Forgive me if this has already been covered, it's a bit late, & I've just skimmed the last 20 or so posts... But... Is your air dam still attached? (And not "flopping around"?) If your car's heating up even during highway driving, that's the 1st thing I'd look at. Also - I inadvertently messed my cooling system up (two ways) when I removed my A/C - first, the switch no longer activates my fan, & second, removing the A/C condenser from in front of the radiator now allows air to escape around the sides of the radiator, instead of being forced through it. Like I said, I'm not sure if any or all of the above has been covered, but if not, they should be pretty easy to check, & cheap to fix if one or more of them applies to you. (I'll probably be fixing mine tomorrow...) Good luck!

im having the same problem. 305 tbi to a 350 tbi.....
my radiator makes a sound "like puting droplets of water in a frying pan" ping ping ping, after u turn the car off. Also after u turn the heat on the car has problems keeping cool.

and whats up with the spark knock i get on the highway...i read the post about that.....but does that have anything to do with me still using the 305 tbi injectors? is the temp rising to high and im getting that UGLY spark knock with the high drops in RPMS?
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oh yeah the city and the highway temps get up around 220 then at a stand still my rpms get go UP and Down like a roller coaster while the temps get a little higher.
whats the deal america?

Ive been going threw some stickies and im fairly sure this question hasnt been asked. I have basically a stock 305 with a fairly large camshaft. I have been running a 160 thermostat. I do make my own chips and have all the temps to work with the 160. I got the camaro (1988) stock with tbi. Then it had 185 PSI cylinder pressure. Now with the camshaft, i now have 150 PSI. I am wondering if i would benefit from the 195 having lower cylinder pressure. I would think cylinder temps would be lower with the lower PSI. Im sure someone has done this before. I installed a new intake manifold today and i have both thermostats sitting here ready to go on. Thanks.
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how can i fix this ?

The air dam that you all are talking about, what does it look like? I have a black plastic thing but its curved on my 89 RS by buddy has an 86 and he has the black plastic actually looks like a dam straight up and down does that mean mine is missing since I have nothing protruding down???

i just read the cts link, i got code 15 and a code 23? so i guess i need to replace the senser and code 23 is iat? does that mean the comp is goin crazy cause the temp is normal but the cts is sayin its majorly cold?

K guys I'm new here and need help I bought a 92 Z28 and the guy has converted the TPI 305 to a TPI 350 it's having overheating issues, at an idle it will just keep getting hotter I don't think the fans are coming on when they should which is what temp? Should I wire in a manual fan switch? The thermostat is a new 160 should I go to 180? Hoses and radiator are good and the previous owner installed an edelbrock water pump what next?

something I did to help cool in the summer and still let you have heat in the winter is splice a wire ti the green with white stripe on coolant fan switch wire run it to a toggle... then the other lead from the spst toggle run to ground then you flip the switch on fan turns on. flip the switch off fan runs when tep switch tells it too.

Where is the fan switch on a 92 rs 3.1 V6? Everybody else seems to know on the 305 or 350 but no info on the V6. Or does the V6 even have a fan switch at all?

hey guys, I just picked up a 92 RS with a 305 tbi and the guy i got it from said it would overheat. What should the operating temp be at?? I know this forum says around 220 but how long should it take to get there when idling? The gauge moves very slowly and it takes about 10 minutes to even start to move. I check the temp at Thermo housing with infrared gauge and it would read around 150 so actually temps are probably close to 175. I got this car as a project so dont need to drive it right away I just dont want to overheat and cause problem. The car runs very smooth and idles great. The only other problem is my oil gauge seems low too, which makes me wonder about my temp gauge

Overheating usually is caused by cooling system problems such as old/bad/leaky/squishy hoses, sticking thermostats, leaky radiators(air and fluid) and caps, CLOGGED heater cores DONT allow coolant to pass through them making engine cooling difficult, fan switches and relays, BAD water pumps, leaky intake and head gaskets, air dam spoiler under the front bumper missing or damaged. Overly rich or lean air/fuel mixtures can also cause heat issues. Check all items except intake/head gaskets and air/fuel mixture yourself. Save some money if you can but when you cant,......see below.

If you cant find the problem within a few days, pay the $100 for a professional mechanic that you trust`s diagnostic or opinion.

I have a real puzzel on my hands. I am losing coolant and I cant find were it is leaking. I wasnt having any problems before replacing the belt tenchiner. There are no visable leaks but on a two hour drive the over flow bottle is empty. Maybe a preassure test I dont know. But with hood up and car running still see now leaks cheaking everywere I can see and even lloking at the block I no smoke either. Please help thanks for looking

I just bought an '88 Iroc 350 TPi and the fans don't come on. I rigged up a temporary switch to bypass the relays. The fan works great with this switch but I want it to run as it was intended. So, question. How do I check to see if the fan relays work? I mean the 2 relays by the car battery NOT the ones by the firewall. P.S. I have a dual electric fan setup.

Checking to make sure they work is easy. Refer to the diagram earlier in the thread, for the connections. Make sure it has power (12V) at the coil side of the relay (the brown wire). Connect a ground wire to the Ground side of the coil (either a dark green with a white stripe or a grey wire depending on the cooling system).

If everything else in the circuits are operating properly, your fans should come on. All this does is bypass the PCM's control of the fans by providing the ground that the PCM normally does.
If the fans come on this is the harder part- finding the problem. The fan with a black and red power wire- the ground wire for the relay's coil runs through the PCM to a temp sensor that passes the signal back to the PCM, then to the A/C pressure switch. If either of these components are faulty the fan will not work. The fan with the black and pink wire has 3 possible grounds. The PCM will ground it depending on engine temp, the A/C pressure switch will ground it when the A/C head pressure hits a certin pressure (ie. when the A/C is on), or the heavy duty coolant fan switch will kick it on when the engine reaches the proper temp (above 238* F- not to be confused with the other switch that operates at 228*).
The last switch is the major weak point in the system. The '88 and down and early '89 used a switch that grounds directly to the block. The switch is notoriously faulty, and when a noob installs one, they automatically use thread tape, shellac, etc. This isolates the switch from the ground it uses to actuate the system, and the fan no longer works......... Newer 'birds used a switch that sends the signal to a seperate ground, eliminating the problem.

Testing the various switches is simple. If the A/C is operating (ie cold air is coming out of the vents) then the A/C switch is good. If your A/C is inop- no worries, that switch only kicks the fans on for the A/C, not the engine cooling.

One Note, the primary cooling fan (the black/red) is designed to shut off at highway speeds. The PCM uses the VSS input to determine when to shut it off.

If the fans do not come on, check the power source at the relay for the fans (orange wire) to ensure there is power present. If there is power there, check the wire to the fans (a black and red or black and pink). if there is power at the fans, check the ground wire (make sure there is no/extremely low, ie less than 120 ohms, resistance when checked to ground). If you have power at the fan, and a good ground, the fan motor is faulty.

Personally, I eliminated the PCM control and used an aftermarket controller. It uses a temperature probe in the radiator core, and has a rheostat that allows you to adjust when the fans come on and controls 2 fans, as well as retaining the systems ability to be actuated by the A/C. I picked it up at autozone- compressor works part number 733647- $34.99.

where at did you find this wiring harness because everyone i look at its like 600bucks or more

All you really need to make it work well is a simple fan controller. Some people will wire in a switch on the ground side. While this is hella cheap- it isn;t the most reliable way to go. The fan controller compressor works part number 733647 will turn the fans on and off, keeping them cycling like they should.

Okay i hate an 85 firebird with a 2.8, i dont have the air dam on and i know thats one of the main reasons its over heating, but also the electric fans wont turn on, do you know what may be the reason to this?? broken wire somewhere or something??/

Okay i have a 85 firebird with a 2.8, i dont have the air dam on it, i know thats the main reason it over heats, but my electric fan wont turn on at all, does anybody know what may be the problem??

I took a look at the common questons helpfull. I'm new to this world of third gen I just bought a 1986 Trans Am car is clean and a little old lady owned it. (Really) but while we were working a deal on price she told me that her son in law had used the car from time to time. And here is were my questions start. First he has made mods to the cooling fan wiring system a real butch job loose wires and but splices I would like to put it back to factory specs. I'm in need of some scamatics and most likley a fan harness and factory relay. I'm a transit bus mecanic for the city of Anchorage I do have some mechanical skils but this is not a bus

I checked the power at the relay connectors by applying the multimeter prongs to the relay coil (brown wire) and the relay coil ground (green wire) and it read that the primary fan connector had less than 1 volt and the secondary connector had 10 volts. I put a paper clip between the brown and green connectors to ground them and nothing happened. So I'm thinking it's the wiring harness. Is there a wiring harness for the fans only or do I have to buy the entire harness? Is there a better way to ground the D(brown wire) and F(green wire) together? cause the way I did it with the paper clip caused some sparks to fly.

Oh and that aftermarket controller you bought, does that connect to the wiring harness?

So upon further inspection I discovered why there wasn't any power flowing to the relays. Apparently the Orange wire that goes in the the relay was torn as show here:





Now I remedied that situation and so I have power flowing to the orange wire as well as the brown wire. So I'm happy cause I'm thinking the problem is solved and now the fans will work. Right? Wrong!!!! So I checked the relay again using the multimeter and this time It shows that there is power going to the fan (black wire with red stripe) only there isn't any ground. Great!!!! So I pinpointed the problem and it is here:



/
As you can see, there IS ground on one side of this connector(V) and NO ground on the other side (X). The problem is that for the life of me I cannot disconnect this piece of crap. When I try to wiggle it loose I can see the right side kind of wants to come loose but something on the Left side (the side with the ground wire) is stuck. So maybe this is related to the problem. I'm thinking something melted inside causing this thing to stick together. Does anyone have any suggestions on how to disconnect this thing? Any suggestions would be welcomed with open arms, a warm smile, and a cold beer. lol.

I wanted to ask anyone if I were to change out my stock CTS to one that turns on at 200* and off at 185*, which thermostat should I use? If I used the 195 then the fans should turn on right when the thermostat opens....right???

Thanks!!!

Is that pretty much the normal temp forma firebird? I am thinking about buying one and the owner told me that due to the design it normally runs 230 range. This seems hot to me

I am looking at an 88 firebird. The owner tells me that its normal range is to run at 230 to 240 due to the design and no exposed grill. This seems a little warm to me. Any input out there?

http://www.chevythunder.com/fuel%20i....%20pg%20C.htm

My 91 305 TPI is bone stock and on the highway will hover around 170-190. In stop and go it will float around 200 to 230.

I've searched and searched to find what the "right" operating temperature range is on these cars and I always find different things. Even the owner's manual does not specify a normal operating temperature.

I also have rust in the coolant system, probably from the radiator. The coolant was brown and then turned brown after a flush. It's definitely not oil-contaminated, though.

The normal operating temp for these cars is 220 degrees, G.M had them run hot to ensure emission standards were met, I changed the thermostat on mines to 180 degree and i drilled a few small holes and it runs so much cooler and you can feel the engine has more power.

Please excuse a Noobie if this question is just downright dumb ,but here it goes. I am rebuilding my 1988 GTA -350 TPI after an accident. The dual fans were smashed and I have everything ready to make her road ready but the fans and brackets. Can I use the single fan from a parts car I have (88 Formula TBI ) to get her running and driveable until my other parts come in ??

I wouldn't see why not as long as you get it to come on when your running hot AND when the AC is on.

Cooling fans come on around 235, so 230-240 is gettin pretty hot, you sure the gauge is reading right? I'd get a temp gun and shoot the water outlet to double check. Its not supposed to have an "exposed grill", the cooling system draws air in from the bottom.

Yeah shouldnt be a problem as long as you have the right top and bottom bracket, and your gonna have make a good connection to the harness , i would solder it and shrink wrap it since those wires get pretty warm sitting there by the rad.