Rebuilt Explorer 5.0 getting warm going uphill

[PeteK70]

I have a rebuilt explorer 5.0 obd2 efi engine with explorer serpentine, champion radiator, factory plastic fan, original fan clutch, 4r70W and fan shroud. Drives around Denver no problem around 190 degrees, even idling for a while. However was heading to Evergreen from Denver and the temp started rising to 220 or so before pulling off i70 to let it cool down a bit right before Evergreen exit. Cooled down and didn't have any further problems but wasn't pushing it uphill after that. I thought maybe there was air trapped in the system and topped it off when I got back home. This last weekend I figured I would drive up Golden Gate Canyon road going at a slower speed and ran into the same problem going uphill. I had the obd2 reader in and it showed 226 degrees at the highest, didn't push it when it got there and let it cool down. Anyone have any ideas where I should start. The champion radiator is 5 or so years old and was used with the pre-rebuilt engine which did have some discolored antifreeze in it when I last drained it prior to the rebuild. I have read about the trailblazer heavy duty clutch fan and that it possibly doesn't work with the plastic fan but not sure where I should start replacing parts to get this issue corrected. Any help would be appreciated.

[Eck]

I would maybe start simple and replace the thermostat. Maybe it’s sticking closed when you’re seeing temps rise…


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[ZOSO]

Broncos trap a lot of heat under hood. Best thing I have found so far is cut out the inner fenders. Now my bronco runs right at 195/200 at all times.

[Eck]

Broncos trap a lot of heat under hood. Best thing I have found so far is cut out the inner fenders. Now my bronco runs right at 195/200 at all times.

I’d say we have very similar engine setups and I’ve never overheated. It’s always interesting to me how it would happen. The only thing I had done was add a full 360 fan shroud.

For reference- 351w, explorer front dress with plastic clutch fan, full shroud, Champion radiator.


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[ZOSO]

Broncos trap a lot of heat under hood. Best thing I have found so far is cut out the inner fenders. Now my bronco runs right at 195/200 at all times.

I’d say we have very similar engine setups and I’ve never overheated. It’s always interesting to me how it would happen. The only thing I had done was add a full 360 fan shroud.

For reference- 351w, explorer front dress with plastic clutch fan, full shroud, Champion radiator.


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Jeff also has the same setup and he never had heating issues either. I never had issues till I went EFI. it would creep up wheelin or on the highway while pulling a long hill. I had seen 225deg many times. I tired all the tricks. What helped the most was inner fenders. Now I dont get any temp creep at all. Now I am watching the ECU temp not the factory gauge. The factory gauge barely moves in a 25-30 degree swing.

[PeteK70]

Just to update, replaced the 195 thermostat with a 180 and drove up the same hill and had no overheating issues. Crossing my fingers that everything is good now.


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