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Powertrain Q & A: Nov 2003

Originally Published in MotorHome Magazine

Q.  We have a 34-foot 1984 Fleetwood Southwind, which has been a
great motorhome. I don’t want to ruin it while it is sitting in a
storage lot. The coach has been stored for the first time in years, and
it may be two to three years before I will be driving it at all. I have
drained all the water tanks, water heater included, put antifreeze in
them, etc. But what about the oil and the grease? How often should it be
run, stirring up the oil and so forth? What would you suggest is the
best way to preserve it?

–Falcon Gayton, Erie, Colorado

A.  There are a lot of things that should be done to the
motorhome before it is stored, especially for this long. The oil and
filter should have been changed because used, dirty oil will leave
sludge in the engine, and the acids in the oil can eat away at bearing
surfaces and other susceptible parts. All chassis grease fittings should
be lubed. The cooling system should also have been flushed and new
antifreeze installed. Brake fluid should be flushed, new fluid added and
the air bled out. Batteries should be removed and stored in a garage.
Use a maintenance (not a trickle) charger designed with a float-charge
mode for storage.

Usually we recommend that the fuel tank be filled up, so there’s
little air above it to form condensation, and fuel storage additives,
such as Sta-Bil, be added. However, even with additives, three years
will probably be too long for the gasoline. Therefore, I’d suggest
completely draining the fuel tank and using the gas in your car. Pour a
couple cans of dry gas into the tank to help absorb moisture.

There are other procedures that are covered in The RV Handbook, by
Bill Estes, for the tires, interior and coach systems; call (800)
234-3450 to order. Please also read the next letter, which refers to
caveats of taking the coach out of storage.

Your suggestions to Lyle Spencer (“Coming Out of Storage,” June)
were right on target. As an RV mechanic, I would like to add that a
gasoline engine that had not run for about 3-1/2 years must also be
checked for contamination from engine coolant.

Coolant could have seeped into a cylinder, which would cause the
engine to hydro-lock when cranked over. I would pull the spark plugs,
look at their condition and squirt a little motor oil into each
cylinder. Then, with the plugs still out, use short bursts of the
starter to crank the engine over while observing that nothing comes out
of the spark-plug holes but the oil that was pumped in.

A compression test at this time would also be in order. Pre-lubing
the cylinder walls and pistons would be very beneficial, and the
carburetor should be primed at the same time. (It’s highly possible the
carburetor float may stick and flood the engine.)

–Ray Hobbs, Hobbs RV, Kokomo, Indiana

Q.  Your June issue had a letter (“Vexing Vibration,” from
Greg Rozman),which described exactly the same problem I had with my 1999
motorhome. The vibration seemed hard to isolate, but felt to me like
flat spots on both front tires. After weeks and months, the Ford service
people put in new wheel bearings, but it was no cure.

Finally a factory representative told me there was a letter out
saying to replace both front wheels and tires. Apparently, the wheel
manufacturer made a batch of out-of-round wheels that were not a perfect
fit to the hub. As a result, every time the wheel rotated, it would
shift just enough to create the vibration. I hope this helps.

–Jim Nielsen, Via the Internet

A.  Yes, there were quite a few Ford F-53 chassis with
defective wheels, which would cause a vibration in the front end. I
suspect that most of the wheels on the affected vehicles have been
replaced, but there are sure to be some still out there, so readers with
this problem should check with their dealers regarding wheel

Q.  We have a 1987 Gulf Stream Sunsport powered by a GM 454- cid engine with 30,000 miles on it. I recently replaced the starter.

After a short while, the new starter began to make a terrible
noise. I put in some shims, but that did not solve the problem. So, I
bought another starter, but before I put it in, I noticed a broken tooth
on the flywheel- ring gear. I can only see a little of the gear, so I
am uncertain if there are any other broken teeth.

If there is only one broken tooth, will the new starter be OK or
does the flywheel-ring gear have to be replaced? Is this a big job?

–Alan T. Consoletti, Bellingham, Massachusetts

A.  You didn’t mention why you replaced the first starter or
if you removed the shims. Shims should be used only if the teeth are
too close and binding, which is evidently not the case. If you add shims
that aren’t needed, it may cause the gears to only partially engage and
skip, which will ruin more teeth.

The crankshaft can be turned to view all of the teeth, but even one
broken tooth is one too many and will require that the flex plate
(that’s what the flywheel is called when you have an automatic
transmission because the torque converter serves as the mass instead) be

In order to replace the flex plate, the transmission needs to be
unbolted and slid back far enough to remove the torque converter. Then
the flex plate can be replaced. This is a heavy job that should be done
by an experienced mechanic. Have the transmission fluid and filter
changed at the same time.


Q.  While reading Rick Cochran’s comments about Ford V-10
air-conditioning (“Dash or Roof Air?,” August), I was reminded of my
experience with my 2001 Winnebago Adventurer. I had very little
air-conditioning at first. The problem was traced to inadequate vacuum
capability to allow it to work properly. The addition of a second vacuum
chamber solved the problem, and I have had no trouble since. This
information might be of interest to others.

–Hank Kerr, Lincoln, Illinois

A.  Lack of vacuum causes the air conditioning to come out
of the defroster vents rather than the dash vents. That is because the
ventilation systems are designed to default to the defrost mode, to
maintain driver visibility if there is a vacuum failure. It does not
reduce the cooling capacity of the system (although it might feel like
it) because the cool air would blow on the windshield, rather than
directly on the occupants.

Q.  We are buying a new motorhome and would like to tow our
2002 TrailBlazer behind it, which I know we can do. Someone informed me
that the mileage would accumulate on it while it is being towed. If so,
is there a way to stop this from happening? I’m a new subscriber, so I
don’t know if you have covered this in a previous issue.

–Richard A. Montgomery, Via the Internet

A.  If the ignition is off, the additional towing mileage
should not register on your vehicle’s odometer. That’s because newer
vehicles no longer use a mechanical cable to drive the speedometer.
Instead they use an electronic vehicle speed sensor, which requires that
the ignition switch be on for it to be activated. This is true with all
current model-year vehicles.

Q.  I had a similar problem (as the one described in “Speedy
Speedometer,” August) caused by an alternator. Apparently it was
putting out electrical spikes under load, which the speedometer took as
digital signals.

–Billy J. Woodfin, Full-timer on the road

A.  Thanks for the tip, Billy. A quick way to test for this
(without using an oscilloscope) is to temporarily disconnect the
electrical connector on the alternator (when the engine is off) and wrap
the terminal with electrical tape to prevent it from shorting out. Then
briefly test-drive the coach (you’ll be running only off the battery,
so don’t go far). If the problem goes away, have some electrical noise
filters installed. These are available from shops that sell two-way
radio equipment and ham radio supplies. There are special capacitors
that go on the alternator to reduce spikes and electrical “noise.”

Q.  How common is the “no start” on the Chevy 454-cid engine
when it is shut off after it has been run awhile? I experience this
often and have to wait 20-30 minutes before the starter will engage. Is
there a fix?

–William Gokey, Via the Internet

A.  This is an age-old problem that used to be quite common,
especially on the pre-Vortec Chevrolet gasoline engines. I’ve written
about it several times (including a full-length article titled “Getting
Started,” July 1997). There are various causes, but the most frequent is
the starter itself. To order a copy of my article, which includes
troubleshooting information and some solutions, call (805) 667-4341.

Q.  We have a 1977 Winnebago with a Dodge 440-3 V-8 engine.
The engine had 20,000 miles on it since a major overhaul, at which point
it used one quart of oil per 1,000 miles, and it had 60 psi of oil
pressure. It also incorporated two oil-sending units: one for a gauge
and one for a light.

When I started it in Texas, there was no oil pressure and the light
was on. After it was towed to a garage, the mechanic connected a gauge

directly to the engine and the gauge read normal. The same thing
happened soon after when I started it, but when I waited 30 minutes,
everything worked OK. At Denton, Texas, a valve broke, went through a
piston and scrambled the engine.

Was the lack of oil pressure a warning, and would that have caused
the disaster at Denton? What would cause the oil pressure to show zero

and then show normal? At the time the engine blew I didn’t notice if the gauge was working or not.

–Otis Beggs, Isanti, Minnesota

A.  You didn’t mention if the engine knocked or clattered.
Typically when the engine loses oil pressure, you’ll begin to hear
clatter from the hydraulic valve lifters as they begin to collapse,
before the bearings begin knocking. If an engine is significantly low on
oil, it can lose pressure, and then when all the oil drains down from
the top end, it can have pressure again when it’s restarted. Another
possibility is an intermittently sticking oil pressure relief valve.

Usually, when a valve breaks off and collides with a piston, it’s
caused by excessive heat in the cylinder, a weak spring, a failed
retainer and/or over revving. If the bearings and camshaft were still in
good condition, oil pressure was probably not the cause. There’s no way
for me to be sure that the oil-pressure problem caused the failure;
however, that’s an awfully big coincidence. The engine should have been
carefully disassembled to determine the cause.

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