Lower Pressure Rad Cap/Cooler Car? - Cooling - Third Generation F-Body Message Boards

TPI86TA · 04-05-2003, 12:30 AM

My cars been running fairly hot.I just recently put it back on the road.Im not running a thermostat and the fan is rigged to be on constantly,and the water pump is fine,and so is my radiator.I was thinking maybe the fans a POS and its just not cutting it.Its just a single electric fan.Someone told me they thought it could be my radiator cap.They said even if its not the cap,i can put a lower pressure cap on my radiator,and the car will run cooler.Is this true? Thanks..Al in NJ

bigREd car · 04-05-2003, 12:08 PM

first off put the t-stat back in.. it doesnt do anything out.. it will not give the coolant time to cool off in radiator.. those single electric fans suck balls sorry.. do you have everything else you need in car?? lower air dam?? as for the radiator cap i would be curious to hear about the also i never thought it was revelant with any cooling issues if it is someone let us know please
Shawn

TPI86TA · 04-05-2003, 10:25 PM

I was always under the impression that the thermostat remains closed till the car reaches a certain temperature,and once it reaches the desired temp,it opens up to cool the engine.I bought the car and the thermostat was already out.I found this out because the car was running hot so i went to change my T-stat,and the kid before me wasnt running one.I also noticed he had the single electric fan rigged up to run constantly.My water pump is fine and the radiator seems fine,and theres no leaks of antireeze either.I drove the car on the highway and it ran as cool as a cucumber,then again my air damn is perfectly fine.I just checked out the pressure rating on my radiator cap and it's a 13 lb. Now im just debating if my fans such an unreal POS or if maybe my radiator cap has something to do with it.And if the cap might not be the problem,is it true about different pressure caps making a car run cooler?

Danno · 04-06-2003, 09:13 AM

First of all how hot is it running? These things will hover around the center of the temp guage and when idleing like to stay in the 220 range. I have seen posts about no stat causing the engine coolant to not cool, all I can say is that in my experience you take out the stat and the car simply won't get warm-period. I have done it many times as well as experiment with stats with holes. The more water that flows through the rad the colder the engine runs no if's and's or but's. I have done it with my 89. No stat=no heat of any kind. The stats restriction to coolant flow is purposeful and functions with the diameter of the piston to maintain as close to target temp as possible. The cap pressure controls the boiling point of the coolant. For every 1lb of pressure the boiling point is raised roughly 3 degrees. The rad cap is basically a pressurized check valve. When it reaches 15psi it pops open and allows the coolant to flow to the recovery bottle. More than 15psi and you run the risk of blowing out hoses. Stick with a 15-16psi cap. I have seen so many "band aid" fixes for basically simple cooling problems. First thing is the rad, is it an equivalent to the OE unit. Even if it looks good doesn't mean it's not partially clogged. A good reverse flush and a refill with a 50/50 mix of coolant and no lower than a 180 stat is a start. There is no reason for the fan to run constantly. Also if it's hardwired is it turning in the right direction. These fans are pullers, meaning they should pull air from the front. Seen that happen more than once where it is hardwired in the wrong direction. Many guys hardwired the fans because of intermittent cooling problems at idle caused by faulty fan relays. The stock ones were horrible. The new ones from GM are redesigned and much more reliable. GM allowed a 25 or so degree swing in engine temp before turning on the fans so as not to constantly cycle them. It chews up the alternator and the fan motor as well as the relay. If the cooling system is OK the electric fan will bring down engine temp pretty fast. I run a zz-4 block with all stock components and it runs just like any other 5.7. Even when it's 100 degrees it pretty much stays in the range it does when it's only 50 degrees. I don't have any manual fan switches or 160 stat, she runs at 195 with the stock fan setup.

TPI86TA · 04-07-2003, 07:33 PM

Well my cars been running between 230 and 240.Once it hits around 240 i usually shut the car,and when i shut the car when its that hot i usually get pre-ignition knock.Sometimes it wants to keep running so bad i even get a nice loud backfire.When the car is cooler its fine though.I checked my fan and its in the puller direction like it should be.I think im gona get a better fan,maybe a twin fan that dont draw too many amps.And im gona definatley do a coolant flush on the system when im changing my hoses.Im hoping to get this all squared away and be able to run with a T-stat like im supposed to without worried about over heating.

fast86z28 · 04-12-2003, 03:05 AM

hey is the puller direction clockwise or counter clockwise? I have my fans hooked up to a manual switch, Im pretty sure their going in the right direction, i feel cold air on my hand if I put my hand in front of it..

bigREd car · 04-12-2003, 11:58 AM

you want you fans PULLING air towards you engine and away from radiator...thats if you have fans on the engine side of radiator... did that make sense???
If you have it on the outside of radiator(front nose location) then it is installed as a pusher..

fast86z28 · 04-12-2003, 01:41 PM

ok that makes sense, mine are right then, I just wanted to double chack and make sure I had them setup right.