TMD40A - where to connect for a HW tank

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Labrador Coaster

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Vessel Name
GALAX
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Bruce Roberts
I have made the two connections to the only outlets that I could find were free. One on the side of the expansion tank, and one to a port on the side of the circulating pump. I ran the motor for an hour or so , hoses did not seem to get very hot. Does this setup look OK? I don’t see any other options on the motor.. THKS.
 

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On my tamd41, I believe that there are 2 ports about where your arrow is. In my faulty memory I am thinking a bit higher and where your panel interface is mounted.
 
Something like this? Yes I see the two plugs where the connections are made. I don’t have those anywhere. I am debating hooking to the white plastic return bottle, give that a test.
 

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From memory, that looks right. I am 95% sure that is where my hot water tank is plumbed.
 
Hope this helps.
1725317138853.png
 
Thank you! Yes, my hook up to the circulating pump is the same.
My expansion tank is different from yours, but has a connection outlet in the back, so should work the same. I am assuming that is the return and that the pump is pushing the coolant out. Tks again.
 
You’re welcome and I hope you get it figured out. BTW, this is my second boat with older Volvo’s and they’ve been very reliable and extremely efficient. Lots of used parts online since they made a million of these TMD40A motors👍🏼
 
That is Good to know, it has been a bit of a concern, especially hearing others talk about the high cost of parts. My motor is a 1987 I believe, but only has 838 hours on it! The owner bought it very early in the boat building process, the boat has spent it's life in Fresh water, motor looks like new.( the Pic I posted is not my motor) He also kept VERY meticulous records of every penny he spent on her ( 43' steel trawler). So I have all of his fuel bills to confirm that it isn't a non functional hour meter. I'm curious, he had the rpm set at 2200 I turned her up to 3000. MAX is 3600??? What rpm are you usually running yours. Good chatting with you.
 
For two reasons, I recommend installing stop valves where the water heater hoses attach to the engine. First and most important, if either hose or the heat exchanger were to fail, that engine would become unusable. Second and less important is that heat exchangers work both ways. If the water heater is on and the hoses are not valved off, heat may travel to the engine wasting power and degrading hot water output. I discovered a "warm" engine which had not been run in weeks.

Daniel Varholy

'89 Tradewinds 43'MY
 
Labrador Coaster said:
That is Good to know, it has been a bit of a concern, especially hearing others talk about the high cost of parts. My motor is a 1987 I believe, but only has 838 hours on it! The owner bought it very early in the boat building process, the boat has spent it's life in Fresh water, motor looks like new.( the Pic I posted is not my motor) He also kept VERY meticulous records of every penny he spent on her ( 43' steel trawler). So I have all of his fuel bills to confirm that it isn't a non functional hour meter. I'm curious, he had the rpm set at 2200 I turned her up to 3000. MAX is 3600??? What rpm are you usually running yours. Good chatting with you.
Click to expand...
Yes, max RPM's for the TMD40A's are 3600. A cruise RPM of 2800 would be fine. I like to run mine at a leisurely 2200 RPM and find the fuel economy to be very good there and it gives me 8 kts.
 
The hot coolant travels from the exhaust manifold, into the thermostat housing, up thru the thermostats when they open, to the HE and then back to the T housing and then to the circ pump. You are looking for an outlet which lies below the level of the thermostats, on the side or rear of the T housing, or even in the front bottom of the exhaust manifold. ( the thermostats lie on the line just below the pressure cap).

Your connection to the circ pump is good, as that is the suction side of the pump. This is the return from the hot water heater. The circ pump pulls cooled coolant from the HE and pushes it down the block around the liners and then up into the head,etc.
 
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