ok i have an 86 iroc-z with the 5.0 fi engine.... single cooling fan also.... ever since i bought the car a few months ago it tends to overheat after only 30 min. of driving or so.... being in louisiana... this thing has to hold up to hot days lol... so far i have flushed the radiator and changed the thermostat.... the fan didnt work when i got it so right now i have it rigged to run constantly.... water pump APPEARS to be working due to the sloshing in the radiator while running.... sooo whats my problem here...lol? bad radiator?... or is my pump bad even though i see the coolant sloshing in the radiator... btw when i flushed the radiator, there was a TON of rust mixed into the coolant....

come on any ideas at all?? also the air dam is still in place....

Have you checked the lower radiator hose ?
If it soft while hot, it can collapse while driving restricting water flow from the radiator to the pump.

At idle, the water pump isn't moving a great deal of coolant. The faster the pump spins with engine speed, the more it draws water from the radiator. If the lower hose is bad, it will collapse, like pinching it off with a clamp.

There are other things too like, good radiator cap to maintain system pressure. How well the water is actually moving through the radiator. If the tubes are clogged with corrosion and 'rust', it can still move water, just not efficiently.

Just a thought.

ill have to check that one...

Also, check to make sure your air dam is on tight. I've had the bolts loosen up on one before and the car would run hot because the air dam was pushing back under the car a little when driving.

Could be something as goofy as a sheet of paper stuck on the front of the radiator, blocking flow. Regardless, i'd clean it.

JamesC

bump....

I'd say most likely the problem is the radiator's water
passages are dirty with rust-probably will need removed
for a good mucking out..Other possible causes are tree
fuzz,leaves,dead bugs ETC built up between the
radiator and condenser and or condenser fins mashed
over and blocking airflow.

For what ?

Did none of the above suggestions work ?

If you're going to 'bump' your post... how about an update.

We aren't psychics....

It's amazing how much crap gets in there.

How much is your car overheating? Are you talking right into the red zone?

cleaned the fins, and same thing.... not quite red zone but well over 220 and i can hear it boiling in the overflow when i shut the car off...

You did refill with the proper mixture of antifreeze and water after flushing right? Like deadbird said, could be faulty radiator pressure cap or hose collapsing

head gasket leaking?

unlikely for head gasket leaking... no loss of oil... except for annoying oil leak... thats another story lol... and no coolant loss... no mixing that i can see of either also.... guess ill replace the radiator and see what happens...

What is a condenser and or condenser fins? TIA

I'm having a pretty much similar problem and I didn't want to start a brand new thread.

Here's what I have a carburated 87' 305. Dual fans which runs from the time the car is started until its turned off. I just put in a new radiator today. When I ran the engine at idle for a little bit.. The coolant overflow container was boiling and looked like it was going to blow up.

Is this a thermostat and or water pump problem?

I just checked my lower radiator hose. It's very rigid. I can't pinch it together like I can with the top hose. It feels like there's something in there. Is that not normal?

Is this something that would cause my coolant to boil in the overflow container?

Thanks in advance!

The condenser is the 'radiator' looking thing, in front of the radiator. It's for the A/C.

Some manufactures will put a spring in the lower hose to help keep it from collapsing.

If the coolant temp is reasonable (normal range up to 220-ish°F), and the recovery tank is 'boiling' (bubbling), you may have a radiator cap with to low of pressure or, it has a bad/weak seal.

Thanks for your answers.

I untightened and tightened everything. Abused the hoses a little bit knocked on everything I could think of. I re ran the car.. drove it around. It looks to be working fine now.

There's no way for me to monitor the coolant temp. Any suggestion as to what I should buy and install in the engine compartment?

A temp gauge would help. I would get preferably an electric one and run it to the dash not the engine compartment. Would be safer to know the temp while you are driving rather than having to open the hood and check.

My dashboard is not functioning. I just bought this car and I'm not at the point of repairing the interior right now. Hence the engine compartment comment. Is that the only option?

Well, a temp gauge isn't expensive and it should be the top thing on your list if you know your car is overheating. A temp gauge is a LOT cheaper than having to replace an engine. If all the gauges on your car aren't working it's probably a simple fix and could be something as easy as a blown fuse.

Yeah. Ok, thanks for the advice.

All of my fuses are in working order.. I have plenty of spare fuses too. The only thing that works in my dashboard is the MPH gauge. Everything else is fugged. Not to mention the brake/turn signals (no it's not the blubs/fuse LOL) I'll work on that section tonight and come back to you guys for advices! LOL But that's going away from the content of this thread. I'll start a new one tonight if needed.

i replaced the radiator cap and... well the tep climbs high on a hot day with the a/c off but cools back down at cruising speed... which is normal... HOWEVER if i run the a/c too then it stays constantly hot.... reccomendations??

For some reason 'MPH gauge' is funny to me. I think most of us say 'speedometer'. And you probably have a car with a mechanical speedometer, right?

Cory, did you ever replace the radiator? How hot does it get now, after just replacing the radiator cap?
Before you replace your radiator, you should at least try and clean it out and see if that makes a difference.
I wouldn't even worry about the temperature unless it was getting close to the red zone on a stock gauge. Today it was 85*+ where I live, and around town, my temperature gets over 230*, and I don't have any problems associated with that.
When you run the A/C and it gets 'constantly hot', how hot is that?

Ok. I'll keep that in mind.

With the A/C on, the fans will be drawing heat off of the condenser which, is right in front of the radiator.
The hotter the temperature is outside, the harder it is to cool things down.

Please define hot, in degrees.

it gets up around 240 ish... would replacing the water pump with a heavy duty style cool things a bit better?

I don't know but, my 88 runs pretty warm on hot days too. Especially at speeds under about 40 mph.

There is always that option in the sticky post. I think it's called something like Willies total fan control or, something like that.

Well, you're the one who stated you didn't have money to work on your interior when somebody stated you needed to get your temp gauge working. It's only common sense that you can't really fix a cooling issue if you don't know how hot your car is running.

By the way, the reason your speedometer works and your other gauges don't is because your speedometer is cable driven and the rest of your gauges are electric. If your fuse is good you probably have another electrical problem somewhere that is affecting your gauges.

Im not saying you have to fix the one IN your dash, just get one and run it through the firewall and mount it on/under/on top of your dash. Probably cheaper that way then replacing the stock in-dash temp guage, unless its only the temp sending unit thats bad, but if that were the case I think your car would idle rough when you start it.

(You're thinking of the coolant temperature sensor)

From the few camaro's ive owned, all of them came to me with overheating problems and it is a pretty simple procedure to find out whats causing it.


First off, check and see if the water pump is doing its job. Take out the thermostat, leave that hose off the theromo neck, start the car, withing seconds water should be gushing out, if not water pump is crap.

Replace the thermostat 190 is a good temp "mise well you already have the neck off and its cheap"

Check and make sure you have an air damn. Its a big long black wing looking thing that sits under the radiator. Its the thing that grind on the ground when you hit a steep incline or speed bump. If thats not there, you will more then likely over heat @ speed.

Check your cooling fans, I seen it said you have one fan. On the passenger side on the block/head there will be the coolant temp switch, which turns on the fan @ 200something, it does this by ground itself. Id take off the piggy back and ground the wire, if the fan turns on, CTS wire and piggy are good, now if the fan came on, time to check the CTS, so plug the piggy back, back in, and start it up, let it warm up to almost the red, if the fan does not come on, your CTS is bad. If the fan didnt kick on when you grounded out the CTS "remember your key has to be foward in the start position then your fans relay, wires, or fan has gone bad. To simplifi this, you can hook up a Ground and Power wire from the battery and take the piggy off the fan, touch the wires to the fans male pins, if it fires up, then the problem is between in the wires/relay.

Make sure your catch tank "overflow" works and has the correct fill level.

Check the condition of the hoses. Let your car warm up again, till almost red, pop the hood, and rev it up pretty high by hand, watching the hoses for collasping.

Double check your hoses and make sure their all hooked up to the RIGHT respective places and are not mix around "which is fairly easy to do". Nothing should be bypassed, even the heater core.

To check and see if your radiator is crap, with the car pretty warm, about 3/4 guage.
Take a garden hose and let the cool water run down the front of the radiator for a few mintues you should see the temp start dropping drasticly. If it barely moves, you got some pluggage somewhere.

I wont even suggest a blown head, if you blow a head, odds are you will know.

Check the car's timing, if its running way lean or rich it could cause excessive heat to build up, same with a partialy plugged exhaust system.


"A bad CTS will do nothing, exactly nothing, its the switch that turns on the primary fan"


If i missed anything, or forgot something mybad, its almost time to go home, and sometimes my fingers move faster then the brain lol.

Hope this helps in your trouble shooting efforts, its helped me.

thanks for the info man i will try everything you suggested and let yall know in a few days....

Yes! thats it, haha. The temp gauge sending unit is under the manifolds correct?

Correct.

ive beeen having the same exact problem with 86 iroc, but i know its not the water pump because i just put a new one in. i think it could be my radiator cap because it is kinda loose to where air can get pass in and out. so im going to try and see if that helps and if not it may be the hoses on the bottom of the radiator.


a lot of detailed info on here, thank you everyone who gave out advice and for coryprine hope everything turned out great for your car

ok update for my issue...... replaced the radiator, upper and lower hoses, thermostat and coolant flush..... damned car is STILL getting up towards the 240 mark when running the a/c... stays about 190 ish without a/c on..... maybe i need to go to a heavy duty water pump??..... also whats the best way to clean the condenser fins out.... might have a lil pluggage action going on blocking airflow....

If your cap is loose and air can get out I would imagine it would be spraying coolant out of it.?

I use compressed air

hey its 50/50 on the coolant, ---->what i do is get a big tuberaware from the closet and mix a gallon of distilled water(filtered with no minerals $1, not the machine water, just DISTILLED)---and i mix that with a gallon of Peak coolant-yellow- stir it and put it in the radiator... oh and i also make a back up and keep in the trunk... I also disconnect the top radiator hose and pour 50/50 mix down into the hose that goes through the engine to PREVENT AIRLOCK, and connect it together again really fast (spilled some) and next i run the engine until the top hose is really hot --->with the cap off the radiator and constantly top it off to help bleed any airout. I had an install one time that had airlock and man----it got hot hot hot fast. i did the above procedure and was able to drive around later with no problems. im thinking of upgrading the cooling system next year, with heavy duty pump, chip, cooler thermistor lower sensor, 160*mech thermo stat. it will run at 175* all the time....only possible with a different chip, because with the stock chip, if u get a lower mech thermostat than 180* u run into problems with the computer. the computer needs to have a 190-235* operating temp in order to have clean emission to pass smog and stay on the road.,(compromises.) -mikey -i need (brake thread) answers BTW

Corypine -
190 without A/C
and 240 with A/C on?
I wish mine ran that cool!