1.8T Coolant Return Hose Badly Leaking - URGENT PLEASE HELP

[Skezza]

Hello,

It is of vital importance I get some advice here..... because currently my A4 is completely immobilized. It can't be driven to the garage because it is failing to retain water. Best I could do is arrange it to be towed unless I can either temporarily bodge fix or replace this part. This is where I hope someone will help here.

The car has been losing a very small amount of water for a good 2-3 months but nothing serious. It's been hard to diagnose the issue because it's been so wet in the UK. Saturday, things took a turn for the worse and the coolant began to drop significantly on a drive home. I was able to top it up but within minutes the warning was back on. With a bit of luck (turning the engine off at lights and coasting with it off etc) I hope I've not completely destroyed the engine.

The part that has failed is this:
New 06B121497F Cooling Hose for VW Passat Audi A4 01-06 Audi A4 1.8T | eBay (https://www.ebay.co.uk/itm/New-06B121497F-Cooling-Hose-for-VW-Passat-Audi-A4-01-06-Audi-A4-1-8T/151692725938?hash=item2351974eb2:g:aHYAAOSwBwBZklA Y)

I will phone Audi and get a quote on this part, although at £10 from China I have a feeling Audi will want 10x as much :D Standard.....

I have a photo. Most of the water was leaking from the rubber hose. I've removed this, trimmed some of the frayed ends, re-inserted and it actually seems a lot better. I could probably crush that metal a bit using some vice grips. However, I notice there's a copper washer and it looks like it might be leaking from there as well. It's really hard to tell as you'll see.

Could I use some RTV around that copper washer and see if that seals it a bit more. Maybe put some RTV around the rubber pipe as well? I know it's not recommended and will only ever work as a temporary fix but it's really important. If you have any advice, please don't ignore this thread. I'm desperate at this point, I'm having to take time off work etc.

https://i.imgur.com/fYzjE3K.jpg


https://i.imgur.com/wcvfwFr.jpg

[arman123]

for a temp fix i would use this Self-fusing Silicone Tape
Permatex How-to: Self-fusing Silicone Tape - YouTube (https://www.youtube.com/watch?v=r2JqXiL4Lww)

[Skezza]

Thanks. How long would such a fix realistically last? Would it do a few days?

[arman123]

i think it will do more than a few days if you put in on properly remember the tape does does not stick to surfaces it sticks and bonds to itself wrap it on tight and stretch it for a good bond

[Crasher]

Yes, £92.17 from Audi. That one has failed by what looks like external oil contamination and it looks like it is about to blow off.

[Skezza]

Yes, £92.17 from Audi. That one has failed by what looks like external oil contamination and it looks like it is about to blow off.
Is that part pressurized then? Is it the return line or the feed in?

When you say external oil contamination? Is that oil dripping onto the rubber pipe? Or is that oil on the metal connections? Or is there oil in the coolant ? I'm amazed how little info on this part is on the Internet.

One thing I've noticed is the actual pipe with two metal connections is a push fit job and having removed it, it has a sort of, tapered fit. I wonder if I could replace just the pipe part. Has anyone ever tried this or do most just jump at the new part? This is where the fun of experimenting could begin.......... I might buy one of those el-cheapo jobs then see if it can be done, if it still leaks buy the Audi part and replace it properly.

[Skezza]

So I'm going to go a little more into detail with regards to what I mean Crasher - I do love an experiment though. I don't mind too much being a crash test dummy for this kind of stuff either. At the end of the day, if nobody ever tries this, nobody ever finds out. The part is essentially a coolant hose connecting what I assume is the flange for the turbo to the flange for the intercooler maybe? I have to hope that i've not caused any lasting damage by getting it home, but one thing i did notice was it was still pouring out yesterday morning so there must have been some coolant in the system. Whether there was enough? I dunno, I'll have an oil change as soon as the car is fixed though. I guess I won't know if my turbo is ****** until, well, it's ****** :)

So the standard procedure for this part is to replace the whole thing, at some difficulty. Seems you possibly have to remove the turbo, or bend your hands into unnatural positions and use a variety of weapons to get at one of the bolts. However, I spent some time looking at the actual hose yesterday and I'm wondering if it was originally designed to be replaced itself? The part cannot be purchased from Audi (I went to a dealer and asked) but you can easily disassemble one of the cheap aftermarket ones in my opinion and just the design screams modular. Just because Audi decided not to sell the hose doesn't mean it wasn't originally designed that way. It may have not have been cost effective, but with the cheap copies knocking about, you could easily replace the hose while keeping the important parts OEM. Let me explain further:

https://i.imgur.com/Ssav7Q7.jpg

I wanted to see if the two circled parts are screw/nut and could be tightened up. Not so much the one on the left which isn't leaking, but the one on the right, which clearly is from the join (as seen in the second photo in the original post), so got under with a set of pliers. I quickly realised it was neither of those things..... it's nothing more than a push fit. Both hoses push directly onto a couple of 'tapered'/staggered ends.

I suspect it's designed to be a one time push connection so I would need to be really careful removing from the aftermarket part, maybe some heat and patience will help. The rubber hose is as a good as ****** at one end anyway and I'm facing either tow or turbo off job so I don't see this as much of a risk at this point. I removed the hose which I had reconnected by pushing it in, and then removed the push fit. It's quite tight but it does come and this is what you might see:

https://i.imgur.com/XKksfbf.jpg
This dropped out. At first..... I thought it was maybe a washer..... but it's too big isn't it? Then I thought it was a seal perhaps.......? I don't think it's either of those two things however...... . That's part of the hose isn't it? You can see from the irregularity. The hose is clearly glued into this part and has now perhaps worn through where the full break is and then sheered off causing the massive leak?

https://i.imgur.com/kqM8hAN.jpg
So this part above I assume has the hose glued into it. So obviously the next question for me, is what do they use to glue coolant hoses in? Could you simply just cut the frayed ends off that rubber hose using some genuinely sharp cutters (I tried scissors but they're not sharp enough) and glue it in with black/red RTV? Maybe some Indian Shellac compound? Permatex 20539 Indian Head Gasket Shellac Compound: Amazon.co.uk: Car & Motorbike (https://www.amazon.co.uk/Permatex-20539-Indian-Shellac-Compound/dp/B0008KLOG6)

I'm reading up on the best product for this job. Apparently RTV doesn't have the adhesive qualities of Indian Head Gasket Shellac compound? Thoughts?

The alternative of course, is to just try the pipe from the other one. However, I am wary that the other end of this pipe appears to have been smeared in some kind of silicone glue as well (hence the colouring). It could be a nightmare to remove.

I got back under the car this morning I'm thinking that de-greaser on the connection here and give this a go before we start throwing the baby out with the bathwater. Note the broken and jagged edges on the hose. Surely a sign that my assertion about the ring of rubber above is hose after all?

https://i.imgur.com/vEVu4Oe.jpg

I must say, it astounds me that absolutely nobody has actually had a punt on this. Not every fix has to be over complicated!! ;)

[Crasher]

You could repair that with some Goodridge push on hose, it is only at coolant pressure so around 5psi, the main criterion is the minimum bend radius capability of the hose. Even then I would supplement the barb retention with a hose clip.

[Skezza]

You could repair that with some Goodridge push on hose, it is only at coolant pressure so around 5psi, the main criterion is the minimum bend radius capability of the hose. Even then I would supplement the barb retention with a hose clip.
That's the plan.

Regarding the Goodridge stuff: Link (https://www.goodridge.co.uk/products/536-series-push-fit-hose?variant=31576277511)

Blue or black, do you know? I can measure if needs, but it looks like blue has a slightly smaller diameter?

[GeorgeE]

That pipe was crimped on to the barbs in the same way as a hydraulic hose is assembled, so not really designed to ever come apart. No, Audi will not have it as individual parts, they will not have the kit to crimp it together in their workshops, they just fit a new assembly.

That said, as Crusher has already pointed out it is only at coolant pressure so nothing stops you using a pair of jubilee clips and a length of suitably sized hose to put it back together, or even at a pinch as a temporary fix you may get away with trimming the ends of the rubber pipe you took off and refitting it (though it may now be too short). Audi don't do it like that because in a factory a pre-assembled pipe is quicker to fit and more reliable.

Now it is stripped apart like that, any form of sealant tape is not going to help.

[Skezza]

So, I fixed the leak using jubilee clips and having snipped the end off. Great.... although, not quite there yet.

Firstly, while getting the car home, I had the heater on full blast to try and avoid any potential issues with overheating. Part way through, all heat stopped and it is yet to return. I've flushed the system using tap water a few times and as part of that tutorial, you are supposed to turn the heating onto low speed high setting, but no heat ever comes through. I can only assume:
A. Huge air lock?
B. Blocked heater core?

Would a major air lock ever escape? Friend of mine who works in a garage thinks the coolant has to be vacuumed in to Audi's otherwise air locks are inevitable and has offered to do it for free for me, so I might take him up on his offer, but that wouldn't explain the heater core would it?

So I guess I'll have to backflush the heater core at some point? Doesn't look a big job. I assume it's just a case of removing that scuttle panel and connecting up a hose pipe at one end and another hose pipe into a bucket? Perhaps a job for this weekend.

Secondly...... *sigh* I used the thermostat to drain the coolant rather than the screw which is absolutely jammed solid. There's a C clip and O-ring. I flushed it several times without an issue. Then after driving it yesterday for about a mile, the thermostat popped out, losing the O-Ring and leaving the clip in place. No idea what I did wrong. £85 towing home :zx11: Should have just taken it a garage :D

I've ordered a new O-Ring from eBay. I also found one that fits in an assorted kit. Does the O-Ring need to be the correct one or will any O-Ring that fits do the job?

[Crasher]

You mean the temp sender popped out, the "O" ring is N 903 168 02 and that is from memory... I had one of those sensors blow out on me many years ago, I was setting up a G60 Golf and as I unplugged the temp sender to put the ECU in setting mode, the sensor blew out, hit me directly between the eyes and sprayed me all over with boiling coolant. I spent the next four hours in casualty and the next day I had to go to Germany for a show with a bright red scabby scalded face and a square dent between my eyes above my nose from the impact of the flying sensor.... :zx11:

[Skezza]

You mean the temp sender popped out, the "O" ring is N 903 168 02 and that is from memory... I had one of those sensors blow out on me many years ago, I was setting up a G60 Golf and as I unplugged the temp sender to put the ECU in setting mode, the sensor blew out, hit me directly between the eyes and sprayed me all over with boiling coolant. I spent the next four hours in casualty and the next day I had to go to Germany for a show with a bright red scabby scalded face and a square dent between my eyes above my nose from the impact of the flying sensor.... :zx11:
Sorry, the temp sensor/sender that's right. The sensor was hanging down completely loose with the C clip still in place and the O-ring was nowhere to be seen. Unsurprisingly, with no O-ring the header tank coolant drains within about 30 seconds, so really I had no option but to pay for a tow. Pain in the rear end though. That sounds absolutely nasty mind. I did another flush and drain and used the generic O-Ring out of the packet as I'm waiting for the new one to arrive. Not only did the generic O-Ring seal it, the C-clip seemed absolutely solid and didn't want to move at all :aargh4::aargh4: Of course that'd be the case when on my drive.


How often do they blow out and does it have anything to do with the clip and O-Ring? Any thoughts on the lack of heat?

[GeorgeE]

Not having had a car with that engine I'll let Crasher respond on how often the blow out.

Lack of heat could be an airlock in the heater matrix/pipework, but it could also be a stuck flap actuator as the motors do give problems. It would be a bit of a co-incidence to happen at the same time, but worth checking. Do you have VCDS to read fault codes?

[Skezza]

Not having had a car with that engine I'll let Crasher respond on how often the blow out.

Lack of heat could be an airlock in the heater matrix/pipework, but it could also be a stuck flap actuator as the motors do give problems. It would be a bit of a co-incidence to happen at the same time, but worth checking. Do you have VCDS to read fault codes?
Sure do. I'll give it a scan tonight. Any tips on clearing air locks? I've tried bleeding it with the cap off and then on.... The only thing I've not done really is taken it for a good drive.

[Crasher]

That O ring has been used since 1988 and is very reliable as long as it is installed correctly.

[Skezza]

That O ring has been used since 1988 and is very reliable as long as it is installed correctly.
Interesting. Well the new clips and O rings should be here today, so I can have a proper good look. I assume there's no reason you can't reuse that O-Ring? I did notice on a video online that the lad was pulling quite hard on the sensor and it wasn't popping out.... so clearly I just need to do that before I can be happy that it is safely installed.

Currently the car is still sat on my drive waiting for me to work on it again. I'm still trying to decide whether to backflush the heater matrix just for good measure or perhaps just take it to my mates and getting it vacuum filled and seeing if it helps. I suppose good thing is that with the backflushing, I can do that without loosing all the coolant as i'm connecting the hoses at the top of the system. I think for the time being, I've 'flushed' (using the term loosely considering the air locks) the system with tap water repeatedly and it's now running fairly clear, I'm just going to run some ordinary coolant system flush one last time a perhaps drive it to work so the coolant flush picks up any grime and filth. I'll take some ramps in the back (just in case :biglaugh:) and then drop it as soon as I get home, flush it with de-ionised water..... then finally fill it properly with a nice fresh mix of coolant + de-ionised. I can't keep putting it off but life doesn't half get in the way right?

Lucky I was able to borrow a Passat off my brother in law.

[Crasher]

I did a rad temp sensor on a Golf 5 today and it is the same part, we use Febi sensors normally which come with the O ring and clip but this was a slightly different one and we had to get it genuine so a pulled a clip and O ring off the shelf, we have a lin bin full of both.

[Skezza]

So a bit of good news today. I decided this has gone on long enough and the car needed sorted. Filled with the coolant system flush and tap water, I drove it to work (with a bottle of spare just for topping up). As I got further, I noticed a small amount of warmth through the vents..... by the end of the trip, the warmth was fully back.... so no need to backflush the matrix :)

I will drop the now probably very dirty tap water, flush with some fresh de-ionised water, flush probably once more for good measure and then finish this job by putting in fresh G12.

Anyone know how many litres the coolant system in the 1.8T is?? I'm surprised how little there is online about it, although one post seems to think 8-10 litres (which isn't as accurate enough imo). Apparently the mix should be somewhere between 30/70 coolant to water and 50/50...... Anything above 30/70 apparently is enough for the UK climate.

[Crasher]

Use a decent rad flush for a week then back-flush with a pressure washer if possible and then use G13 purple.

[Skezza]

Use a decent rad flush for a week then back-flush with a pressure washer if possible and then use G13 purple.

Not G12 pink?

[Crasher]

Nahh, old hat, purple G13.