Car Heat/Overheating Issue (???)

[MetaLord 9]

Enough of you know your way around anything with wheels that I might be able to get a solid lead from you on this one.

Here's the deal:

For a while, the car had occasionally smelled like coolant outside, after driving it a bunch. I didn't recognize the smell and didn't notice any issues with the car. End of September the A/C started becoming intermittent. One day we notice the temp gauge is about to hit red. I pull over as it's hitting red, pop the hood, and walk to go get some coolant. we keep driving after the engine cools down, go pick up a new radiator cap and, once the air bubbles have a chance to get out of the system, things are better. AC seems to works regularly, etc.

Only issue is that there's a smell of coolant in the car soon there after. I figure out the water pump's cracked so my buddy & I replace it. Coolant smell goes away in the cabin, but (since now it's later in the year) the heater works intermittently. So I replace the thermostat. Because of where it is, I've gotta unbolt it & re-seat it the next day as it was leaking from improper seating. I go to drive it to work and it starts overheating after maybe 10 minutes of driving. after limping it to a safeway & adding more coolant, striking off, and limping back again, I realize I knocked the radiator return hose off. I reconnect drive off again before having to limp back. Just as the temp gauge hits red I turn the car off, crack the radiator cap and let all the air that was blocking the system escape.

After more coolant, the car runs at temp just fine. I don't get a coolant smell in the cabin, and I'm only getting a faint smell of coolant in the engine compartment which I assume is all the coolant the blew around the compartment just burning off. Still no heat though.

After a while, I start to notice a faint smell of coolant after driving and getting out of the car, but it doesn't seem to be coming from the engine compartment. I smell it more around the mid area of the car. Still no heat.

I added a little more coolant to the system this morning because it looked low. On the way to work this morning, I warmed the car up in the garage for 15 mins, drove to work and on the on-ramp to 470, the revs were a touch high and the temp was 5/6 the way to red. As soon as I got up to speed, the temp dropped right back down to operating temp.

I can't see any coolant leaking from the thermostat or water pump that I replaced, or anywhere else in the compartment, and I can't smell a lot of coolant burning up anywhere like I could before. However, it seems like I've got a leak somewhere. I still have no heat either.

Any ideas on what/where to check next?

Oh, the car's a '99 Mustang if that bears any relevance. Thanks for reading

[rybo]

Heater core. A mini radiator mounted in the heat system for converting engine heat to cabin heat.

That would be the next place I checked. They are often a bear to get to.

[salsashark]

almost sounds like you have another bad thermostat.

as for the faint coolant smell in the engine compartment, my truck has that as well. I talked to the mechanic who did my power steering work and he said I may have a pinhole leak in the radiator but unless I was loosing coolant, not to worry about it.

[MetaLord 9]

Well it seems like I'm losing coolant, at leas that's the only way I can explain the system almost overheating today versus being fine on other days.

I thought about the thermostat being bad again due to the high temps after I knocked the res return hose off.

Scott, do the coolant lines run to/through the heater core? I thought about looking at the hoses to/from the heater to see if they're clogged, but they shouldn't have anything to do with the coolant I'd think. I'm wondering if I might have mutually exclusive issues now: heater core or hoses and then a leak somewhere

Oh, one other thing I forgot to mention. After I replaced the pump, I'd get heat (warm, not hot) into the cabin when the car got up to temp. The heat would still be intermittent and it smelled a little humid (which I've read could be a heater hose).

[Mother Goose]

Moved to the car forum.

[MetaLord 9]

Thanks, I keep forgetting we've gone one of those...

[MetaLord 9]

Heater core. A mini radiator mounted in the heat system for converting engine heat to cabin heat.

That would be the next place I checked. They are often a bear to get to.

I've looked into it and the damned thing is behind the dash. F.


So if I can find & check the heater hoses, I guess I'll try that. If they're fine, then...anyone know a good deal on someone who can replace the heater core if neccessary???

[salsashark]

I know there are certainly closer places... But if you can't find one, these guys have always treated me right.

Johnny Good Inc
Ste E, 462 Laredo Street
Aurora, CO 80011-9209
(303) 367-2416

[TFOGGuys]

You've got an air lock in the heater core. Procedures for clearing them vary by vehicle, but usually involve allowing the car to idle up to operating temp with the radiator cap off, and then either opening a bleed screw, or loosening the upper heater hose briefly to allow the air to escape. then you fill the cooling system to the top and reinstall the radiator cap.

Note: this time of year, don't screw around, use premixed coolant, otherwise you can get ice blockages in the radiator, which can cause permanent damage to the rad, as well as overheating.

[rybo]

FTAR (factory trained auto repair)
Chris Weed
MRA racer and great auto mechanic

Located in Westminster
(303) 650-2257

[King Nothing]

The problem is written right on the grille.

[httc84]

Best way to eliminate thermostat is remove it and drive. If car overheats - it was the thermostat, if car runs cold - it was a bad thermostat. I don't recommend driving for long without a thermostat - lower operating temps mean reduced fuel economy, less power, poor emmissions, etc.

If you do this, ensure the coolant is topped off again prior to driving.

[Canuck]

Air lock.

[MetaLord 9]

Air lock.

How can you be so sure? Car has been cooling fine for the past two months, despite no heat

[Canuck]

Or heater core restricting flow.

[usmcab35]

i think your problem is your heater core, possibly where you are smelling that coolant from, could have a leaky hose or maybe a pin hole??? really hard to say what it is without it in front of you.

[sloridr]

Is the passenger floor board wet? Chis if you don't get the thing fixed by the time I get home my garage is open to use. Complete with tools and heat we can get you fixed up for the price of half rack. I wont be home till Feb 24 roughly. But my guess is its your heater core maybe a blockage in it. Said air lock is also very possible. Cross your fingers that's what it is! Good luck till then.

[MetaLord 9]

Thanks Justin!

I've got the compressor at home and some tools to work with myself, so (on a warmer day) I'll check the heater hoses around the firewall and if that doesn't work, I'll try flushing the core both ways

[The GECCO]

Another way to test if it's the core is to take it out of the loop. There should be two hoses leading to/from the core to the engine. Hose A flows from the engine to the core, hose B flows back. Disconnect one end of hose A and the opposite end of hose B. Connect the free end of hose A where hose B was, and vice versa. Top off the cooling system and drive (you'll have no heater at all, BTW) for however long it takes to determine if the symptoms are gone.

If the symptoms are gone, then I'd think the core has a small hole in it, probably up high. This would limit the amount of coolant leaking out when the engine is hot, and would allow air to get sucked back in when it cools.

If the symptoms are still there, I would start thinking blown head gasket. Is the oil milky?

[MetaLord 9]

I haven't checked the oil yet, but after adding a good deal of coolant to the res last night, the car didn't overheat at all today. Temp was fine, everything functioned well. Still consistent heat tho. The head scratcher is that I had the floorboard heat on and it actually started blowing warm air for a time. It was "hot" but it was definitely warm. However, the warm air got colder and eventually just became temperate after a couple of minutes.

If the temporary heat I was getting was just out of the engine compartment, wouldn't it stay warm since the engine temp stayed the same?

[OUTLAWD]

even if its the heater core, it shouldn't be hard to do yourself...some cars you may have to pull part of the dash out

Hell, if I did one in a Fiero, a mustang can't be that bad

[MetaLord 9]

I know requires pulling the dash on the mustang. I don't have that kinda experience with cars, especially not pulling dashes, etc. I'm gonna try some less time consuming & invasive fixes first to see if I can avoid having to pull the dash or pay someone to do it

[cbrjohnny]

without looking at the car first hand its hard to say what the real problem is. but, it sounds like the heater core. i just had the pleasure of replacing one in a 2003 s10 pickup... the book called for 8 hrs for removing the dash. (to give you an idea what the labor may be)

the heater core was leaking and the fluid was building up in the heater compartment, not all over the floor of the car.

have the system pressure tested to be sure there is a leak, if you can not see the leak it most likely is your core.

btw... i would not use any "leak fix additives" as they can cause blockages in your system.

[The GECCO]

I haven't checked the oil yet, but after adding a good deal of coolant to the res last night, the car didn't overheat at all today. Temp was fine, everything functioned well. Still consistent heat tho. The head scratcher is that I had the floorboard heat on and it actually started blowing warm air for a time. It was "hot" but it was definitely warm. However, the warm air got colder and eventually just became temperate after a couple of minutes.

Again, I'm thinking possible head gasket problem. A blown head gasket will allow compressed gases into the cooling system, which will overpressurize the system and start blowing coolant out past the radiator cap. Now you have air in the system instead of water. On most systems the heater core is the highest part of the loop, so it's where the air will gather. Once the heater core has air in it instead of coolant, no more hot air for your feet!

Here's another test. I assume you have a radiator overflow tank, yes? If so, empty it. Then top off the radiator and take the car for a 30 minute drive. Shut the motor off and check the overflow. If it's still empty or near empty you're probably OK, especially if it empties as the engine cools.

If it's FULL you may have a problem....let the motor cool for two hours and check again. If it's still full (ie, the coolant didn't get sucked back in as the engine cooled) then you definitely have a problem. What this would be is coolant being pushed out of the radiator into the overflow tank by the cylinder gases. Normally whatever is in there (as a normal part of the motor heating up and expelling a little bit of coolant) gets sucked back in when the coolant cools off and contracts. If the head gasket is blown bad enough there won't be enough of a vacuum to suck the coolant back in.

If the temporary heat I was getting was just out of the engine compartment, wouldn't it stay warm since the engine temp stayed the same?

No, that's not how the passenger compartment heating/cooling system works, you don't get any hot air from around the engine (unless you're driving a very old VW bug). The air that blows into the car when the heater is on is drawn in through the cowl (the little slotted vents in front of the windshield) and then goes across the heater core or A/C core to be warmed or cooled before blowing on the passengers.