compyelc4

Here's a rather strange one. Bear with me; long story but an interesting read to experienced backyard mechanics.

I have a fantastic '17 SL with 42,000 easy miles. Uses no oil between 7,500 mile oil/filter changes, and she uses zero coolant. Always use top-tier fuel. For the past couple of years I have noticed, on the way to work, that I can literally cover the 2-lane road behind me with white "steam" if I put my foot in it to pass. Normally it would take about 4 "floors" until the smoke would disappear. This is after starting it up on a very cold day in a warm garage and driving about 3 miles on secondary roads and maybe another 4-5 miles on the interstate. I put maybe 10,000 miles per year on it. Usually 50/50 around town and interstate to work (17 miles total). I have surmised that the smoke was the biproduct of "blowing out the loaded up cats" because after about 4 throttle mashes the smoke would stop. Today I got more 2nd person evidence. My son-in-law was toying with me in his V-6 turbo Audi (A4?). He really seemed like he had nothing on me. We were driving back from my grandson's soccer game, taking it easy and behaving ourselves, and were about 10 miles down the road. We reach a 3-lane uphill ramp onto the interstate. He was following. I gave it maybe 60% throttle to merge in front of him. I then mashed it for an instant to show him what my little normally aspirated V-6 would do, and it did well. Surprised him. When we got back to my house for dinner my son-in-law said that when I mashed it he could barely see through the "steam" I had created. Keep in mind it was about a 50 degree F. day but after 8-10 miles you would think that the engine and exhaust system would have been plenty hot to have burned off an condensation from the system or carbon from the cats. I asked him if the "steam" smeared as he used his windshield wipers to clear the liquid mist from them (I was thinking head gasket at the time and thinking about my warranty...geesh!). He said, "No, the mist evaporated cleanly with each wipe of the blades". By then I was about 4 car lengths in front of him and just cruising. His comment convince me that I am indeed throwing water vapor instead of antifreeze, and that I do not have an engine problem (she idles and has beaucoup power with no stumbling). Well now I am really confused as to why this engine produces so much condensation on a cool or cold day and why it would take so long to burn it off. Any suggestions? Googling produces no hints based on the facts I know. Seems like this little V-6 is a real condensation producer couple with taking more time than I ever thought to burn off that condensation.

robtroxel

My 2016 and current 2019 does the same thing when I mash it at highway speeds! After about 30 minutes the water vapor goes away. No leaks and 22000 miles on the clock. Always figured it was the muffler design.

Richard66

See if I read this correctly. After 8-10 miles of cruising at highway speeds (car is fully warmed up) you mash it, and the steam produced is so thick the driver behind you is almost blinded and has to use his windshield wipers to clear away the water and you guys think its normal operation.

compyelc4

Only quoting what my son-in-law said about his visibility and the volume of vapor I have noticed through my rear view mirror.. He may have exaggerated the amount of vapor a bit but he did say he had to use a couple of wiper cycles and the water evaporated without streaking his windshield. I have never noticed this vapor during the summer or just after a cold start. I tried it again today after about a 6 mile warmup (from a cold start) on a back country road from about 40 mph and I saw no vapor, although today was quite a bit hotter oud. My thought is it may have something to do with the design of the exhaust system. I looked at my mufflers and I see that they do not have condensation weep holes like the mufflers in the other cars, so maybe all my around town driving is not allowing the condensate to drip out, but instead evaporate out over 3 to 4 full-throttle "gooses" after exhaust gets very hot (my ASE certified brother has the same theory and he mentioned that he has had a few other Maxima owner complain about the same thing). He says it is condensate water being blown out during high-throttle operation. I'm going to drill a small weep hole in each muffler just out of curiosity, and possibly to extend the life of the mufflers. I expect to find water leaking out of them.

Richard66

Makes sense, as I never have the white vapor no matter how hard I goose it. I do have weep holes in my 7th gen model exhaust pipes about 4 inches from the end, not in the muffler itself.

denoose

First thing that occured to me was a head gasket issue as mentioned by the OP, and his research seems to have eliminated that- I am at a loss as I have owned eight new Maximas, all of which had a minimum of 120K- some more- when traded and have never seen any "steam"- I have had visible water vapor from the exhaust, particularly when the engine is cold and I have accelerated hard, but never any "steam". I will be interested to see what the diagnosis may be..

compyelc4

Never thought to look there. Holes may be plugged up. Thanks.

compyelc4

Well I called it steam and condensation. It is probably water vapor, and a lot of it when floored. I can floor it about 4 times and then the vapor does not happen. Thanks for the thoughts.

robtroxel

When it warms up here, I am gonna drill some 1/8 inch weep holes in the lowest part of the mufflers. My car is always full up on all fluids right to the next oil changes.