[folivier]

Is your generator engine a Yanmar or other tractor engine? If so you might find the thermostat and gasket at a tractor place.

[Tf175]

Diesel Power Services in Birmingham were helpful with parts and information on my Perkins . They also do Yanmar , Kubota and other industrial engines . 205 592 2077 . It reads like the overheating started almost all at once ? That would indicate thermo stuck closed or a failure of something in the water pump . 
Look at radiator flues if possible as well . 
Chris

[bestgenman]

I am always reluctant to get involved in these discussions requiring part numbers as there are several iterations of the Yanmar engine.  If you have a  4TN84TE-RKRV model engine (found on the valve cover),
Thermostat 129155-49800
Gasket under stat. 129150-49811
Tstat  neck gskt  129795-49551
I rather suspect there is nothing wrong with the water pump.  I never have had one go bad! And, there are a couple of different ones depending on your model number.
Pump 729428-42003
Gasket 129100-42020
You might be wise to replace the belt.  121492-42290
My suggestion is to call the Yanmar dealer for Ohio who also supplies sets to Newell.   Martin Diesel  419-782-1198.  Prompt 3 takes you to parts.  HAVE YOUR MODEL NUMBER HANDY.  You’ll go nowhere without it.
A couple things to check,  look into the radiator directing your vision to the tubes.  They should be open and not obstructed with buildup.   Look at the fins on the engine side, they MUST be clear of debris.  If not, clean them and remove any oily residue that would cause dust to stick to them.
A side note, my 20KW Kohler runs 4 tons of air conditioning and a few additional loads in 90 plus ambient without overheating.  My digital gauge runs normally at 155 and the highest is 185.  The shutdown switch is 223 degrees.  Also, the engine temperatures are a little higher while underway.

[pairodice]

Thanks Gordon! That is exactly the model that I have - I should have posted the picture of the plate! I went to the storage building this morning early and pulled the radiator and the T-stat to match up - the auto parts store didn’t have anything but i will call with the numbers you supplied! If not I can get the parts on Amazon and will order them today! Thank you SO much for the information!

[360]

Had almost the same exact issues that Adrian is experiencing on my maiden voyage back home yesterday. Was 90+ degrees yesterday in LA when we left and a couple hours into my trip when I got to feeling a little more comfortable I took a good look at the gen gauges as we were running the generator to power the roof A/C and noticed the temp on the gauge showed 235 or so. Pulled off and checked to make sure fluid coolant was not low and it took maybe 1/3 of a gallon max. Didn't have a digital temp yet so stopped off to get one of those and checked both temp on the fins of radiator at which I get readings on the right side ranging from 210-200 and on left side from 120-160. Thermostat housing reads 219 when analog gauge on dash reads just shy of 250.

I shut the gen down and sweat us out for a couple of hours and then fired it up a little later in the day. As the ambient temp came down so did the gen temp to where from 9pm on where temp as 75 gauge on dash ran right around 180. So I'm assuming from Gordon's post that was probably closer to 150's since my gauge is clearly off by about 30 degrees.

One other thing Steve recommended since the temp was so different from one side to the other was I pulled the cap when running and the coolant inside was not moving. Sounds like there may be some kind of blockage so I'm going to have the radiator rodded and see if that helps along with a digital temp gauge so that I can see accurate gen temp.

[pairodice]

Thanks to Gordon for sharing the part numbers and his contact at Martin Diesel! I called them yesterday and ordered the parts - they came in (overnight) this morning - I was very impressed with their service.
Coolant not moving is a good thing to check - how long did you have to wait for it to (not) start moving or what temperature does it start moving? I would think the thermostat would have to open (at >200F?) to start the water moving…
I have gone full demo and have removed the radiator and sent it to a shop to have it cleaned - they are now stalling and it hopefully will be done tomorrow. I will be installing the new t-stat and gaskets this afternoon and just waiting for the radiator now…

[HoosierDaddy]

Brad, I might have missed some information here but I would check/replace thermostat before removing radiator. Also remember to add anti-cavitation additive to the coolant once you have everything sorted out.

[pairodice]

Brad, I agree with HoosierDaddy, check the thermostat - if it is the same genset that I have then it is VERY easy to remove (two bolts and a hose clamp). I went ahead and pulled the radiator and it was pretty easy to pull out also - I pulled the front fiberglass cover off the genset to pull the radiator but you may not have to. It was a lot lighter weight than I thought it would be…

[pairodice]

Got the radiator back in and we are heading to TX due to family health issues. I put everything back together with the new thermostat and freshly cleaned/flushed radiator and filled up the radiator tank with 2.5 gallons of coolant. Ran the genset for about 20 minutes with both ACs on high and it got over 220 on the guages before I turned it off. Maybe I need to burp this baby? Not sure why it’s still overheating.
Any suggestions???

[folivier]

Do you have an overflow tank on the radiator? If not you might consider adding one, Autozone or others will have them for $20 or so, easy to add and might take care of burping.