Pumping Problems (Photos: Richard McCuistian)
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Today's transversely mounted V6 engines are stuffed in really tight engine compartments, particularly in minivans, and handling
heat on those platforms is always a serious concern. A healthy emission-friendly engine generally needs to run no cooler than
200 degrees F and not much above 230. With that in mind, it's quite interesting that some electric cooling fans don't even
kick in before the Engine Coolant Temperature (ECT) sensor reads nearly 230. That's a pretty tight temperature window, and
little things can upset the balance.
Cylinder heads are almost always aluminum nowadays, and they love to warp and blow gaskets if the temperature needle drifts
into the red and stays there for too long. Over time, hoses can split, plastic radiators can crack or clog with debris, electric
cooling fan motors can fail, water pump bearings and seals can give out and ferrous water pump impellers can be consumed by
rust. Electrolysis can cause cavitations on the timing cover or water pump surface opposite the water pump impeller blades,
and in some cases, an improperly installed serpentine belt can spin the water pump backwards. Ever seen that?
This is the water pump leak on the Ford Windstar — very unusual for a water pump to fail this way. Other folks may have seen
one, but this was my first.
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What complicates matters even further is that so many of today's vehicles have their all-important high temperature coolant
flowing through plastic parts at 16 psi. It's a good idea to sell your customer replacements for a lot of those components
if their wheels have rolled more than 100,000 miles, because plastic parts that carry coolant often fail suddenly and cause
catastrophic engine damage. Spring-loaded belt tensioners can pop without warning as well, but that's another story.
Just about everybody uses aluminum radiators with plastic tanks nowadays, and if that weren't enough, there are plastic heater
hose tees and plastic elbows o-ringed on each end that can fail without warning. GM 3.8L engines had two plastic elbows that
routed coolant through the belt tensioner bracket (go figure), and earlier 3.8L models had a dandy plastic bypass hose fitting
that was neatly concealed behind the alternator and could dump a heap of coolant in short order. First: Windstar Water Pump
Here's a close-up of the cracked water pump housing from the Windstar.
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This month's title vehicle is a Dodge Caravan, but before we get to that one, let's talk about a 2002 Windstar that came in
for an oil change and wound up getting a water pump along with it. There are several ways a water pump can fail. The guy doing
the oil change noticed coolant dripping from the pump, but it wasn't coming from anywhere near the weep hole. There were no
leaking pipes or hoses.
This was a strange leak, to be sure, and a pressure test revealed a cracked water pump casting, which (in my limited experience)
is extremely unusual. That water pump would have been a cakewalk if it hadn't been for that stiff steel coolant tube that
was flanged to the top of the pump. The point here is that aluminum and cast iron parts can develop cracks, too, and when
those cracks allow coolant to escape, well, Mom isn't always watching her temperature gauge when it moves into the danger
zone.
One way or another, the Windstar had to have a water pump and some fresh coolant. It was a dandy and vitally important upsell
that probably saved that Windstar 3.8L from destroying itself.
