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Old 12-17-2003, 10:08 PM   #1
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Cooling System and Gasket Leaks FAQ...Read this first

I'm gonna try to cover as many cooling system related questions as I can in this thread. Please read this completely before posting a new question. If you have any new info pertaining to this topic, please PM me and I will add it to the FAQ.

First things first, it's important to know that the cooling system is a closed system so technically it should never need topping up. However, in the real world this is never the case though and it could probobly be topped up every oil change.


Parts of the cooling system include the radiator, water pump, coolant level sensor, fan switch, hoses, thermostat, and lower intake manifold gasket. The location of everything should be pretty self explanatory except for the coolant level sensor and fan switch.

The coolant level sensor is located on the coolant resevoir. Sometimes ot comes on and off while braking or accelerating. This is beacuse when you stop is cause the coolant is moving around in the tank causing it top drop lower than the sensor. Same thing when you accelerate. Simply top it up and watch it.

The fan switch is located underneath the throttle body. It reads the temperature of the coolant and turns the fans on and off based upon that. If you find your fans aren't turning on, first check the fuse. If it's ok, jump the fans. This is done by disconnecting the wires from the sensor and connecting them directly to a power source. If the fan runs, replace the sensor. If you still get nothing, you may have to look into replacing your coolant fans. NOTE: The fans aren't set to turn on right at the normal operating temp, but above so don't panic right away if they aren't on.



Whenever you lose alot of coolant, it is important to follow a certain procedure when topping up your coolant. Following this procedure ensures your system is properly filled and removes all air from your system which can cause overheating. When filling, you must fill your resevoir with a 50/50 mix of coolant and water. Try not to mix coolant types. Doing so will void all longlife properties of your Dexcool.

When filling, keep pouring in coolant until your resevoir is full to the max line. With your coolant cap off, run the car. Your coolant will drop as it fills the system. Keep topping it up until it doesn't drop anymore. NOTE: Make sure your heater is turned on while doing this. This will cause coolant to flow into your heater core. In addition, make sure your car is blowing hot air.

This method is the best method. Our cars have bleeder valves, but this method is easier and works just as well. It is the preferred method of alot of other car manufacturers.


Should your car have a leak, it can either be diagnosed visually, by adding dye to your coolant, or by doing a pressure test. You can find a leak visually yourself. The other 2 methods require certain equipment, but if you have access to the equipment are extremely easy to do.


The lower intake manifold is fairly common on Grand Am's. GM even released a TSB. Sometimes it leaks very slowely for a long time and sometimes it happens real quick and gushes alot of coolant out at once. It can either leak externally or internally. Externally just makes a mess. IF IT LEAKS INTERNALLY DO NOT DRIVE YOUR CAR AND GET IT FIXED. You can tell by pulling out your engine oil dipstick. If it looks milky, you have coolant in your oil. Coolant in your oil will destroy your bearings which costs ALOT to fix.

Parts you need to fix this include upper intake maniold gaskets, lower intake manifold gaskets, valve cover gaskets, 1 distributer plug gasket, and two EGR gaskets. If you go to the dealer and ask for the intake manifold gasket kit they usually know exactly what you're talking about and will get you everything you need. Note GM made some new intake gaskets that are entirerly black and have matal rings in them. Make sure you get these.

As far as I'm concerned this is an easy job, just time consuming. That's why it's so expensive. It is very labour intensive. You have to take off the entire top half of the engine and gut all the externals around it just to get at the lower intake manifold. Here's the run down on how to replace them, but please only attempt this if your are mechanically inclined:

- remove intake tube attached to throttle body.
- remove EGR
- remove coil pack and spark plug wires.
- remove upper intake manifold
- remove front valve cover
- remove alternator
- remove serpertine belt
- remove power steering pump (you will have to unmount the engine to get at some of the bolts holding this on. Make sure if you support the engine using a floor jack that you use a block of wood or you WILL CRACK YOUR OIL PAN)
- remove accessory brackets
- remove rear valve cover
- remove lower intake manifold
- loosen rockers and remove push rods (keep them in order)
- remove distributor dummy shaft to replace O-ring
- reassemble and follow the coolant filling procedure

* label everything and keeps similar items together so you know where it all goes
* get the torque specs for the engine. It is very important that everything be tourqed back to factory specs or you will be doing this job again
* everything except the block is aluminum so absolutely no over tightening or you will easily strip something in your engine. Then it's time for tap and dye
* if a bolt starts going in crooked, take it out. DO NOT FORCE ANYTHING IN. Go slowely if that happens. Once again, alluminum. If you don't do it right and watch yourself, you'll have to break out your tap and die set

TONS of pics can be found at courtesy of djrkd



When the water pump goes there will be coolant all over the passenger side engine bay and you will find yourself having to top the car up on a weekly basis. Usually, your car will not drip all the time, but will gush a large amount of coolant out after driving it. Just one gush, then nothing. This is because it leaks under pressure. After driving, there is alot of pressure built up in the cooling system which has to be released. It is released through the weep hole in the water pump.

The water pump is seriously easy to replace. The Grand Am uses a core, not a full pump. Here's the run down on how to replace it:

- take tension off the serpertine belt so you can get it off the waterpump pulley
- remove water pump pulley (you will have to use something to stop the pulley from turning)
- you will now see the water pump core. Remove the screw holding it in and take it out
- clean gasket area
- install new water pump core making sure all holes line up on the core and gasket.
- reinstall pulley
- reinstall serpertine belt
- follow topping up coolant procedure

As stated, it's that easy. I can do this job in 10 minutes flat



Hoses can usually be caught before they go by squeezing the hose. If it feels hard or brittle, replace it. If you don't, it could crack out of the blue and spew coolant all over.



Clamps are as easy as making sure they are tight.



A crack in the radiator is harder to diagnose and requires more advanced methods, but it's a rare leak anyway so no worries.

Last edited by Filter; 12-18-2003 at 09:41 PM.
Old 12-17-2003, 10:21 PM   #2
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A bad fan switch will allow the fan to come on when you turn on the A/C providing you have one. So in the event that you overheat on the road switch the A/C on. and it should start the fan!
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Old 03-17-2004, 09:07 PM   #3
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The parts you listed are for the you know what parts are needed for the 2.4L?
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Old 05-02-2004, 06:04 AM   #4
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This is great information. I had a Gasket leak a couple of years ago on my 99 GAGT. It cost me $810.00 to have repaired. In this case I had Oil in my coolant not coolant in my Oil. I'm also sure that my fan switch has not worked properly in a long time. My car never overheats in the winter but in the summer or if I'm sitting in traffic it would. Turn on the AC and it would go back to normal. See my first Post about my 99 GAGT you'll be surprised ..
Old 08-25-2004, 08:00 PM   #5
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The 2.4 is fairly simple. The filling procedure is the same. If you are leaking from the "drivers side" check the water outlet housing( ~ $19 at dealership). They are notorious for cracking ( I know i just replaced mine today) Also there is an O-ring that you need but isn't sold with the housing (go GM) If this part cracks it won't leak until you shut the car off and will dropabout 1/2 gallon of fluid. Which is about the capacity of the lower radiator house. (got bored @ work and figured it out. Knew geometry would come in handy) If it leaks from the passenger side, check around the water pump and the hose coming out of the water pump. The metal pipe the runs under the engine to the radiator is subject to lots of abuse. ~$40 at dealership.
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Old 11-18-2004, 09:17 AM   #6
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might wanna list that you have to take off the fuel rail when doing the repair as well
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Old 11-29-2004, 06:36 PM   #7
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anyone get a new cold air intake and check engine light come on? i have no clue how to turn that friggin light off. How do turn it off?
Old 12-07-2004, 07:22 PM   #8
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The whole procedure was very informative, especially the water pump core...didn't know that.
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Old 02-16-2005, 08:17 AM   #9
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Hi I have a leak and I not sure what the part is. There is a metal tube that goes into the left side of the radiator, I have the 3.4L V6. Anyway it's leaking at the fitting that goes into the radiator. It was slow at first but now I am having to top of the tank every week. What is that part and is it easy to fix? Thanks

Last edited by Chemboy; 02-16-2005 at 08:22 AM.
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Old 02-16-2005, 01:03 PM   #10
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might want to get yourself the Haynes GM Pontiac Grand AM maintenance and repair book from autozone, maybe pepboys. $15.....will tell you what that part is.....I have the book right in front of me and there are actually several metal lines that connect to the when you say left side....where exactly....driverside? passengerside? on top of radiator? under radiator?

The one right in front of your alternator on top is the A/C line and the cylinder shaped thing with a black bracket around it next to it is the Condenser inlet fitting. That goes across the car from right to left.

Underneath that on the passenger side is the Upper transaxle coolant line. I'm reading this from the book, so I don't know if you have that in your car and I'm too lazy to go check my car. If there is another metal line underneath the A/C line in front of the alternator, then thats what it is.

And underneath the radiator there is another metal line which is the lower automatic transaxle cooler line. And I've been under my car so many times, I can tell you that there is a metal line there. I believe its on the passenger side.

If thats what the problem is.....go to and see if they have that part or go to and do the same or try autozone. And if its leaking at the fitting, try tightening it or take it apart and visually inspect it....You may just need to put an O-ring in it and tighten it back on.

I've never had this problem, but that's what I would do. And if that didn't work, I would pour gasoline all over my car and set it on fire. (cuz I want a new car)
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Old 02-16-2005, 01:14 PM   #11
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Thanks its the line on the passengers side right near the top of the radiator. Coming out of the radiator it does down and then heads right toward the driver side. I am not sure where it goes from there.
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Old 02-16-2005, 05:44 PM   #12
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that would be A/C line. And that is connected to the Condenser Inlet Fitting.

""""The one right in front of your alternator on top is the A/C line and the cylinder shaped thing with a black bracket around it next to it is the Condenser inlet fitting. That goes across the car from right to left."""""

U can try finding a replacement part for that or see if you can tighten it. I don't know, but you might be able to take it apart and put in a rubber O-ring (autozone) to keep the fluid from leaking out. Sometimes the morons at autozone can give u some advice on that
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Old 03-02-2005, 07:03 PM   #13
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Who here has replaced a heater core in a 94 GA with the 3.1 V6? my buddy has one and he was told that it would cost at least $400 to replace and he told me he would give me $200. i looked on Alldata and it said 3 hours to replace which means it will take me 5-6 hours.
Any ideas or opinions? I plan on doing it this weekend, so if anyone has any tips let me know. Sorry for jacking the thread!
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Old 03-30-2005, 12:20 PM   #14
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If it was an internal leak, would you smell the antifreeze pretty strongly after driving the car? I am noticing a little bit of antifreeze sitting on the top of the transmission case after driving the car. At most, I have seen 5 drops of antifreeze on the ground after driving. I think it's a small leak but dont know really where it is coming from. This all started after our trip back from Denver, CO to Kansas City.
Old 05-12-2005, 10:30 PM   #15
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Hey when you put the push rods back in how did you adjust the values did you tighten them till u go the backlash out than gave them a half a turn but only if #1 is on TDC of compression and go like #1 #4 and what ever is closed than turn your crank one full rotation and tighten the rest or how did u do it.
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Old 08-21-2005, 02:22 PM   #16
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i am having problems dont know what to do my car overheat and it overflows from the coolant resevoir after it passes the middle line in the temp gage i got the fan sensor and a new water pump put on i took it out form the mech i drove it no problem the car ok i turned it of and drove after it started to pass the middle line it did the same thing it got hot and it was smoking from the resevoir and you could see it boiling i turn the ac to cool it but still smoking dont no what to do help please i feel help less
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Old 08-23-2005, 12:47 PM   #17
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So about what temp should the fans come on? and what temp is normal? I have a 2004 gt v6, and my temp runs durning normal driving, on the first mark past 200, is this ok?
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Old 08-23-2005, 01:05 PM   #18
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The PCM commands Low Speed Fans ON under the following conditions:

The engine coolant temperature exceeds approximately 106°C (223°F).
The A/C refrigerant pressure exceeds 1310 kPa (190 psi).
The vehicle is shut off when the engine coolant temperature is greater than 140°C (284°F) 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 110°C (230°F).
The A/C refrigerant pressure exceeds 1655 kPa (240 psi).
When certain DTCs set.
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Old 08-23-2005, 05:59 PM   #19
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Originally Posted by TheChad
Hey when you put the push rods back in how did you adjust the values did you tighten them till u go the backlash out than gave them a half a turn but only if #1 is on TDC of compression and go like #1 #4 and what ever is closed than turn your crank one full rotation and tighten the rest or how did u do it.

I gotta ask this question too.......I am i the process of doing it.....

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Old 09-13-2005, 03:31 PM   #20
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I just replaced a defective cooling fan motor on my grandaughters 1993 GT, Quad 4. Now the car runs at about 120 deg. Seems like the fan runs almost all the time. I'm thinking it is the sensor you mentioned that turns the fan on and off. Anybody know anything about this, where did theyn hide it, how can you test it, etc.

Sorry to ask such a stupid question but I'm an oldtimer that hasn't messed with much of this newer stuff and I don't want to make more problems than I already have. Used to work on them when you could take the hood off, sit on the fender with your feet on the frame and do some work. I can't find anyplace to put my feet on these new ones and the fenders all have narrow edges that are hard on the butt. Oh for the good old days when if your fan didn't run, you got yourself a new belt and you could actually see where it was supposed to go.
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