[Nebster]

Hey all,

I have the PT 20kW genset sidemounted with the remote radiator.

Yesterday, after a 3-hour generator run, I came back to find it shut down with a "high water temp" error on the ECU.  Not knowing what to try first, I looked at the coolant overflow tank (white plastic thing sitting below the fill tank at the top of the engine) and saw it was basically on empty even after the engine had fully cooled.  I added coolant to the top, which proceeded to overflow the top radiator cap/tank.  Only by futzing around with the hosing and the connection to the white plastic tank would some finally go down through the little hose.

I ended up adding more fluid directly to the white tank per Newell's recommendation.

Next, I started up and noticed that my radiator blower fan motor was shutting down randomly.  I think it has simply gotten filled with too much dust, as it was pretty caked.  But that seemed definitely like the problem.

I went to Grainger and got a replacement motor.  Actually, I got two motors, because my PT genset had a 1/2hp motor, but Newell said I should get the 3/4hp and make it fit instead.  I was able to get the 3/4hp one installed without too much trouble, and it is blowing great.

Now, after 32 minutes of runtime, my generator shut down AGAIN with the same high water temp.  

So I guess I have another issue, but I'm not sure where to start.  Any ideas?

Thanks,

Ben

[rwg200]

Hey all,

I have the PT 20kW genset sidemounted with the remote radiator.

Yesterday, after a 3-hour generator run, I came back to find it shut down with a "high water temp" error on the ECU.  Not knowing what to try first, I looked at the coolant overflow tank (white plastic thing sitting below the fill tank at the top of the engine) and saw it was basically on empty even after the engine had fully cooled.  I added coolant to the top, which proceeded to overflow the top radiator cap/tank.  Only by futzing around with the hosing and the connection to the white plastic tank would some finally go down through the little hose.

I ended up adding more fluid directly to the white tank per Newell's recommendation.

Next, I started up and noticed that my radiator blower fan motor was shutting down randomly.  I think it has simply gotten filled with too much dust, as it was pretty caked.  But that seemed definitely like the problem.

I went to Grainger and got a replacement motor.  Actually, I got two motors, because my PT genset had a 1/2hp motor, but Newell said I should get the 3/4hp and make it fit instead.  I was able to get the 3/4hp one installed without too much trouble, and it is blowing great.

Now, after 32 minutes of runtime, my generator shut down AGAIN with the same high water temp.  

So I guess I have another issue, but I'm not sure where to start.  Any ideas?

Thanks,

Ben

Hi,
I recently had a similar problem, 9 (i have coach 1218, 2008 side mounted genie)
It was a large air lock in the system not allowing the coolant to circulate properly through the radiator, I ended up having to take the thermostat housing off to allow the system to fill correctly and to fill the radiator, once the system overflowed through the thermostat housing i put it all back together and its been fine since,
I think its just a hard system to bleed fully,
Mine also had water in the overflow tank but just couldn't suck it down!
good luck,
Rob

[bestgenman]

Ben and Rob, you both are on the right track.  The PT sets are hard to get the air out of the system.  The ideal fix is to insert a fitting at the highest point with a petcock to allow venting.  This eliminates having to remove the thermostat housing or remove hoses.  You may have to have a tube fabricated for the 1-1/2" hose (or whatever your hose size is) with a port for the petcock.  If you don't have the capability, then Newell or a radiator shop will make one for you.  It just saves down time when you are out on the road and this happens.

[Nebster]

Hey Gents,

Thanks for the quick replies and suggestions. The guy at Power Tech echoed your suggestion, but he went on to say these things:

1) there is already a petcock on the top line, but he says it is really tedious to use and can take 3 or 4 hours to fully burp out all the air, so they don't recommend using it.

2) Instead, he says to pull the output hose off the thermostat at the top, press fit a water hose to it, and turn on the water. He said as soon as fluid starts flowing out of the thermostat side, it is burped. He said it would only take a very small amount of water.

I didn't know how to find this thermostat or how to manipulate the hoses, so I went to a diesel mechanic and had them help me. They first tried using the petcock and even running the thing with the radiator cap off for a while. We couldn't get it to get very hot. We decided that maybe it had worked the air out of itself already.

I drove off this afternoon, and ten minutes later I had another high water temp shutdown!

I went back to the mechanic, and he tried the flushing process described above, but we were both skeptical based on how it went that there was much there to be burped out. Also, I was confused why I was seeing good heat drop (25F) between the hose going into and the hose going out of the radiator, even at the point when the thing shut down. It seemed to me that an airlock would stop the flow mostly or entirely.

Anyway, I glanced over at the scroll fans that exchange the air in the generator compartment (separate from the big blower fan that cools the radiator), and wouldn't you know: both of them were free-wheeling instead of spinning hard like they should.

What's weird is that both were dead, and I just had one of them replaced at Newell a few months ago. Seems strange to me that they both died so suddenly.

So that's almost certainly my problem. Well, one of the problems, since the radiator fan motor was also dying a slow death as described above and also needed swapping.

I'll have to source the fans and order them before we can run the genset with the doors closed, but I think I can run it with the bay door open if I need it between now and the time I get the parts.

I'll update here again if it turns out I was wrong or that there is more to the story.

[Nebster]

There is a little more to the story: I still have not had a chance to replace the scroll fans that exchange the air in the generator compartment, but I HAVE now watched the Powertech ECU shut the generator down with a "high water temp" error when the temp sender was reading 160F.

So, what this surely means is that there is a SECOND temperature sensor, probably on the generator head (or whatever that's called, the thing with the stator and rotor that makes electricity!), that must be in series with the water temp sensor. This second sensor is shutting the genset down when the generator head gets too hot, since the bay can't get fresh air without those fans. But the ECU only has the one "high water temp" error code it can report.

I'm posting this so that the next person who has to diagnose a side-mounted genset with a PT ECU can learn that there may be a different reason, other than coolant vapor lock or radiator fan issues, that a high temp shutdown can occur.

Why Power Tech couldn't be bothered to mention this to me when I spoke with them last week is a mystery.

[bestgenman]

Revisiting the "air in the coolant" again, my post meant to say "the highest point in the radiator hose".  The petcock Pt is referring to is on the top of the thermostat housing (if my old memory is correct) and getting air from underneath the stat is very difficult.  This is why a tube 2" long of the same diameter as the hose with a petcock soldered in works the best.  I does away with trying to force water into the system to evacuate the air.  Th air will work it's way to the highest point (where this new petcock is located) and just cracking open the petcock will let the air escape.  True, it does take a while but works much better than  the petcock on top of the housing.

In response to your second thermostat.  The controller uses a grounded signal for shutdown on pressure and temperature.  these switches are paralleled rather than seriesed.  Any grounded sensor will result in a shutdown.  I believe PT uses an ambient air temp switch inside the enclosure which is connected to the HWT shutdown input on the controller.  High ambient temp appears as HWT since there is only one input.  Since your enclosure fans are not working, your enclosure temp exceeds the switch setting.  Resolve the enclosure cooling problem and then tackle the coolant problem.  Or, unplug the ambient switch but keep in mind these are installed to protect the engine and disconnecting could cause a scored piston so, be careful running with disconnected switches.  Keep your guard up!!

I'm not aware of any sensors on the "head" for these sets.  If it were a 2000KW set, it would make sense.

I can send you a wiring diagram if you let me know the model of your set.

You are on the right track, keep at it and your be successful.

[bestgenman]

I want to correct my statement about the petcock.  The petcock in the hose would be in the same place as the top of the thermostat, that is, in the highest point.  The air is trapped underneath the stat and can't get through.  Yanmar and others use a tiny hole in the stat to facilitate air removal, that is why it is so slow.  I believe the best fix is to use one of the ports underneath the stat for a vent.  There aren't many ports underneath and most are used by the HWT switch and the temp gauge sender.  If there is another port, then certainly look into fixing a petcock there.  I believe this will correct the trapped air issue.

[Nebster]

Thanks Gordon. An ambient air sensor makes sense as well. Either would protect the generator head from overheating, presumably?

My model is a PT20SI.