How much coolant will drain when removing engine hoses to water heater?

[leecea]

Hi,

I have to swap my water heater out and I want to make sure I can catch all the engine coolant that comes out of my 3GM30F when I remove the bypass coolant hoses from the heater.

The engine manual doesn't seem to help.

Has anyone done this? How much engine coolant will come from the hoses going to the water heater?

Thanks,
Andy

[jt11791]

Most small diesel systems have between 4 and 8 quarts of coolant total. It's hard to guess how much of that will drain out of your system as it depends on the installation (is your heater above or below the engine HX tank?). I would prepare for at least 4 qts.

[5BTM]

Just googling "yanmar 3gm30f coolant capacity" gives this result and probably thousands more like it.

https://c320.org/article.php/2006021...0heater%20loop.

[UFO]

Why not simply drain the coolant from the engine then you will have a minimal amount at the heater or if you do not want to drain the engine get a joiner and quickly join the input/output coolant lines from the heater once removed - best done with 2 people.

[ItDepends]

Minimum amount to drain: almost none.

Maximum amount to drain: Capacity of the engine PLUS the capacity of the coils in the water heater.

Realistic amount: between the two above numbers.

Without knowing the details of your setup it’s impossible to tell.

[Jammer]

Originally Posted by leecea

Hi,

I have to swap my water heater out and I want to make sure I can catch all the engine coolant that comes out of my 3GM30F when I remove the bypass coolant hoses from the heater.

The engine manual doesn't seem to help.

Has anyone done this? How much engine coolant will come from the hoses going to the water heater?

Thanks,
Andy

I just did this on my boat, which has a 3JH2E.


For reasons of access I disconnected both hoses at the engine and drained all the coolant from them with a battery powered shop vac. I got very little coolant from the engine (less than a quart) and about a gallon from the hoses, water heater, and reservoir which, in my installation, was just above the water heater.

[leecea]

Thanks. Sounds like more than I'd hoped for.

Maybe draining the engine will be best. Or trying something with a liquid transfer pump. I'll have to check access when I am back at the boat and come up with a plan.

[NioMarvin83]

I did mine about two years ago. I drained the coolant out from the petcock then refilled with distilled water through the surge tank. I then took my terrain on a drive to get it up to operating temperature. I then drained the coolant again, I measured how much it came out and it was only draining about 4 quarts out of the 8.2 the system holds. I did not drain from the water pump plug. In the end I drain and filled around 4 times to finally get the water to come out clear, and since I knew from measuring that only half the coolant/water was draining out, once the fluid came out as pure water I then poured a 4qt bottle of straight prestone dex-cool into the surge tank. I did this because I knew from chat at WXChat with my father there was already 4 quarts of water trapped in the system, so there was no need to cut it with water to get a 50/50 mix. Once the bottle was empty I topped off with distilled water. I then started the terrain and let it run with the surge cap off for 15 minutes to let any air out.

[JimsCAL]

Just pulled the heater connected to my 3GM30F the other day. Didn't drain the coolant. Very little came out. Will just top off after installing the new heater.