White smoke or steam?

[wotan2525]

Afternoon, people. Last night I had an amazing surf night (wake is getting more and more dialed in every day.) Problem: white smoke or steam. I've never run a thermostat in my boat before... yesterday I decided to put one in just to try and avoid and "sludge" or buildups in the engine and to try and eek out better fuel economy. I'm not sure if it was related but there was a LOT of smoke/steam produced now.

Old build-up burning off?
Steam? Where from? Engine Block is stable at 165F.
Stuck open choke?

Other ideas?

[Hematoma]

Afternoon, people. Last night I had an amazing surf night (wake is getting more and more dialed in every day.) Problem: white smoke or steam. I've never run a thermostat in my boat before... yesterday I decided to put one in just to try and avoid and "sludge" or buildups in the engine and to try and eek out better fuel economy. I'm not sure if it was related but there was a LOT of smoke/steam produced now.

Old build-up burning off?
Steam? Where from? Engine Block is stable at 165F.
Stuck open choke?

Other ideas?

Wotan it was prolly steam 165 is normal. Before you had a constent flow of water into the risers because of not having the thermostat. Now that you have one the water kinda starts and stops sorta. Hard explain.

[wotan2525]

Actually.... I'm pretty sure there is still a constant flow of water into the risers.... the water goes from the water pump -> thermostat housing -> risers when the thermostat is closed. When it's open it goes from water pump -> thermostat housing -> block -> risers.... right?

[csuggs]

Actually.... I'm pretty sure there is still a constant flow of water into the risers.... the water goes from the water pump -> thermostat housing -> risers when the thermostat is closed. When it's open it goes from water pump -> thermostat housing -> block -> risers.... right?

Yep - that's right. So there is water flowing through the risers all the time, but when the thermostat is open, the water is hotter because it has circulated through the engine block prior to reaching the risers. I can sometimes see steam coming from my exhaust - perfectly normal - and my motor stays right at 160F until I shut it down (then it goes to about 200F until I start it again - which is also normal).

[wotan2525]

Alright... so let's say it's normal..... How can I be SURE it's steam?

[michael hunter]

Sounds normal to me . Does it smell like oil burning [Old Outboard].

[Salty87]

i'm going with normal too. your stat is making the boat run a little warmer so there's more of a difference to the water you're in....being WI, must be cold. my home water is cold too since it comes out of a dam. in the morning and evening when the air temp drops, i'll see steam but not in the afternoon when it's hot.

[wotan2525]

Alright... good news! Doesn't seem to smell like oil, nor is it black like oil would be. Water temp is 67F right now.

[DKJBama92Mariah]

Most likely normal. Was the air temp cool? Mine really steams a lot on the cool late fall days at the end of the season.

That being said, it wouldn't hurt to check your impeller to make sure its intact. The boat can actually run with a toasted impeller and not immediately overheat. I know this b/c I unknowingly ran the first two outings of this season with 3 blades left on the impeller. The boat ran fine, maybe a little warm at high speeds and with an increase in the amount of steam. All I can figure is that the boat's forward motion was enough to force at least some water into the cooling system, just not enough to keep the manifolds from steaming.

The culprit turned out to be that the screw-in hose barbs on the water strainer I installed last season had loosened up enough to allow it to suck air bubbles for who knows how long and destroy the impeller.

I've been meaning to fix a way to monitor the raw water pump output pressure like is done on higher-end outboards. At first I wanted a gauge on the dash like the outboards have. Lately though, I've been thinking that I might just drill and tap a hole into the top of the thermostat cover where flow from the RW pump enters. Then I'd just screw in a generic off the shelf 30 psi pressure gauge. That way I could at least get a little info on the health of the raw water pump. I may try that this weekend actually. I'll have to find somebody with a drill press though.

[wotan2525]

Checked the impeller and it was almost done.... replaced it yesterday and steam was slightly better.

This is the 3rd or 4th impeller I've done but I have a question..... where do all the rubber bits end up? I've never found any of them stuck in the thermostat or anywhere else for that matter.... do they end up flowing into the risers and then burn up??