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Genset temps VERY hot while driving
#1
My 20kw genset runs VERY hot while driving.  And it never shuts off.  (I chicken out and shut it down manually when temp guage approaches 250 (max)). Here is what I know.

1. I've had the coach a year. It seems well maintained by PO.
2. PO advised me of this condition. He had had it checked out at Newell and they said it was "normal" to run quite hot while driving.
3. Temperature is under 200 when stationary
4. It does not lose coolant
5. Cooling fan seems to work properly (although after reading a prior post, i'll see if squirrel cage blades need cleaning.)

Questions/Concerns:
1. On the front of the engine (where I think the thermostat is located) are 2 things with wires attached to them. I assume they are:
    a) Temp sender for overheat shut-off
    b) Temp sender for dash temp guage.     Am I correct about these two? and which is which?
2. How can I make sure each of these are working correctly? (Especially the auto shut-down one)
3. At what temp should this be shutting itself down?
4. Opposite side of the thermostat housing is a plug.  Is this for a third sensor? (Could it be used to validate reading from dash guage?)
5. Would pointing an IR temperature reader at the housing tell me the temp as well?

Ideas for lowering the operating temp...
1. I will wash out radiator with a hose.  Not sure how dirty it is, but i do see some build up of dirt on inside of it. Is hose cleaning sufficient?
2. See if blades on squirrel cage fan need cleaning
3. I see a smallish (9-12") piece of rubber seal hanging down under front of the generator. I'll put it back in place. Could a small seal leak be letting in enough negative pressure to keep it from cooling?  
4. What else????

Thanks for your help.

Alan Johnson
Dallas Tx
#485 1998 Newell
Alan Johnson
Dallas Tx

Newell #485
1998 2 slides
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#2
i am heading out for the weekend but i will give my opinions on a couple of things.

if you point your ir gun at the thermostat housing where the temp sensor wire is, it should give you a good reading of temp.

if feel the air coming out from under the genny where that scoop is and it feels like a hurricane, then you have enough airflow

mine does not get any hotter driving than when sitting still. ambient temps and load make temps go up some, but i run it when it is 115 degrees no problem.

if you can verify it truely is getting hot, then i would have the radiator looked at and change the thermostat. in both of my newells i had the genny radiator cleaned and done at a radiator shop.

others can pitch in

tom
2002 45'8" Newell Coach 608  Series 60 DDEC4/Allison World 6 Speed HD4000MH

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#3
oh, and that seal on the front in my opinion should not make that much difference. but put it back up

tom
2002 45'8" Newell Coach 608  Series 60 DDEC4/Allison World 6 Speed HD4000MH

Reply
#4
(06-09-2018, 07:53 AM)AlanJohnson Wrote: My 20kw genset runs VERY hot while driving.  And it never shuts off.  (I chicken out and shut it down manually when temp guage approaches 250 (max)). Here is what I know.

1. I've had the coach a year. It seems well maintained by PO.
2. PO advised me of this condition. He had had it checked out at Newell and they said it was "normal" to run quite hot while driving.
3. Temperature is under 200 when stationary
4. It does not lose coolant
5. Cooling fan seems to work properly (although after reading a prior post, i'll see if squirrel cage blades need cleaning.)

Questions/Concerns:
1. On the front of the engine (where I think the thermostat is located) are 2 things with wires attached to them. I assume they are:
    a) Temp sender for overheat shut-off
    b) Temp sender for dash temp guage.     Am I correct about these two? and which is which?
2. How can I make sure each of these are working correctly? (Especially the auto shut-down one)
3. At what temp should this be shutting itself down?
4. Opposite side of the thermostat housing is a plug.  Is this for a third sensor? (Could it be used to validate reading from dash guage?)
5. Would pointing an IR temperature reader at the housing tell me the temp as well?

Ideas for lowering the operating temp...
1. I will wash out radiator with a hose.  Not sure how dirty it is, but i do see some build up of dirt on inside of it. Is hose cleaning sufficient?
2. See if blades on squirrel cage fan need cleaning
3. I see a smallish (9-12") piece of rubber seal hanging down under front of the generator. I'll put it back in place. Could a small seal leak be letting in enough negative pressure to keep it from cooling?  
4. What else????

Thanks for your help.

Alan Johnson
Dallas Tx
#485 1998 Newell

You have a ground problem on the gage
Rolleyes Ashley Pardue Coach 589
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#5
Tom and Ashley, thanks for the input.

I'll check the volume of air coming out under it. Coolant is nice and green... so leads me to think radiator is probably ok. But I know that isn't a guarantee. Do you know what temp it should be shutting itself off at?

Ashley, I don't know how ground problems on guage affects it. But let me see if I understand. With a ground problem it could read at a normal expected range while not driving. But it would go up drastically when driving? (I am assuming somehow a slight increase in temperature would be exaggerated on the temperature guage??)

Thanks!
Alan
Alan Johnson
Dallas Tx

Newell #485
1998 2 slides
Reply
#6
Great post, you gave the detail needed to get good responses. I am sort of echoing what others have said.

First, use an IR gun on the thermostat housing to verify the temp is real. If you really are seeing 250 then the genset over temperature would have shut it down and coolant would be boiling over. You mentioned neither.

But if it is real, look carefully at the airflow and where it is sealed to force it through the radiator. Not going to comment on the loose rubber piece other than to say make sure the airflow path is as sealed as possible

As you drive the outside air pressure at the louvered door will be less than when stationary. In addition to making sure the air path is sealed, make sure the belt is tight from the motor to the blower.

One last thing that occurred with an owner many years ago was that if he cranked the genny while driving the motor would turn backwards. I never really understood that electrically but the result was the gennie would over heat and shutdown

Let us know what you feel find
Richard and Rhonda Entrekin
99 Newell, 512
Subaru Outback Toad
Inverness, FL (when we're home Cool )
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#7
(06-09-2018, 11:31 AM)AlanJohnson Wrote: Tom and Ashley, thanks for the input.

I'll check the volume of air coming out under it.  Coolant is nice and green... so leads me to think radiator is probably ok. But I know that isn't a guarantee.  Do you know what temp it should be shutting itself off at?

Ashley, I don't know how ground problems on guage affects it. But let me see if I understand. With a ground problem it could read at a normal expected range while not driving.  But it would go up drastically when driving?  (I am assuming somehow a slight increase in temperature would be exaggerated on the temperature guage??)

Thanks!
Alan

YES
Rolleyes Ashley Pardue Coach 589
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#8
You don't mention the manufacturer but likely it is either a Kubota or Yanmar powered set.  The sensors are nearly identical for both engine makers, the sensor with the bullet connector is the HIGH WATER TEMPERATURE switch, and the threaded connector is the gauge sender.  I concur with Richard in that while driving the airflow is reduced into the fan bay so it is normal for the temps to be a little higher.  Certainly clean the radiator if you see debris on the engine side of the fins and wash from the front to the engine side in reverse to the airflow to keep from embedding dirt further into the core.  Check the seal around the door for air flow when you are sitting still,  if there is air escaping, fix it so the seal makes contact by whatever means necessary.  Look inside the box for any holes,  sometime PO repair personnel cut holes in the back for access and their access panel may be letting air escape.

Back to the sensors,  if you pull off the bullet connector from the HWT switch and take the wire to a ground point with the engine running the engine should stop.  there may be a ten or so second delay or it may be instantaneous.  If it does not stop your controls are at fault.  If it does then your sensor may be faulty, not a common occurrence but can happen.  They are not terribly expensive and can be tested if removed.  The sensor connects the bullet pin the the threads (ground) at the set point which is ~220 degrees F.

The gauge is probably your high reading culprit, they are not terribly accurate.  They work by applying 12V to the gauge and the sensor is a variable resistor to ground.  The higher the temperature the lower the resistance, therefore the more the gauge needle moves to the right.  If while the engine is running, the wire lead is grounded, the gauge should go full scale.  Dakota digital sells a pretty accurate direct replacement. The wiring is the same, no additional wires needed and the gauge is 2" to fit your cutout.

Richard also make a good point about your belt, check it's condition.  He has also posted elsewhere on this site a P/N for a direct drive blower.
Gordon Jones
2000-45'-2slide-#567
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#9
(06-09-2018, 11:31 AM)AlanJohnson Wrote: Tom and Ashley, thanks for the input.

I'll check the volume of air coming out under it.  Coolant is nice and green... so leads me to think radiator is probably ok. But I know that isn't a guarantee.  Do you know what temp it should be shutting itself off at?

Ashley, I don't know how ground problems on guage affects it. But let me see if I understand. With a ground problem it could read at a normal expected range while not driving.  But it would go up drastically when driving?  (I am assuming somehow a slight increase in temperature would be exaggerated on the temperature guage??)

Thanks!
Alan
Alan, two years ago i was having a similar problem. several things were done; I change the blower motor for the gen radiator to a 3/4 HP. when I removed the old blower I found an air flow limiter and I removed to increase the air flow. also, i flushed the coolant system and I found a leak, although small, in the radiator. I pulled the radiator, had it rebuilt and made sure good coolant flow was there. The other thing was to install 120 vac pump in the return line to the engine on the genset. That really helped a lot..

If the temp gets about 195 degrees, in my case, the fire suppression system will be activated. the ground issue is probably making it intermittent on the  temp gauge..  right now, the gen is completely remove to fix several things. normally in a loaded condition it runs about 165 degrees.

Gordon is your man. 

Ron
Ron Gripon
2003 coach 660-F150 
2005 Porsche Boxster
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#10
@AlanJohnson

What is the status of your situation with the hot generator?
Richard and Rhonda Entrekin
99 Newell, 512
Subaru Outback Toad
Inverness, FL (when we're home Cool )
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