4.0 Sohc overheats under load.Fan Clutch? | Ford Explorer Forums - Serious Explorations

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4.0 Sohc overheats under load.Fan Clutch?

biggiesize

Well-Known Member
Joined
December 17, 2008
Messages
113
Reaction score
4
City, State
Martinsville,Va
Year, Model & Trim Level
1999 sport
My 99 sport runs fine unless the engine is under a load.If I am out on the interstate it does fine but if I have the a/c on in the city or climbing a hill,the temp gage shoots up.The fan clutch feels the same no matter if the engine is hot or cold.Could that be my problem?
 



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When the engine is cold, you should have some noticeable drag when turned by hand. If you have never changed it, now would be a good time to. When you do make the change, get the one for severe duty. You can really hear it when it kicks in.
 






While the fan clutch may need to be replaced realize that it's there mainly for low speed driving. When you are driving at speed the air across the radiator is all that is needed to cool the engine. If the radiator is stopped up internally it can't cool under a load and because it may stay cool in the area in front of the fan clutch thermostat the fan clutch may not opperate even if it is ok!
 






Just as an fyi I have had brand new thermostats that did not open correctly in the past. As a result I always boil a new thermostat in a pan of water on the stove to check function before installing. In these times of more chinese parts this little step becomes doubly important.
 






As a Followup to what drbenz noted, the radiator has to have good flow. I have been chasing a cooling problem on my '93 Ed B for a while. I thought the new fan clutch has fixed it, because the guage had stopped going all over the place. Unfortunately it still over heated with the guage in normal range. The transmission puked out the front seal and now the front pump is bad (according to the only transmission guy in this little town. $1350.00 is my quote. OUCH!!!
 






Either a plugged radiator or a stuck thermostat.
 






I replaced the fan clutch,water pump,thermostat and serp belt last weekend.Still doing the same thing.I ordered a new radiator and it should be in tomorrow.Hopefully that will fix the issue.
 






I hate to tell you this now but the fast way to check the radiator to see if it is stopped up is to run the engine long enough to get it up to temp and then shut it off and reach past the fan blades to touch the engine side of the radiator, it should be pretty evenly hot with no much cooler spots (why do they almost always occur right in front of the fan!).
 






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