Hey all-We have a 2005 Holiday Rambler with a Cummins ISC 330. On our way to Flagstaff AZ, at 7,000 feet, we began to experience some overheating. The water temp gauge spent quite awhile in the red zone. We unhooked our tow vehicle, which didn't seem to help a lot. When we were level or downhill the temp dropped, as would be expected, but on any climb at all, it headed back up into the red. It was probably in the mid-80's outside, not terribly warm, and the road was what I'd call a moderate incline, certainly not excessively steep.The coolant level seems normal, as well as the oil level. I had the coolant SCA level checked within the last 6 months and I was told that it was fine.Interestingly, the OIL temperature seemed normal; the oil temp gauge stayed down where it normally is. It would seem if the engine is running hot then the oil temp would be up too, but it didn't seem to be.Anyway, I'm planning on taking it in to a Cummins shop on Friday, but I thought I'd run it by the forum to see if y'all had similar experiences, or any thoughts.Thanks!Dave

Assume you have a rear radiator:Access the engine from the bedroom/closet.Shine a strong flashlight into the fan shroud/between fan blades. Make sure that the perimeter of the CAC and radiator is as clean as the center (the fan blades sling the debris to the perimeter.It is likely that dirt is blocking some of the radiator and CAC surface.

I have the Cummins 350 and was having an overheating problem also. I had Gaffney Freightliner check it out while doing the 36000 mile maintenance and they found that it was the fan clutch leaking oil. They replaced it and is running great now. That problem was Freightliner. Two days later the turbo went out and then it was Cummins turn.

Another common problem with that engine is a cracked or broken exhaust manifold which will reduce turbo drive pressure and result in very high eng. and exhaust gas temps.

I just had the same problem coming home from Arizona with our Monaco. Dirty radiator was the cause and after cleaning no problems.

did you downshift when you came to the hill? how many RPM were you running at.

Engine overheating | Good Sam Community

wolfe10
Explorer
Jun 04, 2013
Assume you have a rear radiator:

Access the engine from the bedroom/closet.

Shine a strong flashlight into the fan shroud/between fan blades. Make sure that the perimeter of the CAC and radiator is as clean as the center (the fan blades sling the debris to the perimeter.

It is likely that dirt is blocking some of the radiator and CAC surface.
Louandsal
Explorer
Jun 04, 2013
I have the Cummins 350 and was having an overheating problem also. I had Gaffney Freightliner check it out while doing the 36000 mile maintenance and they found that it was the fan clutch leaking oil. They replaced it and is running great now. That problem was Freightliner. Two days later the turbo went out and then it was Cummins turn.
ScottG
Nomad
Jun 04, 2013
Another common problem with that engine is a cracked or broken exhaust manifold which will reduce turbo drive pressure and result in very high eng. and exhaust gas temps.
conmoto
Explorer
Jun 04, 2013
I just had the same problem coming home from Arizona with our Monaco. Dirty radiator was the cause and after cleaning no problems.
squeakkos
Explorer
Jun 04, 2013
did you downshift when you came to the hill? how many RPM were you running at.
FIRE_UP
Explorer
Jun 04, 2013
dshinnick wrote:
Hey all-

We have a 2005 Holiday Rambler with a Cummins ISC 330. On our way to Flagstaff AZ, at 7,000 feet, we began to experience some overheating. The water temp gauge spent quite awhile in the red zone. We unhooked our tow vehicle, which didn't seem to help a lot. When we were level or downhill the temp dropped, as would be expected, but on any climb at all, it headed back up into the red.

It was probably in the mid-80's outside, not terribly warm, and the road was what I'd call a moderate incline, certainly not excessively steep.

The coolant level seems normal, as well as the oil level. I had the coolant SCA level checked within the last 6 months and I was told that it was fine.

Interestingly, the OIL temperature seemed normal; the oil temp gauge stayed down where it normally is. It would seem if the engine is running hot then the oil temp would be up too, but it didn't seem to be.

Anyway, I'm planning on taking it in to a Cummins shop on Friday, but I thought I'd run it by the forum to see if y'all had similar experiences, or any thoughts.

Thanks!

Dave

Dave,
First off, is this the first time you've experienced this on this rig? Have you had it on long grades before, at about the same ambient temp and the same load? If so, how'd it act then? And, as Wolf and others have stated, if you haven't done so, get in there and look real close at the back side of the CAC and perimeter of the radiator to see if you have "fin clogging" due to oil residue/dirt/dust/debris etc.

I don't know about Cummins but the CAT engines have a blowby tube that unless is extended, it can cause oil mist to be transferred to those fins and the, the fan, like a giant vacuum cleaner, sucks up every particle of dust and debris from the road surface and deposits all of it on those oil/mist coated fins and what do you have, pretty soon a solid surface and no FINS!!

Now, not saying this is your problem but, it's a place to start. If you do have clogged fins, and it is that bad, it's going to take some serious time and effort to get them clean thoroughly. Not an easy job.
Scott
crasster
Explorer II
Jun 05, 2013
Make sure the radiator isn't clogged with anything. Also, consider the thermostat & water pump....

Is the radiator cooling fan getting up to the correct speed?
Executive45
Explorer III
Jun 05, 2013
Assuming you were on I-17..that's a long grueling climb..did you happen to notice where you kept your rpms? My bet is on a dirty radiator, but when you experience a heating problem, make sure you're not lugging that diesel. Shift to a lower gear if necessary to keep your rpms in the engine's comfort zone. Remember to hose off that radiator regularly. It's the dirt, oil and grime behind the radiator where you don't see it, that affects it's cooling capacity. Let us know what the techs say....Dennis
wolfe10
Explorer
Jun 05, 2013
FIRE UP wrote:

I don't know about Cummins but the CAT engines have a blowby tube that unless is extended, it can cause oil mist to be transferred to those fins and the, the fan, like a giant vacuum cleaner, sucks up every particle of dust and debris from the road surface and deposits all of it on those oil/mist coated fins and what do you have, pretty soon a solid surface and no FINS!!

ALL diesel engines of that vintage had blowby routed to atmosphere (open vents-- usually around 1"ID).

It is only more recent EPA mandates that have closed crankcase breather systems.
FIRE_UP
Explorer
Jun 05, 2013
wolfe10 wrote:
FIRE UP wrote:

I don't know about Cummins but the CAT engines have a blowby tube that unless is extended, it can cause oil mist to be transferred to those fins and the, the fan, like a giant vacuum cleaner, sucks up every particle of dust and debris from the road surface and deposits all of it on those oil/mist coated fins and what do you have, pretty soon a solid surface and no FINS!!

ALL diesel engines of that vintage had blowby routed to atmosphere (open vents-- usually around 1"ID).

It is only more recent EPA mandates that have closed crankcase breather systems.

Brett,
Yes Sir, I was pretty sure that all the bigger diesels all had blowby but, I was, and still am, unschooled on just how Cummins routes their blow by. I was only familiar with the CAT C-7 of my vintage.
Scott

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