Hot Water Tank Connections

[Beachbob]

I have a 1989 300 Weekender, 7.4l raw water cooled. The PO replaced all the engine hoses on the port engine. When he did, he did not reconnect the exchange lines for the hot water heater. Does anyone know where to connect the hot and cold lines to the engine, maybe a schematic?

 

[SCORPIO]

On my '89 300DA with 5.7s, there was a tee fitting in the lower big hose going from the water pump to the theromostat housing. The other line came out of the top of the waterpump. I removed this setup since I didn't want to run heated salt water thru my water heater. Your setup should be similar.

 

[LmannyR]

Can someone post pictures of the connections? Want to make sure mine is connected correctly from PO since it only seems to work with shore power.

Pictures would be a BIG help here.

thanks!!!

 

[Daniel P Thomas]

Going down to my boat today.
Still under the shrink wrap.
I will try and get a couple of pictures.
Sould be similar.
Dan

 

[Lazy Daze]

Beachbob - just for your reference, there really isn't a "hot or cold" line. It's simply a loop. There are multiple places it can be hooked up. While I can't say how it was originally done on yours - I can tell you on mine that one connection is on the circulating pump and the other is on the top of the engine near the t-stat housing.

You're looking for "plugs" that are about the same size (exactly?) as a garboard drain plug.

If the HWT hoses are laying there, they likely have a set to them and you can probably just hold them up towards the engine and they will just about tell you where they are supposed to go.

You'll need to get the "pipe to hose" connectors.


HOWEVER: My first question would be to ask why the PO disconnected it. Is it because he didn't want to use it... or was it leaking?

 

[Beachbob]

Scorpio, Thanks for the reply. Sounds like that should work. I'm in and out of salt water her so I think I'll give it shot.

Dan, Pics would be great.

Thanks,
Bob

 

[Beachbob]

Dennis,

I believe PO was chasing down a high speed overheat problem that turned out to be risers. He really didn't use the hot water away from 110 from what I understand, so the exchanger was not needed. He left the hoses, but had cut them back a pretty good length. Sorry about hot and cold reference, really not accurate. Thanks for the info.
Bob

 

[chollyjohn]

Assuming that the HWH exchanger is good and in working condition, an engine maintenancne manual will give you specific instructions of where to connect to the engine. Meanwhile, the flow thru the HWH exchanger is both ways.

Auxiliary Hot Water Heater Installation
IMPORTANT: When connecting a cabin heater or hot water heater, certain requirements must be met:​

•

Supply hose (from engine to heater) and return hose (from heater to engine) MUST NOT EXCEED 5/8 in. (16 mm) I.D. (inside diameter).

​

​

Make heater connections ONLY at locations described in the following instructions.​

​

​

Check complete system for leaks after heater is connected into cooling system.​

Check for overheating condition (of engine) after heater is connected.

This data came from my mercruiser manual off a 8.1L engine.
Overheating problems, if any, usually stem from an air lock in the hose supplied to the exchanger.
​

 

[my3sons]

This might help, not the detail you may really need to see it though.
The 5/8" lines with the white zip tie on them, centered in the pic directly in front of and below the drive reservoir bottle are the heat exchanger lines. One fitting on the circ. pump, one on the side of the thermostat housing. Application is a '95 330DA, should be the same or similar to yours

(please no comments on the oil filters, guys, sometimes we have to agree to disagree :grin

 

[Stray Cat]

HOWEVER: My first question would be to ask why the PO disconnected it. Is it because he didn't want to use it... or was it leaking?

Dennis, I took my hoses off the heat exchanger so the generator could load up more after an initial start up. Otherwise with a 5 gallon tank of HW, their isn't much for my 5E to load up with.

 

[Lazy Daze]

Dennis,

I believe PO was chasing down a high speed overheat problem that turned out to be risers. He really didn't use the hot water away from 110 from what I understand, so the exchanger was not needed. He left the hoses, but had cut them back a pretty good length. Sorry about hot and cold reference, really not accurate. Thanks for the info.
Bob

OK, gotcha, Bob. My only concern there was that you get it all hooked and then find out it leaks. Sounds like the PO supplied you with enough info, though, that that is not a concern. Some buyers are not supplied (or neglect to ask for) information. Glad that's not the case here.

Good luck! :smt001

 

[Daniel P Thomas]

Bob
Pictures below show 7.4 L Bravo II:
1. Port Engine black hose attached to hose barb on top of Water Pump and to hose barb below Thermostat.

2 & 3. Starboard Engine blue hose attached to hose barb below Thermostat, black hose attached to hose barb on top of Water Pump.

I take both off of the Hot Water Heater and put a barb connection to the 2 of them for winterization.

Hope this helps.

Dan

 

[Beachbob]

Thanks guys. It's clear now where to tap into the system.

Bob