Straight talk from the TL tech team

High-Flyin' Ford

We recently purchased a 1999 Ford F-250HD with four-wheel drive (4WD), V-10 engine and automatic transmission. The truck is used about 10 percent of the time to tow a 30-foot fifth-wheel trailer. The back of the truck bed is so high that the trailer rides with the front higher than the back, and I have trouble with the back end dragging going in and out of gas stations, etc. Also, the front of the trailer sometimes hits the bed going over dips and uneven ground. My dealer wasn't very helpful. Do you have any suggestions?

DAVID SMITHERS

VIA THE INTERNET

There are several things you can do. If the trailer's leaf springs are located under the axles, you can have the springs remounted over the axles (see October TL, page 46, "Increasing Hitch Height"). This is a fairly straightforward job that many RV dealers do quite often. Another possibility is to install a special low utility body in place of the pickup bed. These are available through truck body dealers.

Ford recently came out with Technical Service Bulletin no. 98-17-2 that covers 1999 F-250HD and F-350 4WD models with this height problem. Ford will remove the 4WD rear-axle spacers and related parts, such as the rear shock absorbers and U-bolts, required for the conversion to twowheel drive (2WD) specs in the rear under warranty. The bulletin notes that the rear of the truck will tilt rearward when loaded and it is recommended that vehicles used for fifth-wheel towing be equipped with a heavy-service front and rear suspension package to minimize this condition.-K.E

Diesel Hard Starting

I'm at my wits' end trying to work with my diesel truck It's a 1988 Ford F-350 with the Navistar 7.3-liter diesel engine, with no turbocharger, either aftermarket or original. The engine is in very good condition, with about 130,000 miles on it, and runs great once it's started. And that's the problem, getting it started.

My dealer and I have been all through the truck. The glow plugs have been checked and are OK, the glow plug module has been updated to a new Ford electronic one, the fuel filter is clean and there's no fuel line restrictions, the fuel injection pump and timing check out OK. In other words, we've looked at all the things that might make it start hard.

If the temperature is below about 50 degrees F, I have to crank the truck a long, long time to get it started. And anything below about 40 degrees, I use the plug-in block heater to help it start. I need to take along an extension cord anytime I'm parking away from home overnight and make sure the truck is plugged in or it won't start. That's kind of a hassle. I have friends with later-model trucks that seem to start at the first crank of the key. Is there any magic solution to this problem? Anything else I can adjust or have checked over?

WALTER GREENE

PLATEAU FALLS, WYOMING

Your problem is fairly typical for those earlier nonturbocharged, indirect-injection (IDI) trucks, Walter, You've already done most of the things we'd suggest to help the starting, such as checking the glow plugs and the like, but there area few other points to have examined.

That new Ford electronic glow-plug timer is indeed an upgrade from the older mechanical counterpart, but you should still have it checked for proper operation. For example, if the glow plugs aren't switched on for a long enough time, they won't provide adequate heating to assist with that first ignition. Even though it's working-as in, the "WAIT TO START" light comes on, etc.-it may not be leaving the heating current on long enough. Have this checked by your Ford dealership.

Another step is to clean the glow plugs. When their tips get caked with carbon and gunk, it tends to insulate them, which allows for less heat transfer to the combustion chamber

Finally, one partial solution that's kind of costly is to install heads from a 1989 or later engine. Navistar redesigned the glow plug position such that cold starting using the glow plugs is more efficient.-JJ.

Huffin' at High Altitude

It has been suggested that I should consider having an auxiliary transmission installed on my 1997 Dodge Ram 1500 Club Cab to help overcome a loss of power in the high altitudes of Colorado. Even a gradual grade gave me loss-ofpower problems. The truck and trailer specs are as follows: 5.2-liter engine, 2WD, four-speed automatic transmission and a 3.55 rear end. The trailer is a 24footer, which has a gvwr of 4,700 pounds. Since my truck has a 12,500-pound gross combined weight rating (gcwr) and a maximum trailer weight of 8,100 pounds, I did not expect to have as much power loss as I do. I am having no problems with this combo anywhere except in high altitudes. I tow with the overdrive off and do not carry excessive weight. In your opinion, should I check further into an auxiliary transmission or trade my truck in for one with more muscle?

JOHN SMENNER

MANCHESTER, GEORGiA

The fact that you're satisfied with the way your Dodge runs, except at high altitudes, leads me to believe that there's nothing wrong with it. I suspect that, being from Georgia, you may not be experienced at high-altitude driving and what a profound effect it can have on vehicle performance. You didn't mention where you were in Colorado, but some of the roads are around 12,000 feet or more in elevation. Since naturally aspirated engines lose about three percent of their power per 1,000 feet of elevation, you're looking at a loss of over onethird of the engine's power at sea level.

Auxiliary transmissions don't add any power; in fact, they are most helpful in situations where the truck's original gearing isn't right, gear ratios are too far apart, or you need a ratio that's lower or higher than what's there. What they can do is allow you to operate the engine more effectively in higher rpm ranges, which result in more horsepower

Unless you intend to drive a lot at high altitudes,you probably don't need to do anything. For high altitudes, you may want to trade up for a 5.9-liter V-8, which is the same family of engines, or get a 5.9-liter turbodiesel, which won't be as affected by the altitude.-ICE

Refrigerator Relight

I have a 1993 Nomad with a Dometic two-way refrigerator, which works fine on electric. When I switch it to gas, it works until it gets cold and cuts off, then it won't relight. I can manually switch it off and then back on, and it lights just fine. I've had this rig in the shop three times and they say they can't find anything wrong. Thanks for any help you can give me.

GERALD DAWDY

VIA THE INTERNET

It seems like you may have a bad thermistor, Gerald. That's the temperature-sensing component inside the refrigerator compartment that tells the unit's electronics when to fire up the cooling system, and when to shut down. It could be telling the unit's "brain board" that there's enough cold, even once it turns off, and keeping it from cycling on again. Your manually-switching the fridge back on overrides the thermistor temporarily until the next cycle. Have your technician check the thermistor for proper operation.

Oddly enough, it could also be the thermocouple in the unit's burner Since it's tied to the thermistor's operation, a crack in the thermocouple tip could also be causing an open circuit once the unit cools down and the tip is heated by the burner The thermocouple would also be worth checking.

Finally, make sure all your apertures and lines are clean and soot-free, as per standard practice, and make sure you have 11 inches of water column (gas pressure) at the refrigerator supply point.-JJ.

Shiftless Suburban

I have a 1993 Chevrolet Suburban C2500 with the 7.4-liter engine, 4L80E automatic transmission and a 3.73:1 axle ratio. It's used to tow a 24foot travel trailer with a 5,000-pound gross vehicle weight rating (gvwr). The truck now has 140,000 miles on it; however, only about 20 percent of the mileage was towing the trailer The truck is well maintained, with the oil changed and lube done regularly; filters, hoses, etc., replaced regularly.

In August, at 125,000 miles, I took the truck about 500 miles (not towing). On the return trip the truck wouldn't shift into fourth gear. Upon arriving home, a local mechanic told me that the transmission was only using first and third gears. I took it to my Chevrolet dealer, who checked it out with a computer-monitored test drive. The dealer stated that the transmission was now shifting properly, but could go at any time. At 135,000 miles, I took a 200-mile trip, during which the transmission acted perfectly.

I had my mechanic drop the pan and drain the transmission fluid. He found the fluid color and odor normal and found no chips or deposits in the pan. He found nothing wrong.

I am loath to use the truck for long trips, or tow the trailer. Other than replacing the transmission for $2,000, is there any probable cause for the behavior of the transmission? How can it work correctly most of the time, and at other times become goofy?

WILLIAM STANLEY

CANADENIS, PENNSYLVANIA

Your dealer's statement that the transmission could go anytime can't be disputed; after all, any mechanical device can fail at any time. This is especially true of vehicles with fairly high miles. However, since the fluid looked good, the pan was clean and the problem comes and goes, I believe the gremlins are electrical in nature. Try replacing the electric shift solenoids and both speed sensors. The shift solenoids have been upgraded by the factory because of similar problems; be sure to get recent stock. These parts are relatively inexpensive and can be installed without removing the transmission.-K E

Refrigerator Smell

We need some serious help with our refrigerator It was accidentally switched off after departing our seasonal site and when we returned two weeks later, everything in the refrigerator and freezer had turned bad. The smell is awful, and we really don't want to air it out and expose the rest of the trailer to its odor

We'd like to find out if there's a product we can use to get rid of the smell, as the trailer is only two years old and replacing it is not an option we'd like to entertain. If you have any suggestions, we'd sure appreciate your help.

JEFF & ALBERTA BAUMGART

VIA THE INTERNET

Boy, that can be a nasty job! But there is a cure. First, buy some Aqua Chem toilet treatment, available at most RV service centers. Place cake pans on the ice-tray shelf and in the lower part of the fridge. Fill each pan with Aqua Chem, obviously not deep enough to spill. Close the doors and leave these in place for 48 hours. The time is important, if you don't give the chemical enough time to do its job, it won't work.

Next, remove the pans of chemical, and loosely fill the fridge and freezer with crumpled up newspaper Close the doors again, and leave them closed for 24 hours. In effect, the papers absorb the chemical odors. This process works well, and should leave the refrigerator as odor-free as it's going to get, under the circumstances. Good luck!-JJ.

Tranny Troubles

I pull a 32-foot fifth-wheel trailer that weighs about 8,000 pounds with a 1989 Ford F-250 with the 460 engine and 100,000 miles. I've had very good luck with the engine and large automatic transmission. My problem is that lately when I tow the trailer the transmission jumps from second to third gear and back down, etc. If I don't speed up or shift into second it will keep doing that. It does that at around 40 or 45 mph. At that speed I also hear a pulsating hum in the engine area. The problem doesn't seem to affect engine power I check the oil level hot and cold and it's always correct. This problem has only shown up when I'm towing or in the mountains.

ROBERT LETFORD

PINOLE, CALIFORNIA

I assume from your description that you have a Ford C-6 transmission, which is a heavy-duty three-speed unit. The pulsating hum is probably the clutch fan going into high-speed mode. The shift problem is likely to be the transmission's vacuum modulator just starting to fail. Remove the vacuum line that goes to the vacuum modulator and look for traces of transmission fluid inside it, which is a sure sign of failure. Modulators are inexpensive, can be changed rather easily and often No bad on high-mileage vehicles.-RF

Touchy Trailer Brakes

We have an almost-new lightweight trailer with an Al-Ko Kober rubber torsion axle and electric brakes. Our tow rig is an Astro minivan with a Tekonsha Voyager brake control that was installed by a professional RV service shop. We've had the brake-control wiring and its functions checked since our last trip, and everything seems to be in order. We have about 1,000 miles on the trailer, and the brake control and wiring are new enough that electrical connection corrosion should not be an issue.

During our last trip we had some strange braking reactions from the trailer After our usual start-up fiddling with the brake control to get the braking action to feel right, we drove about 400 miles with no problems, then were parked at a campground for two days. It rained real hard for part of that time, then dried up. No settings were changed on the brake controller during the time we were parked. When we left the campsite and were traveling about 20 mph on clean dry pavement, the first time we checked the trailer brakes by manually activating the brakes via the lever on the Tekonsha, the trailer brakes locked up solid. One wheel stayed locked up after the brake control lever was released. We backed up a few feet, and that seemed to release that locked brake.

Using the usual tow rig brakes, the trailer was really grabby and locked up a couple times again from low-speed stops in city traffic. We had to dial way back on the brake control gain to get the brakes to behave. Later, we manually tested the brakes again, and had to dial in more brake control gain to get the trailer to apply the right amount of brakes.

Is this something we should check in the trailer brakes, or does it seem like a brake control issue? The trailer brakes work great much of the time, after we've finished fiddling with the brake control gain settings.

MARK TANNERSON

HILL CITY, NEBRASKA

The changes in braking performance from first start-up through later in the day are something of a characteristic of your brake controller, Mark. Some adjustment may be necessary as the day wears on and you keep driving. However, the grabby brakes also relate to the brake adjustment. The brakes in your nearly-new trailer take a few miles to get broken in, or burnished, to specifically fit the shoes to the drums. Once this happens, and it can be in as short a distance as 200 miles if you've made a lot of stops, the brakes are kind of a loose fit and they should be adjusted to take up the slack again. With too much slack in the adjustment, the brakes can literally lock up because there's too much movement in the mechanism.

With the wheel off the ground, use a brake adjuster to snug down the shoes, then back them ofa bit to allow the wheel to turn freely. This should make the brakes perform smoother, without lockups.-J.J.

Noisy GM Automatic

I own a 1997 Chevrolet heavy-duty K2500, extended cab, shortbed with 7.4-liter engine, four-speed automatic transmission and 4.10 rear end. Since new there has been a ringing or whining noise coming from the transmission in first gear and also in reverse. As soon as the transmission shifts out of first, the noise is gone, and it seems to operate normally in all other forward gears. I've had the truck to several dealers, and some say the noise is normal due to first gear being straight cut to provide more power on the heavy-duty transmission. The noise became so loud that, at 5,000 miles, the dealer replaced the gear set.

The noise is still present but not quite as loud. I now have 7,600 miles on the truck To date I have not towed anything, but will be using it to tow a 9,000-pound fifth-wheel trailer, and I'm concerned that the transmission will not hold up as it should. Is this really a normal condition, or do I have a unique problem that needs to be corrected?

BILL GERMER

LITTLETON, COLORADO

The dealer who told you about the straight-cut gears was right. Light-duty models have angle-cut gears, which run much quieter, but use up more power and can't handle as much torque as the straight-cut gears. Some of the straight-cut gearsets are noisier than others, but they're all audible. If the current gears are quieter that's about all the dealer can do. If you didn't plan to tow anything heavy, you could switch to the lighter-duty trans if you can't stand the noise.-KE

Clutch Concern

I have a 1991 Dodge W-250 with a Cummins 5.9 diesel and five-speed transmission. After 150,000 miles, I decided to have the clutch replaced. My mechanic was unable to find a 13-inchdiameter clutch, due to a lot of back orders, so he put in a 12-inch unit. How much difference is there between the two? He has not been able to find out anything from his suppliers.

STEVE BROWN

VIA THE INTERNET

First, congratulations on how long your clutch lasted. It's always best to replace parts with ones that are at least equivalent to the originals. If at all possible, I would have taken the time and effort to find a 13inch clutch, just for peace of mind. You didn't mention what you tow, but based on how long your clutch lasted, you probably will be able to get by with the smaller clutch. I don't know what brand you used and, therefore, can't track down its torque rating. Since the clutch is already in there and clutches usually give some advanced warning when they're starting to fail by slipping, you might as well leave it in until you have problems.-KF TL

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