Rear coolant flange

[norad97]

Rob, reading your post on rear coolant flange,

Project 2.0tfsi , Engine rear coolant flange replacement guide.

As in the title really chaps, my first short project for 2017 is on the joys of replacing this failure prone part. Having found this part leaking on my old bus some months ago I have now decided it is time to sort it out, moreso because my coolant level is dropping faster than previously noticed...

www.audi-sport.net

So I ordered the parts you listed, the flange comes with oring already fitted, so what did you use the other oring for, ?
I thought it might be for the quick connect hose on the flange, but not sure.
You said yours was leaking at the joint, so how did you fix this?
I know it was a while ago and us oldies can forget some things, but hope you can


BTW, I'm going to do my Oil filter housing at the same time, saves draining the coolant twice.

 

[Charlie Farley]

just doing a BBQ Richard , I'll put my thinking cap on and get back to you shortly.

 

[norad97]

BBQ already, Guess your wearing shorts and a flowery shirt, and shades

 

[Charlie Farley]

Lol

 

[Charlie Farley]

The flange assembly does come with its o-ring , one is already fitted ( the engine block connection) , one small o-ring which is for the temp sender port and the third larger o-ring is for the heater quick connector fitting port.

 

[Charlie Farley]

 

[Charlie Farley]

I think i replaced all the o-rings Richard , the block one was leaking a lot and the other two connectors were leaking to a more or lesser degree , they had to be disconnected anyway so i replaced the failing o-rings on all the ports.

 

[norad97]

Hi, Them problem I need to understand is that the Oring you listed in the parts list is the part number of the Oring on the flange,?
according to my parts list, it does not list an Oring for the quick connect pipe?
So that's why I'm asking as dont want to pull out Oring from quick connect pipe and find ring is wrong.
Thanks

 

[Charlie Farley]

I'll check the parts schematic Richard.

 

[norad97]

Hi Rob,
I think I found the answer on a USA forum,
Someone asked the same question about the quick connect oring,
It seems that the temperature sensor oring is the same as in the quick connect hose, N90316801.
It was said by one guy to put the oring on the housing and slide the hose up until it clicks,
apparently this stops it binding up when connecting the hose.

 

[norad97]

Hi Rob,
I think I found the answer on a USA forum,
Someone asked the same question about the quick connect oring,
It seems that the temperature sensor oring is the same as in the quick connect hose, N90316801.
It was said by one guy to put the oring on the housing and slide the hose up until it clicks,
apparently this stops it binding up when connecting the hose.

Not sure now, getting a bit confused over the oring needed.

 

[Charlie Farley]

I'm just doing a bit of work Richard, i'll clarify in a bit.

 

[norad97]

I'm just doing a bit of work Richard, i'll clarify in a bit.

Hi Rob,
Did you remember what you did about the quick connect oring?

 

[Charlie Farley]

Hi Richard, sorry for the delay, had some issues to deal with.

Anyway, the coolant flange comes with the o-ring (wht001688) so you don't need a separate o-ring there, but you will need N90316801 which is for the coolant temp sender.
I just don't recall what the format is with the lower hose connection as circled yellow in the above reply, logically it is a watertight joint so must have a seal and as it's a detachable joint it must be an O-ring.
I'm looking back at my notes now to see what is needed.

rob

 

[Charlie Farley]

Looked back at my notes and the inner reaches of my grey cells and i think i have the answer.
You only need the flange, which has the o-ring included (wht001688 is the p/n for the single o-ring) and you'll need the temp sender o-ring N90316801.
The heater hose bottom fixing has the seal in the hose if I recall so you don't need it, I'll triple check but I think your good to go with just the two..

 

[norad97]

Looked back at my notes and the inner reaches of my grey cells and i think i have the answer.
You only need the flange, which has the o-ring included (wht001688 is the p/n for the single o-ring) and you'll need the temp sender o-ring N90316801.
The heater hose bottom fixing has the seal in the hose if I recall so you don't need it, I'll triple check but I think your good to go with just the two..

Ok, but when I seen you quick connect hose was leaking,, I wondered how you fixed it ?? As oil incres swells the oring.

As I only want to removed coolant from the block and not the whole system, I read in your write up by removing the hose from the oil cooler
will drain it down?

 

[Charlie Farley]

also here, shows the 2 o-rings needed as individual parts but the flange is supplied now with the main o-ring.
That said the main o-ring (wht) is still available from some sources.

 

[Charlie Farley]

Ok, but when I seen you quick connect hose was leaking,, I wondered how you fixed it ?? As oil incres swells the oring.

As I only want to removed coolant from the block and not the whole system, I read in your write up by removing the hose from the oil cooler
will drain it down?

I didn't drain down the whole system, just enough to allow the removal of the flange, that does by default mean a fair bit will be removed as the heater will be emptied along with what's in the cylinder head etc,.

 

[Charlie Farley]

Update on that lower heater hose connection Richard, there is a seal in the hose push fitting as i suspected, well that had to be really as i changed it due to a leak, its just not marked on the parts list, so i may have used another o-ring , i'll need to check.

here

 

[Charlie Farley]

If you are doing the oil filter housing/cooler assembly then just drain down the system and refill afresh after you have done all work on the cooling system.
With the coolant flange replacement,I don't think there is any really ideal method to be honest, just whichever way works for you, my guide was only a guide and you may find a shortcut on some of the bits.
If I had to do it again I probably wouldn't, but if circumstances dictated and i had to, i'd do a few things differently, it's not really an easy one with very limited access and clear vision, a lot is just fiddling around blindly.

 

[norad97]

Update on that lower heater hose connection Richard, there is a seal in the hose push fitting as i suspected, well that had to be really as i changed it due to a leak, its just not marked on the parts list, so i may have used another o-ring , i'll need to check.

here
View attachment 266576

If you can find what you used it would be great help, as I wrote what I found on US forum, one guy states it's the same oring as the temperature sender,
but need to be sure.

 

[Charlie Farley]

here you go, the o-ring clearly visible in the heater hose flange couplng.

 

[norad97]

Yes thanks, but would oring did you fit?

 

[Charlie Farley]

Now where I sourced the o-ring I used, it is not listed as a separate part so I may have used a generic one from my o-ring box.
Or , it may be that the o-ring that fits the temp sender is also suitable for that coupling.
I definitely did the fix with the bits i ordered, just racking the grey cells on this bit.
worse case if yours isn't leaking then maybe wise to just lubricate it and refit.

 

[Charlie Farley]

have you had a good look at the flange to see which ports are leaking Richard?

 

[norad97]

have you had a good look at the flange to see which ports are leaking Richard?

Hi, Yes I looked using light and mirror, the hose looks fine and also the temperature sender, what I did find it looks like it's starting to leak
at the flange to head, so I guess the seal on the flange is going.

I'm losing some coolant but cannot really find where its leaking from, checked all hoses radiator top and bottom, nothing.
Oil filter housing is leaking slightly so it could also be the oil cooler seal, so I might as well change them both to be safe.

 

[Charlie Farley]

Hi, Yes I looked using light and mirror, the hose looks fine and also the temperature sender, what I did find it looks like it's starting to leak
at the flange to head, so I guess the seal on the flange is going.

I'm losing some coolant but cannot really find where its leaking from, checked all hoses radiator top and bottom, nothing.
Oil filter housing is leaking slightly so it could also be the oil cooler seal, so I might as well change them both to be safe.

The flange to the cylinder head is always the main culprit, starting as a small weap and gradually getting worse, best to get it done Richard.
The O-ring inside the heater hose connector is the same as the temp sensor or let's say it does the job very well.