I had my 01 Millenia S checked at my local garage because of overheating at idle. They dx radiator leak and said the thermostat and hoses were all fine. I replaced the radiator myself this morning. I probably should have replaced the thermostat at the same time but didn't. The car is still overheating, but seems to be getting hotter faster than before. If I run it at 50+ it cools down but heats up very quickly in stop and go traffic or at a light. Any suggestions?

 

Sounds like the cooling fans are'nt running. At 50 mph it does'nt need the fans since it has a 50mph wind across the radiator. At idle it needs the fans.

 

When I stopped and left it running the fans were both going. I'm almost embarrassed to ask this, but if I didn't add enough coolant after installing the new radiator would it act the way I described?

 

That both fans were running is good.
That you short changed the engine on coolant is not, and could be the reason for the rapid overheating.
You should top up the coolant, turn the interior heater to full hot, run the engine at a fast idle for about five minutes, recheck the coolant level, and top it off as needed, and repeat until the coolant is being displaced into the overflow reservoir to a depth of an inch or so. (This ensures that any residual air will bubble through the overflowed coolant and be replaced by coolant sucked back from the reservoir as the engine cools).
Your garage should have done a thorough cooling system maintenance if they found the radiator was leaking. If it had to be repaired or replaced, the full treatment is to drain and flush both the radiator and engine, replace the top and bottom hoses, replace the thermostat, inspect the overflow hose and reservoir for integrity, and check the cooling pump and its belt drive condition and tension.
Then test drive the car ensuring that engine temperature is normal, interior heating and air conditioning are OK, and that both of the cooling fans are operational.
Finally, pressure test the cooling system, inspect for leaks and verify that the engine exhaust is colorless. (White exhaust is OK on start up, but coming from a warmed up engine it indicates water ingress into the engine, usually caused by a head gasket failure or a cracked head or block).

 

Vehicle starting overheating: found the hose to the heater core was broke (changed/fixed). Then a small hose above the thermostat housing leaking (had a hole,changed/fixed) Car still overheating. So we changed the thermostat. Car still over heating not as fast but slowly going to Hot. What could it be (radiator,water pump...) out of things to look at. Pls help. Im gonna try one thread i read about not having enough coolant. Now it that does not work im lost.
thanks in advance
2MuchChik

sorry it a 97 mazda millenia

 

Did you make sure you filled properly with coolant? If it is slower to overheat than it was it may be low. I only bring it up because, like an idiot, I made that mistake.

There could be a leak in the radiator. I found mine by having it pressure tested at a local garage. ($80 I think) They wanted $425 to replace the radiator. I found one for $125 and did the job myself.

Good luck!

 

pressure testing is really easy. go to oreilly auto parts, autozone, or some place that rents the tester. you take off the radiator cap(in this case, the coolant resevoir cap), install the adapter, and pump it up. a gauge will tell you how much pressure you have, and if the gauge goes down, then you know you have a leak. when you return the tester, you get back your deposit. final cost, 0. watch out for the radiator. if you get an all metal one, it wont have a drain. BIIG pain in the butt. course, if you dont change your coolant every year like you are supposed to, and wait till it is way old, and full of electrolytes, and it has corroded your engine, and the coolant has depleted its additive package, and cannot protect from freezing, then obviously a drain is of no use to you. 425 is really high if just for labor, but for parts and labor, it is not bad. i paid about 200 for each radiator, but i got radiators that look oem, plastic tanks, and aluminum cores, WITH drains in the correct place. also, a shop wont make the mistake of not adding enough coolant. and a shop aint gonna get the cheapest radiator on the planet, they are going to get one that is good quality, and will last a long time. i would expect the price for the radiator from a shop to be at least 300. 125 for install is not bad for a 2.3. there is a lot of stuff that has to come off. also, generally, with a new radiator, a shop is going to want to replace the thermostat and radiator cap, and probably a new upper and lower hose. if they just replace the radiator, and not the other parts, i would not go there.