Classic K, Coolant Change
PLUS Heat insulation under the tank,
etc.
(All the fun details!)
© Copyright, 2011, R. Fleischer
K bike section, #13
k-coolant.htm
NOTE
1:
BMW began manufacture of the 1993 K bikes in
early 1992, which was unusual for BMW, as normally BMW begins the
next calendar year production right after the annual holiday of
August. 1992 production of 1993 model year K bikes
had a Bosch 400 watt alternator. Late in 1992, BMW began
shipping the 1993 models with 700 watt Bosch alternators.
If you are planning on installing the larger 700
watt alternator, which became a stock item from approximately the
end of 1992, at coolant change is a good time, as
you will want to
install the later overflow tank and new longer hose to it.
The later overflow tank has the hose nipple to the rear, compared
to the original...which gives more room for your overflow hose
and wiring that passes by a close frame area. There
was a factory service bulletin (SI) on SOME of this, the longer
hose (1 meter of which is 17-11-1-152-866).
NOTE 2: If you have
not already closed off the system that vents fuel tank fumes to
the crankcase; and installed the overflow cup for the tank at the
frame backbone, you SHOULD consider that modification.
NOTE 3:
Consider doing some insulating to reduce heating to
the fuel from engine heat, and the amount of heat thrown back at
you, the rider (various areas under the tank). This
means improving the sealing areas done by BMW under the fuel tank
(the K1100 was better than earlier models, but still not really
great). Information on doing insulation work, and
alternator conversions, etc., is located at various places on the
Internet, including the
www.IBMWR.org website. I do suggest you install, if missing,
aluminized insulation material on the underside of the fuel tank.
BMW sells an insulation kit for the underside of the fuel tank.
You do not have to use BMW's insulating item. You
can, at such places as Lowe's, Home Depot, etc., get a roll of
Duct Insulation; of the type that has a self-adhesive foil/foam.
This product is used on heating and air conditioning ducts, and
the type I purchase is 12" wide, 1/8" thick, and the roll has 15
feet of this stuff....plenty for lots of K bike jobs, and other
things.
There is another product you might be interested in, for areas
that need heat reflective tape, but not an insulating tape.
This is HVAC industrial aluminum tape.
foil tape.
NOTE 4:
It is beyond the purpose of this article for an
in-depth discussion of various insulating schemes, installation
of the alternator, overflow cup, diagnosing fuel economy problems
due to a faulty temperature sensor, etc..
There is another product you might be interested in, for areas
that need heat reflective tape, but not an insulating tape.
This is HVAC industrial aluminum
foil tape.
THE
coolant change and flushing (there are minor variations between
models, what follows is for K1100LT):
NOTE: An example of one of the
simpler, small differences, is that the K1100RS is drained at a
screw plug on the water pump, while the K1100LT is drained via
the water temperature sensor removal.
There are more differences with the earlier models.
I did this job recently to another
K1100, similar to my own, so still have the notes on what parts
were used. The RS and LT, at least on the
K1100's are different....the LT has its water temperature sender
up front below the oil sender. The oil sender has a 15/16" hex,
the water
sender is a 14 mm hex. Don't mix them up.
The RS has a PLUG in place of the water
sender. Don't unfasten the oil sender by mistake. No harm will
be done,
but you won't see the water draining, because it won't!
When re-installing the water temperature sender, tighten to about
9 Nm.
The sender on the K1100LT I did recently was the small one, it
used a COPPER washer #07-11-9-996-072. There is a -073, in
aluminum, used
on the Airheads, I suggest you use the proper -072 copper
version.
NOTE: This procedure can be modified, and the engine run with the fuel tank slightly elevated on the right side especially.
It is up to you how you do your coolant flushing/changing.
You will need a new water temperature sensor
gasket (crush ring) if you have the model that uses its removal
(K1100LT).
I VERY MUCH prefer to use one of the long life
coolants....see later herein for details.
Drain your K bike's coolant system when it is still a bit warm
from the engine having been run.
Unfasten the front of engine located water temperature sensor and
drain from there (LT); for RS it is the
PLUG. Remove the radiator cap to help the draining.
Inspect the rubber gaskets at the cap carefully...and if at all
doubtful, replace them.
Flush the now mostly empty system, at the radiator cap neck, with
a considerably amount of quite hot water, unless the system is quite
gunked/grunged up. I actually
use a teakettle
and near boiling water for this. If your system is very
badly gunked-up, obtain a commercial
cleaner used for this
purpose, and follow the instructions.
Be SURE to flush VERY well after using such a cleaner.
If you use such a
cleaner, take your time to use the product properly. The
more 'plated' hard insulating 'stuff' you can remove from the
system, the better
your system will cool.....and the less your fan motor will come
on. It is important to put the fluid in SLOWLY.
****Use of NON-long life
coolants, failure to change coolants on a schedule, ETC......can
result in a type of 'plating' of the internals of the entire
cooling system. The result will be poor cooling, excessive
use time for the electric fan, etc.
Strong coolant system cleaners can help, but
are not perfect.
Remove the contents of the overflow tank using something like a
turkey baster (not nice to borrow the one in the kitchen!). I
also like to clean
and
flush that tank if it is grungy. You can do it all with the
baster; tank remaining in place. Purchase a baster
just for this job, and keep it in
the garage...not the kitchen! Flush the baster when you are
ready to store it.
Inspect the large hose from the radiator; and the
other end too......and the small hose to the overflow tank.
If you have an extremely grungy system, with built-up deposits,
you will have to use a commercial cleaner product in order to
obtain the best cooling. You need only do this
once, as you WILL be using a long-life coolant, as
recommended...right?
Flush the system truly super well after using such a product!
After draining, and a thorough flushing with hot water (and using a cleaning
solution if required, then repeatedly flushing with
hot water),
replacing the sender (or plug) with a new crush gasket,
you are ready to refill the system.
Use an antifreeze mixture, NEVER just plain
water, even if you live all the time in hot weather.
Use 40% or 50% concentration of coolant,
mixed with DISTILLED OR PURIFIED WATER. The % of
coolant in the mixture you make up depends on conditions you
store/ride in. I
recommend the 40% coolant mixture that BMW recommends, which will
be OK to -28°C. (-18.4°F). Increasing the concentration
to 50%
could be done if you store your motorcycle where it can
experience extremely cold temperatures. For storage in arctic
conditions, below -30°F,
consult the coolant container.
NOTE:
Coolants
RAISE the boiling point, not just LOWER the
freezing point. This means that use of an 'antifreeze'
mixture is helpful
for both hot weather riding as well as cold weather
riding/storage. You should NEVER run plain (or
even purified or distilled) water in your
K-bike, NO MATTER THE
WEATHER CONDITIONS.
NOTE:
BMW wants you to use a coolant with NO silicates,
NO nitrates. Many have used common coolants that HAVE those
chemicals in them. I do not.
It is my belief that
coolants containing these chemicals can, under some circumstances, 'plate'
areas on the
inside of the engine and radiator, such that they
act like a very thin insulating blanket, and detract from cooling ability. I have no other
explanation
for what I have seen in the engines; that is, how they
obtained improved cooling by
a very thorough cleaning and then use of a
proper coolant. I do NOT purchase 'pre-mixed' coolants.
I use Prestone
Extended Life coolant, because it is a
trustworthy brand. I will change it every 4 years (perhaps
even 6) on my own
K1100LT,
and it does
not contain silicates
nor nitrates. I drive my K sidecar rig in the Winter, and
it can be cold...in the teens sometimes.
I use the
BMW recommended 40%
coolant, and 60% DISTILLED water. I do not use common tap water,
I believe it simply ages the
coolant faster,
and increases
carbonate deposits,
which also act like an insulating blanket. There is a possibility
that BMW's recommendation
was not only
for the plating effect I
have seen, but also that the water pumps could be injured by the
wrong coolants (I doubt that for BMW). Honda had
that problem, and
specified NO silicates. I believe
the factory knows best in this
regards, so I follow BMW's advice.
READ CAREFULLY!
The trick to refilling is to be as sure as you can that the
system is refilled as much as possible without air
bubbles. This means dribbling the
coolant mixture into the neck VERY slowly, and
'burping' the system a number of times by squeezing the hose as
you very slowly refill.
I have found
that it helps for the final burping's if the neck is filled to the
ledge and the cap FULLY tightened, before the squeezing. Then I
remove the
cap and continue refilling
until I can't do more filling without the coolant mixture going
into the overflow tube.
I fill the overflow tank at this point to not quite half-full.
Do not fill it too high. The overflow tank level will
shrink some after the engine is
run and cooled. Just how much the overflow tank level
will go down, after a full heating-cooling cycling of the engine,
depends on how
well you did your job.
Ride the bike enough to get the water hot enough so the fan comes
on. I do not recommend this be done in a garage setting unless
you have a
very big squirrel-cage fan, as the exhaust system and exhaust
ports can get considerably hotter than I think is OK for them. Squirrel
cage fans
are very
handy....and often free from heating and cooling companies, who
have old worthless house heaters you can remove a fan unit from.
After the bike is completely cooled, recheck the overflow tank,
its level will usually have gone down a bit as the system sucks
the fluid back. If
it did not suck back anything, remove the radiator cap, and see
if the system is full. If it is not, you may have a bad
cap, or bad cap gasket
(there are two gaskets at the cap).
If the overflow tank level is quite low or near empty, then refill to nearly
half-full, and repeat the ride and cooling.
Recheck the coolant tank after this second ride.
NOTE! It is a lot easier to add a small amount of
coolant to that tank, than to lift the tank, unfasten the fuel
lines, and refill at the radiator cap.
NOTE as said earlier in this article, that some will prefer to
block up the tank on the right side, and leave the engine runable,
during the procedure.
So, refill the main system slowly and methodically
as I have said. If you have done the job carefully, and
were not
in a hurry, then only one
refilling, if any, of a small amount of coolant, will be needed
for the overflow
tank. After there is no longer a drop below minimum on the
overflow tank after the
engine has cooled fully, you set the final amount for the
overflow tank. I use a bit above the minimum mark.
Do
NOT fill it to 1/2 (or above 1/2....this will almost for sure cause an overflow in
hot weather).
BMW said in its literature that for this bike it uses 3.4 L of
40% coolant. That is 3.6 U.S. quarts....about what I found
necessary. I made the
mixture from 46 ounces
of the concentrated Prestone Long Life Coolant, plus 69 ounces of
distilled water. I use an old antifreeze jug I had
(with a clear edge
area to see liquid
level) when mixing. I filled the overflow tank
to 1/2 before starting the engine, since I knew from
past
jobs that this was going to reduce its
level the next morning down to a bit above the minimum, but not
need refilling.
Note: I think BMW made a size changes to the sensor and plugs in
late 1993 or into 1994....so, CHECK!
For the nerdy:
The Radiator cap has a small gasket I have had to replace, it is
17-11-1-460-759. The larger radiator cap gasket was usually OK,
but if you need
one, it is 17-11-1-460-316. The radiator cap has both a
pressure valve and a vacuum valve built into it. Cap releases at
1. BAR at 120°C;
and the vacuum releases at -0.1BAR. You want to be
sure the rubber gaskets
are OK...not deformed or broken, so that those cap valves work
properly...and, that the cap does not leak.
Rev:
12/23/2009: Expand entire article, to include specifics
on the alternators, and other suggested modifications during the
coolant change.
Add information on the insulating products.
06/20/2011: Clean up a bit
© Copyright, 2011, R. Fleischer