90 Grand Am LE 2.5L Overheating

[AZCS-B]

It has 161k miles.

I replaced the thermostat about a month ago and it seemed to fix it. The problem has now returned. I took the thermostat out again and checked it in boiling water on the stove and it worked as advertised.

My fan comes on at the right time but the engine never cools down. I found what I thought was a leak but it is some type of drain coming off the firewall between the engine and passenger compartments. Nothing comes out of it until the car starts to get hot and this is the first time I have noticed anything coming from there since these problems began. There are no other visible leaks.

The heater is working fine but it doesn't seem to help cool the car at all when it gets hot.

I do have what looks like steam coming out of my tailpipe. I have never seen water on my dipstick. I changed my oil today too and did not see any water. I pulled my spark plugs and they all looked like they were in decent shape. They were dry but did appear to have some corrosion on them.

A friend told me that water pumps rarely go bad and when they do it usually makes an awful noise. I can't hear anything strange coming from the water pump.

Any help would be greatly appreciated!

Edit: I think it might be the heater core. I've read somewhere on here that it shares in cooling with the rest of the system. I can smell coolant inside my car and my defrost is humid so it fogs up the windows. Any thoughts?

[AZCS-B]

I tried taking the heater core out of the loop by joining the intake and output lines. Nothing changed. The top radiator hose coming off the thermostat wasn't hot so I think I'm going to try another thermostat.

[grfnkl]

It sounds as if the heat core is going out as first suspected. There is possibly a crack or clog in the line leading to to or a crack in the core itself which will cause the car to overheat and for the windows to fog up with a smell of antifreeze. You can still replace the thermostat to see if that makes a difference. I would still lean more towards the heater core. Good luck hope this helps.

[gmack221]

You obviously have a heater core issue (the fogged up windows & smell of antifreeze & coolant draining from the over flow pipe in the firewall). As for the rest of your problems, i'd start with a dealer thermostat (i can't say it enough, dealer or napa's best thermostat is the only way to go!). If after you change those two things your problem hasn't went away i'd change out the water pump. If you have 161K on the orig water pump it needs changed anyhow, sometimes they make noise when the bearing goes bad (the pump impellers touch the casting) but its more common to see antifreeze or corrosion coming out of the hole on the bottom side of the waterpump. If there is a green stain there, your pump is shot and should be replaced. A coolant flush and new coolant is never a bad idea either, thru the years coolant does actually go bad.

[AZCS-B]

Thermostat didn't help but I don't think the water ever got there so I went and got a new water pump. Now if I can just get the old one off! There are 2 bolts that are obstructed by the engine mount bracket and 1 bolt that I should be able to get to if I pull off the air conditioning compressor.

Not a fun job for a novice and the cost sure starts to add up when you need a "few" tools.

[AZCS-B]

I finally got the water pump off. Whoever designed where that went should be shot!

Is there a way to see if it is bad or not? I can't see any obvious difference between the new one and the old one other than the old one being easier to turn. It also has some dried residue from the lower drain hole.

[gmack221]

If you have residue around the hole in the bottom of the pump then your pump is shot, when the bearing inside wears it allows the coolant to run out that hole. When the bearing goes it allows the shaft and impeller to tilt, sometimes it wears slightly on the impeller blades (if they hit the casting behind it), why the pump doesn't work is because it pulls the other part of the impeller away from the casting, allowing the fluid to get behind the impeller instead of the impeller pushing it the way it was designed. Im guessing once you change your pump most of your problems will be fixed, but im afraid you may still have a bad heater core. keep us updated!

[AZCS-B]

I changed the pump and the heater core. The heater core was definitely blown but I'm wondering if something else caused it. The problem is still the same. I grabbed the top hose coming off the thermostat to the radiator and it was soft and cool. I've put 2 thermostats in it so I doubt that's the problem. I don't think water is making it to the thermostat.

The water pump sends water to the heater core. It goes from there to the intake manifold and into the engine. Are there any valves or anything along the way that could be sticking?

[grandmad]

Have you got the air out of the system. I have been dealing with this for about two weeks. Pull your vehicle up on a incline and take the radiator cap off, and let the engine run. You will see it bubble. I worked with mine for about an hour and a half. so far so good.

[AZCS-B]

I've still got it on jack stands so I'll give that a shot. Thanks.

[grandmad]

Hey AZ, just curious how things where going with your Grand Am. My sons is still doing good. We have went the longest (so far) without working on it.
Hope everything is good.

[AZCS-B]

I don't have any daylight to work on it during the week so I have to wait until the weekend. I'm gonna try burping it Saturday hopefully.

[AZCS-B]

Well, I'm home from a short deployment and it's still acting up.

It was low on water so I added some and burped it. The water came rushing out once it got hot so I let it cool off. I let it cool then added some more water and took it for a drive. I didn't get 2 miles before the temp started shooting up. The fan came on but didn't seem to help. I tried turning on the heater and the air was cold to begin with and only got lukewarm which was strange considering the engine temp.

So I'm down a heater core and a water pump and still don't know what the problem is. The cold air with the heat on really bugs me. It seems like the water is not making it from the radiator to the heater core and the engine.

[AZCS-B]

It was air in the system. I took off the top radiator hose and was able to get a lot more water in than through the plastic tank. Thanks for all the help guys.

[grandmad]

These cars are real finicky, Mine almost drove me nuts. You may have to bleed it some more yet.