Author Topic: CAT C7 - Water Temp drift (186-195  (Read 215 times)

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Offline rgrimm

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CAT C7 - Water Temp drift (186-195
« on: August 22, 2018, 12:37:03 PM »
Hi Dave,

I look for changes in what has been  my  coach's normal operation to perhaps indicate a problem or start of a problem. I have noticed a slight change in my water temperature range. Perhaps you can enlighten me if it indicates a problem or just not that critical.

History: I have a 2006 Winnebago Journey, purchased used in 2014 with a 350 CAT C7.. I was unable to find any service history on the Engine or Allison from the two previous owners, so I had the CAT oil filters (oil and fuel) changed, the cooling system flushed and replace with Extended Life Antifreeze. I also had the Allison Trans Transend Fluid and filters changed to have a service bench mark.

The Engine Oil and filters have been changed every 7000/7500 miles or less since my ownership. The ‘Slober Tube’ had already been extended to right behind the rear hitch when I purchase the coach. So one of the previous owners had this done.

My concerns:  This isn’t necessarily a problem, but it is a change from past conditions. I have been used to watching the water temp move from 186 to 192/194 as I drive. It moves up in 2 degree increments to it’s peak and then back down in 2 degree increments, maybe over a 1-2 minute timeframe. On a recent trip down I95 from the top of FL to the Mims area I watched the temp go from 185/188 to 195/197 and even a couple times hit 199 and 201 (my speed was 65 via cruise control). After a stop at a rest stop where the engine idled for about 5 minutes and a return to cruise speed the temp drift eventually went to 192 and pretty much stayed there for the next 60 miles. A couple time it did drop to 190 and then back to 192. While I don’t see these temps as an overheat problem I do see the change in the range as a change in the normal operation I have been use to.

So is this 8 to 10 degree temp drift up and down normal for the CAT engines?

At what temperature is it considered starting an overheat situation? My local CAT dealer manager just told me that up to 205 is considered a normal temp for a C7.

While a common concern with these rear radiator coaches is the CAC (Charged Air Cooler) and the Radiator being plugged with oily dirt, reducing air flow through the radiator and causing a degradation of its cooling capability. But I would suspect if the radiator/CAC were blocked that the low temp of the swing would be higher, its actually the same even a degree lower at times, and I would think the coach would not have spent that 60 miles sitting at 192 as it did if the CAC/Radiator were blocked. If there was a blockage, air flow restriction, that would be a condition that would not improve by itself.

So what is causing the temperature’s swing to creep on the high side? Possibly the thermostats (CAT refers to them as regulators I believe) being bad?

I have cleaned my radiator with Simple Green from the back of the coach twice a year and I know that isn’t really getting to the CAC. I guess I need to access the engine from under the bed to see if I can see how the CAC looks.

Thanks in advance for any input.

Russ Grimm
Yulee, FL
« Last Edit: August 22, 2018, 02:44:23 PM by rgrimm »
~ Russ and Arlene ~
Yulee, FL
2006 Winnebago Journey 34H ~ CAT C7 350
Toad - 2013 Ford Edge

Offline WallyNM

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Re: CAT C7 - Water Temp drift (186-195
« Reply #1 on: August 22, 2018, 02:50:55 PM »
Not sure of interval but as I recall Cat recommends replacing all coolant hoses and all thermostats on a set schedule of 3 or 4 years. You might check with them.

Offline David.e.atherton

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Re: CAT C7 - Water Temp drift (186-195
« Reply #2 on: August 22, 2018, 03:45:43 PM »
Regrimm, you are asking a very good question. First of all the thermostat on your C-7
has a upgrade and possible is where the temp is variable. Let me give you some engine
technical information on your thermostat. Your thermostats begains to open at 191 Deg F,
and is full open at 206 Deg F. Your old style thermostat has what is called a jiggle pin in
Edge of thermostat and it has reason for being there . First it allows trapped air to exit through
Jiggle pin hole when engine is shut down. As engine runs and her is building and pressure
Begains to happen in cooling system the jiggle pin will moves and shuts off exit of air. This
could be possible differences in heat or dirty connection to sending unit. The new upgrade
thermostat does not have the jiggle pin any more. And when changed out you will notice
Heat range holding steady. But will indicate warmer temperature on heat gauge. Thermostats
caterpillar recommends change out every two years. Last question temps around  220 Deg F
225 Deg F  you need to cool engine down slow and  shut down.
Ask Dave! Dave Atherton Retired Cat Mechanic



Offline rgrimm

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Re: CAT C7 - Water Temp drift (186-195
« Reply #3 on: August 22, 2018, 04:09:13 PM »
Dave - Thank you for the explanation and information about the differences in new and older thermostats.

I have owned this Coach since 2014 and never changed the thermostats, so they are at least 4 years old so I guess it is time to have them replaced.

Thanks again.
Russ
~ Russ and Arlene ~
Yulee, FL
2006 Winnebago Journey 34H ~ CAT C7 350
Toad - 2013 Ford Edge