Technical Inquiries: December 2003

Note Of Thanks

Now that we have safely returned from a five-week trip to the Midwest, we want to thank the 25 to 30 FMCA members who cared enough to call, write, or e-mail in response to my plea for help in a letter published in the May 2003 issue (“More Stalling And Surging,” page 28).

The majority of those who responded recommended replacing the fuel pump in the gas tank, which we did. The result was smooth-as-silk performance this year in all conditions and temperatures, including getting stuck in traffic more than once. In addition, as predicted by some who responded, the engine had more pep, and gas mileage increased from 7.7 mpg last year to 8.1 mpg this year (towing a car). Not only that, but the Ford folks sent a check reimbursing us for approximately two-thirds of the expense of replacing the fuel pump.

We are most grateful to all who responded. The whole experience has made our membership in FMCA more than worthwhile.

Dan & Amy Reid, F262040
North Wales, Pennsylvania

A: Glad you’re happily on the road again.
“” J.B.

This is in response to Daniel Reid’s letter in the May 2003 issue (“More Stalling And Surging,” page 28) regarding his experience with the Ford 460 engine in his motorhome. We had the same trouble with our Newmar Mountain Aire with a Ford 460 engine this winter. The motorhome is eight years old and at the time had approximately 45,000 miles on it. As we pulled into a campground in Louisiana, we heard a noise that we thought sounded like a stone that was kicked up by our tire and hit the Jeep. Upon inspection, there was no damage to the Jeep. This happened again in Mississippi while traveling at low speeds.

Then, in Florida, as we slowed down to stop at a rest area, we heard the noise again, only this time it was much louder. When we tried to leave the rest area, the engine backfired and would not idle. When we got the rpm up to 1,500 (with difficulty), we could keep the engine running. We limped back to Interstate 75, and as soon as we got up to speed, the engine purred. From the interstate we limped to a gas station to top off and continued on to our next stop without a bit of trouble.

We again experienced the same type of trouble when slowing down to cross the bridge to Key Largo. Three weeks later we topped the gas tank off and headed north without any problems until we approached a “parking lot” on Interstate 95 near Delray Beach late on a Sunday afternoon. We leapfrogged from the center lane to the exit ramp to get off the highway. Fortunately, there was a large Ford dealership at that exit, and they were kind enough to allow us to stay in their parking lot that evening. The next morning the Ford technician ran every type of diagnostic engine test and vacuum gas line test, and all was normal. Also, the “check engine” light did not indicate any problem, and the engine would not act up. We left there after paying a sizable bill, filled up at the next station, and continued on without a bit of trouble.

Our next stop was at an independent garage located in Palm Bay where the mechanic drove our unit several miles, and again the engine ran perfectly. To say the least, we were baffled, as was the mechanic. Farther up the road near West Melbourne, a Ford service rep referred us to a nearby RV sales and service center. The technician there performed all the necessary tests, checked the in-line gas filter (it was relatively clean), and drove the motorhome, again without a problem. His suggestion, by process of elimination, was that our problem was being caused by one of two things: a faulty gas cap or a dirty filter in the fuel tank. He also suggested that we start using a fuel injector cleaner product in the gas.

Our next stop was at a Ford parts department where we purchased a $16 gas cap. (We drove until we were down to a quarter-tank of fuel before refueling just to check whether the problem was still there.) After replacing the gas cap, we have driven more than 3,000 miles without any major problems. We must add, however, that we are still having some minor backfiring at idle speed only. We’re hopeful that this will clear up with the recent addition of fuel injector cleaner additive.

George & Sondra Davis, F235559
Grand Rapids, Michigan

Q: I own a 1989 Foretravel powered by a 300-horsepower Caterpillar 3208T engine. A previous owner added a pre-oil system to the coach. The system is supposed to pump up the oil pressure to the point where the dash light goes off, which indicates adequate pressure prior to starting the engine. However, this only happens for a short time after an oil change. At other times, the system’s pump runs but does not cause the dash light to go out before the engine is started. Is it possible that oil is being distributed throughout the engine when the pump is running even though the dash oil light remains illuminated? The system uses a separate filter, which a Fram PH8A seems to fit.

According to the Caterpillar manual, the engine should take 20 quarts of oil. The oil dipstick is, according to a technician at FABCO of Wausau, Wisconsin, a Caterpillar service center, the wrong dipstick for the engine. An old invoice for an oil change that I found in the coach indicated 22 quarts of oil were added, which would make sense, because the pre-oil system must have increased the capacity. But when I add 22 quarts of oil, the engine oil pressure runs very high.

I have contacted Caterpillar and was promised that a technician would look into the system. I have taken the coach to FABCO, Foretravel of Texas, and three other diesel repair shops, and no one can tell me how the system operates. The electric pump for the system contains a tag on which is printed HYL5004, 15VDC, DIAC108. The system is activated by a switch mounted on the steering column. I would like to obtain an instruction book for the system or the name and address of someone who could describe the operation of the system.

Robert Klein, F248729
Stevens Point, Wisconsin

A: A representative at Caterpillar informed me that prelube systems generally are gravity-fed, but since this system has an electrical switch it is possible that some oil pressure is developed from the oil system to the engine, but it would be nominal.

Pat Massart, FABCO operations manager, shared the following comments about your letter:

“I investigated the prelube system on your 1989 Foretravel. The chassis was built by a manufacturer in Wisconsin called Oshkosh Truck. Caterpillar supplies engines to Oshkosh Truck and your engine was one of them. The engine supplied to Oshkosh did not have a prelube system on it. Also, Foretravel stated that they do not put on prelube systems. The 3208 did not require a prelube system. If the system is not working correctly, we will need more information as we are not sure who manufactured the system you have. Perhaps the previous owner felt it necessary to have the prelube system to protect the vehicle in long storage conditions.

“The sump capacity for oil in this engine is five gallons with a filter change, and 4.5 gallons without a filter change. You were also told by the FABCO Wausau service department that you have the incorrect oil level gauge. I looked at the parts supplied by Caterpillar, and it is confusing as to which part is used. If you look at your oil level gauge, it should be stamped with the Caterpillar part number 9N6648.”

One thing you might want to do is to check the pressure switch that turns off your dash light, as it may not be working. This can be verified by having a mechanical gauge installed in the oil line adjacent to the pressure switch. A mechanical gauge will indicate the true oil pressure. One more thing: the prelube system is nice to have in order to pump oil throughout the engine following a long winter’s storage, but it is not critical or necessary for this engine and could be removed.
“” J.B.

Q: I was very interested in the information about the ice makers in the March 2003 issue of Family Motor Coaching (“Understanding Your Ice Maker,” page 68). We have a Dometic side-by-side in a 2000 Bounder. The ice maker works fine, but we can’t find out why water from the ice maker runs down the back of the freezer and freezes. We have tried several things, but nothing helps. We have to defrost more often as the ice container gets pushed out away from the back wall and the cubes fall behind it.

Dick LePage, F276379
Las Vegas, Nevada

A: Water for the ice maker mold flows up the back of the refrigerator through a 1/4-inch inside diameter (ID) tube, connected to a larger “fill tube” (probably a 1/2-inch ID). The fill tube is sloped downward slightly where it gravity feeds into an open top rectangular chute (called the fill bearing) that then funnels the water into the open top ice mold.

This provides two opportunities for the water to partially miss the mold. If a lot of frost or ice is present at the end of the fill tube or at the discharge of the fill chute, some of the water can be diverted to overflow the chute and run down the back of the inside of the freezing compartment. The remedy for this condition is relentless defrosting to be sure all the ice and frost are gone from the very back of the ice maker mechanism. Many people pay attention only to the frost that is visible, but attention to the very back where the fill chute is located would cure this problem.

Another possibility is that the ice maker mold is not level, either because of its installation in the refrigerator or because the refrigerator is out of level. This sloping would allow the water to simply run out the back of the mold and down the back of the freezer. Your problem might be compounded by the water fill adjustment allowing too much water to flow into the mold. Adjusting this is simple; the control can be found behind the white square cover on the face of the mechanism.
“” B.H.