Hi, I've read through god knows how many posts and I know many have asked this but I've tried everything I can find on here. Driving down road at 35 mph and up runs cool and great 180 tops. During stop and go whether its hot outside or cool, temps raise drastically 220-230. I havent let it get any hotter but I'm sure it would. Now I have a new built 350 motor, mild cam, headers, cylcone intake, holley 650, non CC distr. New 2 core bigger radiator, 160 degree thermostat, manual clutch fan (working) belt driven and 2 pusher fans on front of radiator, good air dam. System was flushed when new radiator put in. Now I know it sounds like a air flow problem cause it runs nice and cool going down road, but with manual clutch fan and 2 pusher fans how could it be an air flow problem? Is it possible that the headers are heating up my engine bay to the point of raising my idle temps like this? Or is it possible that my waterpump isnt pumping sufficient at idle? I'm lost and need any advice, but please keep in mind all I have posted when trying to diagnose this. Thanks in advance for all your help.

 

Are you running a fan shroud? Also make sure the fans are pushing the air through the radiator and not pulling the air out. The blades could be on backwards.

 

Yes I have fan shroud and yes Both fans are pushing not pulling. Anyone else have any ideas here?

 

Well just a thought here but the 3 fans might be a bit much. the 2 pusher fans might just hinder the performance of clutch fan. At a stop when air flow is limited by the bulk of the pusher fans... Just a thought anyways... hope it helps...-Rev

 

Was doing the same thing before I added the 2 pusher fans, thought maybe it wasnt getting enough air at stops so added the pusher fans but has no affect. Any other ideas?? Anyone?

 

air pockets?

 

If I had air pockets I dont think I would be running 180 on highway. Nobody has had this problem and worked it out? Is there any chance that it is just that my underhood temps are so high that when no air is moving through engine bay it is affecting my actual temerature? I'm really not sure what else to try.

 

I recently had this problem in my 1991 pontiac firebird 305. I replaced the thermostat with a 160, which you have done, also I drilled .15 inch holes in the thermostat. After that I replaced a temp sensor near the thermostat housing, also replaced the cooling fan switch under the engine block on passenger side. Then I replaced the cooling fan switch relay near the firewall also on the passenger side. I gave it a coolant flush and so far it seemed to have done the trick. I am not having any more problems. Keep in mind with these cars the primary cooling fan doesnt turn on until 222* F. Also when the fan initially turns on there will be a jump in heat but it will fall back to around 185, then of course it will go back to 222 and repeat the process. However, depending on what you have done to the engiine it may be safe for your car to run at around 240. As long as the fans are turning on and the temp is under 250, no steam is coming from your engine you should be fine. I hope this helps =)

 

Thanks for reply....lot of this doesnt pertain to me as the motor is completely old school...ie belt driven fan, 2 pusher fans hooked up to direct toggle switch so I control them...no relays, sensors etc. I have done everything else you mentioned other than drilling holes in thermostat. What exactly does this accomplish as far as heating up at idle? Again thanks for reply.

 

my crate engine is being cooled by just a stock LG4 cooling system, and i have no problems to report. it only seems to heat up when i sit for a long period of time, but then my electric fan takes care of things just fine. normal driving is a tad under 180*.

a thermostat stricts coolant flow to a measured degree to allow an engine to run at a certain temperature. drilling holes in a thermostat would keep coolant cycling through an engine so fast that it wouldn't build up heat, in other words overcooling.

I had one of those god forsaken Mr Gasket ( I would rather use a loaf of bread to fix my car than another one of their products) "high flow" 180* thermostats. you know what high flow got me? a car that wanted to stall out ever time it sat at a red light. temp gauge never went over 120, ever. went to autozone and bought a plain jain no name 180, whole new car again.

worse comes to worse, just get a aftermarket electric fan kit. summit has a few. 40- 80 dollars depending on what company you want to support.

 

When the speeds are low your fan system is the thing that should keep you cool. No need to drill any holes, no need to get outside of what a normal cooling system does.

Like mentioned before 3 fans sounds a bit much. Sure, I can see how you can "overkill" the fan situation because of the lack of flow on these cars. However, one fan should be more than enough to cool the system. Running other fans creates trouble that you never see. Like fans spinning the wrong direction. Spinning fans from both sides sounds like a good deal, but in reality you are blocking more area, and are creating a zone between the back and front where the air flow is lower than just having a plain ol fan pullin/pushing through it. I would seriously look into the fan set up.

There is just not enough air flow when the fans should be keeping ya cool.

I would personally find a dual fan set up and keep one fan running at all times. I do that on my car and never break 180.

I would flush the system through the whole engine and just keep one fan working.

PS, I read the post in more detail, and I would look into the water pump too. A nice replacement one should be adequate. However, make sure you get one that is right for your belt set-up. Still, the fan is what you should be looking at.

 

I have an 85 firebird t/a 305 with a clutch fan changed everything rad, water pump, sensors, belts the entire system overlooking one thing the fan clutch. It will kill you if you have sit and heatup problems on a fan clutch system check the clutch first its easy grab a blade(engine off only) and give it a twirl if the fan spins at all then replace the clutch... that should solve your problems(if its the fan clutch) solved my problems lol just need to figure out whats up with my electice fan on a 88 tbi camaro lol-RevZ28

 

i second reverendz28

 

The cooling fans on third gens are PULLERS! Dump your fan clutch, install your dual fans correctly and your problems should be over.