Billowing White Steam Under Hood...

[gathermewool]

97 Subaru Legacy GT 201k miles

 

A couple of times over the past month I've noticed a bit of steam issuing from under the hood when stopped after driving for a bit. I changed the coolant maybe 8 months ago, and the level hasn't moved a millimeter - very consistent hot and cold. By the time I got to a place where I could check under the hood there as no noticeable steam. The distinctive sweet smell wasn't present either.

 

Today it rained A LOT, with wind to boot. When I started my car I noticed the a big billowing cloud of white steam. I popped the hood and noticed a lot of steam issuing from the passenger side of the engine bay, seemingly from the exhaust or transaxle area. Again no sweet, coolant smell. I'm not talking about a small amount of steam or smoke whisping about. When I say billowing, I mean billowing. At this point the car had only been on less than thirty seconds, so I'm not sure the exhaust would be hot enough to flash dripping water, let alone at that rate. Again, all levels ok: coolant, ATF, front diff.

 

I immediately drove to the auto hobby shop, but by the time I got there I couldn't find a thing! No noticeable exhaust leak, leaking water, or smell of coolant.

 

Any ideas?

[Stang70Fastback]

Two things with my car (98 Legacy Outback):

 

1. Ever since the radiator was replaced when we did the head gaskets (around 170k miles - it's now at 229k) the radiator has steamed in the rain. I guess it's just when it gets wet the water evaporates due to the heat, but obviously other cars don't do that, so I have no idea why...

 

2. Oil leaks from a lot of seals on my engine, and one of the places it drips is on the exhaust pipes on the passenger side (you can see them if you look down that open area) and that produces smoke. On a normal drive, if I pull over at a rest area, you can see a bit of smoke coming out of the hood scoop. Normally you barely notice it, other times it's enough to make people around me eye the car curiously.

[gathermewool]

Two things with my car (98 Legacy Outback):

 

1. Ever since the radiator was replaced when we did the head gaskets (around 170k miles - it's now at 229k) the radiator has steamed in the rain. I guess it's just when it gets wet the water evaporates due to the heat, but obviously other cars don't do that, so I have no idea why...

 

2. Oil leaks from a lot of seals on my engine, and one of the places it drips is on the exhaust pipes on the passenger side (you can see them if you look down that open area) and that produces smoke. On a normal drive, if I pull over at a rest area, you can see a bit of smoke coming out of the hood scoop. Normally you barely notice it, other times it's enough to make people around me eye the car curiously.

 

Thanks for the info. I first thought radiator, but the car was just started from a cold, sitting-all-day condition. Also, the steam was very obviously billowing from some where near the trans axle, from beneath the car.

 

I have a weeping driver-side valve cover gasket that doesn't drip, but forms a small amount of residue on the cover bottom. The rear main seal, however, does drip, but imperceptibly, meaning I never see drops on the ground, but will see drop formation on cross member, diff casing and a small amount of discoloration on the exhaust heat shield, right at the Y.

 

I started up today with out a single whisp of steam. It seems that most likely the few times this has happened were freak occasions where water or what ever lay on a spot where it could easily flash, even though it was JUST after starting the car from a cold-iron condition...