How hot is tooo hot?

[aoriii]

I've seen a lot of discussion regarding how hot our C4's tend to run, but I've not seen any posts regarding what temp they should run at. I've been battling high temps and the Alabama summer months, and have developed my own little psychosis about heat (I'll call him Fred). Anyway; I've just finished my own work around solution as suggested by friend who once owned a C4. I've wired the front cooling fan to an ignition hot wire under the hood, so now whenever the key is in the ON position, the fan is running, this takes the computer out of the equation of deciding when to come on (I'll likely do the fan behind the radiator the same way).

So, back to my original question? Where should our temps be? Before I did the re-wiring, my car would run between 195 an 220 while I was moving, but when I stopped the temp would rise RAPIDLY . I've seen it get as high as 235 sitting in a parking log with the A/C running. Since my re-wiring, it runs between 190 and 203 when the car is in motion (it'll get down to 190 when I'm on the highway @ 60+). When I stop the car it will not get to about 220 if it sits for awhile....

So again, how hot is too hot, what should the normal operating ranges be???????




Trey - steamin' in bama.

 

[ErnieN85]

Well actually it depends on Oil temps and what coolant you are using. 50/50 antifreeze & water will boil at about 260 with the stock radiator cap. so any thing under that is ok. Evans NP cooltan is good for higher! Straight water for much less.
as long as it's not boiling its technically ok.
However most of us worry more than that and the oil needs to stay under max of about 290 with synthetic or 240 for dyno oil.

 

[65TripleBlack]

Trey:

I also have a 1985, mine has 33,000 miles, and is all original and cherry. I am the original owner, and I know the car in and out. Listen:

If the engine is idling and the car is not moving, the temp will slowly and steadily climb, and the fan will be off. NORMALLY, the cooling fan will come on at 227 degrees, and the temp will rapidly drop to about 200 degrees, and the fan will then shut off. This process repeats for as long as you are not moving. Once underway, depending on speed and ambient temp, the coolant temp will not get any higher than about 190 degrees.

NORMALLY, once you turn on the A/C, the fan runs all the time, regardless of coolant temp.

Let your fan run the way it was designed--if everything is OK, then it is a bulletproof system. The cooling system has lots of extra capacity designed in (unlike the C1's, C2's, and early C3's). I would check the thermostat first. Make sure it opens fully. If not, replace it with the proper 195 degree unit. If that is not the problem, then I would look at the radiator, it is either externally or internally clogged. Any other solutions you choose are just "band aids".

Joe

 

[Gman]

Trey, I know your steamin' in 'Bama right now, but come winter you're probably not going to want to run the fan constantly. You can change your fan on and off temps just as easily as rewiring. Just costs a bit more for the kit. But you won't have to worry about overcooling in the winter or watch your fan experience a premature death.

 

[aoriii]

Thanks to all...Good info all around. I feel a littel better about the temps I'm getting. I was always more than a little worried when the temp got above 220. It also seems that the A/C blows colder since I've rewired the fan, but that may just by skewed perception.

thanks again

Trey

 

[jmccloud]

Coolant fan

It's actually detrimental to cooling to have the fan on when the car's speed gets up to 50+mph. The computer should be shutting the fans off at highway speeds. Some wire-arounds inhibit this control.
I live in Maryland and often see 227 in really crowded traffic. The fans cycle off/low/high with the a/c off and low/high with the a/c on in traffic. The temperature readout follows the fan cycling.
I'm told the computer shuts the fans off at highway speeds but can't verify it.
Running 50/50 antifreeze keeps the boiling point way above 230 (the antifreeze bottle should have a chart) and helps cooling even though pure water can carry more heat. Trouble with pure water is it boils too low.

 

[Alfonso Gomez]

Mid America sells a manual fan switch that enables you to switch one or both fans whenever you want to. The instructions are easy to follow and should not take more than 30-45 minutes. The switch is a three position switch (OFF, one fan, two fans). It is way better than the wiring which you refer to because you will shorten the life of your fan motors. With this switch you only use the fans when needed, if you leave it in the OFF position, the computer takes over.
My 2 cents worth.

 

[larryfs]

However most of us worry more than that and the oil needs to stay under max of about 290 with synthetic or 240 for dyno oil.

where did you get the 290 number from.
mobil1 says 400 degrees +
flash point is 491.
idiot light comes on at 300*F oil temp.

Just curious???

 

[ErnieN85]

Well the 290 isn't the safe temp for the oil. it's the safe temp that the oil can reach before it's too hot for the bearings. Engine bering material starts to soften at 350 f so if the temp in tghe bearings is about 50 higher than the oil. we really do not want the oil any hotter than 350 minus 50 or 300 max I don't want mine even that hot. as it's simplt tooclose for comfort with extended use. yes the oil will protect to 400 and more but if the bearings get soft and squish out............... (even a little). your looking at higher clearances, knocking, loss of oil presure. you see where i'm leading? it will work that hot but it will not last!

 

[larryfs]

ok, but where does the 350 number come from?
people say 270 is max, 250 is max, 400 is max.
see where i'm going. noone can substaniate there claims. they just throw out numbers.

call 1800askmobil, and they say no problem, the oil can take it.

if you ever track your C4, the oil temp gets pretty high.
1 guys saw 307, I saw 290's

 

[ErnieN85]

Larry, the 350 comes from the bearing manufacturers. I have not looked this one up personally as it was stated to me from the Vettenet.org quite a few of the people there are racers (the real ones) as to actual temps I have seen 272 with an air to air cooler on the track at Poco raceway I have an aquaintance who gets to 290 with his C5. usually I dont run over 215 on the street. befor the cooler I would hit 240 on the street and backed off on the track when i hit 240. Doug Rippie says never over 240 on his engines. so once again the oil is safe to over 400 however it's not agood idea for long term. I'll try to see what federal-mogul or clevite has to say some time today

 

[vipereater]

Trey, I recently developed a heating problem. My water temp would run 250 no matter what the air temperature was. I felt it was either a collapsing hose, bad thermostat or a plugged radiator. My car is a 91 with 52,000 miles. I had the radiator boiled out, replaced the thermostat with a 160 degree (a 160 was what I removed) and replaced both radiator hoses. I drove the car 45 miles in 100 degree temps and my water temp never got above half way on the gauge. I'm very pleased with the outcome and the car performs better when it runs cool. I live in Kansas so I can appreciate the bama heat. Personally I wouldn't be concerned with the 220 that your running but as the others pointed out....watch that oil temp.

Vipereater

 

[ErnieN85]

Well, here is the answer from Dana corp, the owners of Clevite, the engine bearing people.
It's not very definative on max temp. on the other hand it could be taken as a very strong recomendation for a max of 230.
Chevrolet has stated that oil temps should run a max of 30 degrees over the coolant temps. so if 240 is ok for short term then 270 would be a max oil temp!

Dear Ernie,

Try to keep the oil temp at or below 220 degrees. It needs to be above 212
so the water will turn to steam on come out but should not exceed 230 max.

Oil begins to deteriorate above that temp, the higher the temp the faster
the deterioration.

Dr. Dipstick


To: <dr_dipstick@engineparts.com>
cc:
09/09/2003 11:47 SubjectocPage
Name: Ernie Naugle
Comments: What is the maximum oiltemp for long life, What temp does the
bearing material begin to soften.
Main bearings Chevrolet 350 Corvette track temp?

 

[HPG]

Code 14 sets at temp's of 266 F

 

[larryfs]

Ernie,
obviously they are talking about dino oil. my C4 on the street will run the oil temps up to 240 if I get slightly aggressive.

and that is a good point about getting it above 212 to boil the condensate out.

we still need to know how hot the bearings can take. I know one GS owner who ran up to 307 and his motor is still in tack.

 

[ErnieN85]

Yes, aparently the bearing people are not talking!
The engineer I talked with did say the metals in bearing materials soften at 350 so........... I'd want it below that by asubstantial margin.

 

[larryfs]

my 96 owners manual clearly shows the oil temp guage goes "orange" at 300-320. however it does not state a temperature. it says being in the shaded or close to the shaded area is too high. nothing definative.

I know the idiot light comes on at 300.

 

[terrykrueger]

I don't know vettes (yet) but most cars have a dual circuit fan so it is 'on low' with the AC on and 'on high' when the temp sensor reaches its setpoint. Man you don't want to be sucking that much juice all the time. A fan could conceivably suck more than the alternator can produce.

 

[larryfs]

fans have NOTHING to do with this. they don't come on when the car is moving over a certain MPH.!