Community Forums

deasnealy · 03-18-2017, 11:14 AM

Just made it over a pass in Southern California from YUMA. It was about 98 degrees outside. I noticed the temp starting to rise after a few minutes. I slowed down to around 45 mph. No change. Finally, an alarm sounded when the temp went to red zone. I had to slow down to 25 mph to finally have the temp lower. I have made these passes before but the temp was in the 60's. I figure the rig should be able to handle this. I am only pulling a CRV and my weight is within limits. Just had annual major service at Freightliner.

Before I take her into check out, is there anything I should be looking at that could be a simple fix. I have always kept the radiator clean, but never used a pressure washer on it. Fluid levels are normal.

I have a Tiffin RED 2010. 340 HP ISB Cummings

Thanks in Advance!

Tizbad · 03-18-2017, 11:31 AM

Did you manually downshift while climbing the grade in an effort to maintain fan speed? I know that Cat recommends around 2000 RPM's to keep the fan blowing across the radiator when climbing grades and I believe that Cummins says this as well.

deasnealy · 03-18-2017, 12:55 PM

Yes. I actually started to see the heat go up rapidly at higher RPM's.

NevadaNick · 03-19-2017, 08:27 AM

Possibly you have a bad fan clutch.

luvlabs · 03-19-2017, 08:28 AM

I believe you have an ISB engine. The proper RPM for climbing is about 2200 RPM and you will want to downshift to maintain that RPM as soon as you begin to slow down. RPMs that are too high or too low will give you overheating issues.

When you can, you should clean the radiator with Simple Green (version meant for aluminum) and plenty of water. If you need a radiator cleaning procedure, search this forum or go over to the Tiffin RV Network and get one.

garykk · 03-19-2017, 12:40 PM

Agree with Roger, most likely your radiator/ CAC is dirty. Just cleaning it from the rear of the MH does not really do anything.

deasnealy · 03-19-2017, 04:19 PM

I was worried about that. I have heard it was a common problem.

Mekanic · 03-19-2017, 04:41 PM

Quote:

Originally Posted by NevadaNick

Possibly you have a bad fan clutch.

Quote:

Originally Posted by luvlabs

I believe you have an ISB engine. The proper RPM for climbing is about 2200 RPM and you will want to downshift to maintain that RPM as soon as you begin to slow down. RPMs that are too high or too low will give you overheating issues.

When you can, you should clean the radiator with Simple Green (version meant for aluminum) and plenty of water. If you need a radiator cleaning procedure, search this forum or go over to the Tiffin RV Network and get one.

I agree with both although the radiator being dirty is more likely of the two reasons.
I'll ask this When was the last time you cleaned the radiator? And just how did you do it?

Tony Lee · 03-19-2017, 07:40 PM

Dash airconditioner on was it?

Combination of going up the hill too fast in wrong gear, plus towing plus dirty radiator.

Get a garden sprayer and spray a degreaser from back and front, let it soak for a few minutes and then use a pressure cleaner (carefully and not too close to the fins) also from both sides. Repeat as needed and thereafter once a year. If your engine has a slobber tube then it needs to be run to where the oil mist does not get sucked up by the fan.

deasnealy · 03-23-2017, 11:02 AM

I turned off AC. It started to lower the temp only when I dropped speed down to around 35.

Old Scout · 03-23-2017, 11:12 AM

Agree--should keep RPMs up to around 2000.....shift down early to achieve desired RPMs....assume this is a rear radiator rig so keeping it clean is an issue--reroute engine breather [if it has one] to clear radiator. Not familiar with fan clutch, but probably a good idea to verify its working correctly.... Challenge is that once radiator is dirty enough to hamper cooling, it will be a real bear to get it clean now [eg, dirt now trapped between radiator and CAC]......

ernieh · 03-23-2017, 06:34 PM

Quote:

Originally Posted by deasnealy

I turned off AC. It started to lower the temp only when I dropped speed down to around 35.

Dash air shouldn't make any noticeable difference. The condenser air doesn't pass through the CAC or radiator.

Tony Lee · 03-23-2017, 08:07 PM

Quote:

Originally Posted by ernieh

Dash air shouldn't make any noticeable difference. The condenser air doesn't pass through the CAC or radiator.

No it doesn't but the engine has to run the compressor and when you are running out of options, turning off the aircon AND turning ON the dash defroster can make all the difference. Long grades in California have signs suggesting turn off AC in hot weather and it is a sensible suggestion.
When conditions are marginal you need to start driving by your engine and transmission temperature guages and forget about all the hoons burning you off in their 600HP rigs
I spent a couple of hours and a gallon of degreaser in a truck wash in Whitehorse getting the radiator and CAC clean and when Betty and I pulled the radiator and CAC out on the side of the road in Mexico a couple of trips later it was still clean. Now a mild clean once every trip is more than enough to keep it that way especially now the slobber tube isn't making a mess

deasnealy · 03-27-2017, 11:42 AM

Thanks. I have initially used some simple green on the rear exterior. Not sure I have a slobber tube on the 2010 Cummins ISB. I am struggling on how to get to interior of the Radiator. I can crawl under the rig and see some areas but it looks clean to be. I used a hose for now as I have been told to avoid pressure washer. I look further into to cleaning techniques and may need to find a truck wash and my RV campground is in Mission Bay and they are very touchy about cleaning on site.