'98 Coolant Temperatures
Racer
Joined: Feb 2004
Posts: 359
Likes: 7
From: St. Paul MN
Originally Posted by 2blklt4
54F outside, freeway and streets no traffic, flat road on both freeway and streets.
1. On freeway temperature read would fluctuate between 196-198F at 75 mph on 5th gear. Steady pressure on gas pedal.
2. On freeway if going at the same speed 75 mph on 6th gear temperature would rise to 205-207F and stay there. If down shift to 5th gear temp will lower again to 198F
3. At idle car would heat up to 225-227F then cool off to about 210F after fans kick in.
I'd like to know your opinion on both 1., 2. and 3. if you think those operating temperatures are normal, and why the temperature would rise when swiching gear (from 5th to 6th) Same road conditions, same speed of driving same temperature outside. I thought that lower revs in 6th gear would make the engine run cooler but...??
Your input is greatly appreciated and please try to answer to all questions separate.
Cheers
1. On freeway temperature read would fluctuate between 196-198F at 75 mph on 5th gear. Steady pressure on gas pedal.
2. On freeway if going at the same speed 75 mph on 6th gear temperature would rise to 205-207F and stay there. If down shift to 5th gear temp will lower again to 198F
3. At idle car would heat up to 225-227F then cool off to about 210F after fans kick in.
I'd like to know your opinion on both 1., 2. and 3. if you think those operating temperatures are normal, and why the temperature would rise when swiching gear (from 5th to 6th) Same road conditions, same speed of driving same temperature outside. I thought that lower revs in 6th gear would make the engine run cooler but...??
Your input is greatly appreciated and please try to answer to all questions separate.
Cheers
65 degree air temps in MN right now. I finished a head/cam upgrade over the winter with a thorough A/C condenser & radiator fin cleaning, and swapped to a new 180* thermostat.
#1 and #2 same results. 6th gear at 201 degrees, shift to 5th gear for 10 seconds and it drops to 196-198.
#3. At idle in the driveway mine settles out about 208* (with both fans on high with a lower setpoint by my tuner). Top radiator hose is fairly hot. Lower hose is downright cold. My radiator cleaning job must have made it more efficient. Rev to 3000 rpms for 15 seconds, and the DIC temp drops to 196. Gently squeeze the lower hose while someone else revs (surge cap is off so system is not pressurized), and you can feel the hose bulging. That thermostat is closed.
Originally Posted by 8VETTE7
For me the faster I go the cooler the engine runs. During track days on the Phoenix International Raceway oval I'm running mid 180 degrees pushing the car over 100mph in 3rd and 4th gears until I come into the pits. I have a 170 T'stat. Yet on the highway at 80 mph on the way home from PIR the car is reaching low 200's in 6th gear. If I drop it to 5th gear the temp comes down about 5 degrees.
I found an old thread (free-180-thermostat-mod) where folks had drilled out the bypass on the thermostat which would flow more coolant even if it were closed. Any pros or cons to just enlarging the bypass?
Todd
Last edited by toddk; Apr 5, 2012 at 09:31 PM.
