View Full Version : Excess Vapour from exhaust....any ideas?

29-01-09, 11:55 AM
Hey Gang,

I've asked on CS & thought I'd ask on here for peace of mind tbh.

Right the issue I have is my car has only covered just over 17,000 miles & all seems well, pulls as normal, idles the same as before, but I noticed as I pushed the car further up the rev range & as it came on cam there was excess moisture coming from the tailpipes so much so that it caused some moisture on the rear window. It's not thick white smoke it just looks like normal exhaust gases albeit more of it.

I have read on CS that the OEM exhaust system holds water then & it'll be blown out the harder you push the car?

It seems to release more vapour than normal on the over-run if I rev it up higher in the rev range whilst static too.
I checked my oil, coolant etc & all fine. No mayo in oil cap, oil clear & coolant is the same,I'm also very fussy about warming my car up before pushing it leading me away from a possible HG prob,

My fuel consumption is currently a lowly 23.5mpg on my current tank. Thats the worst I have ever had & I've been driving carefully due to the state of the roads. Although I do let it idle from cold until the cold start lumpiness is gone (90 seconds or so). But this tank was filled before Xmas & it has been bitterly cold & I understand the 182 lump is a greedy so & so when cold.

Could it be one of my O2 sensors is playing up & the excess vapour is just silly amounts of fuel being pumped in.

I only get it once above 5K. I've not driven it hard due to worry, but I can get the same thing revving @ idle.

Any advise would be great....thanks in advance

Does this sound like the OEM system is full of water & could need changing shortly or is there more serious things to worry about?

Any advise would be great....thanks in advance

29-01-09, 12:02 PM
There are a bunch of threads from quite a while back on this. I think, especially as it's not been used a huge amount and the weather, that it's probably condensation in the exhaust, i used to get this even in the summer sometimes. Maybe keep an eye on it but i wouldn't be worrying too much.

29-01-09, 12:14 PM
Same as above - used to get loads on the OEM exhaust but nothing now i have changed

29-01-09, 12:41 PM
This sounds like water in the exhaust to me.
I used to get a vapour trail too.
When I took off the standard exhaust you could hear the water sloshing around inside it.
Since the Miltek was fitted there's been no vapour trail and no annoying water spray up the rear window.

29-01-09, 01:08 PM
Cheers guys :wink:

I'll just have to wait for the OEM exhaust to rot off & then give her a treat replacement :twisted:

29-01-09, 01:27 PM
i also used to get a lot of vapour - at one point i was actually worried the engine was on the way out as it was a fog not too dissimilar to blown engine, but after changing the exhaust i've not had it at all from memory.

re over fuelling - this is not a scientific test or anything but it can be a guide - clean the tail pipes with some metal cleaner, get them gleaming and go for a 30 mile spirited drive.

If, when you get back, they are tarnished with carbon deposits and not just 'off shiny' you may find the fuelling is out, if so i'd take it to a decent garage and get them to do a air fuel ratio test - this will show up any issues.

29-01-09, 01:32 PM
Cheers Cue :wink:

Your description of the exhaust vapour is bang on.
Not been wanting to put my foot down to to thinking about it going pop tbh :oops: :lol:

I'm half sure the poor fuel consumption has been down to short drives & very cold starts of late tbh buddy.
Thanks for the tip with the exhaust test/guide...I'm friendly with a couple of decent Jap tuners that I'm sure could do a A/F ratio check for me.

Thanks again people....it really is much appreciated =D>

29-01-09, 01:40 PM
My car was like a steam train when I got it. Put my food down and massive spouts of steam came out of the exhaust.
The best way to get rid of it is to floor it a few times I found.

18-02-09, 05:24 PM
My car was like a steam train when I got it. Put my food down and massive spouts of steam came out of the exhaust.
The best way to get rid of it is to floor it a few times I found.

yep, gun it and the clouds will vanish after a couple of mins.

18-02-09, 05:30 PM
When I removed the standard exhaust last week, the back boxes had quite a bit of water in them...

George K
18-02-09, 06:31 PM
On a previous car (Turbo 2CV!!)as the silencer was not quite horizontal, I drilled a small hole (2mm) at the lowest point - quite a lot of water used to drain out, but it cured the steam, and reduced the risk of it rotting from the inside out. Sadly we had to sell the car when our daughters started driving.

21-02-09, 07:10 PM
Im still on my oe exhaust and suffer the same , mostly due to the lack of miles i do in the car , im sure i even went back to renault to get it checked , and i had it checked on the rolling road , its purelly water trapped in the exhaust and hafter a good spirited drive its not long in dissapearing , it is a bit embarrasing though when u cant see out the back window :wink: