2004 Blowing Steam From Tailpipe After Rain

If it were a head gasket, why does this only happens after it sits in heavy rain? Wouldn't it also do it in dry conditions too if it was a head?

 

Does it start immediately after startup? It takes a while for exhaust to get hot enough to boil off water. If you start steaming immediately after startup, it's not the exhaust.

 

I should think so. Still don’t think it’s water in the exhaust causing steam, it has to be caused by getting water into one or more cylinders since it steams immediately on starting. If water in the cylinder(s) isn’t coming from the coolant then that leaves what, the air intake? I could see how that would play up with the symptoms. Heavy rain infiltrates the air intake and pools up somewhere and gets sucked into cylinders and makes steam until the pool is depleted. Have you checked the air box after a rain?

 

Yes. It starts up fine. It takes about 10 to 20 seconds before the steam starts up. Starts slow, then gets worse as the engine heats up.

 

Airbox was replaced with cold air intake. I don't see any water getting near it. But could be worth a shot to remove the filter anyway next time it rains to rule it out.

 

That's an issue, I bet it's sucking water through that CAI .. there's lots of posts on here of people having more water problems in the rain after they install one of those, you'd be surprised how much water can enter the engine bay from underneath when you drive in the rain.


Do you still have the rubber inside fender protectors?

 

Not driving. The truck sits in the driveway. It rains on the truck (truck is motionless), then problem occurs only on first startup after rain.

 

You said you have leaking welds from new exhaust installation, are these welds anywhere where rain water running off the cab or box could be dripping on them and getting inside the exhaust? Looks 100% like it’s rainwater getting inside the exhaust to me. Doubt it’s from the air box as that means it is entering the combustion chamber and going through the FI, it would be running like crap with any amount of water there.

Maybe there is an exhaust fitting where the female pipe fitting into the male pipe is “upside down”, ie. so water hitting the pipe runs down into the exhaust and pools somewhere until you heat it up when you start it up?