Low coolent temp
Thread Starter
Racer
Joined: Feb 2012
Posts: 442
Likes: 23
From: Seattle Washington
Low coolent temp
Hey guys. My 85 L98 Z51 has a top coolent temp of 178 degrees. Sounds low based on some of the info gained here. Also, when starting the RPM's stay at 1100 for quite some time causing cocern about shifting into gear at that level. In addition I'm averaging 13mpg around town again sounding low. Rebuilt ECM with stock chip recently installed and fans operating correctly. Any thoughts?
Le Mans Master
Joined: Aug 2007
Posts: 8,735
Likes: 413
From: WV
Sounds like maybe your thermostat is stuck open..If its a stock stat and working properly you should stay around at least 190-195 degrees..The high rpms at startup could be the "Idle air control" sticking or dirty, or a vacuum leak...WW
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
Gauge could be reading wrong
Have you independently confirmed actuall engine temp?
If engine was at the temp you say ,the fans would never run at all seeing that stock fan ON temp is 228F
Have you independently confirmed actuall engine temp?
If engine was at the temp you say ,the fans would never run at all seeing that stock fan ON temp is 228F
Thread Starter
Racer
Joined: Feb 2012
Posts: 442
Likes: 23
From: Seattle Washington
Ok, going to need some help here. Took the vette to a vette specialty shop for other issues. Mechanic noticed the fans were operating at all times (key on). here is thier report/invoice "inspect cooling fan relay and found the wiring appears to be correct but the relay is still receiving the signal that makes it engage the cooling fan. After some research we found that the ECM has an aftermarket E-prom chip and that, in combination with a possibly bad ECM, could be causing the ECM to be shorted to ground in the circuit for the cooling fan running continuously when the ignition key is on.
Replaced the ECM and Prom chip and retested the cooling fan system, works as it should at this time, the fan comes on at 175 degrees and goes off at 166.
Hypertech Chip-s #11542 $206.00
ECM-s # 77-6870 $158.00
Labor $245.00"
Sorry for the long details but wanted you to know the full story. Whats wrong with this picture?
Replaced the ECM and Prom chip and retested the cooling fan system, works as it should at this time, the fan comes on at 175 degrees and goes off at 166.
Hypertech Chip-s #11542 $206.00
ECM-s # 77-6870 $158.00
Labor $245.00"
Sorry for the long details but wanted you to know the full story. Whats wrong with this picture?
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
Le Mans Master
Joined: Nov 2009
Posts: 6,882
Likes: 234
From: Bangkok, Thailand
I read that as him having replaced the ECM and unknown chip with a Hypertech chip and a reman ECM.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
Most on here would say that is too low for normal driving;