Coolant Hose Diagram

[Hilux2400]

Could you please help in providing a link to a coolant hose layout for a 2003 996 Carrera 2 3.6.

My workshop CD only has the Turbo diag for some reason.

I am trying to find the source of a coolant leak. It's somewhere at the front of the engine (behind passenger seat RHD UK model) and fairly high up. It's not the coolant reservoir bottle or any of the hoses that connect to it. I don't think it's near the tiptronic heat exchanger but its somewhere towards the rear of this point after the pipes pass through the cross member and then rise into the engine. Coolant is dripping down over the inner lower suspension pivot point.

I can't see the leak. I need to get the car on a ramp for a good look, which I will do tomorrow. I am just hoping I don't have to move anything major to get to the source.

Thanks for reading.

H

[logray]

That sounds like a leak coming from the AOS, and I think you mean rear of engine.

The front of the engine points towards the back of the car (it's installed "backwards").

"after the pipes pass through the cross member and then rise into the engine"

If you are speaking of the hard pipes, the connection from hard to soft are in the rear corners (rear of car) in the engine bay.

Edited April 1, 2013 by logray

[Loren]

Narrow body or wide body?

[Hilux2400]

Thanks for the swift replies.

In line with your description of "back" and "front", the leak is at the back left of the engine (left when looking from the back of the vehicle).

I believe it's a narrow bodied car - non turbo - 2 wheel drive.

If it is in the area of the AOS, does the AOS have a water jacket and if it does it is prone to failure?

H

[Hilux2400]

I have found some decent diagrams here:

http://www.autoatlanta.com/porsche-parts/996-99-05/porsche_911_parts.php

I really should have looked a bit harder.

It seems that the AOS does have coolant connections. Is this right? Is it possible to access these points without taking off the alternator and left side induction bank?

I am just trying to anticipate the size of the task in front of me.

H

[krazyk]

If I am correct, technically thats not the AOS. It is just referred to as an "oil separator" or "oil-vap. separator" and part of the emission system. AOS also refers to the parts in the engine sump. I hope these pics help.

Edited April 2, 2013 by krazyk

[Hilux2400]

Thank you for the diagrams.

I will know by tomorrow, but it seems that the leak is from this area and the diagram, I think, shows two coolant hoses at 12 &13. There also seems to be a coolant heat exchanger chamber on the top part of the AOS.

Happy days

H

[logray]

Please delete post. Mistake

Edited April 1, 2013 by logray

[logray]

Yes those are both coolant hoses going to the AOS. The Aos itself can also crack.

[Hilux2400]

Well I have had a look with the car on the ramp and there is an worn part on a small diameter metal (about 15mm) pipe that rises towards the AOS. It has worn because it is in contact with a metal cable clip on its route up towards the AOS.

The pipe will have to be replaced and now I am wondering which part it is. I suspect it's 996 106 225 54 which is a left side vent, but I am not sure. Any info would be useful.

I have decided to replace the AOS while I am doing the work and also the coolant reservoir. It is impossible to gain access to this metal pipe, from which coolant is leaking, without taking quite a bit of stuff off the car. As I am doing this a new coolant reservoir, AOS and short AOS bellows seems sensible.

I am lucky to have found this failure when it has just started to leak as it has the potential to empty the coolant system in a very short period.

H

[perryinva]

Just so you know, the MKII cars (2002+) do not have a bellows, the AOS was redesigned. The picture of the AOS in krazyKs post above is the MKI and the AOS does not look like that where it connects to the engine. It does not go in sideways as shown, but straight down. When you get your new AOS, compare it to the old one to be sure you have the right one, as they are not at all interchangeable. For some very odd reason, Porsche added a small rectangular "U" shaped plastic feature, maybe it is needed for another car, that is not on the original. It is obvious in a side by side comparison. If you do not cut off the legs of that "U", you will not be able to get the last intake manifold bolt in, as it completely blocks the opening to get a socket of any kind in there. Depending on the mileage on your car, if you are going to drain the coolant, it would also be a good time to proactively replace the water pump and put in a low temp thermostat. Does wonders for the car. my '02 only had 48k mile son it, and the original 11 year old water pump already had a slight amount of play in the bearing.

When I replaced my AOS and other parts, I found that a number of the pipe supports and such in that area had broken over time, so I padded and tightened them to the support areas with heavy duty Ty-raps, to minimize movement and rubbing. I can easily see what happened to yours.

Edited April 5, 2013 by perryinva

[logray]

I would be very surprised to see a metal coolant pipe worn through like that, perhaps it is leaking down from somewhere else.

The AOS is in that area and is much more common, either due to the AOS cracking or the rubber hoses deteriorating/scuffing/clamps/not tightened enough.

99610622554 is the bleed vent to radiator in the front of the car.

I think you mean the other end of the coolant bleed vent line #13 in the diagram below (99610668159), since that is the only small coolant hard pipe in the vicinity of your leak. One end goes to the top of the radiators and the other end goes to the top of the coolant reservoir.

http://www.autoatlanta.com/porsche-parts/996-99-05/105-05.php

[Hilux2400]

Logray

Thanks for the reply and also to perryinva for the AOS advice.

I have got my money on pipe "13" as "4" is a large diameter metal pipe.

There are several variations of "13" and I think the later mod is a form of plastic so the dealership tells me.

I will post some pictures soon.

Thanks to everyone for the help and guidance.

H

[Hilux2400]

Well here it is and it's pipe No 13 in this diagram.

http://www.autoatlanta.com/porsche-parts/996-99-05/105-05.php

It's the aluminium vent pipe that returns to the header. I have attached a photograph of the hole where it has been rubbing against the clip near the block.

Just waiting for the part and we are changing the AOS and coolant reservoir at the same time.

H

[logray]

Nice work! Maybe you could wrap that area with something to keep it from happening again?

[Hilux2400]

The pipe has now been replaced and it has been threaded through convoluted tube to avoid a second failure. I have attached a pic, with a broom as a reference.

Despite replacing the item I had a go at a repair using Durafix.

www.durafix.com

It was both easy and successful and I did a pressure test afterwards to ensure that there was a seal. This is the first time I have used Durafix for a real repair job and it really is good.

Thanks for all the help along the way.

H

[logray]

Thanks for not pouring in a can of stop leak and refilling with dex-cool. ;)

[scruffyj]

I think I have either a similar issue or the exact same issue. I can only tell that it's right above the crankcase vent area (AOS) when looking at it from below. I just can't tell exactly where.

How did you end up replacing this? Were you able to get at it from the top (after pulling out the left intakes, alternator, etc.)? Or did you have to drop the engine? It seems too tight to reach from underneath - but I don't want to pull off everything from the top if that's not going to get me to resolution...

Thanks!

Jeff