Running hot?

[Billy Mild]

Originally Posted by We Gone

I think you may have a bad thermostat, My car ran around 205-215 down the road stock, when I stated have issues with the thermostat not opening all the way it would get to 226 + or - a few and stay all the time unless in traffic or stop and go than it got to 230's and the fans would never shut off.

Changed it and went to Marc's prom now I never see over 212 stop and go and the fans will always bring it back to 200 + or - 5 and cycle off. 205 running at speed on a hot day.

It sounds like my thermostat might be going bad.

How difficult is it to replace the thermostat? Also what do I need to do to clean the radiator properly? Sounds like I am going to have to play with coolant again.

I hate dealing with coolant.

[A26B]

To properly clean the radiator, it needs to be removed to get all the small stuff out of the core. It's amazing how much gets stuck in the fins.

Thermostat halfway done when the radiator is removed.

I would say you are looking at about 3~4 hours to do it all. The small shroud screws accessible from under the front of the car are a bit of a PITA. I also trimmed my shroud around the Oil Cooler hose connection to make it easier to remove & re-install.

[Billy Mild]

Originally Posted by A26B

To properly clean the radiator, it needs to be removed to get all the small stuff out of the core. It's amazing how much gets stuck in the fins.

Thermostat halfway done when the radiator is removed.

I would say you are looking at about 3~4 hours to do it all. The small shroud screws accessible from under the front of the car are a bit of a PITA. I also trimmed my shroud around the Oil Cooler hose connection to make it easier to remove & re-install.

Might as well change the oil cooler lines and coolant hoses while I'm in there.

FFFFFFFF yet another project.

[A26B]

Originally Posted by Billy Mild

Might as well change the oil cooler lines and coolant hoses while I'm in there.

Definitely a good time for the coolant hoses, especially the water pump inlet & bypass hoses.

Just look at it like foreplay, part of the process to the ultimate enjoyment.

[Billy Mild]

MOTORAD Part # 308180 {#19114506, 30880} OE Standard
Temperature: 180F; OEM Recommended Temp

I saw this thermostat on Rockauto. Are all the thermostats 180 degree? Would this fit my car and be the proper type?

[A26B]

Use only Stant 14068.

[Dynomite]

Keep the LT5 Cool using a Stant 180 deg F Thermostat and Ron Davis Aluminum Radiator.

Also Clean/straighten all fins on Oil Cooler and AC Condenser

180 deg F Thermostat



Ron Davis 1-16CV8996 Aluminum Radiator for 1990/1991 ZR-1s

1989-1996 C4 Type V8 All Part No. 1-16CV8996

-Rated HP: 800*
-Manual transmission
-Core is thicker than factory unit, shroud must be trimmed.



LT5 Thermostats
LT5 Radiator and Initial Coolant Fill Tricks

To read Digital Coolant Temperatures.....

1. Push and hold up and down (each side of Fan Control button) until you get zeros in display on left.
2. Then push up button to right until you get to 16 in the display.
3. Then push center fan button to read digital coolant temperature in degrees C continually in the display until you hit the temperature button.
80 C is 176 F
85 C is 185 F
90 C is 194 F
95 C is 203 F
100 C is 212 F
105 C is 221 F
110 C is 230 F
115 C is 239 F
120 C is 248 F
125 C is 257 F
130 C is 266 F

Keeping the LT5 Cool and Radiator Debris Screens

Solving the Hot/Warm LT5 once and for all

Installing two of the Ron Davis 1-16CV8996 Aluminum Radiators next week (one in each of two 1990s and a third 1990 later).
Tired of running just a tad hot as I like to stay between 85 deg C and 95 deg C (185 deg F to 200 deg F).

[Billy Mild]

I noticed that when on a long highway drive the car was under 50% on the temp gauge the whole time. As soon as O was in the city driving the car would start to run warm.

I assume this points towards a airflow issue.

[mike100]

I have had to clean mine every two to three years. Taking it out the first time might be required to undo 25 years of debris and fine dirt. Or at least pop the upper radiator shroud off and you can blow water and compressed air over a good portion of it.

This is where you make the decision to buy a new radiator etc, but I decided to keep mine after i was able to thoroughly clean and pressure test it. That was four years ago... I cleaned it once after the oil cooler lines misted it and eventually dust collected, but that was another issue entirely. I would recommend cutting the corner of the shroud near the a/c hard lines to the condenser- it just saves so much time.

[Dynomite]

Originally Posted by mike100

I have had to clean mine every two to three years. Taking it out the first time might be required to undo 25 years of debris and fine dirt. Or at least pop the upper radiator shroud off and you can blow water and compressed air over a good portion of it.

This is where you make the decision to buy a new radiator etc, but I decided to keep mine after i was able to thoroughly clean and pressure test it. That was four years ago... I cleaned it once after the oil cooler lines misted it and eventually dust collected, but that was another issue entirely. I would recommend cutting the corner of the shroud near the a/c hard lines to the condenser- it just saves so much time.

I let the ZR-1 sit over night then disconnect the Oil Cooler Adapter (one 6mm x 1.0 x 35 mm bolt in center) without disconnecting the Oil Cooler Lines from the adapter. This makes it much easier to lift the Drivers Side of the Shroud first. When the Drivers Side is cleared, lift the Passenger Side letting the shoud tab under the AC lines bend and pop up.

The Shroud really comes off fairly Easy but you just have to apply a little pressure and lift it off in sequence Drivers Side then Passenger Side.

On the Installation the reverse installing the Passenger Side bending the Tab down inside the AC Lines and then the Drivers Side lowering onto the radiator. I did not cut the Shroud in any way.

Originally Posted by Billy Mild

I noticed that when on a long highway drive the car was under 50% on the temp gauge the whole time. As soon as O was in the city driving the car would start to run warm. I assume this points towards a airflow issue.

Yes it does point to an airflow issue.....Daryll (Goldcylon) I recall installed higher flow rate fans and others have installed Aluminum Racing type Radiators. But what you describe is normal for the ZR-1 with Stock Radiator. To keep the Coolant Temperatures below 225-230 deg F on HOT (100+ deg Ambient) idling in traffic one MUST turn off the AC. And even then it is sometimes difficult to keep the temperature down. It is amazing that just a little air flow (20 mph) will usually start bringing the Temperature under control.

Like Mike and Jerry and others have said ....You MUST clean the Radiator, AC Condenser, AND Oil Cooler to assure Air Flow.