On my '90 GT that I recently purchased I smelled a bit of antifreeze after I was driving for a while. After I put it up on the lift at work I noticed a small leak at the water pump(gasket). The radiator is full but the overflow tank was completely empty. I already bought a new water pump and plan on putting it in tomorrow but now I noticed another problem that i think is related. My water temp seems to stay rather low (around 150 I'm guessing, near the bottom of the "normal" range). I assume that is why it never blows very hot air, just warm air at best, and now because of that i'm having a defrosting issue...

Is it a bad thermostat that is keeping my water temp down or is it something to do with the water pump slowly leaking? I'd think if I was leaking a lot of coolant i'd be overheating. I noticed today after a 15 mile highway drive after I stopped some steam was coming out from the hood (not very much). I figured that was the coolant coming out of the water pump.

So is it the thermostat thats causing me to run cold? and if so should I replace it while i'm tackling the water pump?

 

Let me start with the defrosting issue first.
I suspect your heater maybe clogged up with rust.
A heater core is nothing more than a baby radiator under your dash.
An easy solution is to flush water thru it with a garden hose. There are the two small hoses that go to your fire wall one from the water pump, the other from the thermostat cover. Any way while doing your water pump you might want to flush the heater core with an outside garden hose. Just put the garden hose up to one of the heater hose ends with the other hose disconnected. You should see a lot of rusty nasty water exit the other side
Do this flushing very slowly as not to break a hole in the core. Though if your already smelling a bit of antifreeze than I suspect it may already be leaking.
On the upside a new heater core is cheap about 20 bucks at Auto Zone on the downside the labor is what kills you. As it is about 200 bucks. or 6 to 8 hours for an amateur mechanic. .

Another after thought to the clogged heater core is as follows
Your heater core is higher up relative to your radiator. Thus when your water gets low your heater core may have little if any water in it yet car is still not showing an over heated condition.
Good luck

 

yeah the heater core is a complete pain to change. i have found alot of mechanics that wont deal with it. if you are changing the water pump go ahead and replace the thermostat anyway. its only like 9 bucks for a good one. and i recommend getting the better one. the cheap ones dont open on the right temp and fail quite often. and i would go with a 190/195 the manual calls for. that might help the defrost problem some also, assuming nothing else is wrong. and check the radiator and all hoses if you are doing the water pump yourself. to check the heater core you can also undo the 2 hoses at the firewall and spray water through it to see if its clear. also if the heater core is bad, it could be leaking. check the passenger side floor board and see if you can smell antifreeze or to see if the carpet is wet. the core is contained in a plastic box. and that fills up over time and the antifreeze spills out into the floor. hope this helps

 

thanks for the helps guys, I'm going to advance auto tonight to get a 195 thermostat (i'd rather have proper heating than gain a little performance from a 160 degree). i'm gonna have one of the mechanics i work with do the water pump tomorrow cause I don't feel completely confident in doing it myself. i don't think theres anything wrong with heater core, no problem with antifreeze on the floor or anything.

once again, thanks a lot!