I realized today that the belt on my truck was slightly misrouted. It is a 4.3 V6 full size chevy truck with one belt for everything. Everything was correct except the waterpump/fan, which was turning the wrong way! To top it all off, the coolant temp guage did not work (I just bought the truck and am starting to go thru everything). It does not look like the engine/head gasket was damaged! good thing these old school engines are tough! So I rerouted the belt and have yet to start it up. I am crossing my fingers. There dosen't appear to be any coolant in the oil...Does anyone know of any other signs of a cracked head gasket?
Does anyone know if some coolant would have circulated thru the engine with the water pump turning the wrong way? I drove three hundred miles with it already (mostly just to get it home), and who knows how long the guy has been driving it like that. He did say he changed the belt recently.
After looking it over again, I think that although the belt was misrouted, the water pump and fan were still spinning the right way (though I am not certain). I should have drawn a diagram of how it was routed previously, because now i can't remember.
The truck did not smell or feel hot after driving it several hundred miles. You are right I should replace that thermostat.
spinning backwards will reduce it's flow rate but if the truck was empty and not towing 5000lbs on a 100 degree day then I would not worry about it. If the truck overheated you would have smelled the antifreeze but since it didn't boil over or anything you are fine. It will usually boil over before the head gets damaged.
You would be surprised how little coolant flow it takes to keep an engine cool with a light load on the highway.
Sweet, that is a relief that it is probably fine. it didnt boil over, and it didnt seem to lose any coolant on the 230 mi drive home, so I guess its fine. Now Ive got the belt routed correctly. thanks for all the replies!