MACS Service Reports - 2015 - JAN6

Paul Weissler
Paul Weissler

Figure 13: Hold leak tester in place as shown (do not squeeze bulb at this
time) and have helper start engine and hit gas pedal, then allow return to idle
for several seconds. Repeat this 12-15 times, squeezing the bulb each time as
engine returns to idle. If fluid changes color from blue to yellow (green for
diesel engine), there is a combustion gas leak.

it and open it (Figure 14), or at least disconnect
the lower radiator hose. Many block drains, when
opened, will kick the percentages into the 60-70%
range. We have seen them on some engines, such
as the Nissan 2.5L, and some Chrysler engines such
as the 3.7L V6, which makes at least a check for one
worthwhile. Overall, however, there are preciously
few block drain plugs on late models but every engine has a lower radiator hose.
The difficulty of draining the typical system is one
reason (yes, there are several others) why long-life
coolants are in universal use. Specifying distilled
or otherwise purified water is done for the same
reasons. The increased packaging of 50-50 mixtures
is done for two reasons:
1) ensures the quality of the water is good;
2) improves the solubility of high doses of many
of the widely used corrosion inhibitors. They dissolve in water, but not so well in the ethylene glycol
antifreeze.
That's why our preference is for using a premium
flush-and-fill machine with back flush capability, to
get the maximum amount of used coolant out of the
system (still not 100% by any means) and minimize
the possibility of air pockets during filling of the
system. But the equipment is not pocket change, so
we recognize it's a hard sell. The low-cost alternative is a vacuum-fill device, which incorporates a
venturi to pull the system into a vacuum, and then
lets the system draw coolant in to fill it.

Figure 12: Top up coolant fill neck, then draw out enough coolant so
detector can be inserted and will not touch coolant. Assemble detector
in coolant fill neck as shown.

lyzer probe in the radiator fill neck, not touching the
coolant, pushing through a plastic wrap over the neck
(Figure 10). But probably the most widely used is the
color-change (blue to yellow) fluid system; the one
we've had good luck with is the UView double-tube
type, which seems to deliver accurate results (no
false positives). See Figures 11, 12, & 13.

DRAINING THE SYSTEM
Normally when there's a bad leak that you fix,
there's no choice: you have to drain and then refill the system. We've said this many times over the
years: even with the best equipment, you may get
only a moderate percentage of the used coolant out
of the system on any vehicle. Ford makes it very
clear with the statement that you can't get any more
than 80% of the coolant out of the engine while
the engine is in the vehicle. So unless you plan to
remove the engine and turn it upside down (yes,
we're being facetious), you're going to leave a lot
of coolant in the system. But don't make the situation worse. Opening the radiator drain cock might
get out 30% of the coolant, and if you empty the
reservoir, you might get the percentage up to nearly
50%. If there's an engine block drain plug, locate

January 2015

MACS Service Reports

Table of Contents for the Digital Edition of MACS Service Reports - 2015