Gravelguy413 Posted June 3, 2022 Share Posted June 3, 2022 Hello all. Have 96 RD with mechanical 300. Recently noticed when hauling a load that coolant temps start to near the red zone on temp gauge within a few miles of driving. Not losing any coolant. Only things I have noticed lately is the low oil/ coolant/ air pressure alarm beeps intermittently after it initially shuts off. I do not hear the fan surging like it used to on uphill pulls. Could this just be a faulty thermostat or what ? Quote Link to comment https://www.bigmacktrucks.com/topic/69892-overheating-problem/ Share on other sites More sharing options...
Popular Post Joey Mack Posted June 3, 2022 Popular Post Share Posted June 3, 2022 I bet you have a viscous fan clutch.. if so, check to see if it is easy to rotate when cold, and see if there is oily residue on the back of it where the spindle comes out. If so, replace it, A new thermostat is always a good idea anyway, is the coolant mixed properly? is there dirt between the radiator and C.A.C.? Is the fan shroud in one piece? jojo 2 1 Quote Link to comment https://www.bigmacktrucks.com/topic/69892-overheating-problem/#findComment-499168 Share on other sites More sharing options...
fjh Posted June 3, 2022 Share Posted June 3, 2022 54 minutes ago, Joey Mack said: I bet you have a viscous fan clutch.. if so, check to see if it is easy to rotate when cold, and see if there is oily residue on the back of it where the spindle comes out. If so, replace it, A new thermostat is always a good idea anyway, is the coolant mixed properly? is there dirt between the radiator and C.A.C.? Is the fan shroud in one piece? jojo WHAT HE SAID! 😁 1 1 Quote Link to comment https://www.bigmacktrucks.com/topic/69892-overheating-problem/#findComment-499175 Share on other sites More sharing options...
Gravelguy413 Posted June 4, 2022 Author Share Posted June 4, 2022 12 hours ago, Joey Mack said: I bet you have a viscous fan clutch.. if so, check to see if it is easy to rotate when cold, and see if there is oily residue on the back of it where the spindle comes out. If so, replace it, A new thermostat is always a good idea anyway, is the coolant mixed properly? is there dirt between the radiator and C.A.C.? Is the fan shroud in one piece? jojo Fan does not rotate easily and there is no play however there is old oily residue on the fins of the fan clutch and fan blades. I ran truck for several hours around the yard moving loads and it stayed at just under 180. Should I just replace fan clutch? Everything else looks good Quote Link to comment https://www.bigmacktrucks.com/topic/69892-overheating-problem/#findComment-499234 Share on other sites More sharing options...
Dirtymilkman Posted June 4, 2022 Share Posted June 4, 2022 Thermostat should be replaced every couple years no matter what. I agree about your fan clutch being bad. Also VERIFY your temp with a heat gun. Make sure radiator is in good shape too. Quote Link to comment https://www.bigmacktrucks.com/topic/69892-overheating-problem/#findComment-499259 Share on other sites More sharing options...
Hayseed Posted June 4, 2022 Share Posted June 4, 2022 10 hours ago, Gravelguy413 said: Should I just replace fan clutch? Everything else looks good Personally I'd also give the C.A.C. & Aircon condensor a good clean/blow out & service the entire cooling System .ie. Give both the block & radiator a flush, change coolant, Hoses & thermostat.. But that's me.. But It's Your truck, your Call.......... !! Quote "Be who you are and say what you feel...Because those that matter...don't mind...And those that mind....don't matter." - Link to comment https://www.bigmacktrucks.com/topic/69892-overheating-problem/#findComment-499260 Share on other sites More sharing options...
terry Posted June 4, 2022 Share Posted June 4, 2022 generally to get it cleaned right between radiator and C.A.C. to pull cooler out and clean it and radiator real good. terry Quote Link to comment https://www.bigmacktrucks.com/topic/69892-overheating-problem/#findComment-499276 Share on other sites More sharing options...
Gravelguy413 Posted June 9, 2022 Author Share Posted June 9, 2022 Well I replaced the fan clutch and the fan now works as it’s supposed to. It also got rid of the loud squealing noise that came on around 1600 rpm however the truck is still heating up when hauling a load up hill. I am changing out the thermostat tomorrow. Anything I need to know or is that pretty straight forward? Quote Link to comment https://www.bigmacktrucks.com/topic/69892-overheating-problem/#findComment-499668 Share on other sites More sharing options...
JoeH Posted June 9, 2022 Share Posted June 9, 2022 16 hours ago, Gravelguy413 said: Well I replaced the fan clutch and the fan now works as it’s supposed to. It also got rid of the loud squealing noise that came on around 1600 rpm however the truck is still heating up when hauling a load up hill. I am changing out the thermostat tomorrow. Anything I need to know or is that pretty straight forward? FYI, the charge air cooler tends to crack. If the truck builds less than 30 psi boost and runs over 1000 degrees on the pyrometer then you need to be looking your charge air cooler for cracks. You can buy a couple pvc pipe plugs to clamp into the rubber intake tubes. Install a tire valve stem into one, and pressurize not more than 30 psi. Look for leaks! 1 Quote Link to comment https://www.bigmacktrucks.com/topic/69892-overheating-problem/#findComment-499751 Share on other sites More sharing options...
67RModel Posted June 13, 2022 Share Posted June 13, 2022 On 6/3/2022 at 8:55 AM, Joey Mack said: I bet you have a viscous fan clutch.. if so, check to see if it is easy to rotate when cold, and see if there is oily residue on the back of it where the spindle comes out. If so, replace it, This is a little confusing to me. Are you saying if it rotates easily when cold (engine not running) then replace it? I though they were supposed to rotate easily when cold. I have a viscous clutch on my E7 and am just doing a good once over on the cooling system since the really hot days are coming. Thanks. Quote Link to comment https://www.bigmacktrucks.com/topic/69892-overheating-problem/#findComment-500114 Share on other sites More sharing options...
Onyx610 Posted June 13, 2022 Share Posted June 13, 2022 (edited) You should have to put some effort into trying to rotate it. Some like on the ASET engines are extremely hard to move by hand. Edited June 13, 2022 by Onyx610 Quote Link to comment https://www.bigmacktrucks.com/topic/69892-overheating-problem/#findComment-500118 Share on other sites More sharing options...
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