Bearing maintenance and lift

RV-CLINIC-BEARINGS

May 20, 2015
Filed under Trailer Q&A

We have a 2007 Keystone Montana with Dexter E-Z Lube axles that have approximately 40,000 miles on them. They’re greased with high-quality lubricant and regularly checked for metal fibers. The owner’s manual recommends yearly inspections of the bearings and seals. Is this really practiced by fifth-wheeler owners?
What is the proper procedure for lifting a fifth-wheel trailer?
Jim Chenowith, Deltaville, Virginia

As you noted, Jim, the owner’s manual calls for an annual bearing and seal inspection on axles equipped with E-Z Lube hubs. Even though you keep them well greased, it’s not a bad idea, and cheap insurance, to do an annual look-see to verify that all’s well with the bearings. This also gives you an opportunity to replace the seals, which can go bad and leak grease into the brake drum area. Some fifth-wheel owners don’t do the annual inspections, and they’re often called “tow-truck customers.”

If by lifting the trailer, you mean raising the tires off the ground for safe access to the hubs and such for wheel work, your owner’s manual will detail the procedure for your model. Lifting the trailer with a jack placed under the frame, not under an axle, and then adding a jack stand as a safety support must be done. Be sure the tires on the opposite side of the trailer are securely chocked so the unit can’t roll. — Jeff Johnston

 

Slideout and Storage

Is it better to store your trailer with the slide in or out?
Ray Barnett, Bronte, Texas

I’d leave the slideouts in, Ray. Among other things, it saves wear and tear on the support structure, and with the slideouts in, the seals should do a better job of keeping moisture out of the trailer’s interior. Apply a slideout seal treatment and mechanism lubricant before you put the unit away, and you should be in good shape. — J.J.

Measuring Tire Temperature

I have a tire-pressure monitoring system on my fifth-wheel trailer, and it also displays temperature. I’d like to know a safe operating temperature for a 205/75R14 tire. We have a future plan for a caravan that originates in Pahrump, Nevada, and we’ll travel there from northeast Pennsylvania.
David Witt, Long Pond, Pennsylvania

I can’t recommend a specific maximum tire temperature because that varies a great deal with ambient temperature, vehicle loading, vehicle speed and so on. In summer, with the pavement in the desert pushing 140 degrees Fahrenheit or more, the tires will naturally run hotter than a rainy day in Washington in the winter. The temperature-measuring feature of your TPMS is useful for comparing the relative temperatures of the tires. If three of them are running at 160 degrees and one is 195 degrees, that means something’s happening, like low air pressure, that’s causing that one tire to overheat, which can cause a failure. If you want to be absolutely sure, you can purchase an inexpensive handheld infrared thermometer, which will allow you to make frequent and highly accurate checks on tire pressure (including individual sidewall and tread temperatures), as well as wheel-bearing and brake-drum temperature and the like, so it’s a handy tool. In short, keep tires inflated to the recommended cold-inflation pressure, don’t overload them, and you won’t need to worry about overheating. — J.J.

Trailer brake anomaly

Until recently, every facet of my truck and trailer brake system worked, as it should. Although the trailer brakes work fine when I depress the brake pedal in my truck, I have found that the breakaway switch on the trailer does not activate the brakes. Also, the trailer brakes do not come on when I try applying the brakes manually by using the built-in switch on the truck console. Could these two problems be related, or do you think these are two separate problems?
W.F. Prim, Mobile, Alabama

You didn’t include any technical, make, model or age details about your tow vehicle and trailer, so that’s going to somewhat limit the scope of our answer.

First, the easy one, though it also relates to the other question. The breakaway switch is a simple on-off switch that activates when the plastic plug is pulled out. If it’s not causing the brakes to fully apply due to the direct 12-volt DC current that the switch routes to the brakes, it means the switch is bad, not connected to the battery, the battery is dead or the wiring is defective. Test the switch for electrical function and inspect all of the related wiring connections. Those switches are often out in the open and subject to moisture-related failure as they age. We don’t know the year of your trailer, so we can’t pin down age as a possible cause.

The manual lever will apply only the maximum voltage as set by the gain-control adjustment. Fully applying the manual brake lever, with the brake-control gain set at 100 percent, sends the truck’s full 12-volt DC power to the trailer’s brakes. You would definitely feel that effect when the trailer brakes slam on full power. This emergency braking voltage is carried by the same line that carries the brake-actuating voltage when you apply the truck brakes, and that activates the trailer brake controller. It’s unlikely but possible that your manual brake control lever is malfunctioning. Start by checking the voltage at the truck’s trailer plug receptacle. The lower-right connector, as you look into the receptacle, is the one to test. With the gain set at 100 percent of its adjustment range, have someone fully apply the manual lever while you observe the voltage reading with a multimeter.

If the voltage doesn’t spike to at least 12 volts, there’s something wrong with the system.

I suspect your gain setting may be too low. When the tow vehicle brakes are applied, some drivers have a tough time determining how much of the perceived braking force is the tow vehicle and how much is the trailer. If your gain is too low, you’ll feel braking, but it’s mostly coming from the truck. When you activate the manual brake control under the same circumstances, you won’t feel much trailer braking. Check your owner’s manual on brake-control adjustments, do the voltage test detailed above, and if in doubt, take the truck and trailer to a qualified RV service center for an examination and adjustment by a professional. — J.J.

Fifth-wheel hitch lifespan

Is there any information or guidelines as to the useful age of a fifth-wheel hitch? The one I use is 10 years old, and I keep it well lubricated. I currently pull a 38-foot Bighorn by Heartland. The loaded trailer weighed in at 13,800 pounds for our last trip. The hitch is a 20,000-pound-capacity Reese.
Bill Terrill, Cartersville, Georgia

Unlike some rubber parts, such as tires, that can decompose with age or ultraviolet exposure, there’s no set lifespan on a fifth-wheel hitch. You’ve kept it lubricated, and that’s more than half the battle for keeping a mechanism in good condition. There are wear points in the hitch that should be inspected now and then, so it wouldn’t hurt to pressure-wash all of the moving parts once in a while so you can get a good close look at the mechanism. Take the truck and hitch to an RV service center, if you aren’t comfortable performing this inspection yourself. This also gives you an excellent reason to repack all the parts with fresh grease, top to bottom, so the hitch can last another 10 years or more. — J.J.

Truck Heats Up on Grades

We are looking for input on a problem we have with our 2006 Chevy Silverado diesel Duramax. About four years ago, we were pulling a long grade on Highway 395 in California with a 28-foot fifth-wheel in tow, and the truck heated up to the red line. At that point, I babied it to the top of the hill. I could find nothing wrong, but it continues to heat on a hard pull even in cool weather. We have changed the transmission fluid to Allison synthetic oil, and changed both thermostats and the fan hub. I am also using the tow mode, which helps, but I must be very careful since it does not eliminate the problem. It continues to heat the motor and transmission to the red line. I just have to back off of it.

We have already been to the dealership, with no explanation forthcoming. I am considering replacing the radiator and installing an aluminum aftermarket unit, but this is a very expensive proposition.
Ken Peterson, Corning, California

Verify fan operation first. Although you changed the fan hub, do you hear the roar of the fan when it gets hot? The dash gauges are good quick-reference guides, but it might be useful to know what the actual temperature values are when these conditions occur, before spending a lot of money on parts.
Since you don’t report having a boil-over, it may not be getting quite as hot as it appears. This temperature information is available from the diagnostic port of the vehicle (OBD-II connector located near the driver’s left knee). Some inexpensive diagnostic tools are available that plug into this port and will display the numeric temperature value that the sensors are reporting. The reason that this information may be useful is that you can determine whether or not the temperatures really are as critical as indicated by the dash gauge.

With a 50/50 mix of antifreeze and water and a good pressure cap, coolant temperature is safe to at least 230 degrees. With synthetic transmission fluid, temperatures of 250 degrees are not too disconcerting. Synthetic oils typically can withstand temperatures of 300 degrees for at least short periods of time.

If you are able to confirm the temperatures and they reach levels that you are not comfortable with, a new radiator may be the best consideration. There is an internal transmission heat exchanger in the radiator as well, so if your problem involves both of these systems, it very well could be that this is where the problem resides.

Your Chevy Silverado is old enough that component age can become a factor. Have you checked to see if the radiator cooling fins are blocked by a long-term accumulation of bugs and other debris? Spraying it out from the back side to push the debris out forward may help. Depending on the quality of the water used in your radiator, it could simply be blocked with mineral deposits inside. Have a competent radiator shop do an inspection and try a commercial-grade cooling system back-flush before you do anything seriously expensive like replacing the radiator. — Ken Freund


 

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