Thermostat and flush running hotter
03-27-2005, 01:09 AM
#1
Racer
Thread Starter
Thermostat and flush running hotter
OK, Flushed the system today. Changed the thermostat, temp sensor and temp II sensor. Now it's running hotter than before. I used Tony procedure on flush and thermostat change. System took a little over 3 gallons of 50/50 mixture. Any ideas? 
03-27-2005, 06:19 AM
#3
Rennlist Member
Is the engine actually running hotter than before, verified by those quite accurate sensory impressions? eg., radiant heat on your face when bent over the engine, smell, and touch of the hoses - if you do not have an IR gun.
Where is the temperature indicated on the gauge? - before and after?
Noted that the temperature probe was changed: is it possible that an improved electrical contact is responsible? - or a different response from the new probe? You may need to retry the old probe ...
What was the temperature stamped on each of the old and new thermostats? 83 C is the norm - but many cars have had 70 C installed by POs.
So many questions .... verify the thermostat first - after confirming an air bleed as Justin noted. For that, I back out the uppermost temp sensor until the coolant runs clear.
Where is the temperature indicated on the gauge? - before and after?
Noted that the temperature probe was changed: is it possible that an improved electrical contact is responsible? - or a different response from the new probe? You may need to retry the old probe ...
What was the temperature stamped on each of the old and new thermostats? 83 C is the norm - but many cars have had 70 C installed by POs.
So many questions .... verify the thermostat first - after confirming an air bleed as Justin noted. For that, I back out the uppermost temp sensor until the coolant runs clear.
03-27-2005, 10:34 AM
#4
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Bill,
After a flush there is some water left in the system. If you use already mixed 50/50 solution, the result is a less than 50/50 mix. This is dangerous, even if you never get freezing temperatures as the corrosion protection is inadequate.
After flushing add full strength antifreeze equal to 50% of the cooling system capacity. 2 gallons on a 928. Then add water until the system is full.
Also, Dexcool is a very poor choice for any car. It MAY be OK if you change it every two years. Best bet is G05 after a complete flush. Zerex sells G05 at many chain stores.
After a flush there is some water left in the system. If you use already mixed 50/50 solution, the result is a less than 50/50 mix. This is dangerous, even if you never get freezing temperatures as the corrosion protection is inadequate.
After flushing add full strength antifreeze equal to 50% of the cooling system capacity. 2 gallons on a 928. Then add water until the system is full.
Also, Dexcool is a very poor choice for any car. It MAY be OK if you change it every two years. Best bet is G05 after a complete flush. Zerex sells G05 at many chain stores.
03-27-2005, 01:05 PM
#6
Rennlist Member
squeeze the hoses top and bottom and repeat until they feel solid with no air or bubbles in them.
concentration of water and antifreeze will not effect cooling for your use. racing maybe, but not for geneneral cooling. check the radiator, see if it feels hot all over. when the car is running as it should be, the radiator will be hot top to bottom. temp should end up in the middle.
mk
concentration of water and antifreeze will not effect cooling for your use. racing maybe, but not for geneneral cooling. check the radiator, see if it feels hot all over. when the car is running as it should be, the radiator will be hot top to bottom. temp should end up in the middle.
mk
03-27-2005, 07:23 PM
#7
Racer
Thread Starter
Thanks guys, checking all and still bruping a little. Added about half gallon antifreeze. Still going a little above the last white line. Before usually stay a little below line. I'll figure it out. Does anyone remember the thread and replaceing the oil sensor? It talked about how that would cause a little higher reading on temp gauage. Anyone had any dealings with that?
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03-27-2005, 09:07 PM
#9
Racer
Thread Starter
Yes I changed the gasket, o-ring, and new thermostat. I drained the block also. Hoses do not feel solid after thrid running the car around town. I'm still squeezing, jeez how much squeezing to get the air out?????
03-27-2005, 09:19 PM
#11
Race Director
Originally Posted by justin
Mine runs at the third white mark all the time,is this too hot?
That seems a bit on the hot side. The way I understand it the first white mark is about 175 and the second (mine only has two)is about 220...so that means your car is running abotu 220...but if its been like this for years and doesn't overheat in the summer with the A/C on then it should be okay....a flush, fill & 75' thermostat couldn't hurt either? My car consistantly runs around the 1st line, unless it is very hot with the A/C on, then its about middle.
07-11-2005, 03:57 PM
#12
Originally Posted by IcemanG17
That seems a bit on the hot side. The way I understand it the first white mark is about 175 and the second (mine only has two)is about 220...so that means your car is running abotu 220...but if its been like this for years and doesn't overheat in the summer with the A/C on then it should be okay....a flush, fill & 75' thermostat couldn't hurt either? My car consistantly runs around the 1st line, unless it is very hot with the A/C on, then its about middle.
Now that summer is here, if I drive it for several hours on the Interstate, it hugs the last white mark and if I run about 80mph (accidentally of course) on a hot day with the A/C on, it will ride 'on top' if the last white mark, but rarely goes past it...(yet anyway). If I back off to around 60, it cools to a little below the mark. How often should one replace the thermostat?
From my reading on this forum, a hot day with the needle on the last white mark is considered normal/okay. (?)
07-11-2005, 04:09 PM
#13
Under the Lift
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Kelly:
As long as it doesn't get close to the red zone, this is "normal". On hot days mine operates like yours. You will see other comments on how they never get beyond the middle of tha gauge. Don't let that send you on a wild goose chase for a problem you do not have.
As long as it doesn't get close to the red zone, this is "normal". On hot days mine operates like yours. You will see other comments on how they never get beyond the middle of tha gauge. Don't let that send you on a wild goose chase for a problem you do not have.
07-11-2005, 04:35 PM
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My 94 GTS with a 75 degree C thermostat runs around 180-185 normally, about 1/8th of an inch above the first white line which is marked 170. This is only a tad cooler than the 83 degree C thermostat I replaced a couple of months ago. The system did take some burbing. My problem was the front electric cooling fans, which now work properly. Good luck after burping.
07-11-2005, 05:49 PM
#15
Racer
Thread Starter
Well, I did change to a 75 C thermostat and it is now summer with some very hot temps down south here. Running the car in traffic and city with heat index of 105, it ran just a little over the half mark and this is running the AC. For my experience only, repeat my experience only, this is the way to have gone. My car used to almost red line and sometimes red line in 80-90 degree temps. I'm completely satisfied with changing to 75 C stat.