sbc 350 overheating issues

Ok here's the deal , My brother has a 1988 IROC with a 350 Gen II? block, no heater core in which he has bypassed from the intake manifold to the radiator, has a new 180 degree thermostat, new radiator, new belts, new water pump, new hoses and clamps, and it still reaches 230+ degrees with ease...what else could be the trouble, it runs great when it is at operating temp, but it just climbs on up and overheats. thanks

maby the water pump is broken so the engine is not getting water

havocnmayhem welcome to the forum
I agree with lexmarks567 and would check for that first.

brand new water pump has been installed and water is flowing great, but it still overheats

Post edited by: havocnmayhem, at: 2007/08/24 15:12

OK, a few of the possibilities I found it could be: the wrong size exhaust sysem, a flex fan without a shroud, it could also be it's gas locked.... and I found many other reasons this could happen... I hope this helps a bit

...so presuming the antifreeze mix is correct, the thermostat wasn't installed upside down (a common mistake when re-doing cooling systems), the coolant reservoir is full to the proper line when cold and rises to the 'hot' line when warm and drops as the engine cools, you can see aggressive water action in the radiator when the thermostat opens, and you have no unusual obstructions in front of the radiator, your cooling system is probably OK. Then the next question becomes "what's different about the engine and load that the cooling system 'as-is' can't handle it?" Are you using a different fuel then you should? Are you using a hotter ignition system or cam/valve train system designed for street performance, but not for just driving around town or long-distance driving? What viscosity range is your engine oil---is it breaking down too soon? Have you installed additional belt-driven equipment? Driving habits?

...and, noticing another post, could there be a problem unrelated to the cooling system that's causing the engine to overheat? Emission system, especially those parts of it directly associated with the ignition and exhaust systems...

Those are quite some things for havocnmayhem to check out. Very important things to consider, KF7VG

i would suggest an external oil cooler and external cooler for tranny fluid as well

i have a 72 350 and the only real thing you can do is upgrade from the stock 2 core rad. to a 4 core. then take the flex fan you guys have and throw it through the woods and get you a good electric fan with a shroud and keep the 180 thermostat because anything cooler will not stay closed long enough for the water to cool. and then plug off the overflow tank cause its useless. the you will still be at about 190-210 unless your in traffic then it will heat up to about 225 but will cool off. But remember factory cooling system with an electric fan and a switch doesnt kick on until 230 and kicks off at 195. Good luck and if you find out something better let me know cause im always open for good advise

has the cylinders been bored at any point?

Before you get to far check that your head gaskets are not blown. This will do the same thing and still run fine.

if the heads were removed for some reason did you put head gaskets on the wrong side or upside down by mistake.

fan relay not working to check uplug engine coolant sensor electric fan should come on.if not bad relay or fan motor G.M.does not have a good track record when it come to power windows heater fan cooling fans. i have 91 olds had all these problems because all general motors cars are junk yard specials.

Post edited by: hobbist, at: 2008/05/25 16:58