SailNet Community banner
  • SailNet is a forum community dedicated to Sailing enthusiasts. Come join the discussion about sailing, modifications, classifieds, troubleshooting, repairs, reviews, maintenance, and more!

Is there an in and out for the coolant hoses to water heater?

2653 Views 16 Replies 10 Participants Last post by  gamayun
You'd think this would be a simple Google search or could be easily found in the manual, but it is not. I would really appreciate advice from someone who knows Yanmar engines (3GM30F is mine). I have torn out the leaky water heater and was really very careful to diagram everything....except.....which way the connections were run to the radiator hoses. The water heater specifies an in and an out so I would assume the engine is the same. The engine has one hose coming from behind the water pump and the other off of the heat exchanger. Does it matter which way these hoses flow into or return from the water heater? I feel like it should, but one person I asked said it should not. I assume the flow from the heat exchanger would be the intake to the water heater and the return is toward the water pump side. What is the consensus on here :confused:
1 - 1 of 17 Posts
For most heat exchangers, in the bottom and out the top is the safe bet in absence of a solid reason contrary. No matter how hard you try to burp the air out, there will always be more leaking in via pump seals and the like, and it will accumulate in HEs that flow downwards, gradually reducing capacity and causing corrosion.

Automotive radiators, for example, generally flow cross/down, BUT there is an air release at the top. Heater cores and engines flow up. Where there is down flow, it is with enough velocity to sweep the air through.
1 - 1 of 17 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.