Sunday Drive and then all the coolant falls out
 

Afternoon all,

Well after fixing the battery in the S8 and going for a drive I was just thinking to myself what an excellent car the S8 is.

Then....

Temp gauge went to the right and red low coolant warning came on the dash!

Ahhhhh and it was all going to well.

Not far from home luckily so got the old girl back and plenty of steam on the right side of the engine (passenger side where the expansion tank is). Clearly leaking, dripping out onto the drive and the expansion tank was empty. Topped it up, drove round the block and it helpfully emptied itself again.

Steam from the right again and plenty of coolant dropping onto the undertray. No leaks from the expansion tank or the pipes in and out of it. Looking more into it I can see drips and steam coming from what looks like below the exhaust manifold so not sure if its there or dropping from a pipe higher up. Though cannot see it that well as its a little crowded in that part of the engine so need to get it up on ramps and take the undertray off. I have had a small leak for ages but this looks like something has just decided to let go, I was thinking oil cooler pipe but from memory that's on the other side of the engine.

That can be next weekends fun job!

I know that feeling.
I'm currently in Germany after the German Audi A8 meet.
On the way there whilst tail end charlie in our convoy I had to drop anchor at about 130MPH. Up came brake pads worn warning.
Replaced both front pads and all was good.
Did a couple of four hour drives at speed still good.
During a 165 MPH cruise a loud banging started. Driving not affected so wasn't a tyre or engine problem. Brought speed down and the noise stopped. Pulled off the road and found the front under tray, or what was left of it was flapping in the breeze. Friday at 18:30 at Germany has started to close down for the weekend. Carried on to Bielefeld, at 160, it was quiet now. Phoned Audi in Bielefeld whilst en route and the night manager said bring it in at 09:00 Saturday.
Poor chap drove car into test bay but had to ask is the throttle still with the right foot.
End story is, cut off with a Dremel all that was still flapping, made safe for the return drive to England today.
Total cost at the stealers . . . . . zilch.
Even received the usual coffee and biscuits but they did not offer an Audi valet

Well got the old girl up on the ramps to wonder where the leak was from.

Could see it running and dripping off the exhaust pipe and followed it up to the engine bay.

Then found this:

http://forum.a8parts.co.uk/picture.p...pictureid=1190

The hose above has perished and split so the coolant is coming from the black rubber pipe above the exhaust and its the one on the left.

Yep, that's not a 10 minute job though need to look at ETKA to work out which one it is.

It might be 4D0121109 but could someone confirm? I can then get to TPS to buy one in.

None of the hoses are available in the UK any more. Used or a German contact to buy from Tradition (which we have) are the only options.

Are you sure its a rubber hose though? That pic looks to me like its the metal pipe joining the two heads together. That is sealed to the head with an o-ring which frequently perishes and disintegrates.

If it is the o-ring thats a mixed blassing - it's still available, but its a hell of a job to change it, plus you'll need a bunch of other gaskets and seals for everything else that has to come off (inlet manifold etc).

http://forum.a8parts.co.uk/attachmen...1&d=1566645312

Its definitely the hose that's the main problem as I could see it cracked and coolant leaking when I looked but could not get the phone to it for the perfect picture.

The coolant went everywhere when it let go hence its rather pink all over the place!

Though I could well see the metal pipe joint on its way out to.

I think first attempt will be get hold of the lower coolant hose as it looks to be from the bottom of the expansion tank down to just above the exhaust which may be doable with some swearing.

Fair enough. Prestige have just taken a 4.2 apart so hopefully should have the hose.

Just ordered it from them +++

Thanks to A8 parts as always as I would have been a little stuck otherwise!

I would not wish this job on anyone!

Its in one of the hardest places to get too right at the back of the engine and my god its taken some doing this afternoon. It was not the lower expansion hose in the end as I thought but the pipe next door to it which is a heating hose 4D2819371B.

Gave it a pull and it tore in two parts easily!

You can see from this photo it was not in the best of condition after 17 years of use!

http://forum.a8parts.co.uk/picture.p...pictureid=1191

On the bench and now in two parts!

http://forum.a8parts.co.uk/picture.p...pictureid=1192

Joy of joys and arms do not look good after that and quite cut up! Right time to order one of those and then the fun of fitting it, I wish I was closer to Devon.

30 second job I suspect if the engine was outside of the car +++

Ooh not fun at all! Look on the bright side though - still orders of magnitude easier than doing the metal cross pipe +++

Hooray!

Its arrived, not that cheap in the end with postage but needed to be done. Now just need to find the time to fit it!

http://forum.a8parts.co.uk/picture.p...pictureid=1194

Spent some time with the car today fitting the new coolant pipe and noticed a couple of interesting items when doing it.

The pipes and the fitting in the engine bay did not look quite right and then noticed that as the car has LPG its taken a feed from the cooling system into the LPG pump in the engine bay. Now due to that installation a couple of problems have been caused, the metal T pieces for the tapped feed are 14mm which is fine for the pipes going to the LPG but the D2 coolant pipe has an 18/19 mm internal diameter, so not a good fit.

Hence I have ordered new pipes, clips and T pieces to get the job done to a much higher and hopefully reliable standard.

Finally and what I believe was the root cause of the failed coolant pipe is due to the above LPG installation. The heater hose is the one that failed and that normally connects to the right feed from the heater matrix in the engine bay. As this has LPG an extra pipe and T piece was fitted for the coolant feed, nothing odd in that but due to the way it was installed it pushed the heater hose 2 to 3 inches down into the engine bay and much closer to the exhaust.

Therefore we had a hose closer much closer to the exhaust than it should have been and I suspect failed much earlier than normal due to the increase in heat is was exposed to.

+++

I occasionally see Jim the LPG man, I’ll feedback to him on this at some point

:)

All repaired and fixed now, driving beautifully again.