Coolant Leak on 2001 Pontiac Grand Am 3.4 L engine

[Steve]

So my latest mechanical issue is large coolant leak forming under the car when she gets hot. Doesn’t overheat but large amount of coolant leak definitely has to be fixed. Can’t tell from where the coolant is coming but it’s NOT coming from the radiator, thermostat, water pump, hoses or reservoir overflow. No problems for driving to the store and back and whatnot but I need to fix it of course. My suspects are: Faulty reservoir cap (it’s the kind that is plastic and seals), thermostat or water pump as a last resort. My dad and I have a disagreement as to what is the water pump (location). I will post a couple of pics so you can verify my argument with him, Lol. Any ideas on other things this might be and I should check before getting the wrenches and billfold out?? (I have added coolant by the way, doesn’t leak after 30 minutes of idleing and getting warmed up at the house but going a few miles to the store and back (uphill I might add) and it leaks the antifreeze.

Sorry the parts I labelled on the pics might be small to read. Maybe can zoom them in. And in one pic, I’m pointing to I think is obviously the water pump. Are my labels correct? Thanks!

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[Bill]

I find those cars are a coolant leak waiting to happen. Since you didn’t say the location the coolant was collecting on the ground i can only take an educated guess. Beside the usual places any engine can leak coolant (radiator,hoses,water pump)The 3.4 has problems with intake manifold gaskets and internal as well as external cylinder head gasket leaks.

You stated that funds are limited but i would take the car somewhere and have the leak diagnosed or raise the car to get under it safely to try and see the leak. If it only leaks when it’s hot you would be burning yourself on exhaust components etc.

[Steve]

I actually had the head and manifold gaskets replaced last November and the oil looks fine now (as opposed to in November). The leakage seems to pool under the passenger side at just in front of the passenger seat area under the car. Can’t pinpoint an exact location for the leak but all the residual fluid pools under that location.

[Bill]

I suppose it could be the heater core leaking and dripping from the A/C condensate drain. Are you topping up the coolant frequently? If not i would say that it’s condensation from the Air Conditioning. The compressor runs in defrost mode so the A/C does not have to be on to create dripping water. You might also check the carpet in the passenger front footwell for dampness.
If it’s wet then the heater core is most likely the source of the leak.

[619DioFan]

From the location I would agree that a heater core issue is a possible culprit. see if you can rent/borrow a cooling system pressure tester from a local parts store. this will make diagnosing the prob much easier.

[Steve]

Yeah I’m fairly confident it’s not a heater core. No leaks inside under the passenger side, heat works fine, etc. Also not AC condensation since the fluid leaking out it green so it’s obviously coolant. I’ve had a few water pumps go bad over my 30 years of driving and those experiences were basically catastrophic failures (pump seized up, broke serpentine belt or sudden, near total loss of fluid and overheating). I also did some more research tonight and seems like doing the cooling system pressure test might be a good place to start. Thanks for the advice.

[Author]

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