Hi everyone...

I just bought an '03 Elantra. I was pleased with the test drive, except that I couldn't drive it too far because the low fuel light was on. As a result, I didn't feel any hot air out of the heater, and the temp gauge stayed where it started, at about 1/4 of the way up. The car passed smog (California enhanced) just a couple of days ago, very clean readings.

But... on the drive home, the temp gauge never did move, and the heater never did give hot air. Also, once it got gloomy, I noticed there is no backlight on the temp gauge either.

After I got home I opened the hood. The radiator hoses feel like a normal hot engine, as do the heater hoses where they go throught the firewall. It appears, then, that the air diverter door is not directing air over the heater core. Does the Elantra keep that door closed to prevent additional engine cooling until the engine warms up? That would tie in with the temp gauge staying low... if the computer thinks the engine is cold, it won't open the air door to the heater?

The backlight is strange though.. there seems to be only one fuse for the cluster lights, and it's fine - and all the other lights are on. It is weird that the backlight would be out on the one gauge that's malfunctioning, but I can't imagine they share a circuit.

If the temp sender is out, would that both result in a low gauge reading and no heat?

Any advice please?

Richard

 

sounds to me like you have a few options...a cooling system is the simplest system on your vehicle. Is your gauge staying in the same spot at all times ? Is it bottomed out or does it move? Did you check the coolant level? Because Lack of coolant will cause the vehicle not to warm up. The last possible thing i could think of is your thermostate. If your thermostate is broken then it will not be able to control how hot your coolant is getting, or how cool...if the coolant is constantly being circulated through the rad it will not be given a chance to warm up. An easy way to see if your thermostate is working is to see if at idle rev it high and see if the heat works and as soon as you drive it cools down...if that is the case your thermotate is stuck open...its a ten dollar fix if you know where it is on the car. Actually there is one more thing...if your thermostate is good you have coolant and your pump is working and everything is preassurized you should check into getting a new heater core.

 

OK, here's the update on my problems. The backlight was just a bad bulb, so we can forget that. While I had the cluster out to change it, I checked the temp gauge itself. The needle moves freely. I left it in the 'hot' position when I reinstalled it to see what would happen when the engine was turned back on.

I have determined that the heater hoses are not really getting hot. They felt hot when I checked them because the car had been parked and idling, and the hoses were heated by proximity to the engine block. Checking them after driving the car finds that they are not hot.

I therefore wondered if the thermostat was stuck open, so I bought a new one. I drained the cooling system, and the coolant looked like milk. On opening the housing, I found no thermostat at all. I inserted the new one, flushed the system twice, and filled it up.

I also replaced the temperature gauge sender while I had the system drained.

When I restart the engine, the temp gauge stays at full hot. No movement at all. I still get no hot air from the heater if I leave the selecter set to hot. BUT... If I leave the selecter set to 'cold' so that there is no airflow over the heater core, and drive for a while then turn it to 'hot', I get a few seconds of hot air, then it goes cold again.

From this I have decided that the heater core itself must be all but a tiny bit plugged. I'm pretty sure that the milky white coolant was the result of the last 'real' owner (I bought the car from a repair shop) pouring multiple shots of "Bar's Leaks" or equivalent in there, and that that stuff has blocked the little channels in the heater core. To support this hypothesis, now that I've flushed the system a couple of times, I have a radiator leak.

I have a new gauge on order from Hyundai, and 'hope' that it will function when installed and that the gauge is not inop because the repair shop snipped a wire somewhere to make it appear not to overheat so as to get it sold. I can't see a cut wire in the harness from the sender, nor in the harness behind the cluster.... I "really" hope that I don't have to chase down a snipped wire somewhere in the bowels of the electrical harnesses.

So, my theory at present is that the car was leaking and overheating, which is why the PO sold it to the repair shop. Either she or they made the leak 'go away' by pouring in loads of Bar's Leak, and removed the thermostat to stop the overheating. The repair shop then cleaned the inside of the engine compartment to remove evidence of the leak, and made sure it had next to no gas for a test drive so that the sucker who looked at it wouldn't realise it wasn't heating up. I "hope" that the gauge was simply broken - maybe by being pushed too high - but I have a nasty feeling it's been deliberately inop'd to, again, hide evidence of overheating.

The new gauge arrives tomorrow. I'll put it in then, and see what happens. Then I have to decide what to do. While used car sales in CA are usually "As-Is", I may have some recourse since it was bought from a repair shop - repair shops are regulated in CA by the "Bureau of Automotive Repair", and deliberately concealing a known defect violates their regulations.

Richard

 

Watch the radiator fill neck for air bubbles as it run, and do a block check test (solution in container that detects presence of HC in cooling system)... over heat on the 4 cyl 2.0 typically results in warped head/blown head gasket.. look at radiator fill neck at surface where rubber seal on the cap lays -----> is it all rough/ate up and the hole ate up, or is it new smooth raised ring and smooth hole ?

Heat and cold is sign there is air in the system... Hyundai does not allow for head resurface, we replace the head, the gasket, and the bolts.