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I have a 1999-2005 Pontiac Grand Am gt 3.4 let me tell u what i have done so far. replaced: water pump twice thermostat twice temp censer twice intake gaskets / manifold gaskets vale cover gasket system been flushed countless times resevoir and cap replaced and still over heating radiator being replaced now! i know on these cars there was a problem with the dex coolant system and was a class action suit that ended in 08 and dose not help my only had it for 6months. but cant find what t do fix the problem. please help
You have replaced a number of parts, most of the cooling system, some of them twice. The first thing that jumps out at me is the electric cooling fan(s). Either the fan(s) are bad or the sensor that controls them is. Usually those fans always have electric and the sensor acts as a ground when they engage. There should be a fuse to the fans. Have you checked it? Are you certain your fan(s) is working? The next thing is collapsed hoses if your hoses aren’t firm, hard to compress they need replaced. More than likely it is the fan(s) or hoses. If those check out good the next thing to consider would be a clogged catalytic converter. Autozone should be able to test for this for free with their diagnostic scanner. After that is timing, again a diagnostic scan would confirm this _ free at autozone. I have given you some things to investigate but to really help you with an answer I must ask for a little more information with all the parts you say you have replaced in a 6 month period of time. Is it only the temperature gauge telling you it is over heating or are there other signs of it over heating, if so what are they? Does the car lack power? What kind of mileage is on the car? When you replaced the water pump did you replace the timing belt either time? Have you tried running it with out a thermostat? What is the temperature rating of thermostat? Was the thermostat professionally installed? There should be more than one temperature sensor on the car 1 for the gauge the other to control the electric radiator cooling fan, you mentioned only replacing 1, which one was it?
Have you had the head gasket checked out? I have seen numerous vehicles overheat because of a blown head gasket, or other gaskets in the engine for that matter. Are you constantly having to fill the car with coolant? Is there any white residue in the oil or on the oil cap? Do you notice any leaking coolant?
This is not an awnser but i have had 7 chevys with the same problem. (that includes pontiac) the 3.4 and 3.1 have a disconnect from the temp switch to pcm or pcm to the relay. If you turn on the AC yhe fans will run and if you unplug the temp switch the fans will run but you will have hard shifting in the trans because it gets info from the temp switch. I belive the problem is in the pcm not the harness as so many cars have that same issue. PS never change anything with out diag your waisting time and money and why would you ever change it twice really think about that.
Head gaskets do it. Just got done doing them on my 2005. Cylinders 1 and 2 were bad. Replaced a bunch of other parts as well. No more over heating. Head gaskets were what took care of the problem.
I have 04 grand am, 6 cylinder, keeps overheating and not blowing hot air in the cab, I’ve changed thermostat, and did a pressure test, not leaking out of water pump or making noise. No luck. Blown head gasket?
I gotta 1999 pontiac grand am se 3.4 it ran ok when I first got it then seripeteen belt broke overheated a lil had problems since.got belt fixed then had problems with the fans not wrking also so hooked them up direct an found out outta 2 fans one wrked. Then this is why u never ever ever let ur woman drive ur car cause she overheated it for God only knows how long an I found out a sensor went out an thermostat fixed that problem an everything seemed alright till i seen resivoir start filling up with oil it started using more an more oil then an now my reservoir is filling up with antifreeze an leaking slowly just started doing that today 12-27-2016 oh their’s more top of spring broke on drivers side drives ok but leans a bit lol window broke on drivers door friend owns pontiac grand am also he said his broke an he fixed his but had to use glue so I decided not to fix.oh yeah power steering pump leaked then went out 60 sum miles away from home I pulled over an the plastic pulley was off but still moving lol it got caught between the motor mount an the middle bar the pulley ran on so I got lucky drove it bk home.pulley had no middle to it anymore an wasn’t turning but belt kept on a moving thank God now I’m thinking should I keep the car an fix heads or actually put another motor in it someone said probably just drop another motor in it if I keep it with all the problems these grand ama have I’m not sure loved it when I first got it brought used with only 112000 now 131000 if I can find a cheap motor 3.4 I probably will fix it
I have a 2003 Pontiac Grandam, last week all of a sudden it started overheating. Temperature gauge maxed out within a 5 minute drive. I let it cool down ran it a couple of miles at night with no problems. Tried it again the following morning still no problems. At noon it started overheating again. These time even when car is cold and I add coolant it disappears. No apparent leaks I fill it up to max capacity and within seconds it’s gone.
Hi @pontiacuser2000 , It may be that the radiator core is partially blocked and needs to be flushed Have you scanned the OBDII port to see if there are any ‘codes’ giving an indication of a problem? There is a coolant temp sensor that sends the temp reading (actually a resistance value that changes with temp) to the ECU and at a programmed ’temp’ setting the ECU operates the fan relay(s) which turn on the fans The number of relays it operates depends on the fan speed required and whether or not the A/C is operating. Suggest that you may wish to check if the sensor is OK. I think that the temp sensor is located where the upper hose goes into the engine but not entirely sure of this There are 4 relays in the engine fuse block for the fans according to this link (Scroll down to engine block fuse panel. Relays 8, 12, 14, 15) If the temp sensor is OK check if the relay is operating. If not try another relay or check the relay’s operate path.
The problem is related to the computer sending a ground signal to the cooling fans. I just fixed my daughter’s 2003 Grand Am GT. The problem is what looks like a relay mounted to the driver’s side fender wall. It’s located directly across from the air filter assembly. Pontiac has located this device there and all your major grounds join here. The mounting plate attached to it becomes corroded which interferes with the grounding signal from the computer to turn on the cooling fans. The bolt that held it in place was actually so rusty that the head of the bolt had broken off as I removed it. I used a circular wire brush attached to my drill to remove the corrosion from the back plate. Used the same brush to create a new bear metal spot on the fender and a self taping screw to reattach it. No more over heating from there on, Fans triggered and varied speed as they should.
