[bighom20]

So does a bad cap cause car to heat up more than normal? i cant really tell if my fans are turning on cant really hear them, also when my temp gauge gets a lil paste 3/4 right before the line the temp gauge needle then goes right to the middle or i little before the middle, maybe fans turning on, Today i noticed when my car has been running for a while and i parked after driving for about an hour on city streets i noticed coolant dripping from driver side of bumper. I then opened hood and saw coolant tank not over flowing but it did have some coolant leakeage cant really tell where but its not a lot. So im thinking is there hoses under bumper? cant be then im thinking is radiator bad? possible but this leak i saw today dont happen often just after long city driving. Lastly could it be a pressure thing? I dont know any advice on this?

 

[bighom20]

If everything is working correctly you do NOT need to screw with the PCM. I live in Phoenix & run a 180* stat, never have an overheat problem...does it get up past 1/2 way on the gauge in city traffic...yes, my primary kicks in at the first mark above 1/2 , shuts off at the 1/2 way mark. When my pri. fan motor died it would get the to mark just before the red before the sec. fan would kick in....still didn't overheat/boilover. Not a 50/50 mix of antifreeze = boilover, bad cap = boilover, no fans while siiting still = boilover. That's just the way it works in these cars. The PCM stuff is when you install a 160 stat...THEN program the fans to come on a little bit earlier. Really , any other advice is pretty much rednecking B.S. IMHO. Unless someone lives in a hotter place, and can justify why they did what they did.

So your saying your fans kick on at half way on gauge? can you hear when fans are kicking on? its weird that i cant hear my fans come on but ive done the test to see if fans are good relays are good and took sensor off water pump while car is running and fans turned right on. Reason i ask this is because u say ur fans comin on at half, and it seems my gauge when driving thru city for awhile and lots of idling it gets to 3/4 alot, but idk if thats normal or not

 

[bighom20]

Also im thinking maybe i need bleed the coolant, idk if air bubbles can cause overheating or high temps, but its a thought.

 

[Gregg-O]

If you see the gauge drop, and your not running down the road for any length of time and you see the temp drop, then yes, that is your primary fan kicking on, it kicks in around the 3/4 mark, can't be exact as the gauges are not perfectly accurate, then it will shutoff around the 1/2 way point...also keep in mind that the engine driven WP does not flow full until 1800-2000 rpms, I found this out when my pri. fan was out. , Keeping the revs up around that RPM helped to keep things cooler. If you let it sit in your driveway with the hood open you should will see then fans kick in & out, you will probably never see the sec. fan run if everything is working correctly...I haven't except when my primary fan was shot. Putting a manual fan switch in can also hamper the cooling if you keep them on during 35+ mph running, you don't need a fan at this speed, or any speed above that, a running fan will actually slowdown the air passing thru the radiator, thus causing you to run hotter.

Alot of air in the system will cause an issue, I believe that smaller one will work their out way after a few heat & cool down cycles. You can always park somewhere with the front angled up and lossen the bleeder vavle a little and see what happens, you might get a little air out if the system has been opened up for any reason in recent past, otherwise I doubt you will get much.

 

[bighom20]

Then why am i getting some coolant leak on driver side under bumper? its not alot and it only happned twice so far, where is this coolant coming from? is it radiator drain plug loose or something?

 

[96SSbbb]

Then why am i getting some coolant leak on driver side under bumper? its not alot and it only happned twice so far, where is this coolant coming from? is it radiator drain plug loose or something?

Drain plug would be the first place I'd check also, and if its leaking you can be it sucking air.

 

[bigakphilly]

Did you happen to check those big fuses in the fuse box that powers both fans?

yea... i replaced the fuses and the relay's... today i just did the cap, no luck... fans wouldn't turn on. I didn't let it get to boiling point where it overflowed though. I just turned it off knowing it would get there.

 

[bigakphilly]

What I am trying to figure out here is, why my primary fan is not coming on. The car is not over heating because of a cracked head, or a leak somewhere. The car is over heating because the fans do not come on. Primary or Secondary.

I just replaced the cap today... it did the same thing. Once it got to 3/4 i knew it was just going to over heat and bubble out as usual, so i just shut her down before that happened.

I let it cool off for an hour or so, and just unplugged my water pump sensor. by doing this, it took a little longer to start, but both of my fans came on and stay on the entire time. This is fine, but the reason why it is doing so, is because the computer thinks my car is 2 million degrees, and dumps more fuel into it. So now on top of a gas leak that i cant seem to find, i have this. Sunoko is going to love me until i figure this out haha.

I am just at a loss for words... I may just run a switch and manually do the fans. I have now replaced, thermostat, both fuses, both relays, cap, water pump sensor and fans are still not coming on..

HERE IS A QUESTION:

How many water pump sensors are there? 1 or 2? I know and replaced the one, to the bottom right hand portion of the water pump. but is there another one somewhere?

 

[Gregg-O]

Does the pri. fan run with the A/C on?

 

[SSweet9C1]

Gregg, Why let it boil over and get really hot when you don't need to? I live in upstate NY and as previously stated have seen my temp get needlessly hot, so when getting pcm work done, had the fan temps turned on sooner... cheap insurance... You don't have to run a cooler Tstat to have the fan temps kick on sooner. If it is even close to boiling, you are WELL above 180* and the stock Tstat is already open. How is that rednecking anything??

 

[SSweet9C1]

oops I was replying to Gregg-o's last reply on Page 2

As he pointed out, you don't want to run the fans constantly, just when sitting in traffic when the temp rises...
Also as stated, don't unplug the coolant temp sensor. Fuel mileage sucks, and it takes for ever to start.. Just turn on AC, and check to see if the secondary fan kicks on.. It should..

OP: You never answered my question.. Is your AC charged and blowing cold?

Also there are two coolant temp sensors. One on the water pump. This is the one that matters, and goes to the PCM

The second one is on the side of the engine IIRC it is on the pass side, but I could be mistaken... This just goes to the instrument cluster.. IF your engine is over heating and coolant comes to a boil, then the gauge is probably working

 

[rickSSimpala]

Did u change the pig tail when u replaced the temp sensor? Did u recently put in a 160 stat without reprogramming?
I put a 160 stat in my car without reprog it and the fans would not turn on at all.

 

[Crime Scene 96]

With the leak on the driver side bumper. Could be as stated a drain plug. I'd also check the bypass line from the coolant housing to the throttle body as well as the line under the throttle body going toward the rear passenger (the rubber portion). Also get a good good look at the radiator to make sure it isn't busted anywhere...

The fans should come on right a 3/4 to the red. At least mine does as this may be normal for our cars.

 

[SSweet9C1]

Hmm, I should change that to "turn on the AC and one of the fans will kick on" For some reason i thought it was programed by GM to kick on the secondary one so it gets some use... I could be wrong.
the point is the same, regardless of which fan the AC turns on.

I agree with kicking on the cooling fans at a lower temp than factory... I think 160* tstats are overkill, but to each his own

Jonathan

 

[Gregg-O]

OK. I'm not saying that the factory fan setting's are the best, just that if everything is working ok you should not be having a boil-over issue. Can you program them down a few degree's...of course, and you probably aren't going to hurt anything, the high setting from GM are due to emissions more than anything else. If you use a reprogram to 'fix' an over heat issue you WILL have a BIG PROBLEM sooner or later as you never addressed the real problem in the first place. Like a stuck T-Stat or a clogged radiator or heater core, or a collapsed hose, or a impeller going out in the WP, or a bad mix of antifreeze, or a bad cap, or a pin hole in a head gasket. Not trying to piss anyone off here just trying to pass on some real world 40+ years of playing with cars to some of the younger crowd, believe me I have jury-rigged/ rednecked just about anything you can on a car over those years...lol.

We here cannot tell what shape guy's car's are in. I think alot of these guy's just see the gauge go up more than normal once and a while and don't take into account what kind of driving they are doing at the time. These cars are 15+ years old, mine is pretty much stock and I pay attention to the cooling system a bit more due to our summer heat here. I ran my car for about a week on just the sec. fan in the middle of summer. It was fine on the open road, but in city stop & go it would get with-in hairs of the red before that fan would kick in, plus at idle the WP isn't flowing at peak...the one reason I may go electric soon. It still never failed me and never boiled over.

 

[Marky Dissod]

Sweet9C1, the primary fan ALWAYS comes on before the 2ndary fan, unless something is wrong with the fan circuitry - it's the primary fan.
When the AC is on - not just requested, but actually ON - the primary fan comes on @ 189 psi, and the 2ndary comes on @ 240 psi.

GM programmed the fans to come on at approx 229°F (primary) & 234°F (2ndary). If everything else in the cooling system is working properly, then those turn-on temps are on the high side of acceptable. (In other words, technically, I can agree with Gregg-O and GM.)

That said, and regardless of the condition of the cooling system's components, can anyone - ANYONE - plausibly explain why fan turn-on temps of, say, 220°F & 225°F are a bad idea?

I personally prefer fan turn-on temps of 203°F & 212°F for the winter (with the 180°F thermostat, of course). Are these temps a bad idea?

I'll admit that a 160°F stat with turn-on temps of 185°F & 194°F are unnecessary, but Gregg-O, have you tried 'em? The engine doesn't seem to mind - maybe because I deleted all motor oil cooling provisions except for 0W30 - and my AC blows colder in the summer for it. (NYC heat AIN'T a dry heat.)

Lately, a lot of people are complaining of overheating. Unless the needle actually touches 'the red', they may be exaggerating [if only by just a bit], but they are experiencing unnecessarily high [head] temps [as reported at the dash temp gauge].
If the [dash temp gauge] needle is 7/8 to the right, that's enough already.

Please don't take any of the above the wrong way. I'm actually asking the above questions in the hope of reasonable responses. Until then, I consider fan turn-on temps of 203°F & 212°F preferable to the point of general recommendation. Further, I'll admit that colder turn-on temps may be unnecessary, but there's a wide gap between 'unnecessary' and 'overkill'. Same goes for the colder thermostat.

 

[Crime Scene 96]

With all the new school cars after 96, they make the fans come on at the halfway mark. Sounds like a pretty good idea with re programming these big bullies we drive. Ya know!

 

[cletus284]

I
I had this problem in my first 94 9C1 and did exactly what you have done.. replaced everything.. turned out that if the AC system is NOT charged, the fans won't kick on.. BUT if you turn your AC on, (working or not) it will turn on 1 fan (iirc its the secondary)

Wrong on both counts. The PCM will still command the fans on whether or not the A/C is charged once the temperature thresholds are reached. When you turn on the A/C, the PCM will also activate the primary cooling fan, assuming there is pressure in the A/C system. This is the only difference.

 

[cletus284]

Please explain why a bad cap would CAUSE overheating? It would cause coolant to boil at a lower temp, but not cause the temp to go up (unless you somehow boiled all the coolant out, but that is a different story)
A bad cap shouldn't cause an increase in engine coolant temperature.. Please correct me...

Simple. A bad cap won't hold pressure, and will allow the coolant to boil before the temperature threshold is met to activate the fan(s). Boiling transforms water to steam, which, at atmospheric pressure, takes up 1600x the volume of the same mass of liquid water. This rapid expansion will rapidly blow large amounts of coolant out of the system. If you don't believe me, get your car good and hot, shut it off and immediately open the cap. It'll be like a geyser, especially if your coolant is old and weak.

Plus, like others mentioned, the steam can render the water pump useless and will create 'hot spots' in the engine as the thermal conductivity of steam is nowhere near that of water.

 

[kpeters59]

On my '96, the fan relay sockets were in bad shape. The fans would come on for a visual inspection, but in reality, they were not turning at full speed due to the voltage passing through the relay sockets to be lower than 12v.

Head temperatures would drop when vehicle speed increased. That turned out to be the major clue.

Innovative Wiring's fan relay kit cured that problem...plus new fans.

-KP