# Lots of white smoke coming from Honda. Possible causes **URL:** \ **Category:** In My Humble Opinion\ **Created:** [March 2, 2017, 12:47pm UTC](https://boards.straightdope.com/t/lots-of-white-smoke-coming-from-honda-possible-causes/781191 "2017-03-02T12:47:36Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Wesley\_Clark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wesley_clark/32/20581_2.png) [@Wesley\_Clark](https://boards.straightdope.com/u/Wesley_Clark)\ **Post date:** [March 2, 2017, 12:47pm UTC](https://boards.straightdope.com/t/lots-of-white-smoke-coming-from-honda-possible-causes/781191/1 "2017-03-02T12:47:36Z")
This isn’t my car, just a car I got stuck behind in traffic. It was a late 90s Honda sedan, and it started producing a little bit of smoke on and off. Like every 5 seconds or so. However within a mile the white smoke became overpowering to the point where I couldn’t see driving behind them. It would produce a huge cloud of white smoke every few seconds. The smoke seemed to be coming from under the car, not the tailpipe. Out of curiosity, what would cause this? The car was still driving but I only followed it a mile when the smoke got real bad. I assume it was burning some fluid. ---
**Author:** ![BrotherCadfael](https://avatars.discourse-cdn.com/v4/letter/b/977dab/32.png) [@BrotherCadfael](https://boards.straightdope.com/u/BrotherCadfael)\ **Post date:** [March 2, 2017, 1:14pm UTC](https://boards.straightdope.com/t/lots-of-white-smoke-coming-from-honda-possible-causes/781191/2 "2017-03-02T13:14:52Z")
_Habemus Papam!_ ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [March 2, 2017, 1:15pm UTC](https://boards.straightdope.com/t/lots-of-white-smoke-coming-from-honda-possible-causes/781191/3 "2017-03-02T13:15:46Z")
If it was white steam and it was coming from the engine bay, it’s probably rupture in the cooling system. Even a smallish leak can let out a good amount of steam. A big leak just dumps water out, but those little pin holes spray steam all over the place (think: tea kettle or steam cleaner). As for being every few seconds, that could be anything from the being low on coolant so it was the liquid and air passing the hole. It could have represented the thermostat opening and closing. It could have coincided with the driver putting his/her foot on the gas pedal or they may have known there was a problem and been turning the car off when they were at stop…could be lots of things, but if it’s a coolant leak, I’d guess that it was low enough that it was just intermittently blowing off steam. ---
**Author:** ![Sir\_T-Cups](https://avatars.discourse-cdn.com/v4/letter/s/ed655f/32.png) [@Sir\_T-Cups](https://boards.straightdope.com/u/Sir_T-Cups)\ **Post date:** [March 2, 2017, 1:23pm UTC](https://boards.straightdope.com/t/lots-of-white-smoke-coming-from-honda-possible-causes/781191/4 "2017-03-02T13:23:56Z")
I would guess his radiator blew, or is at least damaged pretty good. ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [March 2, 2017, 2:20pm UTC](https://boards.straightdope.com/t/lots-of-white-smoke-coming-from-honda-possible-causes/781191/5 "2017-03-02T14:20:33Z")
Coolant is under 15-21 psi of pressure so it doesn’t boil inside the system. Even a small leak can generate a lot of steam from the flash boiling. Also, it still could be burning coolant from a failed head gasket; if there’s an exhaust leak somewhere it could still emit from under the car. ---
**Author:** ![Pleonast](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pleonast/32/1183_2.png) [@Pleonast](https://boards.straightdope.com/u/Pleonast)\ **Post date:** [March 2, 2017, 3:01pm UTC](https://boards.straightdope.com/t/lots-of-white-smoke-coming-from-honda-possible-causes/781191/6 "2017-03-02T15:01:31Z")
Could it be smoldering oil from a small leak? ---
**Author:** ![74westy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/74westy/32/3950_2.png) [@74westy](https://boards.straightdope.com/u/74westy)\ **Post date:** [March 2, 2017, 3:21pm UTC](https://boards.straightdope.com/t/lots-of-white-smoke-coming-from-honda-possible-causes/781191/7 "2017-03-02T15:21:59Z")
I doubt it but brake fluid burns white. ---
**Author:** ![chronometer](https://avatars.discourse-cdn.com/v4/letter/c/c2a13f/32.png) [@chronometer](https://boards.straightdope.com/u/chronometer)\ **Post date:** [March 2, 2017, 3:51pm UTC](https://boards.straightdope.com/t/lots-of-white-smoke-coming-from-honda-possible-causes/781191/8 "2017-03-02T15:51:16Z")
I’ve had that same problem before in my Camry. Lots of intermittent white smoke that could have resulted in fines for pollution had a cop or RTA inspector been around. In my case it was a compromised O-ring that allowed small quantities of engine oil to leak onto a hot surface. Replacing that sub-$1 item cost a couple of hundred to fix, because the engine had to be taken apart. ---
**Author:** ![Weisshund](https://avatars.discourse-cdn.com/v4/letter/w/ba8739/32.png) [@Weisshund](https://boards.straightdope.com/u/Weisshund)\ **Post date:** [March 3, 2017, 9:20pm UTC](https://boards.straightdope.com/t/lots-of-white-smoke-coming-from-honda-possible-causes/781191/9 "2017-03-03T21:20:45Z")
Head Gasket ---
**Author:** ![Amateur\_Barbarian](https://avatars.discourse-cdn.com/v4/letter/a/59ef9b/32.png) [@Amateur\_Barbarian](https://boards.straightdope.com/u/Amateur_Barbarian)\ **Post date:** [March 3, 2017, 9:37pm UTC](https://boards.straightdope.com/t/lots-of-white-smoke-coming-from-honda-possible-causes/781191/10 "2017-03-03T21:37:49Z")
Transmission fluid will also burn white-gray. I had a vacuum modulator go bad and the small amount of fluid that got pulled up into the intake was enough to blanket blocks. ---
**Author:** ![Earl\_Snake-Hips\_Tucker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/earl_snake-hips_tucker/32/3269_2.png) [@Earl\_Snake-Hips\_Tucker](https://boards.straightdope.com/u/Earl_Snake-Hips_Tucker)\ **Post date:** [March 3, 2017, 9:41pm UTC](https://boards.straightdope.com/t/lots-of-white-smoke-coming-from-honda-possible-causes/781191/11 "2017-03-03T21:41:27Z")
Japan has a new Prime Minister? ---
**Author:** ![doorhinge](https://avatars.discourse-cdn.com/v4/letter/d/a5b964/32.png) [@doorhinge](https://boards.straightdope.com/u/doorhinge)\ **Post date:** [March 3, 2017, 9:45pm UTC](https://boards.straightdope.com/t/lots-of-white-smoke-coming-from-honda-possible-causes/781191/12 "2017-03-03T21:45:05Z")
> [@Weisshund](#): > > Head Gasket +1 I’m assuming the white smoke was coming from the tail pipe. Antifreeze + water entering the combustion chamber makes a lovely, and expensive, white fog. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [March 4, 2017, 2:54am UTC](https://boards.straightdope.com/t/lots-of-white-smoke-coming-from-honda-possible-causes/781191/13 "2017-03-04T02:54:34Z")
OP: > [@Wesley\_Clark](#): > > … > The smoke seemed to be coming from under the car, not the tailpipe. > … > [@doorhinge](#): > > … > I’m assuming the white smoke was coming from the tail pipe. Antifreeze + water entering the combustion chamber makes a lovely, and expensive, white fog. Poor assumption. ---
**Author:** ![Nightaudit](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/nightaudit/32/17181_2.png) [@Nightaudit](https://boards.straightdope.com/u/Nightaudit)\ **Post date:** [March 4, 2017, 3:16am UTC](https://boards.straightdope.com/t/lots-of-white-smoke-coming-from-honda-possible-causes/781191/14 "2017-03-04T03:16:29Z")
> [@BrotherCadfael](#): > > _Habemus Papam!_ No… Lateran Accord:p:D ---
**Author:** ![HoneyBadgerDC](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/honeybadgerdc/32/1033_2.png) [@HoneyBadgerDC](https://boards.straightdope.com/u/HoneyBadgerDC)\ **Post date:** [March 4, 2017, 3:48am UTC](https://boards.straightdope.com/t/lots-of-white-smoke-coming-from-honda-possible-causes/781191/15 "2017-03-04T03:48:18Z")
Smoke or steam? bad piston rings will cause smoke on acceleration while bad valve seals will smoke while slowing down and idling. ---
**Author:** ![doorhinge](https://avatars.discourse-cdn.com/v4/letter/d/a5b964/32.png) [@doorhinge](https://boards.straightdope.com/u/doorhinge)\ **Post date:** [March 4, 2017, 4:46am UTC](https://boards.straightdope.com/t/lots-of-white-smoke-coming-from-honda-possible-causes/781191/16 "2017-03-04T04:46:41Z")
for historical reference - > [@Wesley\_Clark](#): > > This isn’t my car, just a car I got stuck behind in traffic. > > It was a late 90s Honda sedan, and it started producing a little bit of smoke on and off. Like every 5 seconds or so. However within a mile the white smoke became overpowering to the point where I couldn’t see driving behind them. It would produce a huge cloud of white smoke every few seconds. > > The smoke seemed to be coming from under the car, not the tailpipe. > > Out of curiosity, what would cause this? The car was still driving but I only followed it a mile when the smoke got real bad. I assume it was burning some fluid. > [@LSLGuy](#): > > OP:Poor assumption. Keyword “seemed”. Phrases such as “huge cloud of white smoke” and “white smoke became overpowering to the point where I couldn’t see” still suggests a blown head gasket. Over the decades, I’ve driven behind two neighborhood cars, both Ford 351 cid, which later proved to have blown head gaskets. The white clouds were huge and very dense. Except for the taillights, I had lost sight of the vehicles. ---
**Author:** ![K364](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/k364/32/5_2.png) [@K364](https://boards.straightdope.com/u/K364)\ **Post date:** [March 4, 2017, 4:44pm UTC](https://boards.straightdope.com/t/lots-of-white-smoke-coming-from-honda-possible-causes/781191/17 "2017-03-04T16:44:56Z")
> [@BrotherCadfael](#): > > _Habemus Papam!_ I looked it up. I laughed. ---
**Author:** ![IvoryTowerDenizen](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ivorytowerdenizen/32/17937_2.png) [@IvoryTowerDenizen](https://boards.straightdope.com/u/IvoryTowerDenizen)\ **Post date:** [March 4, 2017, 4:58pm UTC](https://boards.straightdope.com/t/lots-of-white-smoke-coming-from-honda-possible-causes/781191/18 "2017-03-04T16:58:33Z")
> [@BrotherCadfael](#): > > _Habemus Papam!_ Dammit, you stole my joke. ---
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [March 4, 2017, 5:13pm UTC](https://boards.straightdope.com/t/lots-of-white-smoke-coming-from-honda-possible-causes/781191/19 "2017-03-04T17:13:53Z")
> [@Sir\_T-Cups](#): > > I would guess his radiator blew, or is at least damaged pretty good. Anyone know that little hill on Sepulveda, south of Venice Blvd.? Once I was behind a Rolls Royce going up it when his radiator/radiator hose blew. The immense cloud of steam was spectacular! 🆒 As for the Honda, I’m also going to guess the head gasket. I once had a Porsche 924 that emitted white smoke from the tailpipe, and it turned out to be a warped head. ---
**Author:** ![Chefguy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chefguy/32/138_2.png) [@Chefguy](https://boards.straightdope.com/u/Chefguy)\ **Post date:** [March 4, 2017, 5:41pm UTC](https://boards.straightdope.com/t/lots-of-white-smoke-coming-from-honda-possible-causes/781191/20 "2017-03-04T17:41:00Z")
Someone may have dumped STP into the crankcase to help seal an oil leak. [Next page](https://boards.straightdope.com/t/lots-of-white-smoke-coming-from-honda-possible-causes/781191.md?page=2)