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You already knew the answer, but what's the solution?

On the Jan 18, 2014 show, a man called in to complain that his Explorer’s heater wasn’t working well during the recent winter storm. I believe it was Ray who knew the answer before the caller finished his question. Just based on the facts that he had an 93 Explorer and a problem related to cold weather, Ray called it as a bad thermostat. He went on to say that there had been a flurry of thermostat replacements for Explorers in his shop. I’m sure that this is also true for Ford Rangers with the same 4-liter V6 “Cologne” engine.

So the solution offered was to replace the thermostat. But is that really the solution? Why do thermostats continually fail in these engines? Is there a replacement part that isn’t susceptible to this problem?

I’ve owned my 94 Ford Ranger Splash since it was brand new. I don’t know how many thermostats I’ve put into that engine, but it’s a big number. The last few have failed within months, or even weeks after installation. Even when the truck was fairly new and still under warranty, the dealer had to replace the thermostat on the first time it failed. I’ve got more than 300,000 miles on the original engine, and now I need to put in another new thermostat (and a heater core).

That’s very strange. You’ve tried different brands of thermostats, correct? Even if not, say if motorcraft had a bad run of thermostats, you’d be buying a different lot#. Unless your auto parts store purchased 50 of them in 94 and your the only one buying them :wink:

I’ve never made any effort to buy or avoid any particular brand of thermostat. Each of them was probably bought in a different store, and also in different towns. However, Ray and Tom seem to be aware of this problem. This wasn’t the first time it’s been mentioned on the show. I just wonder if they have any idea why this would happen consistently on the Ford 4-Liter V6 in Explorers and Rangers.

What type of coolant are you using?

Failing to flush the cooling system and change out the coolant with new every 2-3 years can cause various deposits and rust to form on the thermostat. That’s the only thing I can think of. I guess if the thermostat was located in a place where there was a lot of turbulent flow, that might contribute to early failure too. If that’s the case there’s not much that can be done about it. If I had to keep replacing thermostats like this, besides following the owner’s manual on the proper cooling system routine maintenance, I’d buy new thermostats from the dealer. Ask for the OEM replacement.