Cooling Issues? *HELP*
Thread Starter
Heel & Toe
Joined: Mar 2014
Posts: 23
Likes: 0
From: Southern New Jersey
Cooling Issues? *HELP*
Hi everyone,
Recently I had a complete engine overbore and rebuild done in my 1986. I'm now 30 over and running a "355" instead of a 350. Before the rebuild, my car would run around 205-215 while cruising, and creep to 225-230 max in traffic. Now, regardless of traffic or cruise, the car steadily climbs until it reaches 247 or 248 and then the fan brings it back down to around 219, only to have it climb back up to that temp as soon as the fan shuts off. My 86 is a convertible and is only equipped with the standard equipment fan from that model year. I recently had it replaced and also had a new radiator installed. I am running a stock thermostat. I just purchased a manual fan switch and 160 thermostat thinking maybe it would help, but I'm no expert when it comes to engine cooling. Any ideas? Thanks!
Recently I had a complete engine overbore and rebuild done in my 1986. I'm now 30 over and running a "355" instead of a 350. Before the rebuild, my car would run around 205-215 while cruising, and creep to 225-230 max in traffic. Now, regardless of traffic or cruise, the car steadily climbs until it reaches 247 or 248 and then the fan brings it back down to around 219, only to have it climb back up to that temp as soon as the fan shuts off. My 86 is a convertible and is only equipped with the standard equipment fan from that model year. I recently had it replaced and also had a new radiator installed. I am running a stock thermostat. I just purchased a manual fan switch and 160 thermostat thinking maybe it would help, but I'm no expert when it comes to engine cooling. Any ideas? Thanks!
Team Owner
Joined: Sep 2003
Posts: 25,331
Likes: 2,722
Hi everyone,
Recently I had a complete engine overbore and rebuild done in my 1986. I'm now 30 over and running a "355" instead of a 350. Before the rebuild, my car would run around 205-215 while cruising, and creep to 225-230 max in traffic. Now, regardless of traffic or cruise, the car steadily climbs until it reaches 247 or 248 and then the fan brings it back down to around 219, only to have it climb back up to that temp as soon as the fan shuts off. My 86 is a convertible and is only equipped with the standard equipment fan from that model year. I recently had it replaced and also had a new radiator installed. I am running a stock thermostat. I just purchased a manual fan switch and 160 thermostat thinking maybe it would help, but I'm no expert when it comes to engine cooling. Any ideas? Thanks!
Recently I had a complete engine overbore and rebuild done in my 1986. I'm now 30 over and running a "355" instead of a 350. Before the rebuild, my car would run around 205-215 while cruising, and creep to 225-230 max in traffic. Now, regardless of traffic or cruise, the car steadily climbs until it reaches 247 or 248 and then the fan brings it back down to around 219, only to have it climb back up to that temp as soon as the fan shuts off. My 86 is a convertible and is only equipped with the standard equipment fan from that model year. I recently had it replaced and also had a new radiator installed. I am running a stock thermostat. I just purchased a manual fan switch and 160 thermostat thinking maybe it would help, but I'm no expert when it comes to engine cooling. Any ideas? Thanks!
You are measuring your temps how? Do you know what the temp the fan actually engages? If all of the cooling system is confirmed good and fan/ECM etc, do as they're supposed to concentrate on the lower air-deflector, there should be a chin spoiler (most/many call it that) and it actually direct air towards the radiator/condenser module and of course it has the lower deflector that goes end to end. Important that it's there. The taller Z51 lower deflector actually helps. The actual lower center deflector, the upper deflector and the fan shrouds are important.
All of this + the lower bumper deflectors "in place and secured properly":
Last edited by WVZR-1; Apr 8, 2016 at 07:34 PM.
Melting Slicks
Joined: Nov 2010
Posts: 2,216
Likes: 112
From: Michigan
Overbore puts more heat into the coolant, thinner cylinders and a tad more surface area to absorb.
Make sure you AC is clean and fins not messed up if you still have it.
Did you change the waterpump? Correct rotation if you did?
edit: Did you increase the compression?
Make sure you AC is clean and fins not messed up if you still have it.
Did you change the waterpump? Correct rotation if you did?
edit: Did you increase the compression?
Last edited by BOOT77; Apr 8, 2016 at 08:20 PM.
Melting Slicks
Joined: Jan 2001
Posts: 2,996
Likes: 303
From: MOORESVILLE NC
You may need a fan on the front AC condenser and the backside of the radiator, a pull and a push. My 88 C4 has both as stock. Not sure what option it was. Mine runs warn but not too hot.
Thread Starter
Heel & Toe
Joined: Mar 2014
Posts: 23
Likes: 0
From: Southern New Jersey
Whose radiator did you buy?
You are measuring your temps how? Do you know what the temp the fan actually engages? If all of the cooling system is confirmed good and fan/ECM etc, do as they're supposed to concentrate on the lower air-deflector, there should be a chin spoiler (most/many call it that) and it actually direct air towards the radiator/condenser module and of course it has the lower deflector that goes end to end. Important that it's there. The taller Z51 lower deflector actually helps. The actual lower center deflector, the upper deflector and the fan shrouds are important.
All of this + the lower bumper deflectors "in place and secured properly":
Attachment 47970766
You are measuring your temps how? Do you know what the temp the fan actually engages? If all of the cooling system is confirmed good and fan/ECM etc, do as they're supposed to concentrate on the lower air-deflector, there should be a chin spoiler (most/many call it that) and it actually direct air towards the radiator/condenser module and of course it has the lower deflector that goes end to end. Important that it's there. The taller Z51 lower deflector actually helps. The actual lower center deflector, the upper deflector and the fan shrouds are important.
All of this + the lower bumper deflectors "in place and secured properly":
Attachment 47970766
Thread Starter
Heel & Toe
Joined: Mar 2014
Posts: 23
Likes: 0
From: Southern New Jersey
Waterpump is new and rotating properly. Coolant does flow once the thermostat opens. My AC compressor does not work however. It's been broken for many years. It's still hooked on my drive belt. Could that be an issue?
Le Mans Master
Joined: Mar 2004
Posts: 5,107
Likes: 171
From: Dublin CA
The FlowKooler water pump will flow 30% more coolant than a standard pump.
When I dropped in my ZZ4 in my 85 I installed the FlowKooler pump and it kept the temps on the freeway in the 185 range and seldom got to 220 in normal traffic.
When I dropped in my ZZ4 in my 85 I installed the FlowKooler pump and it kept the temps on the freeway in the 185 range and seldom got to 220 in normal traffic.
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Racer
Joined: May 2015
Posts: 265
Likes: 21
From: Grand Rapids MI
You say the temp comes right down when the fan kicks on, so let it do so earlier--all signs point to the car wanting a lower temp fan switch. I run a 200 on / 185 off switch & 180 stat; your car should be happy with that combo if your new radiator is stock equivalent or better.
355 won't create that much more heat than a 350, unless you upped compression from stock too. 160 stat will do nothing better for you, except keep your car from running colder than 160, post-warmup, in chilly ambient temps.
If cooling remains insufficient after the switch swap, look into an auxiliary fan. Seems to me improved airflow is the solution, though a high volume pump couldn't hurt if you've got extra income to dispose of.
355 won't create that much more heat than a 350, unless you upped compression from stock too. 160 stat will do nothing better for you, except keep your car from running colder than 160, post-warmup, in chilly ambient temps.
If cooling remains insufficient after the switch swap, look into an auxiliary fan. Seems to me improved airflow is the solution, though a high volume pump couldn't hurt if you've got extra income to dispose of.
Last edited by 84Z51J; Apr 9, 2016 at 02:10 PM.
Team Owner
Joined: Sep 2003
Posts: 25,331
Likes: 2,722
You say the temp comes right down when the fan kicks on, so let it do so earlier--all signs point to the car wanting a lower temp fan switch. I run a 200 on / 185 off switch & 180 stat; your car should be happy with that combo if your new radiator is stock equivalent or better.
355 won't create significantly more heat than a 350, unless you upped compression from stock as well. 160 stat will do nothing better for you, except keep your car from running colder than 160, post-warmup, in super cold ambient temps.
If cooling remains insufficient after that change, look into an auxiliary fan. Seems to me improved airflow is the solution.
355 won't create significantly more heat than a 350, unless you upped compression from stock as well. 160 stat will do nothing better for you, except keep your car from running colder than 160, post-warmup, in super cold ambient temps.
If cooling remains insufficient after that change, look into an auxiliary fan. Seems to me improved airflow is the solution.
He needs to separately confirm the TEMP GAUGE sender and the cluster gauge. If gauge or temp ender are in error maybe there's actually no problem.
OP - an IR gun I've been told isn't very reliable at all when doing coolant evaluations. Other evaluations yes and I have access to a very good one. I use it in the house, around the car and nearly every place imaginable.
Last edited by WVZR-1; Apr 9, 2016 at 02:08 PM.
Thread Starter
Heel & Toe
Joined: Mar 2014
Posts: 23
Likes: 0
From: Southern New Jersey
Also, I'm running regular Prestone 50/50.
Thread Starter
Heel & Toe
Joined: Mar 2014
Posts: 23
Likes: 0
From: Southern New Jersey
OP has a '86 and NO AUX so his fan is all controlled by the ECM. Fan I believe turns on @ 234 ( I believe) so maybe the OP just does an ECM CTS replacement and confirms the operation of everything with a scanner. He questions maybe performance so the scanner is NEEDED not just a maybe.
He needs to separately confirm the TEMP GAUGE sender and the cluster gauge. If gauge or temp ender are in error maybe there's actually no problem.
OP - an IR gun I've been told isn't very reliable at all when doing coolant evaluations. Other evaluations yes and I have access to a very good one. I use it in the house, around the car and nearly every place imaginable.
He needs to separately confirm the TEMP GAUGE sender and the cluster gauge. If gauge or temp ender are in error maybe there's actually no problem.
OP - an IR gun I've been told isn't very reliable at all when doing coolant evaluations. Other evaluations yes and I have access to a very good one. I use it in the house, around the car and nearly every place imaginable.
Thread Starter
Heel & Toe
Joined: Mar 2014
Posts: 23
Likes: 0
From: Southern New Jersey
You say the temp comes right down when the fan kicks on, so let it do so earlier--all signs point to the car wanting a lower temp fan switch. I run a 200 on / 185 off switch & 180 stat; your car should be happy with that combo if your new radiator is stock equivalent or better.
355 won't create that much more heat than a 350, unless you upped compression from stock too. 160 stat will do nothing better for you, except keep your car from running colder than 160, post-warmup, in chilly ambient temps.
If cooling remains insufficient after the switch swap, look into an auxiliary fan. Seems to me improved airflow is the solution, though a high volume pump couldn't hurt if you've got extra income to dispose of.
355 won't create that much more heat than a 350, unless you upped compression from stock too. 160 stat will do nothing better for you, except keep your car from running colder than 160, post-warmup, in chilly ambient temps.
If cooling remains insufficient after the switch swap, look into an auxiliary fan. Seems to me improved airflow is the solution, though a high volume pump couldn't hurt if you've got extra income to dispose of.
Team Owner
Joined: Sep 2003
Posts: 25,331
Likes: 2,722
Do you have the FSM? See 8A-82 for diagnostics,
A typical replacement gauge sender is: 100º F -- 1250-1600 ohms, 220º F -- 138-156 ohms,
The CTS for the ECM is pretty much done to this table. You'll find discrepancies from time to time but I believe it safe to assume these or very/very close:
http://pe-ltd.com/assets/coolant_temp.pdf
In your FSM Check CODE 14 in 6E3-A-35 and there's a chart included there.
With a scanner compare what the CTS sees vs. the dash unit. You could supply the dash gauge withe similar resistance values as in the temp sender and expect to see similar cluster readouts. Some year FSM actually may have the OE spec listed in a similar table.
6E3-C12-3 for cooling fan diagnostics.
Last edited by WVZR-1; Apr 10, 2016 at 06:24 AM.
Melting Slicks
Joined: Nov 2010
Posts: 2,216
Likes: 112
From: Michigan
I'm talking bout the part in front of the radiator, AC condenser. Make sure it's clean and the fins aren't all folded over, I've seen some that were pretty hammered by rocks.
Melting Slicks
Joined: Aug 2008
Posts: 2,082
Likes: 50
From: Palmdale CA
^^ This gets widely overlooked! from a casual observation this coil may look good, but if you Back-lite it, and look through it from the opposite direction it may be loaded up with embedded bugs and you name it. Mine was so bad it took hours of cleaning to get it right.
Melting Slicks
Joined: Jan 2009
Posts: 3,482
Likes: 195
From: folsom california
^^ This gets widely overlooked! from a casual observation this coil may look good, but if you Back-lite it, and look through it from the opposite direction it may be loaded up with embedded bugs and you name it. Mine was so bad it took hours of cleaning to get it right.
between the A/C condenser and radiator I spent several hours picking out several thousand dead bugs, grains of sand and who knows what; I would also suggest using brake cleaner to dissolve / remove any film that has built up on the fins and tubes
Thread Starter
Heel & Toe
Joined: Mar 2014
Posts: 23
Likes: 0
From: Southern New Jersey
^^ This gets widely overlooked! from a casual observation this coil may look good, but if you Back-lite it, and look through it from the opposite direction it may be loaded up with embedded bugs and you name it. Mine was so bad it took hours of cleaning to get it right.