Mystery Cooling Problem

[jlangholzj]

So, I'm hoping that this isn't "which one of these is not like the other" but I'll explain.


So, put a 3g on the stang (works AWESOME!) and previous to, i never had any cooling issues (e fans and aluminum radiator). would run about 180* idling around town on a hot (~90) day. Well after putting the new alternator on, when i first run it, it will cool fine but if i stop, shut it off, let it sit for a bit and then drive it, it gets hot. ~210 ish. I'm thinking my t-stat is getting stuck because my radiator is cool to the touch (well warm ish but not as hot as it should be). My temp sensor is on the engine block so I'm assuming that I'm not getting proper flow.

my DUH meter says "what did you change" oh! the alternator....but I don't have a weird ground anywhere and its charging fine.....so my next option is a water pump or a t-stat.


thoughts?

 

[woodsnake]

That seems normal to me, that it gets hot after sitting a while. Basically just hot water sitting in an iron "pan"..How long does it take to cool off once you start moving again?

 

[madspeed]

normal

Sent from my rooted, rommed Galaxy Nexus....

 

[jlangholzj]

no no no....difference between heat soaking and sitting. I meant sitting for a good 45 minutes to an hour. The goofy thing is the temp never really comes back down. Even driving on a cool night it still will hang around ~200 or hotter and it gets better if I'm not "on the throttle". It fluxuates pretty fast, which is why i was thinking there's not good enough flow through the block.

Regardless of how long it sits or what order of events i run it in, it will run considerably warmer than it used to.

 

[bartl]

Check it with mechanical means. Ever consider that the 3G is putting out more voltage than your old alternator and this is throwing the gauge off?

 

[jlangholzj]

Check it with mechanical means. Ever consider that the 3G is putting out more voltage than your old alternator and this is throwing the gauge off?

i did think of that and i also was concerned about a floating ground issue but on an initial start up and drive, I get normal temperatures and functionality. The radiator also seems at the right "hand temp" after it hits 180* or so on the initial drive. Also the gauge itself would be thrown by a floating ground, not a voltage output. The sensor is a resistive load that works as a voltage divider through the gauge. Typical input power to the gauges can range from 5-18V without any issues

 

[bartl]

You didn't use any sealant on the sending unit, did you? Also, could it be a mismatch between non-linear/linear gauge/sending unit?

 

[jlangholzj]

okay so all i changed was the alternator. All systems were normal previous to this change. I made sure that there were no ground loops and that everything was properly hooked up and wired. Everything previously installed on the car came in a kit, matched sensors to gauges and everything worked fine.

 

[bartl]

If it's not something related to the alternator then it has to be coincidental. Where "on the block" is your coolant sensor located, by the way?