Engine Operating temperature


larryb512

GT Owner
Mark II Lifetime
Nov 2, 2016
21
Austin Tx
This probably is a simple question but My temperature gauge varies between about 180 degrees and about 220 depending on how fast I am going. Stop and go it gets up to about 210-220 and cools off when I return to speed. Since it is way below the overheating red area on Gauge of about 250-260 I assume this is normal but I am not used to the temperature fluctuating this much on a newer car. I have been an owner for a little less than a year so I may have just noticed it or something has changed. This normal?

Thanks for any feedback.

Larry
Austin Tx
 

NorthwoodGT

GT Owner
Jun 12, 2009
1,215
Michigan
larry, 210 degrees is not considered outside the norm. 220 and above I would start looking at a few things. the computer compensates for engine temp. by throwing more fuel into the system when the engine gets too hot. you might also have someone with a fluid uplift system try and bleed any residual air that may be trapped in your system that makes it fluctuate that much. also, another great thing to do is have a knowledgeable person put a tune on the car. the tune can actually turn the fans on quicker and longer which makes a big difference as well. Rich tuned my red car after installing a Whipple and it has never run so cool since I've owned it even with the larger supercharger. runs at 180 degrees all day and maybe jumps to 195 in slow traffic where before the tune, I was running 200-210 most of the time before. all jmo
 
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Beach-GT

GT Owner
Mark II Lifetime
May 8, 2006
887
Seminole Florida
I'll second the notion there may be air in the cooling system. It is a pain to get out in my experience. I added a switch to the cooling fan relay so I can turn the fans on if I feel like it before the computer does it for me.
 

nota4re

GT Owner
Mark IV Lifetime
Le Mans 2010 Supporter
Feb 15, 2006
4,176
The GT is relatively unique in modern vehicles insofar that the coolant temp will vary a LOT. What you have described sounds 100% normal and I wouldn't lift a finger to look for a problem that's not there. Every GT I have driven (maybe at least 50) has the same fluctuations.
 

Tomcat

GT Owner
The GT is relatively unique in modern vehicles insofar that the coolant temp will vary a LOT. What you have described sounds 100% normal and I wouldn't lift a finger to look for a problem that's not there. Every GT I have driven (maybe at least 50) has the same fluctuations.
Please see PM...thanks!
 

Tomcat

GT Owner
I had Torrie tune the ECU (when I did the pulley/tune) so the cooling fans come on earlier than the original factory setting. I saw some fluctuations in traffic before the tune (never getting close to the red but with Pantera experience I was spring loaded). Also as an experiment (as I recall, and the experts can correct me if I'm wrong) I turned on the air conditioning as the engine temp gauge started to climb (in traffic) and the engine temp actually went down (since the fans automatically come on with the AC)...demonstrating that all I needed was a little fan (earlier). The new temp setting resolved all my "concerns" (as there never really was a problem).
 

AJB

GT
Mark II Lifetime
Le Mans 2010 Supporter
Jun 28, 2006
2,943
Bloomfield Hills, Michigan
mine fluctuates also. Has done so for over 13 years. if I am in traffic and become concerned, I just turn on the A/C. (as noted above.)
drops 20 degrees.
andy (ajb)
 

fjpikul

GT Owner
Mark IV Lifetime
Le Mans 2010 Supporter
Jan 4, 2006
11,475
Belleville, IL
Has the coolant been changed since you've owned the car? I think I saw pics of your car in Cedar Park. Might be worthwhile to change and flush with the proper coolant and make sure no air is in the system. The petcock for the radiator is at the left front of the car and you should drop the front Airdam to get at it. When mine was new, it fluctuated much more than after the dealer changed the coolant and we got a little air out of the system. Runs cooler now but does fluctuate some. Please remember the gauge is a real gauge and gives you real-time readings, something most people are not used to.
 

larryb512

GT Owner
Mark II Lifetime
Nov 2, 2016
21
Austin Tx
Wow What a group of people with this kind of knowledge. Thanks to everyone for all the help. This is exactly what I needed. I will keep a close watch on it and go forward.
 

larryb512

GT Owner
Mark II Lifetime
Nov 2, 2016
21
Austin Tx
Thanks that helps. I had fluid checked recently and was told it is in good shape.

Thanks for your helpful information.
 

PeteK

GT Owner
Mark II Lifetime
Apr 18, 2014
2,267
Kalama, Free part of WA State
My '05 with 55Kmi stays pretty close to 180 in street and highway driving. At Rally 12 in Utah this summer, I was getting up to 230ish on the race track. Stock engine and tune. Make sure any air is bled out.
 

junior

GT Owner
Mar 9, 2007
1,151
So Cal
Not much to add to what was said, performing the air suction procedure from the coolant system during the coolant change made a welcoming difference in temp rise, car runs much cooler. Service performed by meister extraordinaire Ryan at Cool Tech LLC (engine and supercharger) using the Airlift kit (Thanks Ryan!). Few pictures:

Hoses full.jpg

full 2.jpg

coolant hoses  collapse 1.jpg

collapse 2.jpg

Airlift gauge.jpg
 

2112

Blue/white 06'
Mark II Lifetime
Are you turning the engine over while under vacuum? Or do you vacuum, add coolant, turn engine and repeat?
 

texas mongrel

GT Owner
Mark II Lifetime
May 3, 2009
1,661
Houston Texas
If you’ve not tried this, it might be worth a shot: turn on the A/C just enough to make the little yellow light come on. This switches on the second radiator fan which makes a big difference in stop-go traffic
 

nota4re

GT Owner
Mark IV Lifetime
Le Mans 2010 Supporter
Feb 15, 2006
4,176
Are you turning the engine over while under vacuum? Or do you vacuum, add coolant, turn engine and repeat?

All of this while the engine is off. Use the Airlift system to draw a vacuum on the entire system (you can see all of the hoses sucked shut), and then you simply let the car draw-in the new coolant. Piece 'o cake. Note that the Airlift kit uses a venturi to create the vacuum and you need to have this connected to a reasonable flow-rate compressor. (Some of the small pancake compressors just can't get the job done.) That said, because of the size of the venturi, it is pretty much impossible to overdue it. You could let it run and run and you won't go more than what is shown in the pics above. Frankly speaking, it is just so much easier to refill a cooling system using this method compared to pouring it in, running the engine, pouring some more, and hoping for no air bubbles.
 

FENZO

GT Owner
Mark II Lifetime
Jul 7, 2008
1,518
Lafayette, CO
Are you turning the engine over while under vacuum? Or do you vacuum, add coolant, turn engine and repeat?

Huh?
 

2112

Blue/white 06'
Mark II Lifetime

Was wondering if the water pump needed to turn to get air out from up front. Just took the scenic trip asking it.
 

FENZO

GT Owner
Mark II Lifetime
Jul 7, 2008
1,518
Lafayette, CO
Was wondering if the water pump needed to turn to get air out from up front. Just took the scenic trip asking it.


Gotcha. Unless there is something unique with the GT pump I'm unaware of, coolant systems exclude any locked volumes by design. Every pump I've seen is a centrifugal type.
 

roketman

GT Owner
Mark IV Lifetime
Oct 24, 2005
7,994
ma.
I did one better and put in the GT guys racing Radiator in.I also removed the screens behind the fans.When they replaced the Radiator they sealed around the perimeter so all the air runs thru the rad pack. My car never goes over 180. On the track it never went over 210.
 

MAD IN NC

Proud Owner/ BOD blah bla
Mark IV Lifetime
Feb 14, 2006
4,211
North Carolina
I had Torrie tune the ECU (when I did the pulley/tune) so the cooling fans come on earlier than the original factory setting. I saw some fluctuations in traffic before the tune (never getting close to the red but with Pantera experience I was spring loaded). Also as an experiment (as I recall, and the experts can correct me if I'm wrong) I turned on the air conditioning as the engine temp gauge started to climb (in traffic) and the engine temp actually went down (since the fans automatically come on with the AC)...demonstrating that all I needed was a little fan (earlier). The new temp setting resolved all my "concerns" (as there never really was a problem).


I am late but with eh Whipple and tune I have.... fans are always on along with AC.... No issues Blk/Blk car in SE.