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Coolant Temperature Low?

I am used to coolant temp running higher but noticed today it about 175-180.  Ambient 75.  Got to wondering if maybe fan speed or thermostat issue or about normal with that ambient?

I can ask Alton tomorrow as Foretravel is working on another issue, antifreeze intermittent leak at the "water" pump.

But thought get your views first.  I thought I ran more like 200 degrees coolant temps. 
Mike
2001 U320 4010 Build 5878 (Gus)
Wrangle Unlimited Toad
Nacogdoches

Re: Coolant Temperature Low?

Reply #1 –
Mike,

Not likely the fan.  More likely the thermostat stuck open/partly open.

Drain a couple of gallons of coolant and replace it along with a new gasket.

If water pump leaking, replace it at the same time.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Coolant Temperature Low?

Reply #2 –
Our U300 runs about 175 to 180 most of the time unless summer on upgrades. 180 degrees is hot enough to evaporate any crankcase moisture. Your transmission temp should be about the same. I watch the temp like a hawk for anything much over 210 on a wet liner engine like yours and ours.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Coolant Temperature Low?

Reply #3 –
The electrical switch on the block of an m11 that turns on a trucks front cooling fan does not turn on until 205F.

Thermostat opens fully at 200. Starts opening at 180

The Cummins dealers owner/shop foreman laughed when I questioned the 210 turn on. 

I have run mine well over 210 for extended periods without issue.

Dash gauge was high by 10 or more degrees versus VPMS
"Riding and rejoicing"
Bob
1997 U320 40' Mid entry, build 5132,  wtbi ce27, 4th owner
2007 Solara convertible
2 prodeco tech outlaw ss electric bikes

1095 watts solar
08 Ls 460 and a sc430
2000 Ford F-250 superduty 4x4

Re: Coolant Temperature Low?

Reply #4 –
When I bought my U320 it ran just under 180 so I bought a new thermostat and now it runs colder. So as soon as I get back from
this trip I will take it back to Cummins.
Peter and Frieda Morin
1999 36ft. U320 Foretravel
Build # 5436
1998 Suzuki Sidekick Sport

Re: Coolant Temperature Low?

Reply #5 –
Bob, my dash corresponds with my vmspc

Pierce, you are right.....those temps within three degrees at that time per vmspc
Mike
2001 U320 4010 Build 5878 (Gus)
Wrangle Unlimited Toad
Nacogdoches

Re: Coolant Temperature Low?

Reply #6 –
Mike it's possible Foretravel moved the engine temp pickup between the years?  Sounds likely.  I think there was more than one possible?
"Riding and rejoicing"
Bob
1997 U320 40' Mid entry, build 5132,  wtbi ce27, 4th owner
2007 Solara convertible
2 prodeco tech outlaw ss electric bikes

1095 watts solar
08 Ls 460 and a sc430
2000 Ford F-250 superduty 4x4

Re: Coolant Temperature Low?

Reply #7 –
If I was on the flat not pushing the temp would be 180
2025 Wanderbox Outpost 32 on F600 Expedition Motorhome
2015 Born Free Royal Splendor on Ford 550 nonslide version  for sale
Former Coaches  covering. 360,000 miles
1999 34 U270
2000 36 U320
2001 42' double slide U320
2018 Jeep Rubicon

Re: Coolant Temperature Low?

Reply #8 –
Mike, my 2001 ISM11 like yours, will run all day at 178°.  Higher outside temps, grades, wind, will push it up to around 190 sometimes more. 
Roger Engdahl and Susan Green
2001 U320 3610 #5879 (Home2) - 2014 Jeep Cherokee or 2018 F150
Hastings, MN

Re: Coolant Temperature Low?

Reply #9 –
Not worth speculating on.  Give Cummins a call with your engine serial number and ask them for the correct thermostat PN/temperature.

Cummins 800-286-6467 

The important thing is that you have experienced a change in temperature-- so something has happened.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Coolant Temperature Low?

Reply #10 –
On our vmspc we run 176 steady.  I too watch this like a hawk!  M11 450 cummins!
Joe & Dottie Allen
Sold!  December 2023.      2000 U320; build # 5645
Our coach " Maxine"
Motorcade #  15922;  Escapee 150950; FMCA F330833; Boondockers Welcome;  Harvest Hosts;  Thousand Trails
'98 U320 from 2000-'06
USAF '62-'66

"Do not spoil what you have by desiring what you have not; remember that what you now have was once among the things you only hoped for." ―Epicurus

Re: Coolant Temperature Low?

Reply #11 –
According to my VMSPC  my temp is 163* That is running all day with ambient temp of 65*. Cummins M11 450
Alan Fink
Waupun, WI
2000 Blue Bird Wanderlodge  LX40
2018 F150 4x4
2020 Jeep Wrangler Unlimited  Rubicon JL

Re: Coolant Temperature Low?

Reply #12 –
Quote from: Big Al –
According to my VMSPC  my temp is 163* That is running all day with ambient temp of 65*. Cummins M11 450
Your temp is too low, probably thermostat. Ambient temps don't the control thermostat.
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: Coolant Temperature Low?

Reply #13 –
Quote from: craneman –
Your temp is too low, probably thermostat. Ambient temps don't the control thermostat.

CORRECT.

Ambient temperature only dictates how much fan is needed for the thermostat to remain "in control" of engine operating temperature.

Said another way, your engine temperature should not vary from thermostatic control because of ambient temperature.

The exception is the normal few degree variation between thermostatic control and fans to max.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Coolant Temperature Low?

Reply #14 –
Ambient temperatures indirectly effect the operating temperatures of our engines. While I can relax and just drive along in cool fall to spring weather, summer temps and our marginal cooling system in the U300 mean the temp gauge creeps higher when heading up any kind of grade. Just because your temperature gauge reads 200 degrees does not mean that your engine is 200 degrees as just the area where the coolant passes the temperature probe is at that temperature. Cylinder head coolant passages around the exhaust valve are much higher and if our cooling systems were not pressurized, the coolant would vaporize/boil causing extreme hot spots in these areas. Heat your engine further and the 14 psi will not be enough to keep these critical areas from localized vaporization.

Altitude will also effect cooling as warm temperatures can result in the density altitude being several thousand feet higher than your GPS/road sign says. This reduces the efficiency of the radiator, the fan, the intercooler as well as raising the EGTs. This catches many by surprise who may not be used to driving the western grades. Translation; altitude results in lower efficiency of several components. Combined with higher than normal ambient temperatures lowers the efficiency even more plus higher EGTs may combine for stressing engine components past their designed operating limits.

So, just because you may have been able to go up grades and have had no discernible effects from temps over 220 on the gauge does not mean that it has not had an effect on engine components. Unfortunately, this can catch up to you even several years later. As we know, even the smallest internal engine problem can result in huge costs if it has to go to a shop.

This is why I drive conservatively with an eye on the gauges all the time.

Pierce

Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Coolant Temperature Low?

Reply #15 –
Quote from: craneman –
Your temp is too low, probably thermostat. Ambient temps don't the control thermostat.
I was wrong, that was my transmission temp. My coolant was 178*
Sorry for any confusion.
Alan Fink
Waupun, WI
2000 Blue Bird Wanderlodge  LX40
2018 F150 4x4
2020 Jeep Wrangler Unlimited  Rubicon JL

Re: Coolant Temperature Low?

Reply #16 –
Yes, as Pierce said, IF (big IF) your cooling system in on the "less than adequate" side, you will certainly overheat more in high ambient temperatures, particularly on long grades.

But, on flat ground in any ambient temperature, any of our cooling systems should be above to keep you in thermostatic control with a few degree increase to where cooling fans go to high.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Coolant Temperature Low?

Reply #17 –
Mike, What did Alton have to say about your intermittent antifreeze leak at the water pump?  I've seen a couple of "cold weather leaks" at the water transfer connector o-ring.  Only happens at certain cold outside temps. 

Glen
Glen & Suzie
1998 U320 36'
Build #5366
2015 Jeep Grand Cherokee Overland
2015 ATC Aluminum 20' Trailer
Previous 1996 U295 40'
Motorcade #17546
Stephenville, TX
 

Re: Coolant Temperature Low?

Reply #18 –
Seems we all run 178.  Thermostat starts to open at 180 and is fully open at 200 according to the shop manual.

Original thermovalve that controls the cooling fans started out at 165 and the fans were on full high at 180.

Wrong.  Minus up to 60hp. 

Changed to 184 to 199 max instead.  Better mpg. More power.  Less wear on fan drive. 

Rest of industry uses the 199 degree fan drive.

The m11 does have a fan switch on its block that can turn on a front fan at 205.  Not our use.

Maybe could be used for something else? 
"Riding and rejoicing"
Bob
1997 U320 40' Mid entry, build 5132,  wtbi ce27, 4th owner
2007 Solara convertible
2 prodeco tech outlaw ss electric bikes

1095 watts solar
08 Ls 460 and a sc430
2000 Ford F-250 superduty 4x4