Cooling Problems...Battery related?

Rob · April 26, 2008, 11:31:09 AM

I was having a dual problem with my cooling system. It was running cool when I was driving it (never above 120) but when I stopped @ a light etc, it quickly went up to 225+. I replaced the thermostat, that solved the too cool problem, but it would still overheat in idle. Coolant level is OK and reasonably fresh (1 year). Then last night I noticed that my headlights dimmed @ idle too. Acting on a hunch, I ran the car this morning until warmed up, let it overheat, then stepped on the gas while in park, and the temp started to drop again. Over the winter, I would occasionally hook up a basic battery charger set to the lowest setting (5 amps) and "top-up" the battery, but one time I forgot and left it for a few days. My voltmeter drops to below 12 volts in idle and I'm beginning to wonder if I screwed up the battery by leaving it on the charger too long. It's a Opitma red-top by the way. Would this make sense? I would rather not buy another battery if not necessary, but I can't think of anything else. I'm going to clean the rad as a "hail mary", but it would appear that the rad isn't getting enough airflow @ idle only, and this was never a problem in the past. I certainly can't leave it like this, because when the temp outside hits 90 and I have the A/C running, the problem will only get worst. Up till now, the only time I start to go above 200, is in the middle of summer, 90 degrees, A/C on stuck in heavy traffic. Like I said, if it's doing it now in 70 degree weather, no A/C, I'm going to have big problems later on.
Any thoughts or suggestions would be greatly appreciated!
Thanks
Rob

wayne petty · April 26, 2008, 12:42:46 PM

check your fan belt tention and alternator belt tention

with the engine off.. and the car out of gear.

put you thumb on one of the alternator cooling fan blades... tighten the belt until it just does not slip... any tighter and it will shorten the life of the water pump bearings... any looser and the belt will slip and it will not charge enough to keep the battery up and the electric fans turning at full speed....

it does sound like a loose belt or bad diodes in the alternator... or a loose or corroded battery cable ..

i dont know about the voltage in optima batterys...

after you remove the surface charge for 1 minute with the engine off and the lights on..

12.65 volts is a 100% charge...
12.45 is a 50%
12.25 os a 25%

with the battery full and the engine running the voltage should stay at 14.1 or slightly more... but usually not over 14.6volts..
except on a few later model gm alternators..

most batterys can be load tested after bringing it to full charge at many chain parts stores...

Jbird · April 26, 2008, 12:54:53 PM

Have you checked the battery voltage with a load tester? Does the voltage come up when you increase engine speed? Does the starter crank the engine over like it should? Does the cooling fan come on when it should? Is the fan spinning at normal speed?

I've only killed one Optima red top. I left my BMW sitting in the backyard with the alarm system armed for about eight months. The only way I knew the battery died was remote wouldn't unlock the car when i wanted to show it to a potential buyer. Batteries Plus warranteed the battery.
Jbird

Rob · April 26, 2008, 02:18:25 PM

Quote from: "Jbird"Have you checked the battery voltage with a load tester? Does the voltage come up when you increase engine speed? Does the starter crank the engine over like it should? Does the cooling fan come on when it should? Is the fan spinning at normal speed?

I've only killed one Optima red top. I left my BMW sitting in the backyard with the alarm system armed for about eight months. The only way I knew the battery died was remote wouldn't unlock the car when i wanted to show it to a potential buyer. Batteries Plus warranteed the battery.
Jbird

The voltage does come up with the RPM's to about 14. I wired the fan to run continuously, it seems to be running at a reasonable speed, although as RPM's increase, so does the fan speed (by a little though, not alot)

Rob · April 26, 2008, 02:21:43 PM

Quote from: "wayne petty"check your fan belt tention and alternator belt tention

with the engine off.. and the car out of gear.

put you thumb on one of the alternator cooling fan blades... tighten the belt until it just does not slip... any tighter and it will shorten the life of the water pump bearings... any looser and the belt will slip and it will not charge enough to keep the battery up and the electric fans turning at full speed.

it does sound like a loose belt or bad diodes in the alternator... or a loose or corroded battery cable ..

i dont know about the voltage in optima batterys...

after you remove the surface charge for 1 minute with the engine off and the lights on..

12.65 volts is a 100% charge...
12.45 is a 50%
12.25 os a 25%

with the battery full and the engine running the voltage should stay at 14.1 or slightly more... but usually not over 14.6volts..
except on a few later model gm alternators..

most batterys can be load tested after bringing it to full charge at many chain parts stores...

Belts are fine, tht's the first thing I checked. Getting it load tested is a good idea, rule out (or in) the battery. I haven't had any other issues in the past (includeng late last year) with the voltage drop @ idle, and leaving the charger on too long over the winter is the only difference

Thanks

wayne petty · April 26, 2008, 02:35:33 PM

there are 3 sets of windings... six diodes at least..

3 positive diodes and 3 negitive... the rotor spins with the belt... the regulator changes the amount of intermitant current applied to the rotor to change the spinnng magnetic field..

the magnetic fields passing through the stator windings (3) send a/c current to the diodes...

any power above 0 goes through the positive diodes to the output term...

any power below 0 goes through the negitive diodes to the case to ground then to the battery...

when individual diodes go bad they do not pass current... bringing up the rpms will bring up the possible current output of the alternator allowing the voltage to come up...

sort of like a v8 running on a few dead holes... it will still make the rpms... but not make the power it had previously...

wayne

oh... and alternators with bad diodes whine...

many computerized alternator /battery load testers can see the a/c coming through or the lack of the even dc pulses... ~~~~~v~~~~~~v~~~~

enjenjo · April 26, 2008, 05:18:05 PM

What do you have for ignition? Some of the electronic ignitions will not advance properly with low voltage.

Rob · April 26, 2008, 07:37:12 PM

Quote from: "enjenjo"What do you have for ignition? Some of the electronic ignitions will not advance properly with low voltage.

Stock HEI. Again, no apparent problems with anything else electrically. Seems to start and run fine, but as I mentioned, the headlights (halogen) tend to dim @ idle too. Should mention that I'm using a 100amp 1-wire alt, which if I recall is supposed to give me about 60 amps @ idle. I don't ever remember the voltmeter dropping at idle before. I have a deepcycle marine battery that I'm going to hook up and see if that makes a difference with the voltmeter...I know that one is OK

wayne petty · April 26, 2008, 07:51:36 PM

this is the part you should be looking at...

Alternator Diode (actually a rectifier bridge)
Duralast / Alternator Diode DR302 or a dr304

there are several other numbers that it could be...

but these two are the most probable for a one wire delco alternator...

Carnut · April 26, 2008, 11:30:56 PM

OK, along electrical voltage lines, my friend r26ford just put a voltage guage in my 61 Chrysler.

It reads about 12 at key on and 14 at idle and will run up to 16 or so when charging. This is also with an optima redtop battery.

Is this normal? I was a little wary at the charge going higher than 14v.

wayne petty · April 26, 2008, 11:48:04 PM

sounds like the 61 has resistance built up in the charging circut . or the in car wiring ...

measure the voltage at the battery... and see if it gets that high...

test the wires with the volt meter... with the engine revved up just for a second....

alternator output to the battery +...
battery+ to Positive side of voltage regulator...

battery neg to engine block...
battery neg to body.....
battery neg to voltage regulator body/mount

with these tests you are looking for voltage differnces on the ends of each wire... it will show up on the digital volt meter. you will not see 12 volts.. except across the battery... you are looking for resistance in the circut... this will only show up with load going through that wire.. this is called a voltage drop test.. hence the reason i said to rev the motor to duplicate the higher reading on the dash gauge...

Rob · April 27, 2008, 04:55:50 PM

To update;

I didn't hear any squealing in my alt, but I did increase my idle speed somewhat, and that seemed to solve the voltmeter reading, but I'm still overheating @ idle.
I think I'd better take a "back-to-basics" approach and flush the cooling system, since it seems that I'm not getting enough cooling from the fan alone, and I've already cleaned the exterior of the rad, so I'm starting to run out of ideas. Maybe the "stop-leak" I put in a couple of years ago is causing me grief...clogged up some tubes.
Thanks for all your input, and I'll keep you posted (since I know you'll be losing sleep over this) LOL!

Pep · April 29, 2008, 01:06:35 AM

Two issues, but not related...

First...the battery charger should not blow up the battery. It should be regulated.

Secondly, at low idle, the alternator will stop charging, but as long as it climbs up to around 14 volts above idle, then all is good. Also, if a diode is gone, you will see the charge light slightly glow all the time, as the AC is getting through the blown diode and lighting the lamp.

Thirdly, if temp creeps in traffic, then it is normally air flow...eg, fan not drawing enough air through the radiator. Don't waste your time flushing the radiator. That only has a bearing at speed.