ok I have 82' pontiac firebird 305 all stock no headers, no cam, nothing special. and i mean nothing. has air dam. timing was checked and is stock 7 degrees timing. NOTE new harmonic ballancer and timing pointer installed. old ballancer had slipped on me. radiator is new delco 1 row radiator stock. stock fan shroud no holes its all there clean factory fan shroud. replaced the stock fan clutch with a heavy duty truck fan clutch and works great I hear it anytime the engine runs and is very anoying but pull lots of air trust me. I flushed the coolant with napa flush and some redline coolant flush didnt help. replaced the thermostat with a 180f thermostat just to make sure it wasnt sticking, that still didnt fix it. im running half gallon of coolant and the rest water also redline water wetter which is helping but still getting hot but not so fast. so im lost at what can be causing my problems. engine runs hotter than 230f especially on a hot day. getting on the freeway I can hear ignition ping getting on the freeway under full throttle. what makes this so wierd is when I turn the a/c on it gets hot faster to this temp. but when i turn off the a/c it still runs hot. so ive been driving the car with a/c off but still doesnt help. i dont think the a/c is the problem on or off its still getting hot. If i rev it up i cant notice the lower hose colapsing or anything because it has a coil spring in the lower hose. my brothers truck is a chevy truck with 350 sb same year. he has no fan shroud and just a thermostic fan and his truck never never overheats. he has the same thermost. so today i got home from a 30 mile drive in the heat and got a temp gun to check the upper and lower hose temps. found the temp coming out of the engine is moving around 203f. but when i laser temp the radiator inlet and outlet i get upper hose 217f and the lower hose was 237f. im really lost here.. isnt the lower hose supposed to be colder than the upper hose??? is there a option for reverse cooling pumps on a sb 305 to cause this?? man im really lost on this and can not figure it out.. any help would be awsome as ive been a mechanic for 15 years working on diesel trucks but not cars but this is way out of my league and makes no sense at all. help help help thanks

 

i highly doubt that you've got a reverse rotation water pump in there- there are no mounting provisions for the alternator or PS pump on them, and the bolt pattern for the pulley and fan is different than a regular rotation pump..

have you checked for water flow? my car has the water return line from the heater core dumping into the radiator right below the radiator cap, so it's easy to see if the pump is moving water right after startup...
could be that the impeller on the pump is shot or fell off and it's time to get a new pump for it..

 

no i havent checked for water flow but when i rev it up the lower hose tries to collapse just very slightly but not enough to collapse against the internal hose spring. my heater hoses go from the intake manifold to the top of the water pump. Even still, why would the top hose ever be colder than the lower hose by 20f degrees ??? had a couple of chief mechanics and the shop foreman check my readings and he cant understand it either. makes no sense. i put some baking soda in it today and will drive it tomorrow and drain the coolant again.. irritating to say the least. ill check coolant flow before i tear everything down again. also ill replace the thermostat again because we all know new doesnt mean its bad. also ill remove the water pump and check the vanes on the pump and might even replace it. just doesnt make any sense.. Im hoping I find something that jumps out at me and find the problem. Cause if i dont ill be really screwed lol.. thanks keep the ideas coming !!!

 

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The only thing that could cause that condition is coolant not moving. Don't get upset but the spring on the t-stat must be into the manifold. If that checks, bout gotta be the water pump or could even be packing material from radiator box inside upper hose connection although not probable.

 

ok so i have an update today... drove the car home got it hot. removed the cap then removed the upper radiator hose and got it to high idle. waited for the thermostat to open and when it did it came out of the hose not from the radiator which is good news!! lol next I removed the thermostat and the spring and wax button is on the bottom side correctly which is good news again.. after this i removed the water pump and took the back of the water pump cover off and inspected the water pump internals look brand new, again good news. it even has slight resistance telling me the seal is working good. then i inspected the inside of the radiator and looks brand new no harsh water stains no deposits nothing Im telling you it is spotless!! So which leaves me no answers which is BAD news!! So again im lost and dont understand. with all the good news I should be happy but only discouraged and dont understand the problem. I did want to give you update the fan is 7 blades stock fan with thermostatic heavy duty fan clutch and the water pump internal impeller is 8 blades. You had mentioned that your heater core outlet to water pump was on the radiator and mine is on the back of the water pump. Im going to move my heater core outlet suction hose to the radiator. I also notice that the heater core hoses are 3/4 inch in my opinion i way huge and rediculous. im even wandering if i should put some sort of restrictor in there so it doesnt flow so much. Anyways im leaving to get parts. im getting a new thermostat, cap, lower hose, replacing the heater hoses and may get a new water pump. let me know what you guys think.. thanks im lost till i can fix it !!!