Hot Cab Question

Hot cab, Tech Q&A

Ken Freund
September 27, 2016
Filed under Resources, RV Tech Q&A


I own a 2007 Four Winds Chateau built on a Ford E-450 chassis with a V-10 gas engine. I experience a large amount of heat from the doghouse around the engine compartment and the floor directly behind it between the front seats. Is there any way to insulate the compartment or divert the heat? I can’t rest my leg against the housing without burning it. I have created a double-insulated floor pad between the seats to rest a cooler on. Ford and my RV dealer have no ideas. Can you help?
Jerry Sheets | Port Orange, Florida

ANSWER: This is a common problem with these chassis. What you need to do is insulate the floor and doghouse areas with a heat-shield product such as one by Thermo-Tec Automotive Products (800-274-8437, Thermo-Tec makes a host of quality products that can be ordered through its dealer network. I suggest you consider insulation under the carpet and doghouse, and also shielding to block the radiation of heat from the exhaust under the cab floor.

Rough-riding Ford Chassis

I am considering a set of Sumo Springs to dampen the rough ride when going over bad roads in my 2000 Coachmen Mirada 28-foot Class A motorhome on a Ford F-53 chassis. I contacted a company online and they did not recommend I install these to improve the ride unless my motorhome was close to being fully loaded every time it was used. The tech said that the ride would become rougher, as the overall spring rate would be increased. In his opinion, the best ride improvements would come from high-end shock absorbers with air suspension. He also recommended a thorough inspection of the factory suspension components, as these vehicles are hard on bushings and steering components (which I plan to have serviced as well).

I have done a lot of research on internet RV forums about F53 ride improvements and there are many different opinions out there. The majority of reviews for the Sumo Springs were positive, with one or two stating that it did not improve the ride, or that they actually made it rougher. I do not have the sway or body-roll issue; mine is more of a rough ride on bad highways (banging, jarring, etc.). I am checking with you to get your opinion on whether they might help to cushion some of the rough ride.

Mike Herman | Austin, Minnesota

ANSWER: Basically, you are riding on a medium-duty truck chassis, and the combination of stiff high-pressure truck-type tires and high spring rates along with fairly limited suspension travel set the stage for a pretty hard ride. MotorHome magazine evaluations have resulted in positive reviews for Sumo Springs, but some owners find they are more of a help if your suspension is bottoming out, rather than just having a hard ride.

First, I would make sure that the tires are properly inflated for the loads they are carrying (best measured on individual wheel scales), not simply inflated to the pressure printed on the sidewalls. Your tires may be somewhat overinflated and thus, somewhat stiffer than they need to be.

I spoke with Eric Davis, owner of Eric’s RV Performance Center (800-488-3697,, as he has worked extensively on the development of chassis-improvement products for the F-53 chassis. Davis recommends checking tire pressures first, and then upgrading the shocks. Then, if you still want more improvement, consider either the Kelderman or MORryde suspension kits, along with front and rear trac bars. Later models built on the F-53 chassis came with Bilstein shock absorbers as original equipment.

Refrigerator Rebuild

I am a full-timer who owns a 2002 Fleetwood Discovery motorhome. I plan to try to sell it within the next 18 months. From what I have read, absorption refrigerators have a lifespan of 10 to 12 years, thus I am living on borrowed time with my Norcold four-door fridge. I’ve heard that it can cost between $3,000-$4,000 to put a new refrigerator in. I have read about rebuild kits, and have seen them online for $600-$900. Do you have any opinion about using these rebuild kits? Given that I plan on getting rid of the motorhome, the thought of spending that much money replacing the refrigerator is not appealing to me.

Rick Cramer | Box Elder, South Dakota

ANSWER: When you start reading some of the online forums about absorption fridges, you’d think the world was coming to an end. There really is no definite lifespan for these refrigerators, and what happens to one person does not automatically equate to others. If I had a failure that could be fixed with a rebuild (which amounts to replacing the cooling unit) rather than replacing the whole refrigerator at a greater expense, I’d do it. I believe in being thrifty and not spending money unless you need to. Therefore, I’d wait until you start having problems with the refrigerator before making repairs. As the old saying goes, if it ain’t broke, don’t fix it!

Dodge Doesn’t RegisterHave a tech question?

I own a 1979 Pace Arrow motorhome on a Dodge chassis powered by a 440-horsepower V-8 engine. The coolant-temperature gauge doesn’t move, and stays on cold even after hours of driving. What needs to be done?

Doug Saint | Greenwood, British Columbia, Canada

ANSWER: Even if the coolant thermostat is fully stuck open, the temperature gauge should register something after driving for a while. Still, just to be sure, start by checking how hot the upper radiator hose gets after driving long enough that the engine is fully warmed up, say, 15 minutes. Shut the engine off and try touching the upper hose that goes between the radiator and top of the engine (thermostat housing). If this hose is too hot to hold your hand against, the engine is warmed up and the gauge should be pointing somewhere to the middle of the range.

Next, check the gauge circuit. Power comes from the fuse panel via the ignition switch to the instrument cluster. Check the fuses, and then check that the wire going to the coolant-temperature sending unit on the engine is properly connected to the sender. If it is clean and connected, try touching the wire’s terminal to a good ground connection. With the ignition on (engine not running), the gauge should make a full sweep when it is grounded and released from ground. If it still doesn’t move, it’s time to remove the gauge cluster and start checking the gauge and its wiring. Check for power at one terminal of the gauge, and continuity from the other terminal to the sending unit. If you have both, the gauge has probably gone bad.

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