Hi Everyone,

My names is Mike, from Clearwater, FL (), and am new here, but definitely glad this site's been here!

Anyways, the reason I'm here is because 2 days ago, Monday, I noticed the temperature gauge on my 2003 G35 Sedan fluctuating between mid-level (about 50%) and about 3/4 or 75%.

Upon my last service I was told that it had a small crack in the radiator, and honestly I thought they were just trying to get me for some more money so declined it, and they just told me to watch it. Anyways, I'd checked the coolant levels and the overflow was dry, so I ran up to Autozone and bought some and filled it up.

Well, I was thinking that that was the issue. Anyways, yesterday on my way to work I watched it all the way. Well, it started fluctuating again, and this time it went past the 75%, and once it got to about 90% (I kept hoping it'd drop) I threw it in neutral, turned it off, and rolled off the U.S. 19 into a business parking lot, called a tow truck and had it towed home cause wasn't gonna let work be the reason I ended up with a blown engine.

So, my first assumption was thermostat. I went and bought a new thermostat, switched them out, and turned the car on. At first I'd thought it was fixed, but then I'd noticed a little leak right below the main hose on top of the radiator (used the little mirror stretch thing), and was thinking, well, it's a very small leak and it's not overheating, so I could live with that for now.

Well, after about 15 minutes the temperature gauge started to rise again, and I'd shut it off at the same point as I did on 19, where it was at about 90%. So, it definitely wasn't the thermostat.

Now I'm wondering, being how there's this little leak in the radiator, would this have an effect on the temperature gauge?

I'd got this idea from my neighbor who has an Audi A4, who said they're pressurized, and if there's a leak it's going to play a role in the reading, but he, self admitted, is not a mechanic, and 'thinks' that could be the issue, and says that as long as there's coolant in the radiator and the overflow that it technically can't overheat. Is this true?Any help or guidance would be greatly appreciated as I'm at a loss here and don't know what to do.

Also, is there something that can seal this radiator leak?


Thanks!

 

are the fans coming on?

 

Hey, thanks for the reply, and yes they are.....just don't know if they're coming on exactly when supposed to cause initially I thought wasn't coming on, then noticed they were, but just thought maybe should've came on sooner, but maybe fans know better?? Was kinda wondering if maybe they were coming on, just not as often as should be coming on.

 

Are both coming on at the speed they need to be? Sometimes the fan motor goes bad and the fan comes on but not at a high revolution

 

Well here's what I don't understand. Yesterday, when my immediate thought was that it's the fan issue, I looked online to see how much one would cost. And the pictures being shown made me do a double take, and I say that cause I only see one fan, not two on mine, but the pictures of replacements show as having two.

I just went out and looked again, and yep, still one fan. On one half of the radiator is the fan, on the other half is horn and some other things, which I definitely don't understand.

 

Whoa whoa whoa..haha

OK, your neighbor is 50% wrong. Your cooling system uses pressure to keep temps down (pressure makes the boiling point of water go up). ANY leak! Even a pin hole can make your car overheat by releasing that pressure. It's not just the coolant that keeps it cool. You must replace your radiator.

I got a brand new radiator from carquest with a lifetime warranty for $130. It's not smart to end up breaking something (like your motor!) by trying to save a couple dollars.

 

Thanks a lot!

I'll try to get one tomorrow.

Quick question though while you're online, does 'Burping/Bleeding' the coolant system really make a big difference? Probably dumb question, but I'd only ever heard of bleeding brakes.....but then again I'm not a mechanic, just a now youtube watcher trying to make it happen guy!

I do know that I didn't bleed it if it is needed, and just found where someone said,

"Unscrew the air bleed screw to the right of the battery. (Large phillips) its plastic
Remove the radiator cap and fill.
Fill the reservoir in between Low and Full.
Leave rad. cap and bleed screw off and start car, turn heat on full blast.
Let car warm up, put towels under rad. cap and bleed area to catch overflow.
When coolant is visible at bleed screw, put the screw back on tight.
When thermostat opens up coolant/bubbles will rise out of rad. cap. Cap it off now.
Check the level in your reservoir, make sure its in between Full and Low.
Let it idle for a minute or two then turn off heater. Let it idle for another minute and shut off car. Let car cool then check coolant level at radiator and reservoir. Fill to previous mentioned levels.
Should be good to go. Repeat steps if any air is suspect in system. "
Anyways, does that sound about right what he'd said? And what will happen if you don't bleed it?

Thanks a lot!

 

Yes. If there's air in the system than it won't work properly.

 

OK, thank you very much!

 

When was the last time the coolant was flushed? Maybe the radiator is clogged. Also, if you see the temps rising, you can turn the heat on full blast and this will lower the temps. I had a car where temps were rising in freeway with a bad thermostat and had the temps drop back to almost mid-way when I turn the heat on max.

 

Thanks for the reply AlexJG!

I'd flushed it when I'd put the new thermostat on. Only has 89,000 miles, and not sure if the flush should've been done before or not, but I've had it for about 30,000 of those miles and never had problem. Maybe I was supposed to change more regularly, I don't know, but anyways was just done.

Thank you

 

Hey thanks again @ScraggleRock . I'm going to their site right now!

 

Getting all the air out is important as well. These cars have been know to need a few burping procedures to get it all out.

I purchased a spill free funnel to help with the process you posted above


Good luck!

 

Thank you very much for this!