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I just bought a 1976 corvette .
it has electric fans installed!
it also still has factory fan installed!
It overheats on highway !
no air pockets in it!
Flushed coolant system !
no leaks !
can't figure out what's wrong with it?
also my battery seems like it's drawing its only putting out about 12 8 volts at idle?!
please help!
11.8 without fans on! Its been running in my driveway for over a hour .These are my readings!!.it hasnt overheated once. But as soon as i take it on the road it overheats within about 20 mins of driving ?!
It is sealed nicely around shroud!
My coolant flow is good!
air dam is good!
hoses are good!
water pump is good !
Fans are working properly!
no leaks !
new oil change and plugs and coolant flushed !
Last edited by Rick Trotta; Jul 5, 2023 at 07:49 PM.
Step one: verify your ignition timing. TONS of threads here and all over the interwebs about proper timing. Improper timing can result in significantly higher engine temps.
My first thought would be to look at the radiator and make sure all the seals are in place. Then I would look at the water pump and hoses. When you are running on the highway the fans should not be working much as the airflow at speed would cool the engine. If it is not cooling, then you probably have an airflow misdirection problem or blockage. You could also have a water pump that is not working or is collapsing the lower hose due to no spring inside.
It seems to run fine not rich or lean !
it ran fine the first couple days but i never took it on highway .
the past few days it's overheating n it takes awhile to get hot !
I will check timing but seems to be good .
here are some pics ive updated!
Waterpump has good flow !
Last edited by Rick Trotta; Jul 5, 2023 at 04:37 PM.
First of all you need to decide if you want electric fans or stock system.....get rid of the other system.
Next, it looks from your pictures that most of the foam seals are missing.....research that and replace them....they are important.
You are really only using about 3/4 of your radiator for cooling......as the plastic shroud is too small. You need to modify it to encompass the entire radiator for proper cooling.
Is the lower air dam in place? It's the piece that deflects air up into the area in front of the radiator. Once again it's a very important piece, as there isn't an opening or grill that air can otherwise just flow into the radiator.
You say that the water pump has no flow, how do you know this?
11.8V without the fans on isn't good, should be 13.3V......It looks from one of your pictures that you have some sketchy wiring going on around your alternator....you might want to see about rewiring this properly for electric fans. Also get a volt meter and check voltage right at the alternator, as it could be different from what the gage reads.
First of all you need to decide if you want electric fans or stock system.....get rid of the other system.
Next, it looks from your pictures that most of the foam seals are missing.....research that and replace them....they are important.
You are really only using about 3/4 of your radiator for cooling......as the plastic shroud is too small. You need to modify it to encompass the entire radiator for proper cooling.
Is the lower air dam in place? It's the piece that deflects air up into the area in front of the radiator. Once again it's a very important piece, as there isn't an opening or grill that air can otherwise just flow into the radiator.
You say that the water pump has no flow, how do you know this?
11.8V without the fans on isn't good, should be 13.3V......It looks from one of your pictures that you have some sketchy wiring going on around your alternator....you might want to see about rewiring this properly for electric fans. Also get a volt meter and check voltage right at the alternator, as it could be different from what the gage reads.
the air damn is on.
That shroud has been cooling that radiator like that for the past 2 years according to the previous owner!
I am going to reroute the wiring!
It doesn't seem to me to be any of those things .just for the fact ive been riding it for the past few days wirh no issues!
this just started happening the other day !.
I did notice my radio isn't working now also
Maybe something to do with that?!
I don't know much about electrical!!
Last edited by Rick Trotta; Jul 5, 2023 at 05:37 PM.
the air damn is on.
That shroud has been cooling that radiator like that for the past 2 years according to the previous owner!
I am going to reroute the wiring!
It doesn't seem to me to be any of those things .just for the fact ive been riding it for the past few days wirh no issues!
this just started happening the other day !.
I did notice my radio isn't working now also
Maybe something to do with that?!
I don't know much about electrical!!
Wow 3 fans..
silly question but can you verify the fans are blowing the correct direction? Should all be blowing towards motor
as mentioned previously look to be sure lower radiator hose is not collapsing at higher rm and has spring in it.
pic from the front under the car? Spoiler area,
There's pic of front . How would i tell which direction fans are spinning? Can barely see them when running .
shoudln't they be spinning towards radiator??Yeah 3 fans i was thinking the samething when i got it . Maybe back up in case electric fans fail....
I'm going to replace both hoses tomorrow but they feel fine to the touch. Haven't seen it collapse..also going to replace radiator cap .
hope one of those fixes it ...
Last edited by Rick Trotta; Jul 5, 2023 at 09:40 PM.
So there's roughly 80 square inches of radiator that not doing much....you should design yourself a new shroud out of aluminum and get the outside edges of that rad working for you....
If your fans are running backwards that would certainly explain why it cools when you are not moving and not when you are driving. The fans are trying to push the air one way, and the slipstream is pushing it the other way. I would suggest you get yourself a factory fan shroud and get rid of the electric fans. Those electric fans are simply not going to be effective the way they are and the modifications required to make them work would be a lot more difficult than simply putting it back the way the factory had it. We know that works.
If your fans are running backwards that would certainly explain why it cools when you are not moving and not when you are driving. The fans are trying to push the air one way, and the slipstream is pushing it the other way. I would suggest you get yourself a factory fan shroud and get rid of the electric fans. Those electric fans are simply not going to be effective the way they are and the modifications required to make them work would be a lot more difficult than simply putting it back the way the factory had it. We know that works.
Taking the fans completely off would also work. This is not an airflow issue (though it would be nice for the OP to confirm that the fans are pulling air through the radiator, and blowing it towards the engine/ground).
With that spoiler, there should be gobs of airflow at speed. It's a water flow problem (or possibly timing, but unlikely)
My money is still on a colapsing lower radiator hose.
1976 corvette overheating !!
