1994 390CPMY water heater replacement

[tonyiiiafl]

The water heater replacement was truly not that bad. i DO recommend disassembling the dinette seat! By doing this you can lean in on the rear of the water heater and heat exchanger hoses. I had very little spillage as I took a couple 6” pieces of hose and plugged them with a 5/8” bolt and clamped. Then when I pulled the heat exchanger hose from the water heater, I was able to slide these on. Then a 5/8” bolt on the heat exchanger hose. Also, PIG MATS are a must! These absorbed any coolant leakage. At engine, same routine followed. remove hose from fitting, put plugged hose on fitting and clamp. PIG MATS! Upon examining the hoses, (original 30 years old ) they were still pretty pliable, however, I was in there and didn’t want to go back over a blown hose, so both were changed out. There was only 1 tie wrap I was not able to replace.

heater Seaward 1100 dropped into the hatch under the dinette. Pull and tug, and slide into position. LOTS of room (inch plus on each side!) screwed it down, hooked up rear heat exchanger hose. Then back to the engine room and connected the hoses to the engine. (If I did it again, I would have filled the hoses with coolant before connecting them. Then wired it up, and started the engine. coolant dropped a bit but nothing as I thought it would. However, after bringing the engine up to temp for a few cycles, i shut off and loosened the clamps on the rear of the heater where the hoses meet heat exchanger. Coolant came out of both. Ran up to temp a few times more and added another pint of coolant. Hoping it drops overnight a bit. Painted it also.

Took the old heater apart, found it was a bottom seam leaking. When I dumped the heater out, it was like a beach came out! Unknown where all that sand came from.

Water heated well with heat exchanger, and also electrically. Total time from start to end was approx 6.5 hours. Like I said, no it a bad project at all!

PS : Start at the bottom for the pictures, They were added in reverse!

[Viper]

6.5 hours? Your typical boater would tell me it should only take me half an hour to replace their water hear, right?
Good job Tony

[g36]

I had to replace mine a few years ago, also bottom seam it was oem from 1997. The "sand" is calcium buildup that lies in the bottom of the heater. you'll also have this build up at home and it's really a good thing to try and flush some if this out using the drain valve on the water heater occasionally.

[tonyiiiafl]

GOOD info! didn’t know that! Thank you