Need help with coolant hose missing from my car

[allroadadi]

I bought a fixer upper RS6 for cheap. The previous owner had the after run pump removed, which is not horrible, but the hose coming out of that area just has a bolt in it, and from what I can tell it was connected to another hose that comes up through the top of the carrier (right above the radiation) but can’t figure out where it goes from there. This hose/pipe combination is missing from my car also. Can someone please post a picture of that hose/pipe combination that goes from the left side of the engine through the carrier and then back somewhere…?
I’m trying to get that after run pump going again or at least trying to figure out if the coolant circuit that got interrupted with a bolt will starve part of the engine of coolant….
Thanks!

[Shoppinit]

Could he have replaced the radiator with the version without the addition coolant circuit? There are 2 versions depending on VIN. The one without is significantly cheaper.

[TOPMAN]

Hello!

The previous owner had the after run pump removed, which is not horrible

I think this is pretty horrible, the whole purpose of the after-run pump is to stop your turbos from frying and to prevent additional air in the coolant system. I recently did my SJP (suction jet pump) on my RS6, so have some recent memories of how this area looks. If you included some photos it would help a lot.
I'll attach some info regarding the after-run pump and it's operation - I'll also dig-out some photos of the pump itself.
My thoughts are that this pump has been unavailable using the standard Audi Part number (077121599) since 01/09/2020 but other pumps will fit (depends on a few things). Because it was unavailable they decided to bypass it, frickin'n cowboys!

[TOPMAN]

Could he have replaced the radiator with the version without the addition coolant circuit? There are 2 versions depending on VIN. The one without is significantly cheaper.

Hi Shop
I thought all the RS6’s got the after-run pump, I’ve not seen any without.
I also thought the difference between the radiators was for those that had HOT COUNTRY option, and those that didn’t. I’m referring to those cars that had the additional radiators behind the intercoolers (example: American cars).
I could be wrong, wouldn’t be the first time


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[Shoppinit]

I'm talking about the main radiator. There are 2 versions depending on VIN. One has an additional circuit in it and is quite a lot more expensive.

Since it wasn't 100% clear to me what the OP was indicating, I thought it could be a reason for trailing hoses if the v1 rad was installed in a car with v2 plumbing, since the earlier radiator as fewer connection points.

/this is independent of whether the car has aux rads, IIRC

[Felix2566]

Slight deviation, Topman, where did you get those diagrams and descriptions from. Looks like a great resource to have for our cars.
Does the SJP throw an error code if it's not working as I've not heard anything running after turning the engine off. Tbf I've not tried listening very carefully for it either.

[asgor]

I think this is the RS6 Study Guide referenced above: https://sb952effb4c14a0dc.jimcontent.co ... gramme.pdf

[Felix2566]

Awesome, thanks asgor, helps with diagnostics, knowing how the system is supposed to work in the first place!!

[allroadadi]

Actually I put in a new auxiliary water pump, and the hose in question is connected to the bottom pipe in the picture and ends with a bolt in it right by the ac compressor. I will try to take a picture of it, but the engine is back together and it’s cramped in there so it might be challenging.
PS: the strap holding the pump is “custom” made, as I could not source one.

[allroadadi]

I found a before picture, if anyone is interested on how to bypass the auxiliary water pump. I mean, the amount of work necessary to get to that pump is not to be ignored, and I think a leak developed there at some point and the previous owner deleted it to save future headaches. You just have to remember to let the car idle for a while after a spirited drive….
Anyway, it was just an aluminum pipe.
On the 2.7T engine this pump works for sure every single time I drive after the low temperature coolant sensor mod. Actually it works so well that when I had a coolant leak it was shooting coolant through there after I turned off the engine.

[Felix2566]

How come you had to make your own retainer for the pump? Re-read your post. The original was missing with the pump. ......ignore me. Haha

[TOPMAN]

I'm talking about the main radiator. There are 2 versions depending on VIN. One has an additional circuit in it and is quite a lot more expensive.

Since it wasn't 100% clear to me what the OP was indicating, I thought it could be a reason for trailing hoses if the v1 rad was installed in a car with v2 plumbing, since the earlier radiator as fewer connection points.

/this is independent of whether the car has aux rads, IIRC

Hi Shop

Gotcha! Yeah the earlier cars had 4 connections >>4B-3-904 100* and used 4B3121251E
And the later cars had 5 4B-3-904 101>>* 4B3121251F

[TOPMAN]

Slight deviation, Topman, where did you get those diagrams and descriptions from. Looks like a great resource to have for our cars.
Does the SJP throw an error code if it's not working as I've not heard anything running after turning the engine off. Tbf I've not tried listening very carefully for it either.

Hi Felix

Looks like Asgor has sorted you out - but if you search the interweb for SSP991303 you'll find it. It's a great little doc for the US market and you always learn something

The SJP (suction jet-pump) and the secondary water pump are 2 different circuits, but both physically located on the under-side of the intake manifold. The SJP is the vacuum system and when it's faulty you'll probably get codes for lean fuel mixture as it normally falls apart and creates an air-leak. The secondary or after-run pump is part of the cooling system and you can hear it running immediately after you turn your engine off. You will need to put your ear close to the engine to hear it's faint whirrrr. Mine was faulty and god knows how long it was not running for, but probably explains the earlier damage to my turbos. It doesn't throw a fault code when it's not working (or at least it didn't for me). You can test it manually once you have removed the airbox.

Regards
Craig

[Felix2566]

Thanks TOPMAN, yes had a look at the PDF on my phone looked very useful. I'll be downloading it later on my laptop for reference.

[TOPMAN]

Thanks TOPMAN, yes had a look at the PDF on my phone looked very useful. I'll be downloading it later on my laptop for reference.

You replied before I had time to complete my edits regarding SJP and secondary pump - please read above the extra paragraph