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Hot?

5.9 Cummins, U-225

We're on our way to Oregon and going through some hot Arizona weather - 103-105 today. We're towing a Subaru Legacy. Anyhow, today during a couple of long pulls, the temp gauge climbed to its usual 216 to 218 or so but today the water temp alarm sounded twice. The red alert lighted and the little beep/siren sounded, kind of anemic sounding as if it was on a low volume. Anyhow, this rig has run quite a bit hotter than this with no alarms sounding. The radiator was plugged up with insulation material and it climbed to around 225 with no alarm. According to the book (and several discussions here) the 5.9 can run up to about 230 before considered overheated. Anyone else experienced this?

Coolant: Right kind and full.
Temp Gauge: It's operating as it has in the past. Idling around 180, running on the straight and level around 195. After the alarm sounded it went right back down to normal as usual.
Fan Belt: Almost new and tight.
Air Conditioner: I did have it on; should have turned it off (hardly works anyhow)

Thanks.
jor
93 225
95 300
97 270
99 320

Re: Hot?

Reply #1 –
John, mine never sounded an overheat alarm and it was over 220 a couple of times. Weird yours would sound at under 220. If you have an IR thermometer with you, point it at the sending unit and see what the temp of the thermostat housing is. Mine was always 10 degrees below the reading on the analog dash temp gauge. I guess its possible that the dash gauge is reading low. The sending unit has two elements, one for the gauge and one for the alarm so the gauge may say something different than the alarm element.
The selected media item is not currently available.Kent Speers
Locust Grove, OK
1993 U300 SSE 40' (Restored at FOT 2009) Build 4323
720 watts Solar
6V92TA DDEC Silver Engine
2014 Subaru Outback

Re: Hot?

Reply #2 –
Thanks, Kent. As it happens, I do have an IR thermometer with me and I'll give that a try tomorrow. I'm hoping it is the alarm itself because, with the exception of the alarm going off, the temperature ranges showing on the gauge are just about what I see every time we travel. It's as if the alarm sensor has changed. Anyhow, I'll try the IR thermometer. Don't want to be like a guy I knew many years ago who blew up his slant six Dodge.

"Steve, what happened to your motor?"
"Ran it out of oil."
"Didn't the oil light go on?"
"Yea, but I thought it was malfunctioning."
jor
93 225
95 300
97 270
99 320

Re: Hot?

Reply #3 –
I had the same issue with the alarm sounding with the temperature in the normal operating range.  It turned out the ground bus at the dash needed to be cleaned.
Peter & Beth Martin
No Forrest? What have you done?
MC# 15890 until Dec 2016; FMCA #F329677
Cincinnati, OH

Re: Hot?

Reply #4 –
With your rear radiator, check the whole front of CAC (Charge Air Cooler). Could have sucked up a plastic bag, leaves, etc as well as the normal accumulation of dirt and debris.

Brett
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: Hot?

Reply #5 –
Quote from: jor –
"Steve, what happened to your motor?"
"Ran it out of oil."
"Didn't the oil light go on?"
"Yea, but I thought it was malfunctioning."
jor

That made me laugh.  ;D A friends of mine's mother, who bred dogs, received a brand new fully equipped GMC van to travel to shows with. A few months later, the motor seized. When queried as to any unusual symptoms, she mentioned she saw the oil light was on, but assumed that meant she had to add oil. She decided she would deal with that later. Warranty claim denied.

Was thinking if nothing else is found, perhaps replacing the temp sensor might resolve the issue. or at least clarify the temps being read.

Steve
1991 U225 Grand Villa

Re: Hot?

Reply #6 –
I would watch my gauge and wouldn't put much stock in the buzzer..
Dub McBride 1996 270

Re: Hot?

Reply #7 –
Until you are certain it is the buzzer and not the gauge, I would really take it easy. I-40 in Arizona with it's long grades and high temps can really stress a cooling system especially with something picked up off highway as Brett says. Made worse with added toad weight. You could be on I-10 with even hotter weather.

I could run 82 mph coming across US without moving the gauge off normal. When I hit the mountains here in the west, I had to shift down an extra gear and go to partial throttle on a lot of grades to keep the temp where I didn't worry. This was without toad.
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Hot?

Reply #8 –
Update
OK, before I left this morning, I checked under the dash. I disconnected and cleaned the instrument panel circuit board and sprayed some electrical cleaner on the ground bus. (everything looked clean and was tight). When the 5.9 reached 180 degrees I took the temp where the temp sensor is located - right on the money with the gauge. Later in the day, with the temp gauge reading about 195, I did the same thing - once again, same reading. I think the gauge is accurate. We did some long and fairly steep climbing today with ambient temps around 100. The temp gauge indicated about the same as yesterday, maybe 116 to 118 but this time no warning light and no buzzer. I'll just continue to watch it closely but at this point I think the gauge is correct.

BTW, Brett, I didn't see any obstruction in the CAC area. Actually, with this rig it would be difficult for that to happen as the whole radiator-CAC is almost contained within a box like structure. I cleaned that CAC for hours and it would have been a lot easier if I could have gotten directly between the radiator and CAC. It looks like a heck of a job to get it apart. Anyhow, at this point, all is well. (kinda hot though...) Thanks to all.
jor
93 225
95 300
97 270
99 320
 

Re: Hot?

Reply #9 –
Speed is a factor too.  Last month on my trip to Tennessee, I kept my speed at about 65-67 and stayed around 180-190.  Today I was in a hurry to get up to Gainesville for daughter's move in appointment at UF so I was running 70 all the way and the temp was right at 200.
Dwayne Keith
1992 U240
3116/MD3060