I have a 2005 non-S that has had the following stuff done:

new power steering pump

fan resistor mod to re-enable low speed

new power steering fan

power steering fan shroud from moss mini

About 2 months ago, the alternator went, and I replaced it with a rebuilt one. This lasted all of 30 days before it crapped out. Took about 14 days to get a replacement. This takes us to this past Sunday.

I popped in the alternator, and life seemed great. We drove around a bit in town, and everything looked fine. That night, we took it out on the highway with a second car and about halfway through a 30min drive, it started overheating really bad. Pulled over and found coolant all over the engine bay. This particular issue was probably my fault, as I had the coolant cap in 'safe' mode but not full screwed in.

No problem, I thought, i'll just drive the other car back home, pick up the coolant, come back, fill-er up and be on my way. This didn't really help, as I was only able to add a cup or two of coolant. The car also re-overheated, and I ended up having to leave it on the highway that night. Next day we towed it home, and I picked up a new OEM thermostat and housing, figuring the thermostat failed and no coolant was cycling. The giveaway to this was that I had NO heat from the vents.

Fast forward to today: I changed out the thermostat with no issues and fired it up. No leaks (never had any before either) and the temp gauge came up to about halfway in a couple of minutes. (it's 37deg in my garage) After about 10 min, I STILL had ZERO heat from the vents, even though I had it set to 80deg. (even tried HI). The upper radiator hose on the passenger side was also never hot. I ran the car for about 10-15 min, until once again, the gauge started climbing, and finally I had to shut it down.

During the heating up, the radiator fan came on at low speed, and then at high speed, so the fan is working. The air coming off the fan IS COLD, supporting the observation that no warm water is in the radiator.


No water in the oil, car runs and idles just fine until the overheat. Not thinking headgasket here.

At this point, I'm down to two causes left:

Bad waterpump: I'm not sure if this is possible or not. It is belt driven, and is not making weird noises. No leaks that I can find. Does it have a plastic impeller? Does it have a geartrain inside that is prone to breaking?

Or clogged radiator: I'm not positive how I would solve this unless some sort of flush operation would clear it.

Help? My wife is owning my car while I try to fix this, and I'd like to get her back on the road, but this has me stumped.

 

for the heck of it, I boiled the old thermostat, and it opened and closed right around the right temperatures. I have not boiled the new thermostat, but am having the exact same issues as with the original.

 

It sounds like air in the system. Just for giggles, try bleeding the system using the bleeder valve.

 

you're right. I did some more reading and decided to just bleed the hell out of it. Before I did, I removed the upper rad hose and pumped in some more coolant. After that I was able to start getting heat! I let the car heat up fully and the fan cycled on and off. I drove it around the block and parked it outside. With the heater off, it cycled the fan on low for about 60 sec, and the back off for several minutes.

I fired up diag mode and found that the fan comes on at 105C and goes back off at 101C. Good info.

I did just about completely round out the head on the upper bleeder on the heater lines. Freaking crazy that they made these out of PLASTIC. I got it closed after dumping some on the ground. I'll have to buy a new one to ever bleed it again though...

Either way, gonna tool it around town over the next couple of days and make sure that it is ok. I feel kinda silly now posting this long diatribe when it turns out I just needed to bleed it. I gotta say, I've never seen a car THIS sensitive to air bubbles...

 

Glad to help with the suggestion