Sudden drop in gas mileage on your Ford Ranger? Check the thermostat.

Dear Car Talk

Dear Car Talk | Jun 01, 1999

Dear Tom and Ray:

I have a 1989 Ford Ranger with a 2.3 liter engine and a five-speed manual
transmission. I used to get between 23 and 29 miles to the gallon. However, in
the space of less than a month, the mileage has dropped to between 16 and 18 mpg.
My mechanic has checked all of the basics -- timing, plugs, filters, electronics
-- and everything appears to be fine. Any ideas on where else to look? -- Steve

TOM: Check the thermostat, Steve. Ford thermostats are notorious for failing, and
that would definitely explain your drop in mileage.

RAY: If the thermostat is not closing, the engine will never get up to operating
temperature. And if it's running cool, it'll be running inefficiently and your
mileage will suffer.

TOM: I don't know why Ford thermostats keep failing, but it's almost a joke at
the shop. Some guy comes in with a Ford and he wants new tires. We write up the
work order as "new tires and a thermostat." A woman brings a Ford in for an oil
change. We write down "oil change and a thermostat."

RAY: Some guy in a Ford stopped to ask directions the other day, and we changed
his thermostat, too.

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