Two great presentations and many questions and answers highlighted our Whitney tech session,
FRED HUDSPETH said our GMC coaches are "TIMELESS
MACHINES" and reviewed the material published by General
Motors and delivered with our coaches which describe, in great
detail, how to keep them TIMELESS. The secret is MAINTENANCE,
MAINTENANCE, MAINTENANCE. Performed as recommended and at the
intervals suggested by GM. As Fred said, if you follow the recommended
maintenance schedule closely, you will have very few surprises
while you are on the road. If you don't have the Maintenance Pamphlet
and the Maintenance Manuals which came with your coach, they are
available from Cinnabar. (1 800 720 2227)
THANKS FOR A GREAT PRESENTATION, FRED.
BILL O'GRADY shared the information he learned
while rebuilding his dash air conditioning.
Bill opened the "box" which contains the evaporator
and the heater core. He cleaned everything and replaced the foam
seals on all the doors. He also replaced the expansion valve.
He cleaned and straightened the condenser fins and replaced the
heater's hot water valve. The drier and the freon hoses were replaced.
Don't expect new hoses to be clean. Flush with alcohol.
Bill researched compressors and found that several are available.
One has a 5" pulley and runs 17% faster than the others with
5 1/2' pulleys. However, the units with larger pulleys are heavy
duly and have larger clutches. He also learned that some compressors,
often with the same part number have metric threads.
Vacuum controls can be a problem.
Hoses deteriorate and need replacement.
The vacuum tank may have water in it. reducing its capacity.
Here are some part numbers and prices he found:
Freon, R-12 $15.00 -25.00 per lb.
Frigc-R406a and Freezone possible substitute for R-12. Never add
more than 1 pound to R-12 system. Cost: $6.81 per lb. Freon, R-134a
requires replacement of hoses, seals, fittings and must change
oil. Cost: $4.04 per lb.
Heater valve, vacuum operated. GMC 12515169, 3028767; Everco H
1991.
Blower motor: Stant 26102; 4-Seasons 35587; Everco M892 Cost $18.50
Compressor & clutch: 4 Seasons
THANKS, BILL!!
COMMENTS AND ANSWERS TO QUESTIONS FROM THE FLOOR
TIRE PRESSURE The pressure shown on the tire is maximum.
Weigh your coach if possible, then check manufacturers bulletins
for correct pressure. (50 -55 rear and 55 - 60 front is often
used by GMC owners)
MANIFOLD GASKETS / LEAKS Machine shop truing of manifold
surfaces is very desirable. If heads are off, truing of head exhaust
surface is recommended. Gaskets recommended: Buskirk sells a copper
gasket. Speed/performance shops sell a good gasket (Fel Pro 1439),
MondeIlo offers a good one. Zack Cartright makes gaskets from
a material called Graph-Oil
HEADERS "Probably offer one of the greatest gain~
per dollar spent"
MUFFLERS "Flo Master brand is recommended". Whatever
you buy, be sure the entire muffler is exhaust pipe size, not
just the connection. The objective is to minimize the sound while
maximizing the flow of exhaust gases.
3' TAIL PIPE (muffler to rear of coach) "Nice. but
may not offer much gain for the added cost"
Byron Maxwell, (your scribe) Reported this. Address all corrections, additions, complaints, etc. to him.
WYE (connects
mufflers to tail pipe). Some shop made pieces restrict gas flow.
Buy factory made part.
RIDE HEIGHT "Get it right" incorrect height adversely
affects driving characteristics. Adjust rear, then front, then
readjust rear. When adjusting front, use special tool to unload
torsion bar. Failure to unload the torsion bar can strip the bolt
threads, costing BIG dollars.
STEERING LINKAGE There should be virtually no "play"
in joints. Exception: tie rod should rotate slightly.
BALL JOINTS If replacing, do not drill. Grind the head,
then punch out old rivet. Consider buying a metric bolt slightly
larger and reaming bolt hole. Be sure bolt body is unthreaded
through ball and frame. After ball joints are replaced, re-torque
them several times. Perhaps each time you lube the chassis. They
tend to loosen.
ANTI FREEZE REPLACEMENT It is no longer necessary to replace
anti freeze each year or two. Suggested alternative, buy test
strips from parts houses, test both freeze protection and alkalinity.
Replace only when test strips indicate. Available at J C Whitney
and possibly from parts stores.
AIR FILTERS Slightly clogged filters dramatically increase
fuel consumption. Replace often. K&N brand washable filters
are performance shop products. Several members felt they were
exceptionally good.
SPARK PLUG REPLACEMENT This is a relatively low cost, fairly
easy maintenance activity, which pays great dividends in driving
performance and economy.
FREON SUBSTITUTE / REPLACEMENT Fred Hudspeth reported that
he has researched the thermodynamic properties of a new product
and finds it at least equal to R 12. The largest air conditioning
maintenance company in Tyler is using it as their first choice.
If you use it, do not mix it with R 12 and label your system.
Failure could be costly. The product is E 12 manufactured by Tech
Chemical Co. of Dallas. It requires 10% less than R 12 and costs
only about $4.00 per pound. Handling, purchase etc. is limited
to licensed technicians.
CRUISE CONTROL The "transducer" (the part to
which the speedometer cable connects) is the most frequent part
to fail. Replacements are available at most parts houses. It is
the same as those used on 1976 Oldsmobiles and other large GM
cars. Duane Simmons and Fred Hudspeth are using a new all electronic
unit named Rostra. It is fully electronic and has all the features
of controls found on more modem vehicles Cost: about $150.00 or
slightly more.
WHEEL BALANCING There is a new powder which is inserted
into the tire. It is said to balance the tire much like the Centramatic
units. Cost: $10.00 to $12.00 per wheel. Some feel that the best
way to balance our tires is to use the "old bubble balancer"
... if you can find one. It was reported that many shops Cannot
correctly balance our wheels (though they think they can). It
is suggested you let the shop balance a tire, take it off the
machine, roll it a turn or two, put it back on the machine. In
most cases, it is no longer balanced. Most machines cannot balance
our wheels. See the September, 1996 issue of Wes Coughlin's Motorhome
News for a very thorough discussion of the problem and a solution.
Marvin urges that we avoid having our front wheels spin balanced
on the coach. He says this procedure can cause severe damage to
the final drive.
TOWING THE COACH Several members have installed a bar below
the radiator as a substitute for the wooden blocks recommended
by the manufacturer. They reported favorable experience using
the permanently installed bar. One member indicate he is considering
offering a model for sale.
HOLDING TANK CHEMICALS Vick Ayres reported that Monsanto
Chemical is producing a new holding tank chemical which has no
formaldehyde and is septic lank friendly. It is said to be very
good at stopping holding tank odors without a great deal of odor
of it's own. Vick provided samples. It is called EnviroChem, comes
in pre-measured containers, and is available at RV supply stores.
NEXT TECH SESSION
At the last few rallies, we have held our tech session all day
on Friday, and left Saturday for working on coaches, being tourists,
visiting ... or what ever. Is this how you want it scheduled?
If not. please call or write Byron Maxwell and share your views.
Until we find a more popular schedule, we will continue this at
Eureka Springs:
Friday - 9:00 - 12:00 a.m, and 1:00 - 4:00 p.m.:
Gordon Dunlap will share some of his knowledge about fuel injection
systems.
LIKE TO CONDUCT A SEMINAR? WE NEED YOU. PLEASE LET BYRON MAXWELL
KNOW.
TRADE DAY (FLEA MARKET)
At recent rallies, we have run the flea market all day Friday.
Is this OK or would you like some other schedule? To give every
one an equal chance to buy please, don't start selling at the
market until 9:00 a.m. Friday
Byron Maxwell, (your scribe) reported this. Address all corrections, additions, complaints, etc. to him.