90-91 temp gauge bars

[JeremyD]

How many bars does your 90-91 show in traffic on a warm day?

[padgett]

Corrected, see below.

Edited May 6, 2016 by padgett (see edit history)

[ol' yeller]

Mine goes to 12:00. When it goes to one bar above 12:00 the second fan comes on and lowers it to 12:00 or 1 bar under. I recently did replace my radiator, hoses and thermostat because of it getting too warm.  The original owner never changed the coolant and when I purchased my car the coolant was rusty.  I had to replace a couple of soft plugs when I first got the car.  I have drained and flushed my system several times since then.

[Guest HuevosRanchero]

don't know the number of bars but it is rock solid at 1 bar below the middle no matter the time of year or how much traffic.

[harry yarnell]

12:00 o'clock. Never higher.

[JeremyD]

On a 100+deg day driving on city streets with the AC running I have seen it reach two bars above center.. I know the 3.8 runs warmer than some engines. Just wondered, as the cars age, if anyone has a different experience. I plan to flush the coolant (it's green but aged)  and brake fluid in the next few weeks. 

[KDirk]

Concur with most here.  12 o'clock is normal running temp if everything is nominal and the weather isn't over 100°F/full sun. Being that you are in Vegas and it gets hot there (much like St. Louis summers with less humidity - but it's a dry heat!) One to two bars over with A/C running and idling in traffic isn't terribly unusual. Padgett refers to patching the ECM ROM to lower the temperature at which the fans engage. This is a worthwhile mod if you are in a climate where operating temp goes to the high side of normal on a regular basis. I have the file to burn the patched ROM (thanks Padgett) but haven't implemented it yet as I've not really had a problem. May do it eventually but requires changing to a lower temp t-stat as well for it to work correctly.

[2seater]

Generally straight up, 1/2 scale , under almost all conditions. It may go one bar above after idling in traffic, but fans take it back down, no issue.  This with an intercooler, transmission cooler and oil cooler directly behind the grill. In all fairness though, I live in a temperate climate.

[DAVES89]

A number of years ago Mc_Reatta [wish he would come back, did I ever say that before?] made up some jumper leads for each one of my cars that would make both fans run at the same time. Keeps my engine cooler no matter the temperature or if I am idling or not. Only have the three and don't know how he did it, but it has factory connectors so it can be installed/removed easily and the original harness has not been tampered with. No programming change either.

[Barney Eaton]

This subject has come up several times........straight up is the ideal reading but like you (I am in Texas) I have seen the reading go 2 bars past straight up.    I consulted with Denny Meyer...a GM power train engineer that also owns a Reatta and worked on the 3800 engine.  His statement was it is not a problem unless it is causing the car to loose coolant.

If everything is functioning correctly, the two fans are running at 1/2 speed until the sensed temp reaches about 230 then both fans go into high speed until the coolant temp drops.

Also remember that with a 14 lb pressure cap, the coolant will not boil 212.....the pressure add roughly 42 degrees so the boiling point goes to 254.

 

You can take some measure to help.........

Have the chip reprogrammed to turn the fans on high at a lower speed,  I have had that done and Padgett that lives in Florida has also done that.

Put a auxillary transmission cooler on the car, this helps two things (1) it keeps the transmission cooler for longer life and (2) takes some of the load off the radiator (the factory cooler goes to the radiator)

In LV you could completely bypass the radiator with the trans cooler.....which I have done.

[padgett]

Just an observation but the engine itself does not care about temperature as long as you stay out of detonation (87 PON detonates the easiest of any pump gas).

I find that keeping the engine in the 180-190 region everything under the hood lasts longer (particularly belts, hoses, and battery), oil keeps its viscosity longer, mpg improves, and the passenger compartment stays cooler.

 

Also at 180 you have plenty of heat even at 0F and the computer is "all in".

 

But that is just my opinon.

 

ps my memory was faulty on the Reatta temp guage. Mustabin thinking about this GTP. Mine is usually one bar under center and halfway is OK. Does not go over.

actual turn on temps are:

1 bar - 38C
2 bar - 47C
3 bars - 54C
4 bars - 63C - TCC begins to operate
5 bars - 74C
6 bars - 82C (halfway)

also found this:

170F: one bar under center
180F: half way
210F - one bar over center
217F - two bars over center
221F - three bars over center

Essentially if everything is right, the center could be anything from 180F to 210F so you need a scan tool or open the diagnostics to know exactly when what happens but it all comes down to how accurate is the coolant temp sensor.

 

 

[Ronnie]

There was a thread that covered this in depth a few years ago. Here is a link to it. I did the chart below as a result of the discussion.