress fracture .. that is in such a strange spot you almost have to think that is a manufacturing defect..

But also what is that inside ? almost looks like engine suffered an intermix at some point. I took my 130k mile engine completely apart and nothing looked like that .. Does this car/ engine have any interesting history ?

I’ve had the car from 117k miles now it has 154k, never noticed any oil and coolant mixing and over the years I only remember putting in a bit of coolant only a couple of times, so looks like no leaks anywhere before this now. But that piece seemed more brittle where I broke it off.


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[Matt2408]

Got cha. The hose separated from the integrated hose end, this being the hose that runs from the cylinder head coolant flange. So part 1 in that same diagram, 8K1819371AB.



So there exists the part number for the end piece, but it's only used as an independent part for VW and VW clone products. Or it's just an alternative people are using as a substitute. But then that leads to the question of the clamp.

Looks like it'll be some Oetiker clamp, I would expect. Usually there's some numbers on it to denote the sizing. Can you find any numbers imprinted on the one still on the hose?

If we look at the usage of that 3B0 part on the CBFA engine in the A3, it's used with spring clamp N 906 870 01, 27x12. That's the connection to the manual transmission; no idea why they bother with breaking out that coupling on only that one single hose.

I will check tomorrow morning to see if there’s a part number on that because anything I order won’t ship today anyway. If the connector piece I ordered is good I was thinking maybe getting a spring band clamp, the same that’s on the other end of the hose going onto the heater core. I think as long as that part fits any clamp will technically work.


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[Theiceman]

I’ve had the car from 117k miles now it has 154k, never noticed any oil and coolant mixing and over the years I only remember putting in a bit of coolant only a couple of times, so looks like no leaks anywhere before this now. But that piece seemed more brittle where I broke it off.


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oh you broke it off ?? maybe i missed that, i thought it just naturally failed there.

[Matt2408]

oh you broke it off ?? maybe i missed that, i thought it just naturally failed there.

Well when a guy in an a5 pulled over on the shoulder to see what happened, he used to be a mechanic in Audi. He reached back there and saw the hose fell off, he removed the metal clip and tried to get this piece off but couldn’t. Yesterday while I was trying to remove it I mistakenly grabbed that brittle piece with the pliers and heard it crack. Then I was able to brake small pieces of with little effort by hand.

Basically the hose slipped off from what I figure and maybe it was because the inner price just wasn’t holding onto the hose.


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[bb-tt]

Would this be a good replacement piece? Part number 3B0122291B.




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dont know if that is correct or not but the qd connector comes on the hose part # i sent you

[audrobotic]

Hmm. Ok so the hose part 8K1819371AB has two ends. One end is “cut” rubber, and the other end has a “integrated” coupler fitting. Your original issue was that the “cut” end slipped off while driving. Then when you tried to remove the coupler end it broke apart.

[bb-tt]

Hmm. Ok so the hose part 8K1819371AB has two ends. One end is “cut” rubber, and the other end has a “integrated” coupler fitting. Your original issue was that the “cut” end slipped off while driving. Then when you tried to remove the coupler end it broke apart.

from the pic that Matt posted above the side with the quick disconnect on it goes to the block the other side goes thru the cowl to connect to the heater core, and honestly if the plastic was deteriorated that bad should probably go ahead and replace the flange the QD connects too while in there as it is plastic also.

[Matt2408]

from the pic that Matt posted above the side with the quick disconnect on it goes to the block the other side goes thru the cowl to connect to the heater core, and honestly if the plastic was deteriorated that bad should probably go ahead and replace the flange the QD connects too while in there as it is plastic also.

It wouldn’t be the worst idea to replace that while I’m there but don’t want to spend too much right now, that’s why I’m also looking to replace just the quick disconnect, and also after taking the piece off the flange feels normal, doesn’t feel soft of look cracked, it’s clean.


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[Theiceman]

new connector , hose clamp and away you go ...

[Matt2408]

now connector , hose clamp and away you go ...

Connector just came in today, it clipped on fine, used a regular hose clamp and it’s snug on there. Just filled up the expansion tank and let it run for like 5-7 min the air was still coming out cold, went for a drive and air started getting warm even very warm. When I got back after a 2 min drive the coolant level dropped to like an inch below min, filled it up to max. The hose going to the heater core is warm, no leaks from there. When I rev it the air feels maybe even a bit hotter. Overall it was warm in the car with the window open. Here’s what obd showed during that drive. No other fault codes, I only ended up filling the tank to max and an inch over later. Should all be alright? I also drove with the cowl cover, should just driving it longer help get anymore air out?IMG_5141.jpg


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[Matt2408]

Connector just came in today, it clipped on fine, used a regular hose clamp and it’s snug on there. Just filled up the expansion tank and let it run for like 5-7 min the air was still coming out cold, went for a drive and air started getting warm even very warm. When I got back after a 2 min drive the coolant level dropped to like an inch below min, filled it up to max. The hose going to the heater core is warm, no leaks from there. When I rev it the air feels maybe even a bit hotter. Overall it was warm in the car with the window open. Here’s what obd showed during that drive. No other fault codes, I only ended up filling the tank to max and an inch over later. Should all be alright? I also drove with the cowl cover, should just driving it longer help get anymore air out?IMG_5141.jpg


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After driving for about 50-60 miles/1 1/2 hour, the air is blowing good. After this I did notice the level in the tank dropped about 1/4 to 1/2 an inch, when I checked with a paper towel the there was like a drop or two of coolant on the connector. Also the connector does slight wiggle side to side, it doesn’t slide of just a bit loose, does this mean I should replace the flange that’s there, maybe along with the temperature sensor.


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[Theiceman]

dont be surprised overnight if the level drops as the car purges itself, this is absolutely normal and to be expected. when you go out firs thing and its cold check level and top up . As far as your leak goes i'm not sure, its hard to tell. i wouldn't over analyze it for now, just keep an eye on it.
replacing that flange looks to be a huge PITA.

[Matt2408]

dont be surprised overnight if the level drops as the car purges itself, this is absolutely normal and to be expected. when you go out firs thing and its cold check level and top up . As far as your leak goes i'm not sure, its hard to tell. i wouldn't over analyze it for now, just keep an eye on it.
replacing that flange looks to be a huge PITA.

It’s only 2 t30 bolts but getting to them is tricky. I ended up spending the $20 for flange, gasket and new coolant temp sensor with clip and gasket. Figured it’s better to order now and have them just in case. I thought it would have been more expensive, if I had known I would have gotten it together with connect. Anyway thanks to everyone that help out anyway they could.


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[Theiceman]

It’s only 2 t30 bolts but getting to them is tricky. I ended up spending the $20 for flange, gasket and new coolant temp sensor with clip and gasket. Figured it’s better to order now and have them just in case. I thought it would have been more expensive, if I had known I would have gotten it together with connect. Anyway thanks to everyone that help out anyway they could.


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I did mine with the engine out lol.
it could be just one bolt, but if it's a pain to get too.......

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