warm up procedure for Yanmar 2GM20F - adding water heater

[bugbitten]

I've recently added a new water heater to my 30 foot sloop (S2 9.2A). The original water heater was not connected to the engine, but, since the new one offered that option, I looked in my manual, found and removed the two plugs on the FWP and thermostat housing, and ran half-inch hose from them to the new heater. Yesterday I fired up the Yanmar, which started reasonably well considering the mid-40's air temp and 50ish water temp. Despite running it for nearly half an hour (mostly around 2K+ RPM, with and without the prop engaged), I was seemingly unable to get it hot enough to open the thermostat. When I first removed the plugs a month or so ago and put in the 3/8" fittings, I temporarily ran a loop between the two fittings (the heater wasn't yet in place), ran the engine maybe ten minutes, and was able to see, toward the end of the run, some coolant coming from the port on the thermostat housing. The weather was admittedly warmer, but I should think that a half an hour of running should be enough to get the thermostat to open. I've got a digital temp gauge bolted to the thermostat housing. It read about 135 degrees, max, during the run. I'd left the coolant cap off so I could add coolant as it started pumping through the hose to the heater. I don't think that ever got over about 80 degrees. I suspect it might've gotten hotter if I'd run it closer to idle, but I thought that wasn't good for the engine.

Is it typical for the thermostat to not open under these sorts of conditions?

Any recommendations on what sort of procedure I might follow to get it hot enough to open, rather than waiting for spring time?

I'll attach a shot of it when I just had the loop set up, for what that's worth. Once this is done, I promise I'm replacing all those hoses, cleaning the heat exchanger, putting in fresh, extended-life coolant, etc.!

Thanks.

John

 

[woodster]

Re: warm up procedure for Yanmar 2GM20F - adding water heate

John two things here first the hose to the right of your pic is after the thermostat and should be before ...there is a plug lower down on the t housing that you need to tap in to

second i would not trust that hose on a permanent install you need to get hose rated for heater hose ......you may need to burp your lines when you install them in order to fill the lines with coolant.....

 

[centerline]

Re: warm up procedure for Yanmar 2GM20F - adding water heate

after getting the plumbing straightened out, it may work better....

BUT.. about the thermostat,
if it doesnt open, the engine will over heat.... if its stuck open and does not close, the engine will NOT come up to temp without being moderately worked...

so after getting the hose routing correct, if it still does not come up to temp, you may need to install a new thermostat.
also, do you know what the temp of the thermostat is?.... it may be so low that the engine temp will never come up to an acceptable temp to produce a reasonable amount of heat from the heater.... 160degree would be a minimum in my opinion... 175 nor 180 would be optimal, but ONLY if is acceptable for the engine.

 

[Calif. Ted]

Re: warm up procedure for Yanmar 2GM20F - adding water heate

second i would not trust that hose on a permanent install you need to get hose rated for heater hose

In most cases wire reinforced heater hose is used, presumably so it can't collapse when under vacuum as the engine cools. I've never seen that clear water hose used on an engine, it may work for awhile but I think it's very dicey.

 

[bugbitten]

Re: warm up procedure for Yanmar 2GM20F - adding water heate

The thought with this hose was that I could watch the coolant move through it to ensure I had the right ports, etc.. Woody, I pulled the plugs per the manual. I'll post the relevant page shortly.

I have new Yanmar hoses for the engine, as well as a new thermostat, gasket, and relevant bits for dismantling and reassembling the heat exchanger, which is long overdue for a cleaning.

I have the hoses now running back to the heater.

I'll pull the thermostat, test and install the new one, and put in the upper coolant hose at the same time. Once I see it's working, I'll drain the coolant, put in proper hoses back to the heater, double-up on clamps, etc..

I need to bake some pies. Once the gorging is over, I'll see if I can track down the Yanmar manual page that shows which plugs to pull.

John

 

[bugbitten]

Here are the two relevant pages from the manual. I went with the older-style pump for the plugs to remove, based on my serial number. I think my temp sender, though, may be in the newer models position. I did try to remove the plug that Woody's suggesting I use, and it rather promptly stripped the hex fairly badly. I have an EZ-out to try, but don't want to go that route yet, if it's not totally necessary.

John

 

[woodster]

Re: warm up procedure for Yanmar 2GM20F - adding water heate

well John i don't guess it matters i just used the side before the t stat ...you may have an air lock in the hose not letting the coolant fill up the hoses i do know that i dont have to wait on the t stat to do its thing to get hot water ..it usually takes me about 15 to 20 min to get the engine temp up running of a 55 gallon drum of fresh water it may change when i am in the water...but i will add why did they make a new style which is what i have if you decide to go lower with the hook up...... get a brass nipple and use it as a hose barb to hook the heater hose

 

[woodster]

Re: warm up procedure for Yanmar 2GM20F - adding water heate

you may have to get a tee also to accommodate the temp sensor

 

[bugbitten]

Re: warm up procedure for Yanmar 2GM20F - adding water heate

Got back to the boat. Took print outs of both pumps and, despite the old serial number, I do have the newer FWP. I'll work on getting that stubborn, stripped plug out and move the heater output barb to that port (which, as Woody said, is before the thermostat). I'll go ahead and put in the new thermostat and hoses while I'm doing this. I'll also get some decent Trident heater hose ordered and installed. Once that's all in, I'll try the warm up procedure and will report back. It may take a bit as I'm still hoping to service the heat exchanger before putting in the new coolant. That's something I've not yet tackled.

Thanks for the replies.

John

 

[kloudie1]

Re: warm up procedure for Yanmar 2GM20F - adding water heate

Definitely hook it up as in the "new" style. The thermostat causes a differential pressure to drive the coolant through the water heater.. The outlet fitting for the water heater has to be below the thermostat, on the higher pressure side.
Echoing the caution on the hose.. That engine should have a 160F thermostat, meaning that it starts to open at 160 and is fully open at 185. way past the normal operating temperature of the clear hose.
The housing that includes the water pump can be fairly easily removed to make it a lot easier to drill that stripped plug out. That is the plug where the outlet must be located to be able to get hot water ..Good Luck with it

 

[Steve Dion]

Re: warm up procedure for Yanmar 2GM20F - adding water heate

Once you know the plumbing is correct and all of the air is purged from the system, it is best to test it by running the engine at the normal operating range. When we are anchored out during the summer it takes a long time for the water to get HOT from the engine alone. If we are underway we have hot water in about 20 min.

 

[Capt jgw]

If you have to drill the plug, try left handed drill bits. They will usually grip the screw and back it out without having to use the easy out. HarborFreight has a set for pretty cheap. Give it a good soak with PB Blaster ot Kroil first.

 

[Capt jgw]

On the plug, make sure you used the
right size metric wrench. I don't know what size it is, but there may be an SAE wrench just a tiny bit smaller. Close enough to feel right but small enough to strip the socket. I've had that happen.There may be enough metal left for the correct wrench to work.

 

[bugbitten]

On the plug, make sure you used the
right size metric wrench. I don't know what size it is, but there may be an SAE wrench just a tiny bit smaller. Close enough to feel right but small enough to strip the socket. I've had that happen.There may be enough metal left for the correct wrench to work.

The other two plugs took an 8mm hex. They didn't want to budge, so I hit them with PB Blaster, got an 8mm hex socket, and got them out with a 1/2" electric impact. Tried the same routine on this one, and it quickly stripped out. It's not completely gone, but close enough that I'm shifting to some Irwin "multi-spline" extractors (see pic). If that doesn't do it, I may just pull the housing and take it to a machine shop and have them get it out.

I may have to back-track and put the plugs back in for now, anyway, as Sunday and Monday might be nice enough to squeeze in a sail!

thanks for all the help.

John

 

[woodster]

The other two plugs took an 8mm hex. They didn't want to budge, so I hit them with PB Blaster, got an 8mm hex socket, and got them out with a 1/2" electric impact. Tried the same routine on this one, and it quickly stripped out. It's not completely gone, but close enough that I'm shifting to some Irwin "multi-spline" extractors (see pic). If that doesn't do it, I may just pull the housing and take it to a machine shop and have them get it out.

I may have to back-track and put the plugs back in for now, anyway, as Sunday and Monday might be nice enough to squeeze in a sail!

thanks for all the help.

John

John you may have to put some heat on the plug to make it expand and contract in order the free up the threads...i use a propane torch to do this some times ..but be very careful of over heating the housing ...try to concentrate the heat to the plug as much as possible...good luck