Overheating on hills

[bryansr]

My in-laws have a 2007 Explorer (90k miles) that's overheating when climbing hills. They have no trouble with the vehicle when they're close to home, but on the last few trips to visit us it overheated going through the hills of western Maryland on I-68.

My FIL has had the dealer look at it a few times (pretty sure they flushed the cooling system) but it's still getting hot. He won't have a vehicle with 100k miles and plans to get rid of it soon, so I'm considering buying it from them and wondering what I'm up against. Fan clutch bad? Radiator clogged?

Thanks,
Bryan

 

[974X4BLACKSPORT]

First thing I would check in a case like this is for an air flow restriction past the a/c condenser and radiator, bugs, leaves, dirt and other debris can reduce efficiency enough to not notice under normal circumstances, but when larger demands are placed on the cooling system due to higher engine loads (heat), like when pulling a trailer, or climbing mountain roads, higher than normal water temperatures prevail.

 

[bryansr]

Thanks. I'll check that out, but the vehicle is immaculately clean so I'm guessing that's not what's causing the problem.

 

[Littleant]

Fan clutch bad-Air in cooling system-
Radiator clogged all possible. Also run engine to operating temperature open cap (be careful) look for air bubble. If you see bubbles possible head gasket. A head gasket can be bad and NOT show white smoke out the exhaust. Drain the radiator down just enough until you can see the core and see if you can see any buildup. Fan clutch Should cycle in and off even at idle. All these cost nothing if you do yourself and easy to do

 

[michael loibl]

Which motor?

And ask him if they hear the radiator fan roaring as the temperature climbs above normal. It should be obvious. And that could rule out a few things

 

[bryansr]

It's the 4.0 V6

 

[Rcflyer330]

It could also be as simple as a sticking thermostat or partially opening thermostat. I have had two go bad one was sticking closed too long and the other was sticking open.

 

[Harley McIntyre]

For me it seemed to be the thermostat, I just replaced mine and so far it's perfect but we'll see for sure in a few days