Getting hot going over mountains

[jlc1988]

So far, our 1995 Southwind Storm Babs has been to TX and OK as well as a few trips to Albuquerque. She drives really well for her age and is a nice place to glamp in. Only issue I have is she starts getting hot going over mountains/hills. Never gets to the H but gets really close. On our last trip, I had to tow a Dodge Charger (on a trailer) and ambient temperatures were in the 90-100 F range. Once we got over a hill, she would cool down. We're about to got to SD for some bike event there. We'll be towing a small trailer with bikes on it.

Am I being paranoid about it getting hot? Is this normal RV behavior?

The engine is a 460 Ford V8 with TBI injection. The coach has 43K on it.

Thanks for the feedback!

[Kirk W]

32 minutes ago, jlc1988 said:

The engine is a 460 Ford V8 with TBI injection. The coach has 43K on it.

If you have not done so, I would have the radiator and cooling system flushed and fresh coolant installed using distilled water. Take a hard look at all of the radiator hoses and fan belts as well. That is very low mileage for an RV that is more than 20 years old. If you haven't done so, I'd also have the brake fluid flushed and replaced. 

[Optimistic Paranoid]

And I would add that you probably need to keep an eye on your transmission temperature, also.  If you really like the rig, and plan to keep it, I would add a separate transmission cooler, if you don't already have one. 

Personally, if it were my rig, I'd probably add an aftermarket oil cooler, too and temperature gauges for both the oil and the tranny.

The oil and tranny coolers will take some of the cooling load off the radiator.

[jlc1988]

10 minutes ago, Optimistic Paranoid said:

And I would add that you probably need to keep an eye on your transmission temperature, also.  If you really like the rig, and plan to keep it, I would add a separate transmission cooler, if you don't already have one. 

Personally, if it were my rig, I'd probably add an aftermarket oil cooler, too and temperature gauges for both the oil and the tranny.

The oil and tranny coolers will take some of the cooling load off the radiator.

It has a trans cooler and an oil cooler.

[The Quiet Assassin]

have you got an electric fan on the radiator?

If not think about adding one or even two depending on the shape of the radiator. Kits are available.

[DJohns]

Did you drop down a gear or just pull the hill in drive?

[FL-JOE]

If you are pulling the grades with good high rpms and not lugging the engine down it should not get close to overheating.  If the antifreeze is original then it is time to have it flushed and changed like someone else suggested.  

[trailertraveler]

15 hours ago, jlc1988 said:

On our last trip, I had to tow a Dodge Charger (on a trailer) and ambient temperatures were in the 90-100 F range.

Are you within your towing and Gross Combined Weight Ratings? If you have a Tow/Haul Mode were you using it? If you have a Transmission Fluid Temperature Gauge, what was it reading. With temperatures that hot it is not uncommon for the transmission fluid temp to get 90 degrees + hotter than the ambient air temperature when pulling a heavy load on steep grades. Have you checked the transmission fluid  level and color? 

[Lou Schneider]

I believe that vintage has a thermostatic fan clutch.  Under normal conditions the clutch is disengaged and the fan essentially freewheels.  When the engine temperature starts to rise, the clutch engages and you should hear a noticeable rise in the fan noise as it pulls more air through the radiator ... kind of like a jet engine taking off.

If this isn't happening, the fan clutch needs replacing.  

[Optimistic Paranoid]

It's been a while since I messed around with such things, but if I recall correctly, a fan isn't necessary at highway speeds.  If you're driving down the road at 50 mph, far more air is passing over the radiator than any fan can move.  Fans usually come on only in around town driving in stop-and-go traffic, or when idling.

[jlc1988]

1 hour ago, trailertraveler said:

Are you within your towing and Gross Combined Weight Ratings? If you have a Tow/Haul Mode were you using it? If you have a Transmission Fluid Temperature Gauge, what was it reading. With temperatures that hot it is not uncommon for the transmission fluid temp to get 90 degrees + hotter than the ambient air temperature when pulling a heavy load on steep grades. Have you checked the transmission fluid  level and color? 

Trans fluid level and color are good.

[jlc1988]

1 hour ago, trailertraveler said:

Are you within your towing and Gross Combined Weight Ratings? If you have a Tow/Haul Mode were you using it? If you have a Transmission Fluid Temperature Gauge, what was it reading. With temperatures that hot it is not uncommon for the transmission fluid temp to get 90 degrees + hotter than the ambient air temperature when pulling a heavy load on steep grades. Have you checked the transmission fluid  level and color? 

We did exceed the tow rating of the RV. 

 

[Lou Schneider]

30 minutes ago, Optimistic Paranoid said:

Fans usually come on only in around town driving in stop-and-go traffic, or when idling.

Or when the engine is working hard dragging the motorhome up a hill and the engine needs more cooling than the ambient air flowing through the radiator can supply,  i.e. when the engine temperature starts to climb.

Since the engine speed determines the fan speed when the clutch engages, you'll hear the fan roar when the clutch engages while the engine is running at speed like when you're climbing a hill.  Not so much when it's running more slowly while idling or running around town.

If you don't hear the fan roar when the engine temperature starts to rise, your fan clutch is not engaging.

[jpcoll01]

Agree with above, flush coolant system ($100ish) and make sure your fan is kicking on that is key when laboring up mountains at 30ish mph (if your rig is anything like mine towing a Jeep Wrangler).

[Ray,IN]

In addition to having the radiator/cooling system flushed and coolant recycled, gently clean the radiator fins of dirt and debris. If any fins are bent or mashed flat, use a fin comb to straighten them. I use air conditioner cleaner in a spray can (which is a heavy-duty detergent) then wash it out of the fins with a garden hose. DO NOT use a high-pressure washer!

[Bill w/bus]

Radiator cleaning, cooling system flush great ideas. 

Next look at your driving habits. Find you maximum speed in each gear.  When climbing  a hill and the speed drops to the max for the next lower gear downshift manually. You don't need to run at full throttle up the hill for most of them. If at a steady speed try lifting out a little on the throttle. If speed drops stop lifting. If the speed stays steady then  continue continue lifting until the speed does decrease. Now you know what amount of gas you need to flow to the engine to maintain speed up the hill. 

What i found most useful with a gas motorhome is a vacuum gauge for manifold pressure. Secondary ports open about 7-8"HG on carburetor engines and fuel enrichment at about the same manifold pressure for fuel injected engines. So the trick was to maintain about 8" HG manifold pressure and let the speed slowly decrease to the downshift point. Manually downshift to the next lower gear. in a 1989 Pace Arrow we were at about 20 MPH going eastbound on I 40 in North Carolina going up the big hill. Took a while but a long time while we trundled up the hill with all the trucks in the right lane. Unless the speed increases with increased throttle then all you are doing is wasting gas and adding heat.

 

Bill

[jimnina]

we had an older Southwind that the previous owner had installed an extra electric fan and a trans cooler. It came in handy when pulling hills up and down the East Coast. When the temp gauge came close to 3/4, before the 'RED' zone, I flipped the switch and the gauge crept back down to the mid point. Never did have it overheat on all the trips we took. It had a 454, 4bbl, 3 speed auto , and 61K miles.

We never toad anything, gas mileage was bad enough:)

 

[Jimalberta]

I agree with Bill w/bus. Get to know your drivetrain intimitely and how it behaves in all conditions. I like what he says about letting your speed drop Slowly and the fact that if you dont get more speed by adding throttle all you are doing is adding heat and wasting gas.

[Al F]

As other has written, in as many words:  Gear down and keep your RPM's up.  If, when going uphill, you can't easily accelerate a little you are lugging and overheating the engine/transmission.  You need to gear down until you can accelerator.  I don't mean to say you need to accelerate, you just want keep in the 3000-4000+ RPM range.

Also as others wrote.  A 20-25 year old radiator is most likely clogged up a bit or a lot.  May be so bad the radiator needs to be replaced.

[Fulltimer51]

Not that the gauge is all that accurate, even over loaded as you say, the temp was still within operational limits. Any vehicle under those conditions will get hot. The ideas mentioned appear to be things done from personal experience and should be considered very valuable. 

[jlc1988]

Great points made by all. With hills/mountains, I try to get a running start whenever possible. I haven't thought about easing off of the throttle a bit to get over a mountain pass. I'll try that. That makes sense to me because you are stoking a fire but not converting that heat into motion therefore creating more heat. 

She's gotten quite a workout so far. We've been through 5 states with her so far. Learning quite a bit about the lifestyle and how to keep the machinery alive.

[beemergary]

Wow  Lots of good info. Don't use good for nothing cruise. Don't lug or over rev. Just find the lowest rpm sweet spot where you can gain alittle speed. I have to run electric fans on my high perfornce street strip cars as a back up. " Biggest Lie" is calling anti freeze a coolant. Any engine will run cooler with water. Distilled water (non corrosive) and a lubricant for the water pump. Look and see if some deflectors can be made to direct more air to radiator. Good luck

[Barbaraok]

Beemergary,  not sure what you are angry about.  Obviously you don’t have a background in chemistry or you wouldn’t make a claim that distilled water is a better coolant that a 50/50 mixture of water and another molecule that lowers the freezing point and raises the boiling point of water.  Much better for any engine.   

 

[beemergary]

20 hours ago, Barbaraok said:

Beemergary,  not sure what you are angry about.  Obviously you don’t have a background in chemistry or you wouldn’t make a claim that distilled water is a better coolant that a 50/50 mixture of water and another molecule that lowers the freezing point and raises the boiling point of water.  Much better for any engine.   

 

Son has a 5 yr. engineer degree from Kettering University former GMI. Works in the heating and cooling division at Chrysler Engineering. Before that did an intership with a company that designs automotive heating and cooling radiators-condensors. Tests vehicles at Death Valley and over the continential divide for Chrysler. Didn't work for only a couple days at his intership and called his mother saying Dad was right about water cooling better than anti freeze. Your radiator cap will raise the boiling point. To be old and wise had to be dumb and stupid

[mptjelgin]

I've heard this claim before, and often the comparison is between pure water and pure (100%) anti-freeze.  I think that everyone agrees that 100% anti-freeze is a bad idea. But the recommended 50/50 mix of water and anti-freeze not only lowers the freezing point and raises the boiling point, but provides much needed anti-corrosion properties and (in diesel engine) cavitation protection. 

I don't know of a single engine manufacturer that recommends pure water in lieu of an anti-freeze mixture. Including Chrysler...