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2001 Mazda Millenia Cooling System question

Matthew Montalto
Matthew Montalto

Thanks so much for getting back to me and that video (sorry for the delayed response… this car is not driven very often, so troubleshooting is difficult)…(and for some reason I never get an email from the forum to tell me you responded….)

That is probably the only video I have seen with an expansion tank and it leaves me with some questions…. but first… let me fill you in on the circumstances of where I am at now….

I tested all my electrical stuff and bottom line is the fans seem to be functioning normally… Ran the car in the driveway which has a very slight incline (not sure if thats relevant, but you’ll understand why I mention it in a minute) and it ran fine…. fans came on… no overheat condition occurred.

Took it out yesterday (I’m in NYC… 35 degree day…) seemingly no problems… drove to my sons school… which includes a good 20 min parkway drive at 55 mph…. then streets with traffic lights…. parked in the lot and waited 5 to 10 min … no overheat occurred…. so I leave to drive home and somewhere along the way I get stuck a light and I notice the temp is climbing past the half way mark (bluetooth scanner says its about 225 or so during this climb…)… once the light goes green… temp drops down without issue…. …and it will run about 218 or so…. [This then happens again at essentially every traffic light all the way home…. about 5 or 6 more times]

(…when I was stopped in the parking lot earlier it was sitting at 222 but the nieedle stayed at the half way point)

So I make it home and park on the street (also a slight incline) and open the hood…. figuring I have a couple mintues to check the fans before it overheats again…. – Under the hood I find the fans are working fine… and the car then maintains about 222 degrees and the needle stays at the half (normal location)….. Now at a loss… I close the hood, get back in and put it in drive and wait… and nothing…. no overheat occurs….

So now I am at a loss… does the fact that i am on a slight incline have any relevance?…..I dont know…. In watching the video you sent, I see there is no need for the funnell…. well when I first bled the system I did so putting the funnel in the top of the expansion tank and when it got hot enough… I came straight up and filled the funnell…. what does this mean? have I now put too much coolant in the system…

Would love to hear your thoughts and opinion on the matter… as of now…. the plan of action I have is to try again to bleed the system by simply cycling it with the cap off the expansion tank and just use a catch pan and see if it overflows…

Thanks for any advice you can give me…..


Matt Montalto