YES!!! A missing air dam is NOT helping your problem at all. NOT saying that it will fix your problem because you are still putting the car under 'harsh driving'...ESPECIALLY if you have the A/C on.

DUB

 

JF Ranch - Your car is operating just as a stock C5 would be expected to. Can the thread hi-jacking be over?

 

No the cat is not on the car.

Just got the high flow pump, will be putting it on the car in the next couple of days.

I do have an IR gun the exhaust manifolds get to 700 the intake manifold area gets to 300 the inlet and exit temps of the hoses get to 210 and various points on the radiator are 250.

 

Wanted give update. I put a new summit 4 row aluminum radiator plus an aluminum high flow water pump on the car. Also, upgraded the fans to 4600 cfm. Still no change. It just slowly climbs to 240+ within 15-20 mins driving. Checked timing multiple times 12 degress tdc. Not sure what to do now except pull engine and see if there is anything I did building engine unless anyone has any other suggestions.

thanks
geo

 

Sorry to hear this, sucks out loud,

What make and model is the fan?

Forgive if i repeat stuff covered,

Have you made sure the temp reading you get is correct, have you tried an ir thermometer and or temporary aftermarket temp gauge,

Have you tried running water through the engine to be sure its not pulled up, obviously the new radiator likely isnt plugged,

So about 15 years ago i was helping a guy with a mid engine kit car,
He had built a pretty radical 427 chevy engine for it and nothing he tried would keep it from over heating pretty quickly,

He tried near the end some crazy stuff nothing helped, he owned a parts house so he could try anything he wanted,

So i cant recall why but he tried to turn the engine over by hand and thought it way too tight,

He figured compression but even with plugs out it didnt want to turn freely,

This however was not noticed with the starter, weird to me,

He tore the engine down rebuilt it and got it turning over better, no more cooling issues,

Not saying this is your problem but, if you get bored try pulling the plugs and turning it over by hand. If it comes to that before actually pulling the engine, see if it turns freely,

 

check your engine oil temps, if above your coolant temps then add an engine oil cooler. This will add cooling capacity and help considerably to control engine temps. The engine oil cooler will help tremendously if the engine oil temps are high, if the engine oil temps are not high then you need to figure out what is wrong within the cooling system.

Neal

 

I like oil coolers plan to run one just because,

But it this threads problem assuming temp reading are correct Besides perhaps blockage in the engine
( the other cooling system parts are swapped out new and should be sufficient )
In this case wouldnt higher than normal oil temps more likely indicate engine build issues over cooling system issues,
I realize coolant and oil temps play together but most cars can keep cool without adding an oil cooler,

I am curious if coolant is flowing through the engine correctly,

 

coolant and oil share the responsibility of cooling the engine and in most cases the water can handle its job but every so often there are engines that exceed the capacity of cooling system. The vette is already challenged with its cooling system and throw on top of this a modified engine and sometimes you end up with cooling issues.

I would like to see the op remove the spring and see if the lower hose is still collapsing as this is a sign of a flow issue. I would think that other than a head gasket issue there really is very few things can cause a flow restriction in the cooling system (radiator needs to be correct for the car).

You can add a large amount of cooling capacity with the installation of an oil cooler if its needed. If the oil temps are checked and the oil temps are at normal ranges then I would say there is an issue with the coolant system but if the oil temps are high (above the coolant temps (200*)) then I would look into the oil cooler. The cause of high oil temps can be a build issue but until we know the oil temps you really cannot diagnose further.

I personally think its a engine oil temp issue as it takes 15 to 20 minutes of driving to cause the coolant temps to get high and then letting it idle does not cool it down but it will idle parked without issue.

Neal

 

I have been around countless engine builds stock to radical and simply never ran into a case where a correct cooling system required an oil cooler not to overheat, ( note , i said correct cooling system )
look at all the hipo vettes here that the radiator alone keeps them cool,
Systems comparable to his,
Not saying it doesnt happen but think of all the cars putting out way higher hp than this guys and no oil coolers are being used, cant help but have it sound band aid to me,
It would be sweet if he added an oil cooler and its all fixed and runs at 190 to 200 all day, but I'm not that lucky,
And it doesnt tell me why his oil ( and coolant ) is getting too hot,
Its a temp issue but i am at the point i fear a build flaw, that i have seen more than once.

 

Other than the initial timing, none of the questions about the timing have been answered. 8* static timing with no vacuum or mechanical advance certainly don't help keep the engine cool.

Still, I'm mostly thinking internal issue in the engine too. Like head gaskets are wrong or the coolant passages are plugged by excess RTV used when installing the intake.

I just recently saw and old tractor where the head gasket was installed with a lot of silicone and the coolant passages from the block to head were mostly plugged. It was acquired cheap because it always overheated.

 

Lionelhutz,

Would you believe timing alone could cause this much problem?

 

I'm running a 496 in my vette it had this issue also, 3 different radiators, multiple fan setups and multiple pumps and what ended my cooling issues was a very large oil cooler. I worked with Stewart Components, Howard Stewart and a Hayden engineer along with the help of the members here to get it worked out. I realize his engine is not a .100" over stroked BB but until we know what the oil temp is we cannot rule out the oil as the cause which could be a mech issue.

 

If the coolant temp is too hot wont that drive up the oil temp?

I dont know your engine but like i said i know a heck of a lot of radical builds that do not need oil coolers...

 

Sorry that I'm a little late to the party, but this persistent problem has many of us here baffled. Having worked with an old racer who endured similar problems, he was very insistent about examining and re-examining head gasket coolant passage holes. We modified a few head gaskets and even race quality products can be tweaked to insure maximum coolant flow. At times we discovered other intake or exhaust related defects by examining the the head, intake, and exhaust gaskets. Getting inside the op's engine seems to be the only solution left.

 

I see this problem arise alot when guys go from the stock system to electric fans.

I think the root of the problem is the design of the C3 corvette cooling system. The system in stock form has a number of components that work in unison to provide a barely capable cooling system for the designed unit. The laid back design, without direct airflow is a huge drawback (for a street car), and it relies on the other components.... the seals, fan, and the shroud to make the system successful.

Now 40 years later.....seals are missing, rads are plugged both inside and out, hoses are of questionable quality, and systems have been modified by enthusiasts.

You have modified your system by installing electric fans. We don't have a pic of your setup, but my guess is your fans are mounted directly to the rad without any form of a
shroud to help draw airflow through the whole radiator.

With this setup you have effectively reduced your forced cooling capacity by 20 percent on a already marginal system.
I went and measured my rad, and the cooling fins measure approximately 26 x 17 inches which is about 442 square inches.
Now yours fans, a 16" and a 14" measure about 355 square inches.....thats about 80% of a stock system.

Instead of ripping your engine down, spend the effort to design and build a lightweight aluminum fan shroud that you can mount your fans on, and draw airflow through the entire rad....

my .02

 

I agree but each engine is different and we see a lot of cooling issues here on the form and most can be solved with the normal troubleshooting but every so often there are the ones that cannot be resolved. The op did not say anything about the engine having other issues so I assume the engine runs fine other than the cooling issue. If this is the case then adding capacity to the cooling system will allow the op to drive the car a little and see if any issues with the engine surface that might be causing the cooling issues.

The OEM's have been adding engine oil coolers to vehicles for years to control engine temps, the vette included so its an easy way to add cooling capacity.

I will add that adding an engine oil cooler when the oil temps are at 180 to 200 while the coolant temps are at 240 will likely do nothing to help.

I do agree that the cooling system should be working correctly before moving to adding capacity. The only issue I see or would like to see if it is resolved with the addition of the new radiator is the issue with the lower hose collapsing. I think the spring should be removed and lets see it the water supply to the pump is adequate, if the hose is still collapsing then I think there is still a issue with the cooling system.

Neal

 

The op posted his up date that the radiator is new the water oump is new , even new fans he said are 4600 cfm,

Same heating up issue,

I gave the the radiator and pump benefit of doubt being new but i did ask make and model of fan as i havent seen any boasting 4600 cfm and if that is the case i might want some,

Its a myth electric fans cause overheating issues, the fact is and what causes this myth is the electric fan being too small for the application, not the fans fault,
Look how many people here love the dual 11 spal, they cool a lot of vettes here, and put out only 2800 to 3200 cfm and even spal only reccomend them for small v8s, it gets by on the
Smaller fan from larger radiator,

Sure on a stock engine factory fans set up correctly do fine, its not what he has,

He did a test, fans running at speeds still overheated, so its not a fan problem in that if a cooling system is up to par for the application it will cool at forward speeds, his wont, so not the fans, it coolant flow not air flow,

I still believe this is an issue of coolant flow, be it from a blockage, collasped hose small gnome or elf living in his hoses etc,
Or an engine build problem which could play into the blockage flow theory,

Other things like timing , seals outside temps etc play a part in cooling systems working right and add to heat but are not going to cause a problem like he is having,

My thing with some engines needing oils coolers to cool correctly,
i support this, for some cases but too many comparable to his builds do not need an oil cooler and cool correctly without one, that my hang up there, is that i want to know why his would it when other builds like his do not,

I dont care what his issue is or who come up with the fix, i just want to be here to find out the problem,

 

I have one thing to add, it may sound silly but does the op's water pump rotate in the correct direction? I know you can get clockwise and counterclockise water pumps depending on your belt and pulley arrangement. There have been cases of people who eliminated a pulley or accessory and inadvertently changed the rotational direction of the water pump causing an overheating problem.

 

I had a work truck that did the same thing recently, the longer you drove it on the highway the hotter it got. My trip was usually 15 miles.

New alum radiator for 95 bucks cured it, can drive it hard for an hour now and it's rock steady at about 1/4 of the gauge.
My truck also has a factory oil cooler.

An additional oil cooler will always help the OP. Coolant only does about 60% of Gen I chevy engines, oil does the rest.

OP should still test the in/out rad temps.

 

Not Likely. Just maybe retarded timing and running lean could.