Volvo D3 what is this

[tranmkp]

I can see the center hose to engine but am befuddled by the top and bottom ones

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[Seakr25]

Saltwater strainer … take a look at the manual for your boat as there could be changes for your year vs others. Typically they run to the head and the deck wash down.

 

[BB marine]

This is the first step of the raw water bottle neck. The Marine hardware SEASMP-NPT-DOME. It has a 1 1/4 " OD barb on the intake side with a 1" ID NPT and on the output side it has ( 1)- 1"NPT and (2) 3/4" NPT. The plumbing that Ranger Tug uses bottles the strainer up even more because they use a 1" NPT barb fitting instead of using the 1 1/4" molded barb. This reduces the incoming water to a 7/8" iD at the fitting. The hose coming off the through hull is 1" and 1" going to the strainer. Then there are( 2) 3/4" ports, one going to the head which must have a check valve installed and one going to the raw water wash down. The Volvo D3 or Yanmar 4 BY requires a minimum of 1 1/4" 6BY 1/1/2 " with limited fittings to function for proper cooling. 1 1/4" is minimum with no reductions in plumbing size to cool the engine as per design. This is also true for the Yanmar 180 and 150. This bottle neck is the main reason that higher operating temperatures are experienced. Running temperatures in a properly installed raw water system should not change more than 5F to10 F After reaching operating temperature when the thermostat begins to open. Gas or Diesel at low power to 100% power properly installed operates within the engine design which is controlled by the thermostat. The engine temperature must be controlled by thermostat. The engine should run in the thermostat operating range and not exceed the full open temperature. My answer to your question, You are looking at the culprit to the Volvo and Yanmar powered Ranger and Cutwater's elevated operating temperatures.

If you operate with this set up in cold waters you will marginally stay in the range but higher end of it. If you operate in southern waters you will see it climb above the operating range. The D3 150 hp to 220 hp and should not see temperatures above 185F if properly plumbed. 190F Max. in elevated ambient water temperatures. The Yanmar 200 F Max at WOT anything above that is telling you there is something wrong. I believe it all starts at the boats raw water plumbing. Marginal to start! This reduces the safety factor the engine manufactures has built in.

Most Ranger Tug owners and Cutwater owners have accepted the higher operating temperatures. Right or Wrong.

 

[tranmkp]

Alright then - that multi port sea strainer only comes in one side so that’s a dead end - nobody else makes on -

A custom manifold could be made…

I’m thinking now to just haul the boat install the new correct size thru hull and 2 smaller ones - it would save space and keep things neater in the compartment


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