WJM Posted December 28, 2004 Share Posted December 28, 2004 Ok..87 RX...completely stock internals. TWE pipes, Elec. Boost controller, intake...straight pipe, 2.5 inches, no cats, WRX TMIC, recirc valve plumbed up properly. Engine was freashly redone less than 10k miles ago with all OE SUBARU gaskets, heads profressionally cleaned and machined true. Upon start up in cold/warm/hot weather...there will be some vapor out of the exhaust. I cant smell the smell of burning coolant..so i thought it was normal. Once the engine got warm in warm/hot weather, it went away...was only present during cold engine conditions. Now, up here in the constantly below freezing temps...at idle, the car always has this vapor/steam from the exhaust. It goes away during accell, cruise, and decell....comes back during idle. Now, ive well tuned the timing, and it doesnt miss a beat. Oddcomp said something about a perfectly tuned engine will have water vapor as a combustion by-product...and I know the cats make more of that during the gas conversions.... So....what ta do? Is this normal? Is this where my coolant leak is? There is nothing else abnormal about the operation of the engine. Its strong, fires right up when cold on the first rototation, and other than the fuel cut gremlin...runs fine, and gets pretty good MPGs. Opinions? Link to comment Share on other sites More sharing options...
Caboobaroo Posted December 28, 2004 Share Posted December 28, 2004 sometimes you can get condensation build up in the crankcase in colder weather. When this happens, the condensation will seap past the rings while its running giving you a vapor from the exhaust. Can't really remember why it does this but a lot of cars in cold weather seem to 'smoke' from the exhaust more The other thing is that your car has heat coming out of the exhaust, duh! Warm exhaust in colder weather will also seem to 'smoke' but goes away when you're driving it because its dissapating from the air blowing around it. Link to comment Share on other sites More sharing options...
All_talk Posted December 28, 2004 Share Posted December 28, 2004 Water vapor at cold start is very normal, and to see some at idle in cold weather seems pretty normally too. Like Oddcomp said, water is a product of combustion (in prefect combustion water and CO2 are the only products), but under most conditions its expelled as a gas so you dont see it. First guess on the leak is intake gaskets, but a small leak that puddles on the block or only opens up under heat/pressure may never leave a drip. Take it out for a good hard romp or a long freeway run, then let it idle and get your nose under the hood and see if you can sniff it out. Also check the plugs, if there is any significant amount of coolant going through a cylinder they should show it. Good luck Gary Link to comment Share on other sites More sharing options...
pmichaud Posted December 28, 2004 Share Posted December 28, 2004 Doesnt the cat converter change the carbon dioxide? into water through some sort of ion exchange? Seems like sulfur is involved as well... cant ( dont want to?) remeber all that chemistry stuff.... Anyways, the heat of exhaust makes that water steam, and visible in the real cold weather, biut not in the wamr air, although its still there.... Link to comment Share on other sites More sharing options...
archemitis Posted December 28, 2004 Share Posted December 28, 2004 its all normal in cold weather. happens all the time. the colder it is, the worse it is, on my cars. you runin a 195 stat? mine did it worse with a 180. Link to comment Share on other sites More sharing options...
All_talk Posted December 28, 2004 Share Posted December 28, 2004 Doesnt the cat converter change the carbon dioxide? into water through some sort of ion exchange? Seems like sulfur is involved as well... cant ( dont want to?) remeber all that chemistry stuff.... Anyways, the heat of exhaust makes that water steam, and visible in the real cold weather, biut not in the wamr air, although its still there.... Ideal combustion for octane (root hydrocarbon for gasoline). 2 C8H18 + 25 H20 ---> 16 CO2 + 18 H2O Of course gasoline in not pure octane, nor is the air pure or the combustion perfect in the real world, so this never really happens in practice, but that’s the theory anyway. Gary Link to comment Share on other sites More sharing options...
NorthWet Posted December 28, 2004 Share Posted December 28, 2004 Doesnt the cat converter change the carbon dioxide? into water through some sort of ion exchange?... Two catalytic processes used in current emission controls: One that oxidizes HC and CO (with O2) into H2O and CO2, and one that reduces NOx into N2 and O2. The exhaust system also tends to have a lot of residual moisture in it on cold start, either from combustion, atmosphere, or both. And has been already said, if it is cold enough then normal combustion vapor will "steam" behind... just look at jet contrails. Link to comment Share on other sites More sharing options...
WJM Posted December 28, 2004 Author Share Posted December 28, 2004 this car has no cats as stated in the original post. Link to comment Share on other sites More sharing options...
NorthWet Posted December 28, 2004 Share Posted December 28, 2004 this car has no cats as stated in the original post. Sorry for the apparent tangent. But the rest still applies: Cold starts in cold climates give condensed vapor. Low-power running in very cold weather can give condensed vapor regardless of engine temp. Any minor leak from intake, HG, or exhaust will aggravate this. This doesn't help you much, other than to let you know not to get too freaked by visible exhaust vapor. Link to comment Share on other sites More sharing options...
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