Whats the highest temps youve seen?

[Lucky90]

On my 90 ,up a steep grade for a long time in slow traffic ,ive seen 245. then it goes back down. Has anyone else approched 245 250, i know the red cross hatch is at 260?

[Dynomite]

Originally Posted by Lucky90

On my 90 ,up a steep grade for a long time in slow traffic ,ive seen 245. then it goes back down. Has anyone else approched 245 250, i know the red cross hatch is at 260?

Hi again Check Out -Solutions-

It has happened before........stay out of slow traffic in hot weather for long periods of time especially climbing steep hills.

Check for coolant in the oil (coolant will sit at the bottom of oil pan). Check for oil in the coolant (oil will float on top of the coolant in the coolant reservoir in front of passenger side). If your oil level seems to be increasing or decreasing or your coolant level decreasing abnormally that is another indicator. You are checking for a failed Head Gasket.

Do a compression test once in a while to make sure nothing is going on with head gasket, valves, rings.

Then sit back and drive up that hill keeping the speed up to at least 20 mph....40 mph preferred........you NEED some dynamic air flow around the radiator

If you continue to do this......definitley turn on your fans at lower coolant temperatures and Turn your AC off at those high temps when climbing that hill (better for you to suffer than your engine)

Stock Fan Control on ZR-1s
'90 - '92 Primary fan on at 226 degs. F, off at 216 degs. Secondary Fan on at 234 degs. F, off at 225 degs.

Marc's chips turn Cooling Fans on at 205 deg and off at 200 deg. Those Chips will give you a few minutes more of cooling you do not have with a stock chip maybe enough time to get you to the top of the hill

Custom Engine Calibrations
LT5 Performance Engine Calibrations

I expect you will have NO issues unless you have run with loss of coolant such that you were circulating air entrained coolant. Or coolant mix was such that those temperatures caused coolant to boil off which you would notice in your coolant overflow tank under right headlight

This from a Google Search for Specifics on Boiling Characteristics of Coolant
The pressure cap on a cooling system is the key to raising the boiling point of the 50/50 mix of antifreeze and distilled water. For every pound of pressure cap rating the boiling of point of the above mixture raises 3 degrees. If you had plain water in your cooling system with a 15 pound pressure cap the water would boil @ 257 degrees. If you had a 50/50 mix of antifreeze and water the coolant would boil @ 265 degrees with a 15 pound cap. The boiling point would raise to 270 degrees if you had a 60% antifreeze mixture with a 15 pound cap. If you had a 70% mixture the boiling point would raise to 276 drgrees.

Don't be fooled by the old wives tail that by adding a richer antifreeze mixture will keep the complete system cooler. In fact it works just the opposite. As you know pure antifreeze has a higher viscosity rating than plain distilled water. The higher the antifreeze mixture percentage its ability to adsorb heat from the engine goes down. The higher the antifreeze mixture percentage also retards the radiator's ability to get rid of the coolant heat.

Race cars use pure water in their cooling systems because it adsorbs heat from the engine and gets rid if it in the radiator better than any antifreeze mixture.

It's to your cooling systems advantage to mix your pure antifreeze/water mixture to protect the engine from freezeing 10 degrees lower than last years coldest day last winter.

Pure antifreeze boils @ 387 degrees Farenheit in atmosphere.

I also happen to know you are at high elevations

This from a Google Search on Specifics on the Boiling Characteristics of Coolant Related to Elevation
With NO pressure cap......Water boils at 212 degrees at sea level. Water boils at 204 degrees at 4,000 feet elevation. Water boiled at 192 degres at 9,000 feet elevation. A 50/50 mixture of water to anti freeze will boil at 227 degrees at sea level. A 50/50 mixture of water to anti freeze will boil at 220 degrees at 4,000 feet elevation. A 50/50 mixture of water to anti freeze will boil at 212 degrees at 9,000 feet elevation. The anti freeze referred to here is ethylene glycol based. Both of these are with no pressure cap on the radiator. You can add 7 degrees to the boling point with the addition of each 1lb of pressure on the pressure cap.

[WARP TEN]

One thing to check if you can is debris in the radiator. Very common problem. Here is a link to Marc Haibeck's web page about this: http://www.zr1specialist.com/HAT%20W...o/radiator.htm.

I had this problem on my 93 QB car. Had the radiator removed and hosed out--it was about 40% obstructed. And as noted elsewhere, with Marc's chip both of my fans now come on at 205. I have not seen temps over about 210 on my 95. --Bob

[scottfab]

Originally Posted by WARP TEN

One thing to check if you can is debris in the radiator. Very common problem. Here is a link to Marc Haibeck's web page about this: http://www.zr1specialist.com/HAT%20W...o/radiator.htm.

I had this problem on my 93 QB car. Had the radiator removed and hosed out--it was about 40% obstructed. And as noted elsewhere, with Marc's chip both of my fans now come on at 205. I have not seen temps over about 210 on my 95. --Bob

This can all be avoided by installing a radiator screen (kludge alert).
It keeps stuff from getting up tight in the radiator stack and is easy to clean:
http://www.zr1netregistry.com/Inform...or-Screen.aspx

My own 90 runs cooler in 5th at 50mph than 4th.
It also always runs cooler leaving the AC on. (both fans running)
In slow moving traffic (20mph) with or without a climb keeping, the rpm at 1500 - 2000 for a good balance on air flow through the stack.
Highest temp I've seen is 226deg (converted) utilizing the AC head for readout. I have a DRM chip. That was when it was 104deg outside and I was in three digits for over an hour.
It's a good idea to periodically check that BOTH fans can run wide open. If one seems slower than the other you've got an issue.
When you get to your destination open the hood up for a time to let things cool down.
Inspect the black air damn under the front of the car. If it is bent too far back it can't do it's job scooping up air. Inspect the wing that is mounted at the intake while under there. It should be mounted like the one in the link for the screen mod given above.

Our cars tend to run hot. If any of these systems are out of optimum (or ripped out) you'll run hotter.

The thing to look for on a stock radiator if you think you've gotten too hot is metal expansion near where the metal meats the plastic side tanks.

[emmvette]

I've not seen my car past 180, however my '90 has a big radiator. Seems strange to me that my gauge has not even gone past the half way point. How are you guys seeing specific temps (226 mentioned above for a '90). I think the newer cars can read the exact number, but on my '90, I don't think there is a way to do this, is there?

[scottfab]

Originally Posted by emmvette

I've not seen my car past 180, however my '90 has a big radiator. Seems strange to me that my gauge has not even gone past the half way point. How are you guys seeing specific temps (226 mentioned above for a '90). I think the newer cars can read the exact number, but on my '90, I don't think there is a way to do this, is there?

On page 1C1-2 of the FSM it shows how to enter the Diagnostic mode.

(hold the AC fan up and down buttons in) from there you use either the up or down button to select number 16 then press the AUTO button to enter. On page 1C1-6 there is a table of what each parameter will show. In some of the FSMs for a 90 the value 16 is not shown.

[mike100]

235 stuck in traffic during a 95 degree day, but it turned out my radiator was half blocked with dirt.

I also have the fans programmed to come on at 205. The c4 radiator should be inspected and hosed off once every two years IMO.