Correct engine coolant temperature

[salvatore1]

Hi,

I know this subject has been visited before, but I'll ask it again anyway. What is the correct engine temperature for the Z? Mine seems too hot for my comfort.

If the car is not moving very fast (i.e. bumper to bumper traffic) the guage starts to climb all the way to top, but then just as it touches the cross hatches a fan kicks in and the needle drops pretty quickly to the 3/4 (still too hot for my comfort). I think the radiator is ok because when the fan kicks in (not sure which one) it does start cooling down. Also, when I'm moving at a good clip on the freeway, the needle will go back to the halfway mark or lower.

I would also like to mention I tried looking at the "digital temperature" via the A/C control and it shows 113 when the guage goes all the way to the top (235) - I guess it's in celsius. After it hits that exact temperature the fan kicks in and it drops as stated above.

Any idea whats happening here?

Thanks
Sal

[Pete]

Sounds about right.

That is how the stockers are.

Call Marc H. www.ZR1specialist.com for a new chip.

Pete

[ZR1Vette]

Couple observations..
-The gauges on ZR-1/C4 are notoriously inaccurate
-Coolant temps should be in 190-205 F range
-LT-5 cooling has always been an issue... partly due to the radiator design & placement. Being a bottom feeder (for air flow over the radiator) all sorts of debris (big like leaves) and small (like dirt/grit/sand etc) which can (1) block air flow over the radiator and (2) actually clog the radiator itself (grit build up in the cooling veins of the radiator). Big stuff you can see collected on the front of the radiator, but the small stuff is not readily seen until the radiator shroud is removed.
-OEM program has fans coming on in a progressive fashion and there are aftermarket chips (Haibeck comes to mind ) that reprograms the fans to have both come on and come on at a lower temp than the factory setup.

How many miles on your ZR? Has the radiator core ever been inspected?

[secondchance]

I have a 94 which means I have a luxury of digital temp readings which 91 does not.

Mine use to run at 198 F at highway speed in cool day and around 202 F on hot weather. What this corresponds to on analog is tough.

As for bumper to bumper, with out AC on, she would reach 223 F at which point fan would kick on and bring down to 218 F or so and turn off until temp would reach 223 or so.

On hot day with AC on, one fan would be running constantly keeping the temp somewhat lower, say about 3-5 degrees.

I wouldn't try to estimate engine temp on analog gage. They are just not that accurate. I see you are in California. How hot a day are we talking about?

Recently I switched to Marc Haibeck chip and and one feature I really appreciate is his cooling fan strategy. Since the switch my Z has been running about 8 to 10 degrees cooler in stop and go traffic.

[salvatore1]

Originally Posted by ZR1Vette

Couple observations..
-The gauges on ZR-1/C4 are notoriously inaccurate
-Coolant temps should be in 190-205 F range
-LT-5 cooling has always been an issue... partly due to the radiator design & placement. Being a bottom feeder (for air flow over the radiator) all sorts of debris (big like leaves) and small (like dirt/grit/sand etc) which can (1) block air flow over the radiator and (2) actually clog the radiator itself (grit build up in the cooling veins of the radiator). Big stuff you can see collected on the front of the radiator, but the small stuff is not readily seen until the radiator shroud is removed.
-OEM program has fans coming on in a progressive fashion and there are aftermarket chips (Haibeck comes to mind ) that reprograms the fans to have both come on and come on at a lower temp than the factory setup.

How many miles on your ZR? Has the radiator core ever been inspected?

Car has about 32K miles. I had partially pulled off the shroud to look at the radiator. but did not get it all the way out. I did not see any bird nests in there, but obviously I wouldn't be able to see sand in the mesh unless I yanked it completely - I really wanted to avoid that if at all humanly possible.

[secondchance]

Originally Posted by salvatore1

Car has about 32K miles. I had partially pulled off the shroud to look at the radiator. but did not get it all the way out. I did not see any bird nests in there, but obviously I wouldn't be able to see sand in the mesh unless I yanked it completely - I really wanted to avoid that if at all humanly possible.

One thing you can try is find a high pressure washer car wash. Then secure the fan so that washer wouldn't run the fan blade and pressure wash between the fan blade blowing out. You can only hit limited area but typically it's the same area where build up was when I pulled the radiator.

http://www.zr1specialist.com/HAT%20W...librations.pdf

Page 12 of this presentation talks about factory fan strategy verses his chip.

[salvatore1]

Originally Posted by secondchance

One thing you can try is find a high pressure washer car wash. Then secure the fan so that washer wouldn't run the fan blade and pressure wash between the fan blade blowing out. You can only hit limited area but typically it's the same area where build up was when I pulled the radiator.

http://www.zr1specialist.com/HAT%20W...librations.pdf

Page 12 of this presentation talks about factory fan strategy verses his chip.

Hey thanks for your idea - I think I'll give it a try.

[secondchance]

For reference, today it was 80 degrees here in Northern Virginia. On the highway my Z was running at 201 degrees and it represented 1/6 below half point on analog gauge.
For stop and go traffic, between 203 and 207 (1/8th below half way point on analog). Never saw 210. This is w/ Marc's chip.

[QB93Z]

I am convinced that the cooling problem with the ZR-1 is related to the bypass flow around the radiator. In both my 1990 ZR-1 and my 1993 ZR-1, I have brand new high capacity radiators (a DeWitt and a Ron Davis) and Haibeck chips.

In both cars when cruising at about 55 mph in sixth gear (about 1600 to 1800 rpm, the coolant temperature will rise to around 225. If I shift to fifth gear, (>2000 rpm) the temperature immediately drops to around 203-205. The drop is rapid (you can see the needle move). This indicates to me that there is plenty of cooling capicity available (ie air flow and heat transfer from the radiator) but that at low rpm most of the water pump output flow is bypassing the radiator through the radiator bypass line.

Under higher engine load, such as running at 80-85 mph the coolant temperature is stable at around 195.

My next research attempt is going to be replacing the thermostat (which also has the bypass flow valve built into it. I may even try to block off all the low rpm bypass flow just to see what happens.

Jim

[PhillipsLT5]

Change to 4.10 gear