Our New Baby, 2024 252SE 🎉

[FSH 210 Sport]

It's pretty interesting that Yamaha would choose to warm the intake water with the oil and then pump that into the block... I guess there's enough volume passing through they figure that's enough (although I get pretty warm pisser water when surfing, not hot to the touch, but warmer than ambient.

Maybe the cooling water passes through the oil cooler first since there isn’t that much heat to extract and there’s less oil in the 1.9.

 

[Acard7]

It's pretty interesting that Yamaha would choose to warm the intake water with the oil and then pump that into the block... I guess there's enough volume passing through they figure that's enough (although I get pretty warm pisser water when surfing, not hot to the touch, but warmer than ambient.

Ya very interesting. But I will say, the port engine pisser was pretty cold when we were on the water in no wake mode, under a load like surfing I have no clue what it would feel like with these new engines. When we go Wednesday after we get done cruising the lake I’ll try to remember to feel the water again to see if it’s any warmer.

 

[BumbleBee255]

Just a guess,,, but sending lake water (at who knows what temp) directly into the manifold may cause a huge temp discrepancy. Maybe even damaging metal parts. Slightly warming to water temp through the more durable cooling fins of the oil cooler may help close this temp difference. Remember that in an auto, the coolant returning from the radiator is only slightly (20-25 degrees) cooler than the engine.

 

[anmut]

Just a guess,,, but sending lake water (at who knows what temp) directly into the manifold may cause a huge temp discrepancy. Maybe even damaging metal parts. Slightly warming to water temp through the more durable cooling fins of the oil cooler may help close this temp difference. Remember that in an auto, the coolant returning from the radiator is only slightly (20-25 degrees) cooler than the engine.

Good point - I don't claim to be an engineer by any means!

 

[FSH 210 Sport]

That’s a good point, thermal shock, but consider this.

The engine is warmed up and is getting a constant flow of unlimited lake water. The thermostat is regulating the water temp based on outflow of water from the block, that water bathes the thermostat and it opens and closes based on that water. In my experience these little engines warm up fast, water passages on the engine, exhaust manifold, exhaust gas mixer (which gets a direct feed from the T fitting) everything is warmed up.
So a few minutes of idling then slowly ramp up the rpm’s over a few minutes before hammering the throttles to WFO is a good plan. I’ll even feel the pilot water outlet water to check to see if it’s warmed up a bit.

I think the water goes to the oil cooler first to keep the oil as cool as possible and deliver it back the parts where it’s really needed and keeps the heat out of the bearing surfaces, and I’m not sure if there are any spray jets on the bottom of the pistons but would make sense, and the oil which is being used as a coolant would be more effective that way at as close to lake temp as possible, and obviously it’s pulling heat out of the engine where there is no cooling water. And on the 1.9L there isn’t a whole lot of engine oil… as @anmut said the pilot water outlet water gets warm when you’re working the engine hard so the oil cooler is doing its job to keep the lubricating oil cool, a great design really. One needs to remember these engines’s cooling systems don’t require any air for cooling them with an unlimited supply of lake water, and water over water is highly efficient compared to air over water, and there is no anti freeze to slow the heat transfer.

One thing is a bit obvious, our boats lack a sea strainer. Hmmm.. may have to look into that, I think RIVA makes a set up for that, I’m sure it could be done DIY once a body knew what cooling system operating psi is. I bet a larger version of the strainer I use for my raw water wash down would work but with a screen that wasn’t so fine.

 

[suke]

It's pretty interesting that Yamaha would choose to warm the intake water with the oil and then pump that into the block... I guess there's enough volume passing through they figure that's enough (although I get pretty warm pisser water when surfing, not hot to the touch, but warmer than ambient.

Our pisser water will damn near scald you when surfing. LOL! I've come by a surfer to pick them up and it get on them and they're like HOLY SHIT, WTF, that's HOT!

 

[anmut]

Our pisser water will damn near scald you when surfing. LOL! I've come by a surfer to pick them up and it get on them and they're like HOLY SHIT, WTF, that's HOT!

Must be quite the extended session. I usually run out of deep water before that happens...

 

[suke]

Must be quite the extended session. I usually run out of deep water before that happens...

yeah we'll go easily for 8-10mins on some long runs. I think the record was 11ish.

 

[anmut]

Damn - if I get to the next song that’s a lot!