: Does your engine stay hot even when off for a long period of time?

08-16-13, 07:35 PM
Good Evening,
I'm noticing my engine stays hot even when off for like 30 minutes.

I can go to the supermarket or park with my daughter, get back in the car, and the temperature gage will read close to half way.

My rebuilt 99 SLS Northstar Engine did not stay hot when off. It actually ran a tad below half way.

My DTS seems to always stay at half way or a tad above half way.
I just had the coolant replaced today at the dealer.

Is this occurring for everyone else? Should I replace the thermostat? Or does the DTS run hotter and stay hotter?


08-16-13, 11:07 PM
it won't cool down much in 30 minutes.... not in the summertime...
This is where my temp stays ....
http://i76.photobucket.com/albums/j40/superjim1944/Speedometer%20Pictures/20130517_100959_zpsa4fd4a22.jpg (http://s76.photobucket.com/user/superjim1944/media/Speedometer%20Pictures/20130517_100959_zpsa4fd4a22.jpg.html)

08-17-13, 06:42 AM
it won't cool down much in 30 minutes.... not in the summertime...
This is where my temp stays ....

Yep, very similar to mine!

08-19-13, 11:24 PM
I checked mind today just for this reason. I got home at 5:30 and the temp was smack on center, just where it is supposed to be. Four hours later when I went to go to the Dairy Queen the gauge was still at about 3/8ths when I turned the key on.
This is probably more of a feature than a bug. A large part of an engines efficiency depends on it's ability to regulate it''s temperature. If it retains heat when the coolant is not flowing temperature variations due to environmental changes (summer/winter) will be much less drastic. Bear in mind that I am neither a thermal or a mechanical engineer.

08-20-13, 02:35 PM
One would think that it takes at least a minute or two to cool off 750 pounds of aluminum, steel, and iron after the key is turned OFF...... especially in an ambient temperature of 75 - 95 degrees.

The (proper) Northstar thermostat is set to begin opening at 188 and be fully open at 206................. so an absolutely normal running temperature is between 195 and about 210. That center tick mark represents a coolant temp of between 185 and 210 degrees, give or take a needle's width. Why such a wide bandwidth for the center mark ??? Because in today's cars ANY "gauge" is little more than an idiot light - if the "gauge" ever moved in normal response to operating conditions 99.999% of drivers would go screaming to their dealer "My gauge moved !!!! Is my car broken ???". What would you do if you had a real oil pressure gauge - one that went from 25 psi to 60 and back between traffic lights during stop&go city driving ???

For the approximate temp of each one of those DTS gauge ticks, look at the annotated gauge picture in my albums - the markings are the same whatever the orientation of the gauge needle. Click my username, open the profile: left column, 2 albums, 6 pages of Northstar stuff.

No, the DTS does not "run hotter or stay hotter" than any other 188 degree thermostat engine on earth.

08-20-13, 02:58 PM
Personally, I wish the gauges "WERE" the old fashioned type, with markings on them....
I like to know what is REALLY going on and that is the type of gauges I grew up with.
But I know what you mean about lots of people would panic if it ever moved... LOL

08-20-13, 05:25 PM
There IS a way to watch 4 of 12 real-time engine functions (but not oil pressure or fuel pressure, unfortunately). Take a look at a ScanGauge-II.

www.scangauge.com (http://www.scangauge.com)

I run one in the car and 2 trucks - I monitor coolant temp, intake air temp, MAP (inverse vacuum), and ignition advance.

For an oil pressure gauge, have a hydraulic shop make up a length of flex braid oil pressure line. Pipe it to the oil pressure sending switch port on the filter adapter and over to a frame-mounted brass piping T which mounts the original sending switch (idiot light) and the gauge sending switch. The T is brazed to an L-bracket (body mounted) with a ground cable back to the engine. (Electric oil pressure gauge, naturally...)

Kicker is, pod-mounted SW gauges look out of place in a Cadillac. I ran the exact same piping setup in 2 Corvairs, a Cougar, and a Taurus 3.8.