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Powertrain Q & A: Apr 2003

Originally Published in MotorHome Magazine

Q.  We’ve owned a 1981 Travelcraft for about 18 years, and it has
been a good motorhome. My brother-in-law leaves his coach plugged into
outside electric service during winter storage. By doing this, his
motorhome batteries are kept charged.
I never have done that, but am considering it. I do have the proper
plug (30 amps), a separate line to the main box (with 30-amp breaker)
with the correct wires (10/2 with ground). It will be stored for
approximately six months. Is this OK to do?

–Bob Griffon, Manchester, New Hampshire

A.  The converters (the on-board devices that supply the
battery-charging current) on older coaches and most newer ones do not
have “smart” circuitry that will switch to a “float” charging voltage
for storage. Many converters do not fully charge batteries because they
never provide more than 14 volts and rarely get higher than 13.5 volts,
which is typical float voltage. If you have no choice, it’s better to
leave it plugged in; however, since many converters don’t charge the
engine-starting battery, it may become discharged and sulfated, so it
eventually won’t hold a charge. The Statpower True Charge 40+ is the
only charger that provides true maintenance charging with a storage
mode. Some high-price inverters provide similar features.

Therefore, we recommend removing the batteries, storing them in a
garage or basement where temperatures aren’t too extreme, and keeping
them on a maintenance-type charger that is designed for storage.

Q.  I am referring to the letter “Stale Fuel Blues” in your
December 2002 column. The problem could be rust in the gas tank. I had
the same problem with my 1990 Bounder; I would go about 200 to 400 miles
and it would stop. I’d let it sit for five to 10 minutes, turn the key,
and off we’d go for 100 or so miles. It took me about two years to
convince Chevrolet that it was the gas tank. After dropping the tank and
cleaning it, my troubles were over. Maybe this will help Bob Masten and
others with this problem.

–Charlie Chambers, Avon Park, Florida

Q.  We have a 1982 Beaver motorhome that had a very similar
fuel problem about eight years ago. It was solved by dropping the fuel
tank and having it steam-cleaned. It sounds like a difficult job, but
with a floor jack, I can have mine down in an hour (drained first). Make
sure you replace all the rubber lines while the tank is down. This will
save you time and trouble later. Can you pass this on?

–Bob Bivins, Aptos, California

A.  Yes, but I must also mention that not everyone can
handle a motorhome gas tank, and of course there is considerable fire
danger when the tank is open. So be careful out there, and when in
doubt, consult a professional for help.

Q.  After reading the letter from Mike Morley (“Engine
Stalls,” January), concerning the stalling problems with his motorhome, I
recall a similar problem I experienced with my 1990 Winnebago
Superchief. My motorhome had a P-30 GM chassis. The problem occurred
during hot weather when the air conditioning was being used. Morley
didn’t say if he was using the air or not. Generally the engine would
stall while going down hill. My foot would be off the accelerator. There
was no indication that the engine was shut down, such as the CHECK
ENGINE light. If I tried to accelerate, there was no response from the
engine. I had to wait for a safe time and then put the transmission in
neutral and restart the engine.

I lived with this problem for two or three summers since I couldn’t
find anyone with a solution. I would raise the question with the GM
service departments and get different answers. Generally they would tell
me to bring the motorhome in to the shop when the problem was

Finally I happened to raise the question with a different service
technician, who asked if the air-conditioning compressor was GM or an
aftermarket compressor installed by the coach builder. My compressor was
not GM. The technician said if it was not a GM unit to check and see if
the computer input lead was connected to the compressor. He said when
the coach manufacturer adds its own compressor the company’s people can
forget to connect the computer input to the compressor. That turned out
to be my problem. Without this connection to the computer, the computer
doesn’t know that the air conditioning is turned on and doesn’t set the
proper idle speed. The result is engine stall whenever the compressor is
operating and the throttle is closed. Making this electrical connection
between the computer and the compressor solved the stalling problem.

–Bob Meeh, Columbus, New Jersey

A.  Thanks for taking the time to write, Bob. This is one of
those solutions that isn’t in the troubleshooting manuals, and it can
save owners a lot of time and money.

Q.  I need to comment on your item in the June 2002 issue
titled “Boiling Brave,” sent in by Jim Steward. I had a 1994 Itasca by
Winnebago and had the same problems for months before a mechanic in
Grand Junction, Colorado, found the problem. In 1994, Chevy changed the
design on the 454 engine. Unfortunately, the company apparently decided
to keep on using the old supply of thermostats and they did not fit the
new design. The thermostat taken out of my engine was about 2 to 21⁄2
inches long. When it tried to open, it bottomed out in the housing and
would only open about 1⁄4 inch. This allowed only a small amount of
water to circulate, which was cooled by the radiator; thus the electric
fan never came on, but the engine ran hot all the time.

I blew the head gaskets on my engine, and the Chevy dealer put back
the same kind of thermostat that it took out. When I had problems, a

call to customer service never got any help – but the savvy of a
good mechanic finally cured it. A standardlength thermostat was
installed and solved my problem.

–Allen Robinson, Pasadena, Texas

A.  Thanks for the note. We get a lot of letters about
overheating problems, and simple solutions are nice. When buying a
thermostat for a P-chassis with a 454-cid engine, have the dealer look
it up, using the vehicle identification number (VIN) to ensure that you
get the right one.

Q.  I have a 1998 American Eagle with identical problems as
those described by Wendel Siewert (“Cummins Cooldown,” November 2002).
From my experience, you solved his problem in your first paragraph.
After I had tried several remedies with no success, the radiator started
to leak. I removed the radiator and the problem was evident. After only
39,000 miles, the fins were restricted by crud and so rotten they
flaked away when rubbed with my finger. The radiator is installed
inboard of the oil cooler and intercooler. This makes proper cleaning
almost impossible. The crud was mostly between the intercooler and the
radiator. Although its deterioration was certainly premature,
replacement of the radiator was the fix.

Here are some additional tips that could be helpful to other
owners: I had a 3⁄8-inch pipe-thread plug vibrate out of the injector
pump, causing the loss of engine oil. I was very fortunate that I
discovered it before damage.

The Bosch dealer who supplied the correct plug said he had seen
this happen several times before. I now inspect the pump closely.

I had a leveling jack that started leaking. The dealer told me that
replacement was the only cure and would cost more than $900. I took it
to a hydraulic-cylinder rebuilder, who replaced the seals for $82 for a
total fix.

–Harold Woodard, Bradenton, Florida

Q.  I have a Bounder similar to Lance Reeves’ (“Fried Ford
Transmissions,” December 2002) except it’s a 30-footer with no slideout.
I have never lost a transmission as yet, knock on wood, but am
concerned with transmission temperature.

I have a temperature-sending unit in the pan and see the
temperature get up as high as 260-270 F on hot days and hard pulls. It
seems to level off at this point. I have yet to see any information on
what Ford or others say about exceeding transmission temp. I use
synthetic Amsoil, which I know has a higher temperature rating than
normal transmission oil, but what will the clutches, seals and gaskets



I installed a second cooler in series with the factory unit. This
was the recommendation of several transmission shops, which say they do
it all the time. They also say they sometimes disconnect the
transmission-oil cooler in the radiator, as it can work for you or
against you, but that you don’t need it on the West Coast. Is that true?

Hayden says to use a plate-and-finstyle auxiliary cooler for the
best cooling because you don’t want the fluid to move through too fast
or it won’t have the time for cooling. A fan mounted in front of the
auxiliary cooler seems to make no difference unless I’m in stopand- go
traffic. The temperature doesn’t seem to change much whether I’m towing
my Durango or not. Does that mean that this temperature is not abnormal?

–Walter Cornell, Riverside, California

A.  Wow, lots of questions! Even though synthetic fluid can
withstand higher temperatures than conventional fluid, it’s best to keep
the transmission-fluid temperature (as measured in the pan) below about
275 F for a brief peak and not higher than 250 F (in the pan) most of
the time. This protects the internal parts.

There have been cases in which coolers in series have caused too
much resistance to flow, which can starve the transmission of fluid and
damage it. Therefore, it’s important to avoid excessive restriction.

Regardless of “cooler” design, the fluid flows slowly enough to
exchange heat. The stock cooler in the radiator helps warm up fluid more
quickly in cold weather, which is helpful because a fluid temperature
that is too cold is not good either. Minimum operating temperatures
around 150 F are good. So at least keep it connected in the winter.

Electric auxiliary fans do the most good at low speeds and tend to
somewhat block airflow at high speeds. Therefore, select them mainly if
you have excessive temperatures at low speeds. If the temperature
doesn’t change much when towing, it probably means the converter is not
slipping more under its load.

Q.  I read “Cantankerous Cat” in the January issue. It sure
sounds like the problem we had with our Cat engine, although ours is a
3116, not the 3126. When hot, the engine would not start from the front,
but would start from the rear module. After a lot of headscratching and
studying the electric schematics, I found a relay switch in the rear
engine compartment that operates the fuel solenoid valve. This relay is
turned on and off from the front starter switch. The rear start is not
connected to this relay switch. I replaced the relay switch and it was
good for about 15,000 miles, and then acted up again, so I replaced the
relay again.

Now I carry a spare relay. The one I use is a common 30-amp Bosch
item. It costs around $5 at an auto-supply store. I don’t know if the
3126 has a fuel-solenoid valve like the 3116, but something has to turn
the fuel on and off. I hope this will help Tom Fitzgerald or anybody
else with this problem.

–Doug Stockman, Richmond, California

A.  Thanks for sharing your solution. It’s sure to help someone among our readers.

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