I have a 99 Ford explorer V6 SOHC, 75k miles. First off, I am a relative newb when it comes to auto repair, but I do my own work. I become a "weekend expert" with a trusty Chilton manual.

The wife brought home the truck today overheated. As the engine sat in the driveway with the engine off, the coolant fill tank overfilled and boiled over. She hadn't driven it very far.

Once it cooled down, I removed pressure from the coolant system by removing the radiator cap, and did the squeeze test on the radiator hose while she put a load on the engine. Pressure did not increase more than I could hold with my fingers. No residue on the oil cap, and there didn't appear to be any oil in the coolant. Exaust seems to be normal, so hopefully no blown head gasket.

Everything appears normal and the heater works. The water pump looks like it's working but I don't really know how to test it. I did not take it for a spin to check if it would overheat again, but the temp remained normal sitting in the driveway at idle for about 10 minutes while I looked things over.

Any idea what this could be? Thermostat? And does anybody know where the thermostat is on this engine? This is the newest car I've worked on, and I'm not used to it at all. Obviously I don't have the chilton yet, but I will be getting one now

Any and all help would be glady appreciated.

Kevin

 

I would start with checking the simple things.

1. Make sure the fins of the radiator are clean and free of bugs, etc. I try to clean out the fins every time I change the coolant (every 2 years).

2. Replace the thermostat, its cheap. I don't have the SOHC 4.0, so I'm not much help to where it is located.

3. I would flush and fill the radiator if you haven't done it over the past two years.

4. Check to make sure the fan clutch isn't stuck engaged. The fan should spin (with some resistance) when the engine is off and cold.

Just some quick and inexpensive ideas for things to check.

 

stubborn1,

thanks for the reply, I thought it might be the thermostat, and since that was the cheapest/easiest fix I went for it. Lucky for me it wasn't all that difficult, and it seems to have done the trick.

Thanks again,

Kevin

 

Wow, usually they are made to go bad in the open position to run cool.

 

I usually see 5 or 6 posts a year from people that have had their SOHC thermostats stick closed. My '97 SOHC's thermostat stuck closed about two years ago. The Ford OEM thermostat seems to last about four years.

 

I guess I was lucky. Mine on my '98 ohv w/ 97k stuck open!

 

Follow the upper rad hose (towards the engine) there you'll find a housing calmped to the hose.... there could be 2-3 bolts... (3 on my 4.0L OHV) That's where the thermostat is.... (don't forget to replace the gasket as well... if it doesn't come with one)

When draining the collant, use a clean pan... if you wanna reuse your coolant. (my system uses 8.1 L)