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topdownman · 10-07-2018, 05:00 PM

I have a 2011 Tiffin Phaeton 40QTH, 380 Cummins ISC. I've owned the coach for a year now. I'm having issues overheating on long grades.

I've changed out the coolant and power washed the radiator. I'm not losing any coolant and I've had the coolant and oil checked by a lab and all is normal. This engine runs hotter than my previous coach (Cummins ISB). Typically, the temperature runs anywhere between about 192 and 207 on flat to rolling ground. On a typical hill pull, it sometimes climbs to 215-217. If I get stuck behind a really slow moving truck I've had it climb to 225 which sets the high-temp alarm. Pulling over it quickly cools down. I've tried driving to the RPMs (keeping them around 2000-2200) and that actually seems to make it worse. If I can maintain 55 mph in about 5th gear it will do ok, anything slower and it quickly climbs.

I'm wondering two things. Is my radiator still plugged up with gunk (I have looked at the back side as best I can with a camera and it looks fine....I've seen what they look like plugged up), or, has my fan clutch failed?

I cannot hear that fan engage to a "roar" when it starts heating up. Although, I can't hear the engine at all in this coach as it's really quiet. However, I never see the temp start to climb, then suddenly drop as if the fan has kicked in. It just climbs and climbs until I either pull to the shoulder or top the hill and start to coast. Then, it'll quickly drop.

Does anyone know how you can test the fan clutch and tell if its working properly? I understand it's electrically activated.

Any help would be appreciated.

2 Stroker · 10-07-2018, 05:21 PM

Quote:

Originally Posted by topdownman

I have a 2011 Tiffin Phaeton 40QTH, 380 Cummins ISC. I've owned the coach for a year now. I'm having issues overheating on long grades.

I've changed out the coolant and power washed the radiator. I'm not losing any coolant and I've had the coolant and oil checked by a lab and all is normal. This engine runs hotter than my previous coach (Cummins ISB). Typically, the temperature runs anywhere between about 192 and 207 on flat to rolling ground. On a typical hill pull, it sometimes climbs to 215-217. If I get stuck behind a really slow moving truck I've had it climb to 225 which sets the high-temp alarm. Pulling over it quickly cools down. I've tried driving to the RPMs (keeping them around 2000-2200) and that actually seems to make it worse. If I can maintain 55 mph in about 5th gear it will do ok, anything slower and it quickly climbs.

I'm wondering two things. Is my radiator still plugged up with gunk (I have looked at the back side as best I can with a camera and it looks fine....I've seen what they look like plugged up), or, has my fan clutch failed?

I cannot hear that fan engage to a "roar" when it starts heating up. Although, I can't hear the engine at all in this coach as it's really quiet. However, I never see the temp start to climb, then suddenly drop as if the fan has kicked in. It just climbs and climbs until I either pull to the shoulder or top the hill and start to coast. Then, it'll quickly drop.

Does anyone know how you can test the fan clutch and tell if its working properly? I understand it's electrically activated.

Any help would be appreciated.

Yes, I would be looking at the fan clutch and even the t/stats. I just replace one of my t/stats because it was broken. 215deg to hot and 225 is a killer. Mine broke at 26,000mi

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topdownman · 10-07-2018, 05:29 PM

Quote:

Originally Posted by 2 Stroker

Yes, I would be looking at the fan clutch and even the t/stats. I just replace one of my t/stats because it was broken. 215deg to hot and 225 is a killer. Mine broke at 26,000miAttachment 221772

Where is the thermostat located? Upper radiator hose?

2 Stroker · 10-07-2018, 11:54 PM

Quote:

Originally Posted by topdownman

Where is the thermostat located? Upper radiator hose?

I don't have a Cummins but I would think it would be where the top radiator hose connects to the block. That is how my C9 cat is.

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RKins · 10-08-2018, 05:33 AM

I have 2 thermostats in the same housing under the top hose. See the attachments.

BigLar368 · 10-08-2018, 06:19 AM

Our 8.3 (2004) only has one thermostat. It's in the upper radiator hose coming out of the top of the block. I have no idea about the newer model engines but I would think the engine would not have changed that much. I would also look at the fan clutch or whatever regulates your fan speed.

Superbee Jim · 10-08-2018, 10:04 AM

I have an 8.3 in my 09 Entegra and when the temp gets up to 215* or so, I can hear the roar of the fan clutch engaging and then the temps cool down quickly. If you don't hear the roar, I would look into the fan clutch.

stevewitt1 · 01-22-2023, 12:28 PM

hey all:

I experienced some overheating on longer climbs right after buying my 2008 38F Bounder, but recently in the morning the temp would rise shortly after starting my days travel with ambient temps in the 50's. Slow down and temps would fall, speed up they'd rise. I'd play this game for several miles then temps would fall and wouldn't act up the rest of the day. The last time it seemed to linger longer. I pulled off the road and looked. The fan was turning but it didn't seem fast enough. A couple miles later the temps dropped. i pulled off the road and the fan seemed engaged more. After further diagnostics it appeared to definitely be the fan clutch. It appears I will have a new clutch to solve the problem. I'm having a new serpentine belt and new thermostat installed as well. 59200 miles. My research told me that fan clutch, if you will have them, seem to show up between 30-60k miles.
Hope this is solved. I hope to take off from the Frozen Tundra heading to Florida in couple weeks.

nehog · 01-22-2023, 04:06 PM

Check your fan clutch (if there is one...) as that will cause this type of overheating problem.

Sinyyl · 04-22-2023, 08:07 AM

No one mentioned radiator yet. It feels to me it's more like a raditor problem. Because you mentioned, pull over quickly cools it down, then the coolant flow must be there. The T-stat has closed for the coolant to flow to rad. But your rad may be cloged. If your engine is coutinuously outputing lots of heat, it can't cool in time.
Before I replace my leaking and very cloged rad, I regularly see 200+ degrees. Now with a new rad and an added aux fan, I rarely see over 190, mostly 178 all the time.
Consider clean your rad with some type of radiator cleaner with water or just gatden hose. It's better to spray water opposite of the air flow, so that the debris sucked in can go out from the way in.