so i live in florida and summer is arriving very fast. much faster than i want it to. and last time i went out and had some fun in my 93 the truck overheated and coolant started coming out of the resevoir. i replaced my thermostat with a 195 degree and the temp needle is still climbing up to just under 220. it doesnt go past 220 but its always way up there when i stand in traffic for too long. if im on the highway it stays around 190 and im good but i do a lot of city driving and in orlando fl theres always traffic.
so far i have a new water pump about a year old, new radiator last month because my last one blew and a new thermostat now. i also have underdrive pulleys with a mechanical fan. i was wondering if that could be my problem. maybe with the underdrive pulleys the fan isnt spinning as fast as it should be. i have future plans of switching to an electric fan but i wasnt' planning on it this soon. i was also thinking do you think it could be a clogged heater core? i havent checked to see how hot it blows yet. maybe ill do that tomorrow but that just crossed my mind. maybe its a clogged heater core? anyways any help would be greatly appreciated. i need to get this fixed before it gets any hotter here i cant afford a blown head gasket right now

 

i think i have a 165 degree in my truck, on the highway it runs between 165 and 180 highway, and in town or towing 175 to 190. if i let it idle for more than 10 minute the temp starts to climb. but i havent seen anything over 200...

 

i was going to get a 160 but i thought that might be worse because it would basically be open all the time and it wont let the water sit in the radiator and cool down. its only 10 bucks so ill give it a shot

 

I had the same proble with my 87 Lariat about 2 months ago and replaced the thermostat with a 190, but in the process of replacing the thermostat I found out that I also had a pretty bad radiator leak, so I replaced that as well. The problem I have is that my temp gague doesn't work at all, so I just ride with the heat on until I smell coolant, lol.

But you have replace the base parts that I would suggest to replace, but a clogged heater core could be a problem. Although it would seem to me that if the heater core were clogged the it would overheating more that what you are experiencing.

 

A clogged heater core shouldn't cause the truck to overheat. The heater core is set up like a bypass on the main system. If the core is clogged it shouldn't affect the rest of the cooling system. My bet would be on something related to the fan. It could be caused by a bad fan clutch or the lack of speed from the under drive pulleys or both.

 

well my fan doesnt have a clutch. its bolted right to the water pump. so as long as the engines turning my fan is turning. yeah that was my first guess, the lack of speed from the underdrive pulleys. i guess its time to convert to an electric fan.
does anyone know exactly what i have to hook it up to? im getting an electric fan and wiring it to a relay and then to a fuse to make sure i dont blow anything but i would really rather not have to wire it to a killswitch just because my girl drives my truck sometimes and im afraid she'll forget to switch it on. and i dont really want it on all the time either just when it needs to be on. any tips? i might do that this weekend

 

You have multiple things going on because of your underdrive pulleys. The fan and waterpump would turn slower causeing less waterflow threw your engine and radiator and less air flow. Your not supposed to run over 15% to 20% underdrive on a street driven vehicle, and the horsepower gains are minimal, 1-3. I would replace stock pulleys and run a clutched fan and all your problems will go away.

 

try a new fan clutch?

to test your current one, get the truck up to operating temp, and then shut it off, the fan should be fairly hard to spin once the clutch is hot. Definitely should not be freewheeling from the time it takes you to shut it off, and come around the front of the truck.

 

i dont have a fan clutch. my fan spins constantly so its not my fan clutch. its bolted directly to my waterpump pulley. i'm going to go ahead and reinstall the stock pulleys tomorrow morning and see if that helps. i didnt think it would make that much of a difference in the cooling system

 

Is your fan shroud in place? Is your fan a large stock fan to move a lot of air?

 

Do you do your own work? If so, I think I see your problem. You said you changed the radiator and water pump. That would mean draining the system of coolant. You refilled (I would hope) yet you never checked to see if your heat was working properly. You need to bleed out the system. Part of the bleeding process would be to leave the radiator cap off and running the vehicle up to normal operating temperature and turning the heat on high in order to remove the trapped air from the system. Once your heat is blowing hot and you have removed all the air from the system, you can continue to fill with coolant if necessary and then replace the radiator cap. Just my .02 cents Start with that and then you can move on to the next troubleshooting step, if necessary.

 

The fan clutch is between the fan blade and the propeller shaft. The fan can spin all the time and the clutch still bad. I had a buddy's truck the clutch was so weak you could stop the fan by hand while the truck was idling. I dont recommend you try to stop your fan, especially if you have metal blades.


Example pic:

 

yeah i dont have one of those clutches. it just bolts directly to the water pump pulley. and yes i do my own work and i did start up the truck with the cap off and wait for the thermostat to open and let water thru and then top it off. i didnt turn the heater on ill go try that right now but im positive i let it heat up to operating temp cuz i watched the water go down when the thermostat openned. and yes my fan shroud is in place and i believe it is the stock fan. its very big and heavy which is why i wanted to convert to an electric fan

 

heres a pic of when i was installing the underdrive pulleys. i am 100% positive its not a clutch. it bolts directly to the water pump. the screws are very long they go from the fan, thru the little extender that you see, thru the pulley and to the water pump bracket that holds the pulley. it spins constantly. so i am positive my fan clutch is not the problem here

 

I think it is safe to say guys that the fan clutch is not the mans problem. He has said many times he does'nt have one and now hes got pictures. All I can say is if you have your thermostat in the right way and your sure you don't have signs of a blown head gasket, then your problem lies in the underdrive pulleys. Those things are mostly for drag cars and such, not for daily drivers.