Reading the water temperature gauge?

[22229stingray81]

Okay, I know there have been past threads about how hot is too hot, but I am a little confused about reading the water temperature gauge. I have the in dash 8-track/radio/clock so I also have an oil temperature gauge. My question is, the hottest I have ever seen the water temp gauge is just over the thick white line. Its not in the middle, but a little to the left.. anyways, just barely over that line, and I was dead stop in traffic for an hour, on an 80+ degree day. When I got moving again it dropped to just under that thick line.. is this too hot?? I think the white line indicates 200 degrees but cannot tell if that is suppose to be for the 12 o'clock position or the 10 o'clock position line.

Also, my oil temp gauge gets just around the 12 o'clock position, never over, is this okay too? I guess its around 250, never more. I am way too scared to use the a/c because these temperatures look a little too high to me, what do you think? Where is the too hot postion on both gauges?

-Tatortot

 

[AUSSIEVETTEMAN]

...I have the in dash 8-track/radio/clock so I also have an oil temperature gauge...Me too, so I think I can answer your questions...My question is, the hottest I have ever seen the water temp gauge is just over the thick white line. Its not in the middle, but a little to the left.. anyways, just barely over that line, and I was dead stop in traffic for an hour, on an 80+ degree day. When I got moving again it dropped to just under that thick line.. is this too hot??...Some would say no, not at all, but I think this is a little warm. It is a little embarrasing having your Vette loose it's cool in traffic. You will have (reading the lines from the left) a thick line followed by a thin line, then a thick line, two thin lines and then red. The second thick line is around 200 degrees. The first line is around 160 degrees (I think) as I have a 160 degree thermostat in our old girl and this is where the temperature guage sits once the thermostat has opened and the cool water has circulated...I think the white line indicates 200 degrees but cannot tell if that is suppose to be for the 12 o'clock position or the 10 o'clock position line...It is around the 200!

...Also, my oil temp gauge gets just around the 12 o'clock position, never over, is this okay too?...The 12 o'clock position is 250 degrees. Ours will touch this only if we are doing highway driving, but around town and cruising this temperature is between the small line and the 250 mark. This will change depending on your grade of oil... I guess its around 250, never more. I am way too scared to use the a/c because these temperatures look a little too high to me, what do you think?...I wouldn't be too scared to use the a/c as this uses an auxillary fan to run the system and this fan will probably kick in and draw more air through the radiator. It is possible to cool the engine with this fan with the a/c on... Where is the too hot postion on both gauges?
-Tatortot

I do not believe your system is too hot, but I would check a few things. You have to remember that the water cooling system is designed to work under pressure with coolant. The reason for this is that the pressure pushes coolant through the water, raising the boiling temperature from just water which is around 100 degrees celcius to 125 degrees celcius (212 to 257 degrees farenheit)
Some basic checks to look at...
(1) Make sure all your radiator shroud seals are in place and the air dam rubber skirts are ok. This will direct airflow through the radiator and not around it. As the radiator is mounted on a slant, it is a common problem for air to be directed around and over the top, instead of through the radiator. The radiator cannot cool without airflow.
(2) Ensure all radiator hoses are ok. The bottom hose will suck in at higher speeds, restricting the water flow and raising the temperature. I do not think you have a problem here. Another suggestion is to change the hoses to Coolflex hoses. These hoses will far outlast rubber hoses and will not suck in. Check out www.coolflex.com We have done this and are very happy with the result.
(3) Depending on your climate, I would suggest a 180 degree thermostat. I would say put the 160 in, but it may run too cold and the oil will not reach the burn off temperature. The burnoff temperature is the temperature in which the oil starts to burn off toxins which can slowly deteriorate engine components. You will note this once you first start the engine in the morning. The oil pressure will be high until the oil heats to this temperature and then it will reduce. This is when it reaches the burnoff temperature.
I have the 160 thermostat in place, but do find that warm ups are a little longer.
(4) A coolant flush off your system may be in order. Periodic flushes are required to eliminate sludge build up, which will raise temperatures as it restricts flow.
(5) A new radiator cap may be needed. These are cheap, but effective. If the pressure is not maintained, then the boiling temperature is reduced from 257 degrees as the coolant is not being pushed through the water.
(6) Have your radiator pressure tested. I would do this first. It will save hours of swearing and cursing!
If you have a head gasket problem in the making, then this test will pick it up.
I think you maybe ok in this area, but a small hole in the radiator could still be a problem and this test will pick it up. I finally had the radiator tested after hours of work and found that even a brand new radiator had four pin prick holes!
(7) I think your water pump will be ok.

Finally, your water temperature shouldn't really get over 200 degrees.

Remember that if you are out in the middle of nowhere and have a heating problem, them sometimes coolant is not always available. Your system should be able to maintain a good temperature without coolant and with just water, but only until you can fix the problem. Coolant has anti-corrosive qualities which protects your engine, so prelonged periods without it are not recommended. Water boils at 212 by itself, so if you do not have coolant and pressure, then at 200 degrees, you are not far from cooking the engine.
A well designed system will run cool without the need for coolant and pressurisation and these will be just a bonus if it does... IMO.

One of the Guru's may have some more things to add. Maybe Hib may have another theory, he knows his stuff.


Tony

 

[22229stingray81]

Thanks much for the post Tony! I had my radiator flushed and checked (including hoses) not too long ago, and have not put many miles on since, so I know that is not a problem (if there is a problem). I will check for holes, but I find it very hard to look behind the radiator for obvious reasons.. any tips on how to get the debris from in between the cores? My hands simply cannot get in there. Sounds like what your saying is that I'm doing alright, but right around the not okay temp. I was contimplating shutting down the engine right there to let it cool down, but I think I was over-reacting. Thanks again Tony. Anyone else have any input?


-Tatortot

 

[Chris Kennedy]

I have an oil temperature gauge in my '81 4 spd as well, and also note that the oil temperature gets to about 250 degrees at 75 mph. Sometimes it will go higher if I drive at higher speeds. If I slow down, and am driving around town, the temperature goes quickly down to about 170-180. The bottom line is that I have talked to a bunch of experts, and no one has a clear idea of WHAT the normal temperature should be, and how hot is too hot. I think the problem is simply that most cars do not have oil temperature gauges, so people pay no attention to the issue. Often, I have thought about getting a larger pan, an oil cooler etc., but always come back to problems involving space, ground clearance, and the problem that our 80 to 85 pans are unique and the selection is not as good----really, there is an amazing lack of knowledge out there about oil temperatures, and what cars really run, etc. The best advice I got was from the experts at Red Line Oil, who felt that on a hot day and a freeway run one should not be too surprised to see 240 degrees. I use their 5 W/ 40, and the engine is in great condition. I have decided not to mess around with coolers, larger pans etc., and just let it run what it runs. How many other people have oil temperature gauges out there, and tell us their experiences??

--Chris Kennedy

 

[81 Corvette]

My 81 has the oil temp guage as well. When the water and oil get hot, they ussally are pointing just about straight up. My thought is as long as both are pointing up, and the oil pressure is there, then i'm not going to worry too much about anything.

 

[Chris Kennedy]

My 81 has the oil temp guage as well. When the water and oil get hot, they ussally are pointing just about straight up. My thought is as long as both are pointing up, and the oil pressure is there, then i'm not going to worry too much about anything.

Yeah, I think straight-up is about 250 degrees (oil temp), and 40 lbs pressure. Again, the more I get into the oil temperature business the more I find that there is a real lack of information on what cars (ours included) are running under various conditions, and how much is too much. I think the hottest I ever got was about 290 after an extended top speed run in August in north-central Texas on an isolated stretch of road (I got this urge to drive to Crawford, Texas to see the town and how close I could get to the Bush ranch---wonderful trip. The media was mulling around the town's high school gym press site looking totally out of place...an absolute hoot to see!). I believe that 300 is about the maximum before you might encounter oil problems. As to oil presssure, this varies WILDLY given type of oil (synthetic/coventional), viscosity and temperature. So, when people say "you should run 'X' pressure" and don't take these variables into account, I know something is wrong. Let's face it, while I prefer gauages to warning lights, they do make you ask questions!

--Chris Kennedy

 

[mikejpss]

Mine has a new crate motor (stock at 240 h.p.) and runs 180 to 200 degrees on water temp and around 210 on oil temp. This is with the a/c off, dont run it enough to give any readings with the a/c on.

I have the 180 degree thermostat and I KNOW the radiator needs flushing, will get to that task later this summer.
I have not seen my oil over 225 yet, and driving in south Louisiana is comparable to driving in Nevada during the summer, only much more humid (95% humidity on most days with 95 degree temps.)
If you find your temps going up in traffic, try shifting to neutral for the red light, etc, this will increase the engine rpm's a few hundred and pull more air over the radiator. If it gets above 225, turn off the a/c along with the neutral trick, it works !
If my oil temp ever gets at or above 260, I will be concerned. Until then, I'm just smiling .....

 

[AUSSIEVETTEMAN]

...I will check for holes, but I find it very hard to look behind the radiator for obvious reasons.. any tips on how to get the debris from in between the cores?...Put a hose down between the radiator and a/c cores and just try to hose it out. ...My hands simply cannot get in there. Sounds like what your saying is that I'm doing alright, but right around the not okay temp. I was contimplating shutting down the engine right there to let it cool down, but I think I was over-reacting...I wouldn't be too worried just yet, but just make sure you have done everything and that there are no leaks. The biggest problems are airflow and leaks because pressure is not maintained.
-Tatortot

Cheers

Tony

 

[AUSSIEVETTEMAN]

...If you find your temps going up in traffic, try shifting to neutral for the red light, etc, this will increase the engine rpm's a few hundred and pull more air over the radiator...Mike has another here. Try ditching the clutch fan for a flex fan. They are a little noisier, but will pull air in at low rpm.

Cheers

Tony

 

[22229stingray81]

Thanks for everyone's replies. Tony, I will try the hose on the radiator. Seems like everything looks normal, though you can't help to be worried about temperatures rising in traffic or high speed driving that you usually don't see. I've never seen my water temp. get to the 12 'o clock position, just the oil temp. so I guess thats a good thing. Usually in traffic the water temp. rises, and the oil temp. is fine, but on higher speed highway driving its the exact opposite.. makes sense with the airflow over the radiator vs. high engine rpms.

-Tatortot

 

[Chris Kennedy]

It's interesting to me that most of us are having the same experience with oil temperature---that is, that at highway speeds we touch about 250, maybe a bit more, and around town the temperature drops quickly to about, say, 170-180. If you were to look at the Perma Cool oil cooler site, they would say that temperatures around 250 are way too hot (they have a little graph which does this by showing that your engine is burning up). So, did GM design an engine and oil capacity that results in too high an oil temperature? I doubt it (incidentally, have you noticed that we have 4 qt capacity pans, and that the oil capacity with filter is said to be 5 qts in the manual, yet even if you use the long oil filter you still run about one-third of a qt. over "full" on the dipstick when you add 5 qts.??). Or do many of the so-called experts on oil temperatures not know what they are talking about? I have also heard that later Corvettes also routinely run around 230-250 or so. My guess is that the lack of oil temperature gauges in most cars is what has resulted in blissful ignorance of oil temperatures, generally. Incidentally, if any of you have looked around for larger oil pans or oil coolers for our cars, THAT is a real experience. There are so many things to consider: size, ground clearance, will the pan clear power steering, starters, etc., piping, new pickup tubes, dip stick changes etc. Even places which claim to know all this (such as Canton Engineering) cannot give you definate answers. I have never seen the aftermarket so stupid as with this issue.
--Chris Kennedy

 

[pauld]

I seem to be the same as eveyone else here, at highway speads my oil temp is reading around 250 (needle pointing straight up) and when slow down it drops down some. I think that if we are all experiancing the same thing then this is the normal and nothing to worry about.

 

[22229stingray81]

Yes, it all seems like we have the same "symptoms". Does anyone want to take a stab at how hot is too hot?? The gauge doesn't go into red until an unexceptable high temp. for my standards, like 320 or something absurd. My question is, if I were to say, cruising at 80 mph on a 95 degree day, how much could my 130,000 mile engine take without undo ware? It's getting to the point where when I have to do long highway drives I will not take the Corvette because I am afraid of overheating.. but highway driving is what it is for! Shall we say (seeing as how the gauges aren't the best designed) at the 2 'o clock position is too hot for water and oil temp.?


-Tatortot

 

[mikejpss]

This is just MY OPINION, so take it for what it's worth- but @130K miles, the oil temperature is on the low priority end of the scale for me. I would rebuild the engine and tranny before taking long trips at that mileage. It's just too inexpensive not to rebuild. How much is a tow back home when you're 500 miles out? $300-$400? Thats 1/4 the cost of rebuilding, invest the tow money into a new/rebuilt motor and forget the tow on the next trip.
Like I said at the start- its only MY OPINION and it's free so take it for what its worth.
Mike J.

 

[KC-21]

If your Vette has the original or stock replacement thermostat in it, then it is a 195-197 degree tstat. It will show between 180 and 210 on the gauge. I just installed a temp switch to turn the electric fan on at 200 and off at 180 (the stock switch is set to come on at 230 and off at 209, too hot in my opinion) or you can locate the electric fan switch between #6 & #8 plugs on the right head and tap into the wire coming from the fan and run it inside and hook it into a toggle switch and run a wire from the other leg of the switch to a ground, then you can turn it on and off when you want to. Just food for thought. The oil temp sounds OK, that's about where mine runs too.

Keith