RV Tech Savvy: Roof Vent Restoration

 

Q:

Is there a product or method for restoring the appearance of my roof vent covers? Over the years from exposure to sun, rain, grime, birds and tree sap, they’re looking pretty nasty. I clean them frequently, but the residual spots only worsen.

Jim Moore | Huntington Beach, California

A:

Vent lids are easy to replace and, as long as you know the brand of vent, they can be found at most RV supply stores and Camping World. Check out the video on our YouTube channel that shows how simple replacing an old lid can be: https://youtu.be/-smmmvWSt5E. Airxcel — manfacturer of MaxxAir ventilation products — also offers the UniMaxx universal kit, which is designed to fit all roof vents.


 

Mystery Sound

I own a clean 2003 Winnebago Brave on a P-32 Workhorse chassis. I keep the motorhome well-maintained. Over the years I have made improvements and fixes to the autopark braking system and the overheating ignition-wire-harness issues, both of which are well-documented. In the spring of 2015 I noticed a fleeting raspy/scraping sound coming from the forward chassis. The sound only presents itself when the coach is rolling at about 35-40 mph, regardless of accelerating or braking, or while rounding a curve or while running straight. It lasts a second or two at a time, and will repeat several times at that speed. I have checked the fender-well shields, brake-dust shields, suspension, air bags, jack springs, etc., but still cannot identify the cause. A local mechanic rode with me and guessed it may be the EGR pump kicking in — but I don’t know much about that, and the noise can occur while going up a hill or especially when coasting at that speed, so it’s likely not vacuum related.

The mystery noise will not occur when the RV is parked and running at any rpm. This will be the third year I am driving the coach with this symptom, and I am concerned something will rear its ugly roadside head in the middle of nowhere. I have searched forums but have not been able to find anything solid for a fix. Can you please give me some specific ideas or things to check?

Joe Maniec | Bloomington, Indiana

A:

Without hearing this noise it’s very difficult to troubleshoot, but I do have some ideas. If the noise is more dash-related, the problem could be with the dash air-conditioning and ventilation system. The engine’s manifold vacuum is used to operate the servos for plenum doors, and owner complaints often center on the discharge airflow changing to defrost-air (the default position of the plenum door with a low vacuum). I’ve only heard of EGR pumps being used on turbodiesel engines to overcome the intake-manifold pressure during boost, and have not heard of such a system on a naturally aspirated gasoline engine such as yours. You might be hearing the noise from the air conditioner compressor clutch cycling. You can simply shut off the system and test drive the motorhome to see if the noise is still present. I suggest that you test drive with the interior engine cover removed and have a mechanic ride along to listen (with a mechanic’s stethoscope, if needed). Sometimes it helps to have assistants listen with their head out the window to determine if the noise is coming from the wheel-well area. I have seen motorhomes where gravel got trapped between the rotors and backing plates, and the resultant sounds varied and went away as the gravel wore down and fell out. I would also try shutting the engine off and coasting at that speed to see if the noise still exists, which would eliminate engine sources (keep in mind you’ll lose steering and braking assists, and should only do this on a wide, straight, level empty road in a safe area). As a reminder, readers can submit short videos (and photos) along with questions and comments to this column. A video with sound could help with my diagnosis. I’d also like to hear from any readers who have encountered a similar problem to this and found a solution.


 

Tow-Rating Change

I would like to increase the tow rating on a 2004 Fleetwood Southwind 32VS motorhome from the current 500-pound hitch and 5,000-pound tow ratings. Can this be achieved by replacing the current receiver with a heavier part? We would like to increase the hitch weight to about 700 pounds and the towing weight to around 8,000 pounds.
Charles Lupinek | Lafayette, Indiana

A:

Have a tech question?You’re probably not going to like my answer. The chassis manufacturer provides a gross vehicle weight rating (gvwr), which is the maximum weight that the fully loaded motorhome and chassis can weigh; and a gross combination weight rating (gcwr), which is the maximum weight that the fully loaded motorhome and chassis and any trailer or towed vehicle can weigh. These numbers are based on engineering designs and analysis and testing, and are limited by brakes, wheels, tires, cooling systems, springs, suspension components, chassis rails, engine and transmission capabilities, in addition to other factors. The  builder rates and certifies the finished motorhome to have certain tow- and hitch-weight ratings. While there are higher rated receivers on the market, weight limitations are dependent on chassis structure and capabilities, mounting positions and leverage applied to the rear of the frame. Hence, the ratings are set by the manufacturers, and they cannot be arbitrarily raised without extensive testing and recertification, which is not practical.


 

Tire Cupping

In the March “Tire Cupping” letter, a reader discussed his concern about cupping at a very low mileage. I had a similar occurrence with my 2004 Newmar Dutch Star motorhome with severe front-tire cupping at approximately 50,000 miles. After replacing the Michelin tires, I took the coach to a truck repair shop for an alignment. It found that the front tires were in alignment; however, the rear axle was discovered to be slightly out of alignment, causing the coach to “crab” going down the road. They attributed the cupping to the rear-end misalignment, and stated this is not an uncommon occurrence. I’ve put 63,000 miles on the coach since then, and have not had the same problem arise.

Kurtis Kindschi | Merrimac, Wisconsin

A:

Thanks for sharing your tip based on your experience, Kurt. It’s easy to overlook rear-axle alignment, but it, too, can have an effect on tire wear and handling. The most common source of rear-axle misalignment with solid axles (non-independent suspension) on heavy vehicles is one (or both) broken leaf spring center bolt, which locate the axle to the springs. This allows the axle to shift location on the spring’s main leaf.


 

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