thermostat - water heater connection

[Ron Hill]

juniad : I'd take that tube with the male threads to your local Kubota dealer and have their maintenance guy identify the threads.  Then tap & die to cleanup everything so you can screw the tube back in.  You should be good to go!

A few thoughts

[KWKloeber]

Only money

True! (But not the replacement part he'd need)!!  Easy to say 'replace," but the larger issue is that replacing the water flange might first need larger surgery (like removing the gear case.)

IMO, what does one have to lose in trying to chase the threads before replacing the part or retapping to 1/4" NPT?  (answer: just the cost of the tap n die.)

[Noah]

Sorry, my bad: thought that housing was what you needed but now this blind man sees that the threads are buggered-up below the housing. Good luck.

[junaido]

So I got the nipple from the local Universal dealer (same price as the Kubota dealer $17). Managed to get it on after some effort. Put coolant into the hose and it almost immediately comes out of the nipple. We put the hose  back on and started the engine. It overheated after about 10 minutes (at least the water temp alarm works great now once I put that loose wire back on the connector).  Tried opening the petcock on top of the thermostat.  Coolant dribbles out the petcock after temp reached 180, but water temp keeps increasing so I shut off the engine shortly after that point (1 - 2 minutes at most). Tried this a few times but engine still overheats after a little bit.  Coolant is hot but the hot water at the sink is still cold. Not sure why? Water is coming out the back more or less normally. Am I missing something? Does the radiator cap need to be off or on when the petcock is open ( we tried it both ways)? There is a cabin heater that apparently uses engine heat, is that another loop that needs air removal? The whole saga started after replacing the large hose that carries coolant back to the heat exchanger, did that hose need to filled with coolant before securing it with clamps? Any advice / suggestions will be much appreciated.

Thanks,
Junaid

[KWKloeber]

First it's difficult understanding which hoses you're speaking of. Putting coolant into THE hose?  The LARGE hose.  Please be more specific.
Maybe this will help you understand the coolant flow:
https://groups.io/g/Catalina30/wiki/9626

It sounds like you need to burp the system if you're overheating. Do a search - there's info on that (maybe in the 101 series?)

I'm confused about the nipple. Is it a different size than what you originally had or just that with new threads  it screwed into the housing. Did you chase those threads?

[junaido]

I put coolant in the 3/8" hose that goes on the nipple and is part of the water heater loop. As for the nipple, the old one had corroded threads which was probably why it wasn't going on.

[KWKloeber]

And which hose did you replace?
As far as the other heater you'd need to trace out the hoses to see what feeds that but there could be air in that.

[Stu Jackson]

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Coolant is hot but the hot water at the sink is still cold. Not sure why? Water is coming out the back more or less normally. Am I missing something? Does the radiator cap need to be off or on when the petcock is open ( we tried it both ways)? There is a cabin heater that apparently uses engine heat, is that another loop that needs air removal? The whole saga started after replacing the large hose that carries coolant back to the heat exchanger, did that hose need to filled with coolant before securing it with clamps? Any advice / suggestions will be much appreciated.

Yes, you MUST remove ALL the air in the fresh water coolant loop.

We have suggested this way to do it many times, in the 101 topics:

Engine Overheating 101 - How to Burp Your Engine (Reply #6)  http://c34.org/bbs/index.php/topic,4518.msg26462.html#msg26462

The concept is to introduce water into the hoses at the highest point.  If the additional loop to the space heater makes it hard to do it this way, you must find a way to get air out of that section, too.  One way would be to remove both hoses at the thermostat and pump water into the system with a hand pump until all the air is expelled and water comes out the second hose, not air.

[Noah]

Burping system can take awhile too. I have had to Start and stop engine a few times with alarm going off before all air finally cleared.

[junaido]

As I mentioned in my earlier email. I took the WH 3/8" loop hose off the thermostat and poured antifreeze in. Almost immediately it started coming out of the thermostat hole. To me that seemed sufficient evidence that that loop was air-free. However I am puzzled why the hot water at sink never heated up despite running the engine repeatedly for the "burping" process.  Is it because the coolant only circulates in the water heater loop AFTER the thermostat opens? That would explain the lack of warm water at the faucet as I had to shut off the engine fairly quickly after the thermostat opened. The coolant itself gets pretty hot by the time I shut the engine off.

[junaido]

And which hose did you replace?

The large 7/8" hose that is about 2-3 foot long and carries coolant from the pump to the heat exchanger was the hose we replaced.

[Stu Jackson]

1.  As I mentioned in my earlier email. I took the WH 3/8" loop hose off the thermostat and poured antifreeze in. Almost immediately it started coming out of the thermostat hole. To me that seemed sufficient evidence that that loop was air-free.

2.  However I am puzzled why the hot water at sink never heated up despite running the engine repeatedly for the "burping" process.  Is it because the coolant only circulates in the water heater loop AFTER the thermostat opens? That would explain the lack of warm water at the faucet as I had to shut off the engine fairly quickly after the thermostat opened. The coolant itself gets pretty hot by the time I shut the engine off.

1.  That's why I suggested using a pump.  Another thing you can do is to blow into one of the two hoses, the one you're pouring the water into.  That will force any air out of the other hose, then continue to fill the first hose.

The "old way" to do this was to use the petcock on the top of the thermostat.  As Noah said, sometimes it took a few tries doing it this way.  Be patient, it may take a few times.

2.  As hot as the coolant may be, it takes at least 15-20 minutes to heat water in the water heater when at cruising speed rpms.  It takes a LOT longer at essentially idle speed.  If you ware working on burping your engine, its not the time to be dealing with domestic hot water.  You could check if the hoses to the heater are getting warm,under the sink.

[waughoo]

I just finished replacing EVERY SINGLE HOSE in the fresh and raw water circuit.  To be clear, this included the original painted hoses the engine came with.  For the lines to the hot water tank, I used a funnel into the 3/8 hose and filled that with water.  Leaving the other hose off, I blew into the funnel till water came out clear.  I then continued to pour water till the watter oozed out of the second hose.  Next, I filled through the exhaust jacket till the water started to come hout of the water pump barb.  I then connected the H2O tank hose to the water pump.  Next I poured more water into the funnel toll water came out the T-Stat barb and then connected that hose.  Next I added coolant till the water in the exhaust jacket was full and started the engine.  As it warmed up, I would jiggle the 3/8" hoses to the h2o tank and press them lower than the filler neck of the exhaust jacket.  I also opened the bleed screw on the tstat housing.  To aid in getti g the engine to temp, I ran the engine in gear at about 1500rpm.  Multiple jiggles, tstat bleeder screw open and closed and a few revs in neutral and she was fully burped.  Ive had it runni g now for about 1.5 hrs and the temp has beeen rock solid!!  It isnt hard, just fiddly.

[Noah]

Alex- You are "the hardest working guy in show biz..." 
if you ever get tired of the NW weather come on down to San Diego. I have plently off hoses you can change!

[junaido]

This morning I went back to the boat and was gratified to see that the coolant had gone down in the tank.  Added coolant and ran at the dock in gear for 10-15 minutes. Temp held steady at 160. Will try venturing out next weekend and see if it still  holds under load for extended periods.  Thanks again for all your helpful advice.