This is a call for some advice. My Max is currently out of commission. Last week, I noticed the heater was not blowing hot air when I was at a stop. Once I was underway, it would blow plenty of hot air. That went on for a few days. I check my coolant levels, then pressed on. I then noticed the next afternoon that I was running really fricking hot. I pulled over and I lifted the hood to investigate. I noticed distinct hissing sound from the back of the engine. It was coming from just underneath the intake MAF area.

Now, before I start to purchase install new parts in an effort to investigate which part has failed, I want to solicit advice from the experts.
So... If anyone has some advice on what I should do first, please let me know.

 

Does the radiator feel hot to the touch? If not, a broken thermostat could be the culprit.

 

strange but mine did the same when the second radiator fan finally failed - I think the intent (of the ECU) was to shut down the air conditioning

 

first burp your coolant system ....

start car
jack up
turn heat on
uncap radiator when cold
wait 30 min or so...

air could be trapped in there somewhere...

 

+1

Too bad you can't Fart the exhaust system in a similar manner when the cats start giving you trouble

 

sure ya can...buy an exhaust system that replaces the cat and has a fart can....problem solved

 

The Radiator was not hot to the touch. I will try to "Burp" the system, then I think I will remove the thermostat. Thanks for the advice. Keep it coming.

I will let you all know how it works.

What about the hissing from underneath the Intake(MAF) area? Is that the Heater Coil? I think I may blown the gasket or perhaps it's clogged.

Thanks,

Judas.

 

Ok..Here's the final verdict. It was the Thermostat and the Coolant "Crossover" Pipe. AKA Coolant Intake Pipe. The problem has been solved. Thanks to "Bring Your Own Parts".
Thanks to all who added their suggestions.

 

If I can resurrect this thread (not tooooo old), currently my car's fans want to run all the time. I just replaced the thermostat and did a coolant "flush". This was not performed at a shop with a full vacuum. I just drained, filled with water, ran engine, drained, filled with new coolant.

If you unplug the fans, it starts to overheat pretty fast. Any suggestions?

I thought I burped it pretty well, but will try again by jacking it up.

 

If you drained it...burped it..and it still overheats? Are there any obvious leaks? Did you replace your radiator hoses?

 

I would suggest that you re-burp the system again. Since the car overheats when you unplug the fans, the temperature sensor is working and says "turn on the fans". Either you put in a defective thermostat that won't open all the way or the engine didn't get all the air out.