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specialwoman30
10-06-2008, 12:58 PM
I just bought a 1999 Gran Am SE. The car keeps overheating and dont know why. My husband put in a new water pump, thermostat, and fan switch. The fans never come on for some unknown reason. We know that they work because he put straight power to them. What does the temp need to be before the fans actually come on? The other problem we are having is the car is idiling rough when you are just sitting there at a light and when you take off it seems to bog down and then it is fine. It back fires every now and then. Does anyone know what could becausing this problem also? Also when you step on the gas it hesitates too.:banghead:banghead

PhantomLover007
10-06-2008, 01:03 PM
Sound like the LIM ya'll?

specialwoman30
10-06-2008, 01:09 PM
Could you please tell me exactly what that is?

DaRkWaVe
10-06-2008, 01:09 PM
Eesh.....sounds like you bought a car that is suffering from the infamous LIM leak. Check the oil to see if it is 'milky'. Also, check the coolant reservoir(tank) to see if the coolant is contaminated with oil. If you can't see inside the tank to check the fluid level, then you need to see a mechanic ASAP.

specialwoman30
10-06-2008, 01:14 PM
My husband checked and there is no oil in the reservior tank and the oil is not milky.

PhantomLover007
10-06-2008, 01:19 PM
Do you see any kind of smoke coming out of the exhaust. Like a white color IIRC. It might be a cracked head.

DaRkWaVe
10-06-2008, 01:21 PM
Does the car rev at around 2000 rpm when you let it idle in reverse?

specialwoman30
10-06-2008, 01:39 PM
No smoke coming out of the tailpipe at all. I never paid attention to where it revs when it is in reverse.

DaRkWaVe
10-06-2008, 01:51 PM
I was just trying to determine whether you have a vacuum leak at the manifold. I bought my Grand Am for dirt cheap from an owner who had just got the LIM gasket replaced and the car was still running bad so he wanted to get rid of it. It turns out the mechanics at the shop he took his car to didn't do put the intake manifold back properly and ripped the fuel injector o-rings, causing a vacuum leak.
I don't understand why your fans don't turn on. It could be a temp sensor problem or a bad relay, maybe a fuse. Have the hubby check the fuse box in the engine bay. If the previous owner of your car experienced the LIM leak, there is a chance a component in your cooling system has been damaged. I would think the thermostat is stuck closed, but since that was replaced I don't know if I can help any further. Good Luck!

specialwoman30
10-06-2008, 01:56 PM
My husband thinks there is a leak at the manifold just like you said. Do you know at what temp the car will get to before the fans kick on? I appreciate all your help.

DaRkWaVe
10-06-2008, 02:04 PM
The PCM commands Low Speed Fans ON under the following conditions:

The engine coolant temperature exceeds approximately 106C (223F).
The A/C refrigerant pressure exceeds 1310 kPa (190 psi).
The vehicle is shut off when the engine coolant temperature is greater than 140C (284F) and system voltage is more than 12 volts. The fans will stay ON for approximately 3 minutes.


The PCM commands High Speed Fans on under the following conditions:

The engine coolant temperature reaches 110C (230F).
The A/C refrigerant pressure exceeds 1655 kPa (240 psi).

Also, is the Service Engine Soon light on? If it is on, I would try to drive to the nearest Autozone and have them check what code is trigging the SES light. If there is a vacuum leak at the manifold, the SES light should come on. If there is a fluid leak at the manifold, the light might not come on at all.

specialwoman30
10-06-2008, 02:10 PM
The service engine soon light it not on at all. We have the stock PCM should we get a new one so the fans come on when the car is off to cool it down?

specialwoman30
10-06-2008, 02:21 PM
It says to use DEX cool is that a special coolant we need to use?

DaRkWaVe
10-06-2008, 02:29 PM
Probably not a good idea right now. The stock PCM is not very likely to go bad and be the cause of your problems. Something else is going on. I would first confirm whether your fans are turning on when your car starts to overheat. You know the fans themselves work, but are they being 'told' to turn on during operation.

specialwoman30
10-06-2008, 02:37 PM
Well if they arent being told to work when they are suppose to what would be causing that?

hass
10-06-2008, 03:52 PM
The stock fans go on LOW speed at 223 I think.
and possibly HIGH speed at 240-250ish.

Also may want to look in to a head gasket leak.
LIM doesn't tend to cause a car to overheat... just loses oil/coolant.

Heads are basically a few steps past the LIM... not that hard really if you can follow basic directions ;D

With the motor running, open the hood at look at it.
Down the sides of the motor, if there is anything leaking out.. It's a LIM leak more than likely.

When you shut the car off, listen for a hissing noise.
It will be very faint. But it will be there if your headgasket is leaking.
(the car does have to be pretty warm for it to do it)

What method did he use to put the power to them?

edit; Did you buy it from a dealer? or a private person?
Might be able to lemon law that sucker.
Since getting it fixed at a dealer is basically 1/3 the price of the car.
I know I got mine used from a dealership (that only sold lexus/volvos and such.. so this car was dirt to them) and they gave me a 30 day warranty on it from anything that goes wrong or was wrong.
Not that I would have taken it back to them if there was... since they were such jerks... but that's another story ;x

2nd edit; When it's overheating, how hot does it get? Does the red light come on? How many times has it overheated to the red (if it does go that high)...
May want to tear it down to the heads and have them resurfaced anyway if it happened a lot... They could have gotten warped or something.
But if it bogs down you may have something leaking down there and not be getting enough compression.

AaronGTR
10-06-2008, 07:08 PM
Might want to replace the coolant temp sensor. I would've done that before replacing the water pump because those usually aren't bad unless they are leaking coolant from the drip hole under the pulley and you can see that.

If you replace the temp sensor and it's reading the temps correctly, and it's still over heating, then it's probably either a bad head gasket/warped head, or a plugged radiator.

Question... how hot does it get on the temp gauge when it over heats? As hass said it has a red zone and the warning light should come on if it gets up there. Does it lose coolant when it does this? If it does this regularly and the fans don't work, you should be getting some type of DTC code and a check engine light.

Just for your reference, it is normal for these cars to run around 210-220. The stock thermostat doesn't open until 195. The computer doesn't turn on the first fan until 223 degrees F (106 C) and off at 217 F (103 C). It turns the second fan on at 232 F (111 C) and off at 226 F (108 C). If you aren't seeing temps over that, the fans won't turn on and it's not over heating. If you are seeing temps over that, and the fans still don't turn on, check the underhood junction box. There are several fuses and relays in there that operate the fans.

specialwoman30
10-07-2008, 02:48 PM
The water pump was replaced because it went bad. I dont understand why they make these cars to get so hot before the fans kick on. I know when it gets a little past 200 it will overheat and all the coolant will be all over the place. It just seems that the fans arent coming on like they should. But if it has to reach that temp before they kick on then I guess that would be the reason. The radiator isnt clogged because we flushed it thinking that might be the problem and it was fine. Let me ask this does the Dex Cool coolant make a difference from regular coolant?

specialwoman30
10-07-2008, 02:49 PM
No warning light comes on because it never goes into the red when it is overheats.

surreal_awakeni
10-07-2008, 03:09 PM
The water pump was replaced because it went bad. I dont understand why they make these cars to get so hot before the fans kick on. I know when it gets a little past 200 it will overheat and all the coolant will be all over the place. It just seems that the fans arent coming on like they should. But if it has to reach that temp before they kick on then I guess that would be the reason. The radiator isnt clogged because we flushed it thinking that might be the problem and it was fine. Let me ask this does the Dex Cool coolant make a difference from regular coolant?

Many newer cars are designed to run hotter so as to be more efficient and cleaner burning.

As for dexcool, the big issues is never, under any circumstances, should you ever mix dexcool and regular antifreeze. You can put regular antifreeze in, but ONLY after a full cooling system flush. I don't know about you, but I have found it difficult to even find conventional antifreeze any more. Mostly I just see the yellow type that supposedly will mix with either regular or dexcool.

AaronGTR
10-07-2008, 03:39 PM
The water pump was replaced because it went bad. I dont understand why they make these cars to get so hot before the fans kick on. I know when it gets a little past 200 it will overheat and all the coolant will be all over the place. It just seems that the fans arent coming on like they should. But if it has to reach that temp before they kick on then I guess that would be the reason. The radiator isnt clogged because we flushed it thinking that might be the problem and it was fine. Let me ask this does the Dex Cool coolant make a difference from regular coolant?

No warning light comes on because it never goes into the red when it is overheats.



Well, the simple answer is... if it doesn't get into the red and the warning light doesn't go on... the car isn't overheating. :rolleyes: It's simply venting coolant for some other reason, which has been heard of before with these cars. If the system wasn't properly bled and has air in it, or if the pressure cap is bad, it could be boiling somewhere and building pressure that the cap will let off out the vent tube, hence loosing coolant. Try replacing the cap on the overflow tank and make sure the system is free of air.

As for why they run so hot, as was stated it's for a cleaner burn to get better gas mileage and less emissions. Every new car is like that.

The difference between the dex cool and the old style green coolant is only in the anti-corrosion and lubricant additives. The actual cooling and anti-freeze components are the same (ethylene glycol). Dex cool is actually different now (new formula) and really it's just a long life coolant that lasts for 5 years or 100,000 miles. There are several brands on the market and any of them can be used. Red, green, yellow... doesn't matter as long as is says "long life".

You actually CAN mix the long life coolants with the old stuff also... it's just that if you put the old stuff in a system that came with long life coolant, it's not long life any more and has to be changed every 2-3 years. The corrosion inhibitors in long life coolant are organic acid based. The old coolants were silicone based and that stuff sticks to the wall in the coolant passages, so once you fill it with that, there's no getting it out unless you empty the whole system and chemically flush it, and take the engine out and hot tank it. lol Not an easy job! The only real important thing with the long life coolants is to make sure they are properly filled and bled and free of air. They tend to build up gunk when they get hot and are exposed to air.

Mike Jung
10-19-2008, 01:13 PM
Is the engine coolant system holding pressure ?

If it is "boiling" over at 200F/93C: it sounds like there is a leak in the coolant system.
(Remember water boils at 100C/212F under normal atmosphere pressure.)
Most commonly the Engine coolant reservoir cap is not holding the 15 psi needed; & a new cap is needed.

gagt Mechanic
10-19-2008, 05:34 PM
agree with aaron on the pressure cap. if it reaches 220, it will begin to boil out if it is not under pressure, the pressure raises the boiling point, no pressure, lower boiling point, 220, whitch is not high enough to turn on your fans.

specialwoman30
10-20-2008, 09:22 PM
I bought a new cap and put in the Dexcool and it solved the problem. Thanks for the replies.