illuminous yellow liquid - Page 2 - Porsche General - PistonHeads UK

I have a 997 and noticed some yellow illumimous liquid under the rear of the car. It was under the exhaust cats but they appeared dry. I wondered if it was coolant but have not been able to move the car as the battery was flat. It has been sitting for 2 weeks. Any ideas?

Have you checked the coolant level?

It is probably coolant. Have a taste test. If the taste is sweetish its coolant.

clorenzen said: It is probably coolant. Have a taste test. If the taste is sweetish its coolant. If it is salty then the neighbours cat has been in

Steve Devaney said: clorenzen said: It is probably coolant. Have a taste test. If the taste is sweetish its coolant. If it is salty then the neighbours cat has been in I nearly spilled my beer then!

Angelus said: Steve Devaney said: clorenzen said: It is probably coolant. Have a taste test. If the taste is sweetish its coolant. If it is salty then the neighbours cat has been in I nearly spilled my beer then! I was going to have a cup of tea but on the other hand...

Would yellow not be A/C fluid perhaps?

Steve Devaney said: Angelus said: Steve Devaney said: clorenzen said: It is probably coolant. Have a taste test. If the taste is sweetish its coolant. If it is salty then the neighbours cat has been in I nearly spilled my beer then! I was going to have a cup of tea but on the other hand... Good one, now I don't feel alone. It could be washer fluid? Perhaps? But then again, I've had a few!

Aircon for sure

That's if it's illuminous

996TT_STEVO said: That's if it's illuminous Is that like fluorescent?

Bill Stein said: Would yellow not be A/C fluid perhaps? This.

hidetheelephants said: 996TT_STEVO said: That's if it's illuminous Is that like fluorescent? Dayglo

Old thread resurrection... Did the OP ever work out what the yellow fluid was? I have the same coming from the rear area of my 911 997.2. The fluid is bright yellow, watery and odourless. I put the car away slightly wet recently and that is when I first noticed it some days later (probably a couple of tea spoon's worth). The car went away very dry at the weekend and I have noticed a very small amount has leaked since. I took the car to my local Porsche indy (Northway) who service the car and they have had a look and couldn't see any sign of a leak and said none of the fluids in the car are as I described (yellow, watery and odourless). I also looked underneath whilst at Northway and it appeared all very dry (although I had just driven for 30 mins on dry roads). It seems as though perhaps residual water or condensation is running through something causing the colour. I'm not worried about condensation but specifically why it is bright yellow and whether this indicates a problem?!? Thanks in advance.

Blinker Fluid perhaps

Chris-55tad said: Old thread resurrection... Did the OP ever work out what the yellow fluid was? I have the same coming from the rear area of my 911 997.2. The fluid is bright yellow, watery and odourless. I put the car away slightly wet recently and that is when I first noticed it some days later (probably a couple of tea spoon's worth). The car went away very dry at the weekend and I have noticed a very small amount has leaked since. I took the car to my local Porsche indy (Northway) who service the car and they have had a look and couldn't see any sign of a leak and said none of the fluids in the car are as I described (yellow, watery and odourless). I also looked underneath whilst at Northway and it appeared all very dry (although I had just driven for 30 mins on dry roads). It seems as though perhaps residual water or condensation is running through something causing the colour. I'm not worried about condensation but specifically why it is bright yellow and whether this indicates a problem?!? Thanks in advance. I think he went with the air conditioned cat answer......

Some more research and I found the below answer down the back of the internet... 95 per cent of the exhaust systems built today are made up of iron alloy and galvanized steel. Exhaust pipes are made of either iron or stainless steel. Heat shields are made of galvanized steel and galvanized steel uses zinc as a rust inhibitor. Zinc, when hot and in the presence of iron and a catalyst, creates yellow zinc oxide in the form of crystals. The connection is the catalyst - salt water - or compacted snow with road salt mixed in. If the snow is able to touch the exhaust heat shields and the exhaust pipes at the same time, the chemical reaction between the two dissimilar metals creates the bright yellow crystals. I'm no chemist but I first noticed this after the car went away following a drive with some slush / snow on the road, so this could be plausible. Interesting that the OP was in January and another in the Monaro forum was in December which both correlate with salt on the roads.

Naa still think it was the cat

See also: https://rennlist.com/forums/996-forum/1043081-yell...

Except the Porsche heat shields are made of aluminium. If your coolant is red, as it normally is for these cars, then coolant it is not. Look in the expansion tank to determine. If yellow then it is almost certainly coolant - "watery". Otherwise would be aircon lube, but this is oil not "watery". It is, however, usually marked with a yellow fluorescent dye to make leaks very evident under UV light.

Perhaps the heat shields are not the source if they're aluminium, but there seem to be too many other tales on the internet of yellow liquid under the exhausts of all sorts of car makes where this is the accepted cause. As I've said I'm certainly no chemist but based on the number of similar stories on forums and the fact the liquid doesn't match any of the fluids in the car, I'm pretty satisfied that there is some kind of reaction between road salt and components of or near the exhaust causing the liquid. I can get back to enjoying the car now :-) Cheers for comments.

Have a look at the colour of the fluids in the reservoirs. If it isn’t the coolant colour then it is likely to be the air con.

Coolant is normally pink. Could that be power steering fluid from reservoir or pump? Or a/c with oil/dye in (will luminesce with black light). If your a/c works (hard to tell at the moment) then it’s not the a/c as there will definitely be no gas left in the system.

Or this explanation (looking at the spread on your floor) from thread above? Zinc, when hot and in the presence of iron and a catalyst, creates yellow zinc oxide in the form of crystals. The connection is the catalyst - salt water - or compacted snow with road salt mixed in. If the snow is able to touch the exhaust heat shields and the exhaust pipes at the same time, the chemical reaction between the two dissimilar metals creates the bright yellow crystals.

I’ve just noticed a similar issue under the rear of my 991.2. Do the photos help narrow down the potential cause? I have not tasted it. [url] |https://thumbsnap.com/WqU9TDk4[/url] Edited to update: Took the car into Porsche today and after (I assume) a thorough check they could find no sign of any leaks and informed me that they do not use any fluids of that colour in the car. Edited by DeuceDeuce on Friday 6th January 19:04

I moved my 997.2 out of my garage for the first time in about three months today to find exactly the same coloured residue on both sides directly under the exhausts. It's completely dry so I presume whatever caused it is water-based which stacks up with the chemical reaction in the exhausts theory although I haven't driven it in the snow.