How about anouther engine temperture thread?

[Heyblue]

1984 I think the last owner put a 160 degree thermostat. Start engine and feel hose from the thermostat housing. Starts to warm as dash reading gets close to 160. At about that temperature (160) it gets quite hot indicating the thermostat opened. Watch gauge and note fan comes on at about 232 degrees and goes back off at about 225, which I think is indicative of a factory original fan switch.
So on a cool morning going into town on a country road at 35 MPH which is mostly down hill the temp gets to about 165 and stabilizes there give or take a few degrees. Side note my 4-3 OD never kicks in. Going home same road going up hill same cool morning temp gets to about 200 and stabilizes. Lastly on warm days the temp regularly gets above 220 while traveling non freeway speeds.
Now the questions:
Is the 200-220 normal while driving?
Shouldn't it be closer to the 160 which the thermostat is?
Is this an indication of the cooling system not doing a good job?
My original thought was to put a 180 thermo with a low temp fan switch (fan on at 200 off at 185) , but that seems would have the fan on all the time. I thought the fan running would only be for idling or stop and go traffic, or low speed driving. The 160 seems too low a temp for good performance, the 232 seems like I would be running close to boil over, especially on a very hot day.
I guess the first thing I need to know is if the cooling system is running fine given the current existing parts.
My 95 truck and 2014 ford fusion both come up to temp (200 in the truck) and stay there. These corvettes seem by design have the temp wandering all over the place.

 

[dougelam]

Sounds like you have a radiator issue, water tube and/or cooling fin restriction

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[DonB]

As Doug eluded to, the first thing to check is that you are getting good air flow through the radiator. C4's are known to get leaves and debris in between the radiator and the A/C condenser. You can't see it from underneath. These are like vacuum cleaners. They suck all kinds of stuff up in there, especially leaves, dirt, etc. All you can see is the bottom of the condenser. But if it is clogged, odds are that the radiator is packed too. The only way to see is to remove the top off of the radiator housing capsule and look down in there. Unfortunately the air-damm needs to be in good shape to deflect air up into the capsule, but with the air comes road debris.
I rebuilt the engine in my '90 last year and I replaced the Radiator and the condenser since they also trap moisture in the debris and rot out. I also use the 160* thermostat with the fan switch modification from Corvette Central. Mine has aluminum heads so I didn't want them overheating. The excessive engine temps "will" eventually cause head and gasket issues especially with the aluminum.
Besides a cooler(NOT COLD) engine produces more power! Mine stays between 160-200. Here in Chicago, at 90* and humid, I have the A/C cranking and the engine temp gauge stays in the center. MAX! The engine runs great and makes plenty of power. Everything has to breathe.

Send me a PM if you like more specifics. Good luck.

 

[Heyblue]

Both posts seem to support my thoughts that the cooling system is not working properly. I will investigate the external part of the radiator, and the deflector which sends air to it.
Question; is the normal operation; The engine temperature comes to about the thermostat rating and stays there unless in slow traffic or stop and go conditions?

 

[dougelam]

The thermostat controls the minimum operating temperature
Once open it regulates the coolant flow

Then it's up to the radiator for keeping the temperature at a tolerable level.
I believe the boiling point @16psi w/ethylene glycol is 267deg

If I reach 230 I'll let it idle until the cooling fan comes on, then it lowers to around 220
At that point I'll shut it off

The cool down is slow and even thru out the engine, I am not sure if heads Crack from the hot soak or just when they feel like it

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[Heyblue]

last night while cruising down the freeway at about 70MPH the temp went from about 170 to about 163. It was quite cool outside. My 4-3 jumped out of OD due to the lower temp. When I got off freeway for the remainder of my trip home, still fairly cool outside the temp climbed up to 190-200. Traveling at 35-40 mph. So this seems to indicate my radiator is not doing the job. I did clean out the leaves and junk between the condenser coil and radiator. Once I get that solved I will have to go to the 180 degree thermostat because I will not always have OD operation with my 4-3 transmission with the 160. Comments

 

[DonB]

I'm not familiar with the 4-3 overdrive, but; What bearing does engine temperature have to do with the overdrive engaging or dis-engaging? Isn't it a purely mechanical engagement(not computer controlled?) Maybe another member with this experience could "chime in."

Although seeing that there was leaves (and junk) in between the Rad. and Condenser is a start. Did you either wash or blow out the cores? That material gets embedded in the fins of the cores. GOOD NEWS though. You are headed in the right direction!
Also keep in mind that at 70MPH on the highway you will get a constant high velocity air flow. At 35MPH in stop & go driving you will get considerably less air flow by volume. So if the engine stayed at 200* with normal driving I'd say you are OK. You be the judge.

CONGRATS!

 

[Heyblue]

Computer will not engage OD until temperature is about 166-170

 

[DonB]

Oh....I see. Well I learned something new today..... You CAN teach an old dog new tricks..... Thanks.

 

[RedHot85Vette]

As Doug eluded to, the first thing to check is that you are getting good air flow through the radiator. C4's are known to get leaves and debris in between the radiator and the A/C condenser. You can't see it from underneath. These are like vacuum cleaners. They suck all kinds of stuff up in there, especially leaves, dirt, etc. All you can see is the bottom of the condenser. But if it is clogged, odds are that the radiator is packed too. The only way to see is to remove the top off of the radiator housing capsule and look down in there. Unfortunately the air-damm needs to be in good shape to deflect air up into the capsule, but with the air comes road debris.

Thanks DonB for telling all about the C4 vacuum cleaner syndrome. You can get a piece of Metal Mesh at your local H. Depot, Valu-Home, Lowes, or similar to place underneath to keep all that big crap out of the Radiator/Condenser area, and your engine compartment in general. Here's an example, but the Seller here is ripping people off... you can get a piece of Metal Mesh that size for next to nothing... I believe any kind of screen will work just as well. It's a lot easier to clean a screen or mesh than it is your radiator.

This is just for Example:
84-91 CORVETTE C4 ALUMINUM MESH RADIATOR SCREEN NEW
84 91 Corvette C4 Aluminum Mesh Radiator Screen New | eBay


I'm overhauling my cooling system, putting in a New 3-Row Aluminum Radiator, a 185-200 Fan Switch, A new Stant super-duper 195 degree T-Stat, some really cool "Blue" Goodyear radiator hoses... the radiator comes with a new radiator cap. My '85 didn't come with a Low Coolant Level Sensor so I'm going to install one of those too from parts I got for an '86 off of eBay and RockAuto. About the 195 degree T-Stat, I just drive around town mostly. I believe the Engineers were thinking to keep the engine at such a temperature to keep sludge from building up, and maybe also to keep one warm in cold climes and times, something like that, ...for the non racers. But I guess if your going to be pasting it quite a bit, cool is definitely the cool way to go. I believe the factory temp is still going to allow me to paste it quite a bit, at least enough to scare the wife and give the dogs a thrill.

3-ROW/CORE FULL ALUMINUM RACING RADIATOR 82-02 CHEVY S10/BLAZER/-90 CORVETTE V8
FIT 84-90 CHEVY CORVETTE V8/S10 WITH SBC V8 CONVERSION

3 Row Core Full Aluminum Racing Radiator 82 02 Chevy S10 Blazer 90 Corvette V8 | eBay

John

 

[Heyblue]

As the OP I would like to state the closer of this subject for me. After cleaning between the A/C and water radiators, wasn't that much, I decided to replace the radiator since the cost and work required to remove and test it was about the same as replacement. After little difference I replaced the thermostat. Noticed the old one would get stuck half way open. Replacing it with a 180 fixed my cooling problem as well as insuring the temp would be high enough for the 4-3 transmission to work properly on cold nights. I replaced the fan switch to a 200 degree one. The original which didn't come on until about 232 was too high for my comfort. My feeling is if the temps could get as high as 232 under normal operation there just isn't enough buffer from that to a boil over if something went wrong. All is well for me with this setup. Thanks to all who responded.

 

[DonB]

Glad you got it worked out.

 

[AussieCorvetteNut]

I'm overhauling my cooling system, putting in a New 3-Row Aluminum Radiator, a 185-200 Fan Switch, A new Stant super-duper 195 degree T-Stat, some really cool "Blue" Goodyear radiator hoses... the radiator comes with a new radiator cap.
3-ROW/CORE FULL ALUMINUM RACING RADIATOR 82-02 CHEVY S10/BLAZER/-90 CORVETTE V8
FIT 84-90 CHEVY CORVETTE V8/S10 WITH SBC V8 CONVERSION

3 Row Core Full Aluminum Racing Radiator 82 02 Chevy S10 Blazer 90 Corvette V8 | eBay

John

Hi John,

Just be carefull with the Chinese eBay 3 Row radiators, the tubing is smaller than the factory tubing, so you end up with less water flowing through than the factory 2 row.

Even better would be to check out Dewitts or Be Cool radiators, yes they cost more but the Dewitts for example has 2 x 1" tubing meaning more water being cooled.
The cheap 3 row jobs won't even get the same volume of fluid than these radiators.
What I am trying t say is that the tubing size in the cheaper radiators is smaller and even adding a third row doesn't get the same volume of coolant through as the 2 x 1" rows.

I am putting a Dewitt's 2 Row in my 84 Coupe here in Australia...at nearly $1000 AUD, it isn't cheap, but neither is warping the RHS Heads!



Tony