overheating

[pelley]

ok, so i was driving the 88 k5 other day and happened to look down, 240 degrees (ouch). pulled over and changed the thermostate. a couple miles down the road, same thing. but when i slowed down at a light it went back to normal. so it turns out if i drive under 35 its fine, over and it overheats. the fan and waterpump seem fine.
so there are lots of jumes getting into the cab, so could a clogged catalyic converter cause this?
its got me stumped.thanks ron

 

[boggerless]

take side streets to work /forums/images/graemlins/rotfl.gifwow thats weird sounds like an electrical problem with the guage. /forums/images/graemlins/k5.gifto /forums/images/graemlins/truck.gif /forums/images/graemlins/dunno.gif

 

[backcountry]

Have you lost any power? Or does it appear normal? If you lost power, it could be your cat.

You sure it's not just your gauge acting up?


clutch fan maybe.

When is the last time you serviced your radiator? It may need to be flushed at minimal. Maybe even removed and taken to radiator shop for repairs. /forums/images/graemlins/dunno.gif

 

[pelley]

i haven't had the thing long, so i dont know its habits yet. but it seems to run ok, but it does need a tune up. i also noticed at 35 to40 mph it would seem to sigh or something and then speed up without moving my foot. and the trans. would every so often shift from overdrive to 3rd . but that might just be the speed it normaly shifts.

 

[spearchucker]

If you have a body lift and the fan shroud isn't modified properly then it won't pull air like it should. Just a thought.
It would help if you filled out your profile. Help us help you. /forums/images/graemlins/thumb.gif

 

[chevy17]

speaking of a body lift and the lower shroud...i have the same problem and was wondering what to do about it.
i have a 1990 chevy 1500 with a 4" body and the lower shroud removed. i dont overheat unless i get stuck, and i'm pretty sure its because the lower shroud isnt on.