4.3L Carb Mercrusier Auxiliary Heater

[68 - 390]

Hello All,
2006 Maxum 1800SR3 Mercrusier 4.3L Engine Serial Number 0W669170
I am looking for a cooling flow diagram to see what ports I can hook up an auxiliary heater to? I want to ensure I don't disrupt the cooling system when installing the heater. I attached a screenshot of an auxiliary heater I've been looking at. Also curious to hear what others have installed on their boats. Any help would be greatly appreciated. Thanks in advance.

 

[Bondo]

Ayuh,...... Depending on which intake manifold you have, there should be a 1/2" pipe plug you take out, to attach a hose for the hot water feed,....
There should also be a 1/2" pipe plug in the circulating water pump to use as the return hose,....

 

[alldodge]

Your serial number is for closed and open cool, which do you have?

 

[68 - 390]

Your serial number is for closed and open cool, which do you have?

I have the open cooling system. My apologies for some reason I'm not getting notifications

 

[68 - 390]

Ayuh,...... Depending on which intake manifold you have, there should be a 1/2" pipe plug you take out, to attach a hose for the hot water feed,....
There should also be a 1/2" pipe plug in the circulating water pump to use as the return hose,....

I think I see the plug to the lower right of the spark arrestor. I do recall there being a spare plug on the water pump as well.

 

[alldodge]

Unable to read the SN, but can go with TKS

 

[68 - 390]

Unable to read the SN, but can go with TKS

Thanks, my serial number is 0W669170 and I believe I have the plug on the top of the manifold there is a sensor on the other side to the left. I do believe I have the pipe plug on the water pump as well. Question is the pipe plug on the water pump for supply? and the plug shown in the picture for return?
Thansk,

 

[alldodge]

The plug on top is supply

 

[Bondo]

Thanks, my serial number is 0W669170 and I believe I have the plug on the top of the manifold there is a sensor on the other side to the left. I do believe I have the pipe plug on the water pump as well. Question is the pipe plug on the water pump for supply? and the plug shown in the picture for return?
Thansk,

Ayuh,.... Those are the right plugs, but you've got the flow backwards,.....

I explained that in my 1st post,.....

 

[68 - 390]

Ayuh,.... Those are the right plugs, but you've got the flow backwards,.....

I explained that in my 1st post,.....

Sorry I mixed that up.... thank you so much for your help.
Is there a certain heater you'd recommend? or are they all pretty much the same?

 

[alldodge]

They all work pretty much the same, and not many here on this forum have installed one. Don't know how much heat your looking for but having a 4.3 means it doesn't generate as much heat as a 8.2 so think about that when sizing

 

[68 - 390]

They all work pretty much the same, and not many here on this forum have installed one. Don't know how much heat your looking for but having a 4.3 means it doesn't generate as much heat as a 8.2 so think about that when sizing

Yeah I’m just looking for a simple 2 vent one that I can run a couple hoses to the kids when they get out of the water. Being in Northern Alberta Canada the water doesn’t get that warm. Just need a heater to take that edge off. Thanks for all your help. Think I got it narrowed down. I’ll keep you posted how it turns out once I get it installed. Cheers and happy boating.

 

[Scott06]

Thanks, my serial number is 0W669170 and I believe I have the plug on the top of the manifold there is a sensor on the other side to the left. I do believe I have the pipe plug on the water pump as well. Question is the pipe plug on the water pump for supply? and the plug shown in the picture for return?
Thansk,

View attachment 400047

Double check but I belive the plug you circled goes into the intake runner not water crossover

 

[68 - 390]

Double check but I belive the plug you circled goes into the intake runner not water crossover

oh, how would I go about checking that? remove it and see if water comes out while running? or something else?

 

[Scott06]

oh, how would I go about checking that? remove it and see if water comes out while running? or something else?

It lines up with the intake runner water cross over is below the thermostat housing it up pull that plug it will be dry won’t run with that much of a vacuum leak

 

[68 - 390]

It lines up with the intake runner water cross over is below the thermostat housing it up pull that plug it will be dry won’t run with that much of a vacuum leak

Hmm, I'm headed out to my lake this weekend. I'll have a better look and get some more pictures and report back. Thanks for your help.

 

[68 - 390]

Here are some more photos. Looks like I have 2 plugs in the water pump. I don’t have any thread seal out here so I didn’t pull that one plug out to check if it was dry or not. Not sure what to think about what hoses and plugs to tie into. Hmm

 

[alldodge]

Don't use the one on top the Cir pump
The one to right of Stat and the lower one for return

 

[68 - 390]

Is this what you mean? Lower plug on the water pump for return line and tee in a fitting on the right hose for the supply line. Or am I missing something? Thanks in advance.

 

[alldodge]

The first pic is the return so that is correct

The second pic NO do not connect there, that is for exhaust

@Scott06 is correct, the plug on top right is to the intake port number 1, so don't use that

When you first posted a pic of your motor with serial number I took it as a 2006 carb motor and didn't notice the 6 port Thermostat housing so was looking at manual 25. The 6 port hasn't been used much since 1999 (manual 18). Could be yours was a new old stock or for some reason they used it on yours instead of the 6 port

So with that, look on the port side below the top hose and see if the temp sensor is there. If it is do not remove, then look on starboard side on housing on the intake for a plug (is it there)??

If temp sensor is installed, and the plug is on on other side, I will suggest what Formula did with my boat for the water heater. Remove the block drain plug (used to winterize). Attach a fitting and then a Barbed hose fitting and that will be the supply side for the heater.

To winterize just pull the hose off or attach another Tee fitting so it can be drained