98 Grand Am Gt Overheating [Archive] - GrandAmGT.com Forum


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03-22-2004, 03:34 PM
I have a 98 grand am gt. 2.4L. The other day the low coolant light came on. I checked the reservoir. It was empty. The hoses were cold. I added coolant. Light went off. Next day. It happened again. It is leaking out the cap because it is building up too much pressure. The engine is not allowed to cool off. Could my t-stat be bad? Can anyone send me a picture of where it is located. Or is it my waterpump thats going out? I followed the hose to the engine block and where I thought the t-stat would be it said. "Thermostat located at water pump". Where the hell is that? Please help. Loosen my mind....

03-23-2004, 05:37 AM
If its leaking out of the cap, then the cap can't hold its 15psi and you need a new cap, either that or you have too much fluid in

...I think thats the issue...

03-23-2004, 09:02 AM
But its overheating, I filled it up just to the fill line. Its getting over 15 p.s.i. cause the coolant isn't being allowed to go the engine.

Mike Jung
03-23-2004, 10:50 AM
Better start saving a lot of money...

The 2.4L 4-cyclinder engine water pump is run-off of the timing chain & the thermostat is right near the water pump.
(I'm at work now so I can't look it up...)

The book labour rate is 6-hours for a water pump & thermostat change; my friend had to get it done on his '98 Sunfire GT (same/similar engine).
& since you will have the timing chain un-hooked; you might want to check out some other maintance issues with the timing chain (I think something about timing chain tensioner or something-?)

If you want to see where it is at; check a Haynes Repair manual at an auto store.

The 3400 V6 engine water pump change is simpler & is like a 1-hour book labour rate & the thermostat is like a 1-hour book labour rate job.

Mike Jung
03-23-2004, 09:57 PM
Sounds like the first thing to check is the thermostat for being no-good & stuck closed.
& changing the Thermostat is a lot cheaper than having to change the water pump (but if you are changing the water pump, the Thermostat has to come out -> so change it anyways)

The thermostat is located on the inlet side before the water pump.
Looks to be accessible (but you got to take off your exhaust manifold heat sheild to get at the thermostat housing area) & then get at it from under-neath near the oil pan on the passenger side via the coolant inlet pipe.

If your car over-heated badly:
I would strongly recommend changing all your fluids after fixing your over-heating problem.
Like engine oil (& filter), ATF (& filter), Dexcool engine coolant (especially since your going have to drain your coolant out to work on it), & maybe even the power steering fluid.

03-23-2004, 10:14 PM
Thanks all for the help. Tomorrow morning begins the adventure of taking it all apart. Wish me luck.

Mike Jung
03-23-2004, 10:46 PM
Originally posted by JawnyRico
...Tomorrow morning begins the adventure of taking it all apart...

Thermostat Replacement on the 2.4L 4-cyclinder engine (according to the Haynes Repair Manual for '99-00 GA's):

- Drain the coolant from radiator.
- Remove the exhuast manifold heat shield (says to disconnect negative battery terminal & unplug O2 sensor before doing this), that is held on by 3-bolts.
- Remove coolant inlet pipe from Thermostat housing by accessing bolts through the exhuast manifold runners.
- Raise vehicle & secure it on jack stands.
- Remove the engine to transaxle support brace.
- Dis-connect the lower radiator hose from the coolant inlet pipe.
- Remove the coolant inlet pipe to oil pan stud & cafefully separate housing.
- Slide the coolant pipe past the right of the transaxle to remove it.
- Note how Thermostat is installed, then remove the Thermostat from the inlet pipe.
- Be sure to replace Thermostat with the correct opening temperature rating of 180F
- If paper gasket was used, use a scaper or putty knife to remove all traces of old gasket & sealant from mating surfaces.

Note: Most of these models do not have a traditional gasket, but rather a rubber ring around the Thermostat. If so replace this ring & install the Thermostat into the coolant inlet pipe without gasket sealant.

- Install the Thermostat & make sure the correct end faces out - the spring is directed toward the engine.
- If a traditional paper gasket was used, apply a thin coat of RTV sealant to both sides of the new gasket & position it on the engine side, over the the thermostat, & make sure the holes line up with the bolt holes in the housing.
- Re-attach the coolant inlet pipe to the Thermostat housing & tighten the bolts to the specified torque ratings of 124 in-lbs.
- the remaining steps are the reverse of the removal procedure.
- re-fill cafefully with the properly mixed Dexcool Engine coolant & distilled water (up to approximately 11.3 quarts)