Normal Operating Temps for 1986 L98 Engine?
Thread Starter
Burning Brakes
Joined: May 2002
Posts: 751
Likes: 8
From: Escondido CA
Normal Operating Temps for 1986 L98 Engine?
Hello Corvette Nation,
I have a 1986 L98 engine installed in a 47 Plymouth (Turbo 350, single electric pusher fan, set to turn on at around 180-190). I have been concerned with operating temperatures. In a previous thread I asked about whether advanced or retarded timing could cause overheating.
This morning I replaced the knock sensor (I was having a problem with intermittent pinging under load). That seems to have fixed the pinging problem. Afterwards I checked the timing (after verifying TDC), it was right on 6 BTDC, no adjustment necessary.
Went out for a 10-mile test drive, combination of freeway and stop-and-go. Ambient outside temperature at the time of the drive was 92 - 95 degrees. Temp gauge stayed around 185-195 on the freeway. Stop-and go around town bumped it to around 200. Last half mile of the run is all slow speed (10-15MPH) uphill to my house, it topped up at 220, then idled in front of the house for about 20 minutes, and never got above 230. Based on how hot these engines run when installed in a Corvette, I think this is acceptable...Yes? No?
PS Temp sender is located in the factory (hottest) location, driver's side cylinder head.
Also, how long after disconnecting and re-connecting the battery will it take for the ECM to re-learn its settings?
Thanks in advance.
I have a 1986 L98 engine installed in a 47 Plymouth (Turbo 350, single electric pusher fan, set to turn on at around 180-190). I have been concerned with operating temperatures. In a previous thread I asked about whether advanced or retarded timing could cause overheating.
This morning I replaced the knock sensor (I was having a problem with intermittent pinging under load). That seems to have fixed the pinging problem. Afterwards I checked the timing (after verifying TDC), it was right on 6 BTDC, no adjustment necessary.
Went out for a 10-mile test drive, combination of freeway and stop-and-go. Ambient outside temperature at the time of the drive was 92 - 95 degrees. Temp gauge stayed around 185-195 on the freeway. Stop-and go around town bumped it to around 200. Last half mile of the run is all slow speed (10-15MPH) uphill to my house, it topped up at 220, then idled in front of the house for about 20 minutes, and never got above 230. Based on how hot these engines run when installed in a Corvette, I think this is acceptable...Yes? No?
PS Temp sender is located in the factory (hottest) location, driver's side cylinder head.
Also, how long after disconnecting and re-connecting the battery will it take for the ECM to re-learn its settings?
Thanks in advance.
Last edited by kbuhagiar; Aug 14, 2018 at 11:23 PM.
Drifting
Joined: Mar 2018
Posts: 1,362
Likes: 400
From: DFW TX
You are probably fine at those temps but you may be on the cusp with that single pusher fan, especially if it is a cheap fan.
Also, temp gauge readings from the cylinder head are almost always higher than temps at the thermostat housing.
My LQ9 will show 200-225 on the dash (cylinder head sender) and only ~185-210 (OBDII) at the t-stat housing.
I was a little worried about my ride until I plugged in the OBDII scanner and realized the coolant temps were much cooler than the dash gauge reported.
Also, temp gauge readings from the cylinder head are almost always higher than temps at the thermostat housing.
My LQ9 will show 200-225 on the dash (cylinder head sender) and only ~185-210 (OBDII) at the t-stat housing.
I was a little worried about my ride until I plugged in the OBDII scanner and realized the coolant temps were much cooler than the dash gauge reported.
Thread Starter
Burning Brakes
Joined: May 2002
Posts: 751
Likes: 8
From: Escondido CA
I don't think it's a cheap fan, it's a Derale 14", but I am working on adding a 16" puller fan on the upper quadrant of the radiator to help with cooling.
