Side or rear radiator diesel pusher

The electric fan clutch shuts the fan OFF when it is not needed saving fuel and horsepower on rear radiator coaches. It does not power the fans to run faster when sitting in traffic. Big trucks have this same feature but the clutch is air operated. Same thing though, even though the clutch locks up when the temp switch says it needs more cooling the fan can only run as fast as the engine is turning. Hydraulic fans can as fast or slow as is needed by the temp switch regardless of engine or coach speed.

avidude wrote:

moisheh wrote:
Ray Chez: You make some interesting comparisons but missed on the HP used. A rear rad usually runs constantly. No variable speed. Thus it is using HP all he time. A side rad only draws HP when the fan is running. And the fan speed is variable.

Not entirely true. This would be the case for older coaches. But starting around 2008 Cummins started using electric fan clutches on all their rear radiator models. ISB, ISC, & ISL. I have also seen some late Cat C7's with fan clutches.

Correct. But, I suspect that 80+% of rear radiator coaches have full time (bolted up) fans, not thermostatically controlled fans.

moisheh wrote:
Ray Chez: You make some interesting comparisons but missed on the HP used. A rear rad usually runs constantly. No variable speed. Thus it is using HP all he time. A side rad only draws HP when the fan is running. And the fan speed is variable.

Not entirely true. This would be the case for older coaches. But starting around 2008 Cummins started using electric fan clutches on all their rear radiator models. ISB, ISC, & ISL. I have also seen some late Cat C7's with fan clutches.

The reason side radiators seem to cool better is the hydraulic fans running regardless of the coach speed. Rear radiators depend on moving air. All radiators are sized for full load @ 85 degrees wet bulb. In traffic the only difference is more air induced across the radiator.

"CA Traveler".....If you read what I wrote and what you quoted....I discussed slow moving traffic where you lost some of the air flow.

We can argue this until everyone is blue in the face. Please show me a Cummins ISM or ISX with a rear radiator.

DSDP Don wrote:


On my well maintaine rear radiator Monaco, when it was a 105 degrees out and I was towing my 6K Silverado, I had to watch the temps, especially in slow moving traffic. There were times that I had to increase engine speed or take other measures to keep the temps down.

Interesting.

My 04 Endeavor 330 ISC rear radiator would run sustained 6% grades in 115 degrees with the engine at 205F and the tranny 170F. 28K rig + 4K toad. Metal to the metal and of course it down shifted as its not a rocket ship.

My 09 Scepter 400 ISL side radiator also runs sustained 6% grades in 115 degrees with the engine at 200F and the tranny 205F. 38K rig + 4K toad. Metal to the metal and of course it down shifted as its not a rocket ship.

Never a issue on the flats with either rig.

While I favor the side radiator here's a non favorable comparison.

My 04 Endeavor had stacked CAC and engine rear radiators. The tranny radiator was below the radiator and connected to the radiator output. The cab A/C radiator was in a compartment with a electric fan. Very easy to clean the radiators.

My 09 Sector has 3 layers of sandwiched radiators. From the inside - engine, CAC and then the cab A/C radiator plus the tranny radiator cover 80% of the CAC. This would be very difficult to clean and so far I haven't perhaps due drawing in clean and oil free air from the side. It will be very difficult to clean.

Side is preferred, but not a deal breaker.

et2 wrote:
LOL - I want one just because it's different. Can I get a new MH?

Ray Chez post made a lot of sense. The one poster who said the side gets fresh air, not from the engine area. Are you saying the air to cool is coming off the outside of the coach into the bay? Is this true? Can someone confirm. If so I would think that is a big advantage - cooler air.

Confirmed, as the air is drawn in from the outside. This also means a lot less dust and rocks on the radiator.

"RayChez".....I'm guessing that 75% of the diesels out there are rear radiator. My last coach was a rear radiator. They do a great job of cooling, or they wouldn't be in use, but there are more advantages to a side radiator than just changing belts.

On my well maintaine rear radiator Monaco, when it was a 105 degrees out and I was towing my 6K Silverado, I had to watch the temps, especially in slow moving traffic. There were times that I had to increase engine speed or take other measures to keep the temps down. My new side radiator coach is 5K heavier, dragging a tag and has a taller profile and just doesn't care if it's hot out. It cools substantially better.

Again, rear radiators are fine and are the majority of what's being used, but please show me a coach made in the last five years with an engine larger than an ISL that has a rear radiator. No matter how you slice it, the side radiator cools better, but just isn't needed on smaller coaches.