Major Coolant Loss
 

Had an incident with the car earlier and still too cold outside to investigate further, so been trying to figure out what it can be inside.

Car sits outside 24/7. I've been using it nearly every day for the last week going down to my brother's (about 8 mile) to help him with some building work. I start the car first thing, crank up the heat and go back inside for 10-15 minutes.

Did the same this morning, but left it maybe for 20 minutes this time as it was still -6 at the time. Started the drive down at no more than 40mph and everything was fine, with temperature gauge sitting at 90. Got to a small hill and as soon as it dropped a gear the needle started to rise quite quickly. I managed to pull off into an entranceway within about 50 metres and the needle was around 160. Switched the engine off and popped the bonnet. By the time I got out of the car, the frost on the front left of the bonnet had cleared and steam was starting to come out. Lifted the bonnet and unscrewed the reservoir cap slightly to let some pressure out. Right side of the engine was steaming.

I waited a while and then headed to a nearby house for some water. Came back with 2x2 litres cartons and poured them in, and they came out almost as fast. Tried having a look underneath while it was still dripping, and the best I could determine was it was coming down from behind/above the power steering and a/c compressor (bottom right on this photo of MJs).

I've looked at the images in ETKA, but can't see any coolant pipes that are on that side of the engine.

Brother arrived and we got the car back to the house. Got brother to pour in 6 litres of water straight in whilst I tried starting the car for a few seconds. Car fired up fine and engine sounds fine, so switched it off again. I'm hoping that when I do have a look at it I can see the issue, but I'm still trying to thaw out at the moment, and just looking for possible areas to look at.

http://forum.a8parts.co.uk/attachmen...1&d=1618774640

Has the radiator vent port broken off maybe? That would have sprayed everything on the left of the engine bay with hot coolant though so ought to be very obvious.

The only coolant thing in the area you describe is the block drain port which is a metal pipe bolted to the block that drops down to the sump so you can drain the coolant out of the lowest point of the block. That frequently gets silted up, but it should have bolt in the end. Possibly that has failed / rusted out / someone left the bolt out and it just unblocked itself...?

I would be disinclined to leave it overnight filled with plain water in this weather.

Went outside and jacked up the car on the N/S so I could have a look around, but couldn't find that pipe. Can't visualise exactly where it is from that image. I also checked the radiator as best I could and couldn't see anything obvious, with both pipes secured in place.

Anyway, as the engine was now dry I decided to pour some water into it to see where/if it would come out anywhere, thinking it's going to be in the same area, but nothing. Instead, it came out from pipe #9 (top of radiator) where it joins to the metal pipe (#11). It wasn't running along the bottom of either pipe to the join, but from the join itself. I removed the pipe completely and examined it from end to end but didn't see any obvious defects. I also checked the end of the metal pipe as best I could. I also took the liberty of removing the other radiator hose (#10) to drain as much water as possible.

Would you have a photo of where the pipe you suggested is on the engine and where it exits, and assuming I can get to it in situ, I'll drain whatever water is left in it.

There might be a pic in one of the WITW threads with an engine on the stand. I'll have a look through the archives. It runs vertically from behind the PS pump down to the sump, not horizontally in the silly diagram, and is bolted to the upper sump casting right behind the ac compressor. You'll need the undertray off to see it.

I have seen them leak from that joint between 9 and 11 when it gets crusty and the spring clamp is no longer able to hold it shut, or when someone has managed to twist the hose while refitting. Its quite a sensitive joint for no obvious reason.

If you've got the lower rad hose off then the thermostat will slowly allow most of the coolant out of its bleed port which hopefully should leave room to not cause any damage if the remaining water does freeze in the block.

Had another search and came across the following thread:

https://www.audiworld.com/forums/a8-...tions-1748666/

Post #6 links to three images. The first and third I can find. Is the second one the one you mention?

Never had an issue with that pipe before and the clip was as tight as a tight thing.

Also one about the link above. In post #4 the person asks about running the engine. Is it safe to do this for a few seconds, and will it really help to drain more of the coolant if the drain plugs are out and radiator disconnected?

It was 2 degrees when I was out earlier, so a lot warmer than this morning, but I'm going to get something to eat and then go out again and see if I can drain more from these plugs.

Those are 32V pics, but pic2 is of the place where the pipe is attached on the 40V. I found this from the barnfind FE thread:

http://forum.a8parts.co.uk/attachmen...1&d=1670962517

You can just see the pipe on the right hand side.

Brilliant. Time to get my big coat on again.

EDIT: So much easier when you know what you're looking for. Now leaving it until tomorrow when I can have another look around.

Stupid question time: Same on a 3.7 AKC?

Yes is the answer. As MJ said, the illustration in post #2 is very misleading. With the picture in post #6 it was a quick dash outside, look in the area, and it's blindingly obvious.

So far, I haven't been outside yet today. Leaving it to this afternoon when it's due to reach a balmy 2 degrees.

A little update. Left it to this afternoon to look at the car, but had an old heater placed underneath the engine just to try and heat it up. Turns out the drain pipe that MJ referred to was partly filled with rusty muck, which I cleaned out. I put a litre or two of antifreeze in the expansion tank and left it for a good while. When I came back to it, it was pure antifreeze dripping out, the rest of it having already come out into a basin along with a little muck. Plugged the drain and refitted the two radiator pipes.

Poured in about 3-4 litres of antifreeze and heard it coming out again. It's still at the junction of pipes 9 and 11. I felt around the metal pipe with my bare hand this time and noticed what I would call a dimple. Now, looking at a picture of the pipe itself, there are two small metal studs near the right end of the pipe. As best as I can make out from feeling it, I'd say that the lower one is definitely missing and this might be where the coolant is escaping from.

I'll jack up the drivers side tomorrow so I can get a better view of it from below.

EDIT: Forgot to ask. If this is the cause, could I get a pipe made up, or is there something about how it is shaped in places, as it isn't that tight a space.