My '65 283 in my '69 GMC still has the temp-driven fan clutch and steel 5-blade fan. Runs a bit warm in these hot Alabama days lately when running the interstate, otherwise, it runs cool on city streets & below 65-70mph. Would getting a late-model electric fan set-up out of the junk yard & adding to the rear of the radiator help a bit? Has anyone done this? BTW, I checked some aftermarket parts books; the radiator for the 250, 292 and the 283 are the same part #s, so I presume the stock one will suffice. I've water-flushed the system and have fresh, low-silicate coolant (50/50 mix) in the system. The only other thing I could do is a chemical flush to get any scale & deposits out of the system, in case THAT may have an effect, but I'm STILL curious about the electric fan add-on. Ideas, please? Thanks!
RE: Additional electric cooling fan [updated:LAST EDITED ON Aug-06-04 AT 00:51 AM (CST)]There are a few more things to check if you havn't checked or replaced. 1) hoses. Make sure that the are not so old as to collapse when heated to operating temps. 2) Fan Shroud. If you don't have one, get one. That alone is good for 5 to 10 degrees. 3) Water pump. If you never replaced it while you owned the truck, replace it. It's cheap and you can get a rebuilt one at a local parts house with a " for as long as you own the vehicle" warrenty. Flushing the system can sometimes dislodge crud that makes its' way to the water pump and cause the impeller to perform smoothly. 4) thermostat. Too cheap not to replace if you never have before. Mine would heat up like you could not believe when in line at the drive thru. Changed out everything one at a time till I hit the water pump. Although the old one didn't leak, Once I replaced it, that did the trick. I added a fan shroud a week later to be sure and it now runs at 185-190 range all the time. ( btw: Summertime in the Sacramento Valley is no picnic either !) When you have done all that, and still have a problem, then consider an electric fan. dv
RE: Additional electric cooling fan I just realized I missed something ! You said you had a fan clutch. Make sure that it's working well. If it's all covered in crud and engine grime it probably isn't working properly. DV
RE: Additional electric cooling fan Well,, since I had something making noise, I've replaced the fan clutch and the water pump, as well as the alternator- there was a squeal somewhere & I found out it was a poor-quality belt! Maybe it was slipping at highway speed, making the engine heat up. But, I still haven't replaced the thermostat...next! Still, it seems funny that at city speeds, 25 to 40 mph, it stays cool, but heats up on the highway @ 65-70 mph. Maybe I should totally flush the system & change the thermostat, then see. Thanks!
RE: Additional electric cooling fan It's normal for it to heat up some at cruising speed. Consider why it is not cooling. The water is not circulating fast enough to cool down at higher engine RPM's. What would cause this ? Water pump, Belt, or fan clutch would be my guess. I had a Jeep that did the exact same thing. It was the fan clutch. DV
RE: Additional electric cooling fan Greetings All, Has anyone thought about all that air at highway speed vs at slower speed. Methinks the problem may be elsewhere. Poor timing can surely have an effect. Just too suspecous sp to me if it runs cool at low speed. Good luck and let us know what happens. Ric H
