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Absolutely one of the worst looking shrouds I've ever seen. Gee, ya think maybe airflow could be important for cooling?
I use factory GM C5 Corvette fans with there built in shroud. A bit of trimming to fit.
Never, Absolutely NEVER run on the highway or at speed.
Kick in at those long lights or crawling down the Esplanade. And I can actually watch the temp gauge drop!
So, when are you getting hot? At speed on the highway when no fan of any kind should be needed?
Or sitting in heavy traffic, long lights?
This is paramount. When are you getting hot. Under what circumstances?
Now, of course your have addressed ALL the other issues that can cause over heating? Timing is correct? Rad seals are all in place? 4 row radiator? Spring is in lower hose? Etc, etc, etc.
Bottom line, my car car runs electric fans that rarely run. Only when stuck not moving so obviously then we need to move air. And then of course, this is how it should be.
Tell us more about your situation and for Gods sake get some better fans!
Last edited by 4-vettes; Aug 30, 2024 at 04:36 AM.
What type of fans did you use? If you used a cheap set, they are probably too weak to draw the air needed. You need to use a quality OEM fan or Spal fan for the best results. Did you seal the radiator with foam seals to the support? Is it running hot at idle or while driving?
Overheating at speed is a fault of the shroud. Overheating at idle is a fault of the fans. Assuming everything else is working correctly (including your ignition timing).
You can follow @Z0Tex's journey with a similar shroud in this thread:
Overheating at speed is a coolant issue. Overheating at idle is an air circulation issue.
The first statement means you are getting a 70MPH wind (air) thru the Rad. But the coolant circulation can't keep up.
The second statement means the water-pump circulation is keeping up, but not the fan.
I also use a C5 fan/shroud set up. Temp switch in the head works one and the ECU for my TPI works the other. What is controlling the fans? 2 different controllers or sensors, one for each? What was going on that made you decide to put the elec fans in to begin with?
79C3Vette
I do not see anything horrible about your setup (well, other than sealing the edges).
Did you verify that the fans are PULLING? (I know it sounds like a silly question but gotta axe it!)
Answer some of the other questions posted and we should be able to narrow it down.
Do you have any performance or design information for those fans?
I use a single Mark-VIII fan and it's been wonderful for decades.....but if I was searching today I would take the C5 Fan advice.
Originally Posted by 79C3Vette
Since I went to electric fans I can not keep this thing cool. Any suggestions would be much appreciated.
Last edited by carriljc; Sep 8, 2024 at 11:04 AM.
Reason: added comment about sealing the edges
Overheating at speed is a coolant issue. Overheating at idle is an air circulation issue.
The first statement means you are getting a 70MPH wind (air) thru the Rad. But the coolant circulation can't keep up.
The second statement means the water-pump circulation is keeping up, but not the fan.
You are absolutely correct. I (perhaps erroneously) assumed that the only change was the fans, and that the cooling system worked properly before.
In the thread I linked, the shroud absolutely was at fault, but it was able to be remedied.
I don't see any seals between the top of the radiator and the support. All the air coming in is just blowing over the rad and through that gaping hole up top.
Maybe this will help a little,
OK, here's my setup, I know it's dirty. Anyway, see upper rad hose. Goes from thermostat housing to radiator. In a fairly direct route. This works. See my lower rad hose? It's black and is made of metal so it actually doesn't need a spring. Much lIke my upper hose but powder coated black. They claim these style hoses help cool. If you do use this style hose do not use the cheap adapters that come with them.
see the foam strip on top of the radiator support sealing to the hood when closed? This too is important. See my C5 fans that came out of a salvage yard Vette. They were extremely affordable and they blow a hurricane. You can see wiring going behind the thermostat housing. That's going to a modern CTS. That coolant temp sensor is connected to my EFI ECU, which switches the fan relays. They are also switched by a trienary switch in my Air-con high pressure line.
These fans actually very rarely run. Which is the point. The factory clutch fan runs all the time. Using power.
Oh , and that Alternator, it's a 140 amp Tuff Stuff unit delivering all the current needed to keep all the electricals happy.
Last edited by 4-vettes; Aug 30, 2024 at 08:13 PM.
Thank you all for your tips and advice. I'm going to do the things listed here that are not done.
Upper rad hose is absolutely a dumb design. Its on the list to replace. Lower rad hose spring, I will have to check but probably replace with a steel flex hose as well.
I'm not running the stock sb. It's a 383 stroker, aluminum heads...... makes 365 RWHP. Had zero cooling issues running a clutch fan. Swapped to electric for less engine draw and looks cleaner IMO.
I'm adding the foam to seal all edges, blocking off the cutouts, swapping upper lower rad hoses and go from there.
Thermostat is a 180 i think. Ill have to check that as well.
I appreciate all the advice.
If I were to go to an electric fan I'd use the Lincoln mark viii unit. But my champion radiator with the stock fan and shroud does a good job in the Florida heat.
Thank you all for your tips and advice. I'm going to do the things listed here that are not done.
Upper rad hose is absolutely a dumb design. Its on the list to replace. Lower rad hose spring, I will have to check but probably replace with a steel flex hose as well.
I'm not running the stock sb. It's a 383 stroker, aluminum heads...... makes 365 RWHP. Had zero cooling issues running a clutch fan. Swapped to electric for less engine draw and looks cleaner IMO.
I'm adding the foam to seal all edges, blocking off the cutouts, swapping upper lower rad hoses and go from there.
Thermostat is a 180 i think. Ill have to check that as well.
I appreciate all the advice.
OP,
Now that you've confirmed that the issue started with the fan change, can you tell us if any other changes were made at that time?
And can you confirm if the problem is at idle (likely the fans themselves), or at highway speed (possibly due to reduced air flow through the new shroud).
Do you have the chin spoiler below the rad? Or, even better, the optional extended spoiler?
As others have stated, if everything else is working properly, you don't need fans at all on the highway. So if temps are creeping up now, and all you changed was the shroud, I'd look at blocked airflow.
Overheating at speed is a coolant issue. Overheating at idle is an air circulation issue.
The first statement means you are getting a 70MPH wind (air) thru the Rad. But the coolant circulation can't keep up.
The second statement means the water-pump circulation is keeping up, but not the fan.
yes and no. If your shroud configuration is such that it does not let that 70 mph air thru, it piles up in front of the rad and does nothing. So the shroud would be at fault in that scenario. (A lot of aftermarket electric fan shrouds are like that.)
This is where the stock fan and shroud is superior. It pulls air thru the rad at slow speeds, but lets all the air past the fan at high speeds.
Maybe this will help a little,
OK, here's my setup, I know it's dirty. Anyway, see upper rad hose. Goes from thermostat housing to radiator. In a fairly direct route. This works. See my lower rad hose? It's black and is made of metal so it actually doesn't need a spring. Much lIke my upper hose but powder coated black. They claim these style hoses help cool. If you do use this style hose do not use the cheap adapters that come with them.
see the foam strip on top of the radiator support sealing to the hood when closed? This too is important. See my C5 fans that came out of a salvage yard Vette. They were extremely affordable and they blow a hurricane. You can see wiring going behind the thermostat housing. That's going to a modern CTS. That coolant temp sensor is connected to my EFI ECU, which switches the fan relays. They are also switched by a trienary switch in my Air-con high pressure line.
These fans actually very rarely run. Which is the point. The factory clutch fan runs all the time. Using power.
Oh , and that Alternator, it's a 140 amp Tuff Stuff unit delivering all the current needed to keep all the electricals happy.
I have a very similiar setup using the same type of rad hoses but I use the $120 spal/be cool clone fan assy off ebay. I have no cooling issues and both fans rarely have to come on in my car. Temps are typically around 175-181. the better fans draw more current.. on a dual fan setup expect to see a 12-18 amp draw per fan on a decent setup. It looks like the OPs fans state 90w at 12v? if im not mistaken that means both fans together would only be drawing about 17amps which would be very weak as far as CFM for cooling. Im happy with my ebay clones.. allowed me to easily fit my spreader bar/brace and it will make swapping my tubular a arms way easier.
Last edited by augiedoggy; Sep 3, 2024 at 03:41 PM.
yes and no. If your shroud configuration is such that it does not let that 70 mph air thru, it piles up in front of the rad and does nothing. So the shroud would be at fault in that scenario. (A lot of aftermarket electric fan shrouds are like that.)
This is where the stock fan and shroud is superior. It pulls air thru the rad at slow speeds, but lets all the air past the fan at high speeds.
It's a "general statement" to diagnose which type of overheating issue is present.
Either coolant issue or air issue.
Once that has been determined, a list a mile long can be more specific to either.
Note that 90% of the overheating issues on the forum have a common denominator of either 230 degrees on the highway or 230* around town. But seldom both issues at the same time.
And I agree, hard to beat a Clutch Fan with a CLEAN radiator.
Last edited by HeadsU.P.; Sep 3, 2024 at 08:00 PM.
I agree, there seems to be 2 obvious things wrong. One is the fans themselves, they both together
need to be pulling at least 2700 cfm. The next thing I see wrong is your fan shroud, it has no vents for highway driving. I ran into these issues already.
