What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

Camaro overheating

JoshHefnerX

JoshHefnerX

3/4 ton status
 Premium
Joined
Jan 7, 2015
Posts
7,311
Reaction score
6,550
Location
Glendale, AZ
Need some help on this one. Bit of a saga here.

My 98 Camaro has had a problem w/ overheating in some circumstances. They’re pretty particular.
Over about 85 Ambient

Idle to low speed. Temperature will creep up slowly to where I either have to drive quick or shut it down. I usually do that around 230.

Above about 35ish the temp will drop quickly. Like a degree a sec and stabilize in the low 190s

When this started the fwy speeds were in the low 210’s generally at any ambient. With A/C on.

The first time this happened, it boiled over. I could hear the overflow tank boiling.

I started simple, replaced the thermostat. No change.

Tested for exhaust gas in the coolant. None found

Replaced the radiator (DeWitts) and got some improvement It took longer to ‘runaway’ at idle and the fwy temps are now really good – as listed above – low 190s

Replaced the fan relays. No change

Noticed I had a leak from the water pump. Replaced. No change

Figured if the fwy speeds were good, this must be an airflow issue. So I’ve tried several things.

Replaced the fan assy w/ a Dorman. No change

Replaced the stock fan motors w/ Delco branded. No change

Got sidetracked and got back to it recently.

Decided to take my variable power supply to run the fans separately. To see if I’ve got an electrical problem.

The high-speed circuit will cool the car down to the fwy temps at pretty much any voltage. I’ve mapped the voltage/rpm as follows. The higher voltages will drop the temp quickly like a degree every sec or so. Even from as high as 220deg.

High-speed:
11.9v 2300 RPM – temps fine
13.2v 2680 RPM – temps fine
14.1v 2780 RPM – temps fine
-
Low Speed: will not keep the car cool at all – at least at these ambients (105-110)
11.9v 1400 RPM
14.1v 1480 RPM
-
Running the fans off the car I noticed the following:

Voltage starts at 13.8 (same as no fan) However, over time the voltage will drop slowly. Not much but it does – 15mins or so is down to 13.5

There’s a .3 v drop between the battery and the fan plug

However, at any voltage I measured above the fans would run at 2450, which is 200rpm plus lower than off my power supply.

Which leads me to questions, I need thoughts on.

If the voltage is the same – it must be amperage starved to not be able to muster the same fan RPM?

This was tested inside my garage – so no direct sun. Would this have made that much of an effect – as the last time I messed w/ this it would creep up at idle?

The voltage dropping as it runs – makes me wonder if the alternator is suspect – 13.8v seems on the low end of normal for an LS engine but 13.5 may be low and it was still dropping when I shut down. HP Tuners didn’t have any settings that I could find that would control this. These particular alternators (the f-body ones) are similar but not the same ones as truck alts but are lower amperage rated – something like 110 ish max. They’re also known to fail when the power steering leaks onto them from above. Which this was prior, and I’ve since stopped that up.

Is a .3v drop unusually high? Such that I need to look for weak connections, grounds?

This cars tune has been played with, and not very well. When I was doing a clutch job on it, I pulled the back cover and discovered a baby cam in it. Most reviews on this cam stated a tune is borderline between being able to idle or not. I also have shorty headers.

Can a tune realistically be so bad that it could run hot at idle/low speeds?

Also, I was unable to test w/ the a/c dumping heat into the radiator as I think the charge is low. It has a small leak and it would kick on, but not stay on. The few sec it would kick on whether the fans were on my power supply or the car would increase temps for a couple of sec.

Any thoughts? Anything I should test?
 
If your battery is low the alt charging voltage will be lower. Need to prove the battery good before condemning the alternator.

As the fans run the circuit will heat. Heat requires more voltage to force the amps through.
The fans are good your supply proved that. I would give thecwiring and esp the fan plugs a good inspection. Including removing the spade terminals from the plug, check tension, crimp and corrosion
 
The battery isn't factory fresh but pulls 650+ amps on test. (out of 720) and spins the engine over w / vigor. So that should be ok. The plugs are a good one. I've got some of those poker keys that are supposed to allow disassembly. Never had much luck with them but def will look at.

I knew tunes can cause some problems - but wasn't sure in reality if anyone had some definitive info on that. I know it's stinky, and doesn't stabilize well after letting off the throttle. If I could get the heat problem straightened out I'd prob take it to a tuner.
 
There’s plenty of remote tuning options available for the LS platform. It’d be worth the few hundred bucks to have them dial that in.

There’s not much else to a cooling system you haven’t replaced. Maybe a hose collapsing once it gets hot? Fans wearing out?
 
JoshHefnerX said:
The first time this happened, it boiled over. I could hear the overflow tank boiling.
Click to expand...
The car should not boil at 210F. Some modern cars run 235+ on purpose. At atmospheric pressure, water or antifreeze will boil, but this is why the system has a pressure cap. The pressure raises the boiling point (i.e. physics), so either the gauge is wrong or there is a leak. This could be almost anything from head gasket, intake gasket, radiator cap, hoses, etc. Are the radiator hoses soft when the car has been sitting and then hard when it gets hot?

centexk5 said:
I can’t remember if it’s too much or too little timing can cause it to run hot so that’s something to look at.
Click to expand...
Retarded (late) timing makes the manifolds hot and the heads/engine to a lesser extent. Running lean also makes a gas engine hotter.
 
centexk5 said:
There’s plenty of remote tuning options available for the LS platform. It’d be worth the few hundred bucks to have them dial that in.

There’s not much else to a cooling system you haven’t replaced. Maybe a hose collapsing once it gets hot? Fans wearing out?
Click to expand...
I have talked to one remote tuner that is fairly well liked but didn't like the fact that he'd lock down my ecm.

Fans have brand new motors in them.


Blue85 said:
The car should not boil at 210F. Some modern cars run 235+ on purpose. At atmospheric pressure, water or antifreeze will boil, but this is why the system has a pressure cap. The pressure raises the boiling point (i.e. physics), so either the gauge is wrong or there is a leak. This could be almost anything from head gasket, intake gasket, radiator cap, hoses, etc. Are the radiator hoses soft when the car has been sitting and then hard when it gets hot?
Click to expand...
It didn't boil at 210. The first time I caught it hot it was over 240 and there wasn't a safe place to stop.

But hoses are new and I've not seen them collapse. Not sure if they would even still at idle. The low/no speed is when the heat is the problem. FWY speeds are excellent. Head gasket was checked w/the chemical tester in the rad. And that was good. The hoses do harden a bit when it's at temp so it's holding pressure.

I may do some more digging into the tuning options. The 98's run an older and harder to get pcm, not the 0411 that's common.
 
Forgot, one question I had was, whether or not the low speed on the fans should be capable of cooling the car at idle? They're def not up to the task - not even close. What's the purpose of the low-speed circuit of the fans if they're not even close to being able to cool the car at idle?
 
Well they probably could at say under 90°F,but not at 115°.

I notice a difference in my AC ablity to get cold quickly takes longer over 105° in the 01.
The 77 goes to middle temp guage but the ac still gets cold quick
 
JoshHefnerX said:
Forgot, one question I had was, whether or not the low speed on the fans should be capable of cooling the car at idle? They're def not up to the task - not even close. What's the purpose of the low-speed circuit of the fans if they're not even close to being able to cool the car at idle?
Click to expand...
Obviously, they are for some condition other than standstill when it's really hot out. A lot of the factory calibrations are really conservative with the fans because they are considered a negative for NVH. Some won't come on until the water gets to 225.

When you say the voltage drop is 0.3V, is that the total voltage at the fan, or the drop in just the supply wire? If B+ to B- is 14V and between the two fan terminals you have 13.7V (under load, of course - with the fan unplugged it means nothing), I would call the wiring good. It sounds like you are considering heavier wire or an external relay. That could make a difference, as the power is proportional to the square of the voltage.

If the alternator is old enough to be stand-alone controlled (not controlled by the ECM), you could probably add a diode to the sense line and increase voltage to the whole car. A Schottky diode would raise it by about 0.4V. If that worked, you could get fancy by having a relay increase the alternator voltage when the fans turn on or something like that. Assuming an older alternator, a simpler idea would be relocating the sense location to some place that sees more droop when the car is under higher load.

JoshHefnerX said:
If the voltage is the same – it must be amperage starved to not be able to muster the same fan RPM?
Click to expand...
The resistance of the motor windings goes up as the motor gets hotter, which can make it slower at the same voltage. A DC motor is kind of a balancing act because as it spins, it's also a generator, making a voltage proportional to the speed (back emf). Simplistically, the current through the motor is (input voltage - internal voltage)/winding resistance.
 
JoshHefnerX said:
Forgot, one question I had was, whether or not the low speed on the fans should be capable of cooling the car at idle? They're def not up to the task - not even close. What's the purpose of the low-speed circuit of the fans if they're not even close to being able to cool the car at idle?
Click to expand...
Yes, the fans on this body style will cool down at idle. Presuming your tests were good, sounds like they are getting voltage

When the ac is on, fans should be on. You can test that cool at idle
If the tune is the only thing that changed, I would be suspect
Otherwise check the coolant quality and flow
 
Blue85 said:
Obviously, they are for some condition other than standstill when it's really hot out. A lot of the factory calibrations are really conservative with the fans because they are considered a negative for NVH. Some won't come on until the water gets to 225.

When you say the voltage drop is 0.3V, is that the total voltage at the fan, or the drop in just the supply wire? If B+ to B- is 14V and between the two fan terminals you have 13.7V (under load, of course - with the fan unplugged it means nothing), I would call the wiring good. It sounds like you are considering heavier wire or an external relay. That could make a difference, as the power is proportional to the square of the voltage.

If the alternator is old enough to be stand-alone controlled (not controlled by the ECM), you could probably add a diode to the sense line and increase voltage to the whole car. A Schottky diode would raise it by about 0.4V. If that worked, you could get fancy by having a relay increase the alternator voltage when the fans turn on or something like that. Assuming an older alternator, a simpler idea would be relocating the sense location to some place that sees more droop when the car is under higher load.


The resistance of the motor windings goes up as the motor gets hotter, which can make it slower at the same voltage. A DC motor is kind of a balancing act because as it spins, it's also a generator, making a voltage proportional to the speed (back emf). Simplistically, the current through the motor is (input voltage - internal voltage)/winding resistance.
Click to expand...
The .3v drop is between the fan plug and the battery. Meaning 13.7 at the battery, 13.4 at the fan plug. Now that was measured w/o the fans actually on - I didnt want to poke insulation, but may end up stripping that loom down.. There is a relay box in the engine compartment that I may be able to access the wires on the back of that.

The alternators on these are pretty shitty from the factory - a lot of guys swap out for truck alternators. They're bigger cased so you lose the rear support but much better alt.

The heat in the motors may or may not have been - I did a couple of sessions while I rewired things and ea session was prob 20min ea. So things were well up to temp. I took measurements throughout the test. That being said 20mins in running on my power supply didn't seem to slow the fans down when hot. At least not appreciably.


Bent77 said:
Yes, the fans on this body style will cool down at idle. Presuming your tests were good, sounds like they are getting voltage

When the ac is on, fans should be on. You can test that cool at idle
If the tune is the only thing that changed, I would be suspect
Otherwise check the coolant quality and flow
Click to expand...


Stock the programming on these set the fans to high when the a/c is on. My a/c is inop at the moment I believe due to low charge. However, like everything on this car it's another crap job because of tight confines. The low service port points right at the EGR valve and doesn't give room to put anything on the port. So I'm gonna have to try to gently move the egr valve and see if I can get one of my lines on that port. It was 108 out and I said ****it today.. lol

All that being said. The tune change did include lowering the fan temps such that the high circuit is engaged pretty much any time the car is under 35mph.

Coolant and water pump are new. And it seems to cool plenty fine at any speed above 35 which is why my focus was on the fans/electrical. And by fine above 35mph. It's immediate. It will drop 1+deg per sec or so down to the low 190s w/ the a/c on (when it was running last time I drove it..) regardless of ambient. Independent of rpm.
 
.3v drop from battery to plug id excellent. Back probe the plug connector for a voltage drop with fan running
 
JoshHefnerX said:
The .3v drop is between the fan plug and the battery. Meaning 13.7 at the battery, 13.4 at the fan plug. Now that was measured w/o the fans actually on -
Click to expand...
Measurement with no load doesn't really tell us anything. I'm going to take that as B+ to B- and the two connector pins relative to each other.

On a sealed connector, you make be able to pull the front seal and run some magnet wire out of the terminals to measure voltage. The standard way is the long skinny back-probe leads stuck between the wire seal and the wire insulation to touch the terminal from behind. You can damage stuff if you're not careful.
 
Well, I managed to get the a/c charged. And the fans would not hold temp at all. Fans were on my power supply (so it could be controlled) and even w/ a fairly high voltage it would rise about 1 deg a min. Shut the a/c off at 220 and the temps started dropping fairly quickly. Hood down had a small negative effect, but not terrible.

So, are my fans still inadequate. If so, why? The car isn't that wildly different from stock.. And this is at idle - if I was driving at low speeds I'd be using a bunch more power.

Could the a/c be somehow defective that it's adding an unusually immense amount of heat?
 
I’m going with tune. Problem started at its install?
 
You must log in or register to reply here.

Latest Posts

Top Bottom