Over Heating issue

[Jsd454]

Hello Everyone,

A little background, I recently got my 1972 MC matching numbers 454BB rebuilt and back in the car. I had a new aluminum radiator installed. It has a 16 pound cap. Was going to get a lower pound cap. I also at this point do not have a clutch fan. The car is running around 200 and hotter when sitting.

I have the original style clamps but the bottom radiator hose blew off so I am also assuming the clamps are not the quality as the originals. I want to order a clutch fan along with a seven blade fan. Do I need a fan spacer since at this point the fan sticks out slightly from the shroud? It is an A/C car but have not added freon to run it at this point. I want to get the car to run cooler. Living in Florida with the heat doesn't help.

Any suggestions would be greatly appreciated!!

Here is a link of my car as of now:

 

[jft69z]

Hey Jeff,

Awesome car! I'm partial to the Custom's myself.

I'm on my way out the door for the evening, but here are a few thoughts.

Get a Hayden 2747 heavy duty fan clutch. What do you have for a fan now? If your car had A/C, there should have been one on there, probably a GM part # 3999265. If not, there are a couple of good alternate parts numbers available (3976064 LS6 454 or 3947772 LS5 with A/C and other hi-perf engines).

At any rate, that Hayden clutch should have the correct height to get the fan blades set in the shroud correctly. That should be with approximately 1/2 of the fan blade showing outside the shroud. If not, wither the shroud has been changed (small block?), or maybe the wrong water pump (short, instead of long legs).

Make sure your thermostat is good, and I wouldn't go with less than a 15 pound cap, no need if everything else is good.

Just a few things off the top of my head.

[Mike Brichta]

Hey Jeff,

The first thing I would do is get a laser temp reader and find out if the engine is actually running hot in the first place. Sometimes the temp sending unit and temp guage show a higher reading then it actually is.

You don't want to be chasing a problem that doesn't actually exit. I had this issue with my 70 SS El Camino with a newly rebuilt 396/402 engine.

 

[Jsd454]

Thank you for your feedback. There currently is a 1 1/2" fan spacer on the car so at this point, the fan does stick slightly outside the shroud. Currently there is no clutch fan on the car. Not sure if it got lost along the way or what. Its also a 5 blade. I did see a 7 blade fan with Clutch fan assembly at ss396.com for the Monte Carlo. Its the original 454 but was just rebuilt and has a mild cam so not sure if that also is making it run hot? what temp should it be at? I put in a 162 degree thermostat. The water has been leaking out of the top radiator hose at the radiator and not water seems to be coming out of the over flow hose at this point. I also got a new water pump but perhaps its faulty, not sure. I do know I need to change the old style clamps for the new style. I will look into your part suggestions. Thank You!!

[Canuck]

14 hours ago, Mike Brichta said:

Hey Jeff,

The first thing I would do is get a laser temp reader and find out if the engine is actually running hot in the first place. Sometimes the temp sending unit and temp guage show a higher reading then it actually is.

You don't want to be chasing a problem that doesn't actually exit. I had this issue with my 70 SS El Camino with a newly rebuilt 396/402 engine.

 

I agree with this. My red 71 SS454 I had was showing high temperatures but the factory gauge was simply reading incorrectly.

[TheBMan]

Just now, Jsd454 said:

Thank you for your feedback. There currently is a 1 1/2" fan spacer on the car so at this point, the fan does stick slightly outside the shroud. Currently there is no clutch fan on the car. Not sure if it got lost along the way or what. Its also a 5 blade. I did see a 7 blade fan with Clutch fan assembly at ss396.com for the Monte Carlo. Its the original 454 but was just rebuilt and has a mild cam so not sure if that also is making it run hot? what temp should it be at? I put in a 162 degree thermostat. The water has been leaking out of the top radiator hose at the radiator and not water seems to be coming out of the over flow hose at this point. I also got a new water pump but perhaps its faulty, not sure. I do know I need to change the old style clamps for the new style. I will look into your part suggestions. Thank You!!

Not having a clutch fan is definitely a problem. Is it THE problem? Can't say for sure, but that car should have a clutch fan. They operate far more efficient than a direct-drive fan. Start there for sure. It's supposed to have one regardless and it may solve your issue completely.

[MC1of80]

Hi Jeff. Late to the responses but I agree with Joe. Install the 7 blade fan and clutch fan, no spacer needed. The heavy duty fan  clutch is the bomb! Only thing I would do is wind the spring on the front one more time and reinstall it. I have done this on all our big blocks and small blocks with great results. Old school trick. 

Also, did you get all the air out of the system initially? An air pocket will make it run hotter and possibly blow off a hose. Also, I use 2 gallons concentrated antifreeze and the rest water. I don't like the 50/50 mix. Never looks 50/50. Lol 

Big Red has a 160 thermostat, 7 blade fan, HD fan clutch with the extra winding on the spring and an original 4 core brass radiator. Very rarely goes over 180 and on the rare occasion it does, usually in stop and go traffic, once moving it goes back to 180. 

 

 

[Jsd454]

Thank you for the tip. I ordered one!!

[Jsd454]

Thanks again everyone!! I just ordered a temp gun just to really know if my original 51 yr old gauge is accurate. That along with a clutch fan and 7 blade fan, hopefully she will run cooler. Will replace the clamps as well. Was trying to keep the Monte looking original as possible. I'm the second owner and the car is in great shape. Once the temperature issue is resolved, I'll have the AC charged and hope she still runs cool. I did purchase a black radiator catch bottle that will install. I know its not original equipment but hopefully it helps. Its Florida weather...

Again, I was suggested by other car guys at shows that I should change the radiator cap that came with the aluminum radiator to go with less pounds like 12 vs the 1.1 bar (believe it to be 16 pounds) cap that is currently on it. Anymore thoughts to that?

Thank you

[jft69z]

9 hours ago, Jsd454 said:

Again, I was suggested by other car guys at shows that I should change the radiator cap that came with the aluminum radiator to go with less pounds like 12 vs the 1.1 bar (believe it to be 16 pounds) cap that is currently on it. Anymore thoughts to that?

Thank you

There is ZERO point in going with a lower pressure cap. The lower the system pressure, the lower the boiling point of water/coolant. That's why they make it a pressurized system in the first place, you'd be going backwards. I'd do a little research before listening to 'the other car guys at shows'. , (or ask here like you did, we'll always try to help people get correct info 🙂).

Every psi you raise the system pressure, you'll get a 3 degree raise in boiling point. 

This link sums it up pretty good:

https://help.summitracing.com/app/answers/detail/a_id/5280/~/why-is-the-cooling-system-under-pressure%3F#:~:text=Water boils at 212°,point by 45° F.

If you're popping hoses off or what-not, figure out what the problem is, because a properly set up system will handle 15-16 psi.

As far as that SS396 fan setup, I'd be a little leery if it were me. Without knowing what exact fan or clutch they used, it would bother me. The hi-perf factory fans (and the repro versions of them available now) have specific blade pitch and tip designs, as well as the HD fan clutch. Hayden makes 3 different fan clutches for our cars  (standard, heavy & severe duty), SS396 didn't get too specific.(It's still probably better than what's currently on the car I imagine though).

 

Realistically though, your car is so broken, you should just sell it to me and not have to deal with the stress and expense of repairing it .

[cbolt]

someone asked if the air is out of the system buy I dont see where you answered that. Did you "burp" it when you first got it running?

[rsorg]

guys, where do you point the temp gun at the cylinder head, radiator hose,etc.thanks roger

[Searsman]

Have a flex fan on my 71 -454,. Seems to do a pretty good job, but from all this talk I think I’ll go back to the clutch fan... great info ,thanks... 

[TheBMan]

12 hours ago, MC1of80 said:

Hi Jeff. Late to the responses but I agree with Joe. Install the 7 blade fan and clutch fan, no spacer needed. The heavy duty fan  clutch is the bomb! Only thing I would do is wind the spring on the front one more time and reinstall it. I have done this on all our big blocks and small blocks with great results. Old school trick. 

Also, did you get all the air out of the system initially? An air pocket will make it run hotter and possibly blow off a hose. Also, I use 2 gallons concentrated antifreeze and the rest water. I don't like the 50/50 mix. Never looks 50/50. Lol 

Big Red has a 160 thermostat, 7 blade fan, HD fan clutch with the extra winding on the spring and an original 4 core brass radiator. Very rarely goes over 180 and on the rare occasion it does, usually in stop and go traffic, once moving it goes back to 180. 

 

 

@MC1of80 What is this winding of the spring you speak of? Tell us more!

[jft69z]

43 minutes ago, rsorg said:

guys, where do you point the temp gun at the cylinder head, radiator hose,etc.thanks roger

I tend to look for temps at the thermostat housing area/ top hose. This is where the thermostat itself is doing its job of temperature control. (also where I like to put the temperature sensors for gauges & EFI control).

For troubleshooting purposes,  I'll also check lower radiator hose, heater hoses, top or bottom of radiator, etc., depending on the type of problems you're looking for.

[420ponies]

For the old small block and the new big block I'll still use my 7 blade, wide fan blade flex fan. It's about 1/8" smaller than the shroud opening. I use solid motor mounts so motor doesn't move in shroud. the shroud is not totally round so adjustments are necessary. I use a 160 deg. thermostat and it never got above 200 degrees in stop and go traffic, bumper to bumper, Carlisle in June (Hot). Also has a 3 core radiator.

 

Edited April 15, 2023 by 420ponies
added content

[cbolt]

Maybe I am missing something, but the way I understand clutch fan operation is that when the temp is such that the fan is unnecessary, the fan kind of disconnects from the drive assembly, but when it gets hot the fan engages and operates all the time to draw air through the radiator. Now it seems the problem with Jeff's car is when its sitting it heats up so a non clutch fan, one that operates all the time, would be working at low speed, high speed, and while sitting. So not having a clutch fan in this instance wouldn't, or shouldn't, change the fan effect while idling. Unless the existing fan is really far away from the shroud opening it should be drawing air all the time, which should help cool the engine at idle. Hey, I may be wrong, but that's how I understand this issue he is having. I suppose a lame 4 blade fan could also be an issue, but we don't know what fan is on the car currently, other than its a non clutch variety.

 

For these reasons I still have to ask if the system has air in it, which would be pretty common after a rebuild and reinstall of an engine. 

 

Jeff, take your cold vehicle and put it somewhere where the radiator is elevated, say a swale or maybe on ramps. Start the car and let it idle with the radiator cap off until the thermostat opens and you can  see water moving inside the radiator, noting any bubbles or air pockets you may see. At that point the air should have worked itself out and you can replace the cap. Then take your car out and let it idle a bit and see if the engine still heats up to 200+. Once you have done that we can see what is happening and go from there. 

 

The clutch fan is a great idea and a good thing to have on your car, but in this instance I don't believe that is your reason for overheating at idle. 

[John S]

I believe there are two types of fan clutches.The type with the spring, which will work on temperature and will lock up when hot, and another one that is centrifugal. The centrifugal does not have a spring and  will lock up at lower RPM and if I can use the word coast at higher rpm. I have the centrifugal one with a seven blade fan on my 1970. I do not have air-conditioning but I have the small radiator that has the three bolt top cover. I replaced the radiator core from a two core to a three core, that along with the combination of the fan and fan clutch has made a big difference, especially being in traffic in the hot weather in Georgia. 
John S

[MC1of80]

13 hours ago, TheBMan said:

@MC1of80 What is this winding of the spring you speak of? Tell us more!

IF you have the type fan clutch like the one pictured in the 396.com add, you take a screwdriver or needle nose pliers and take the end of the spring where it is anchored on the outside and wind it tighter by 1 TURN and reanchor it. The fan clutch works way better. 

I have found IF using the "thermo" coupler type and you race the car or drive spiritedly they have a tendency to internally overheat quickly and freewheel rendering it useless. 

[McCall72]

The only time my 72 has ever ran hot was because all the air wasn't burped out of the system. Park it on a incline, take the cap off and let it burp the air out (if any) would be my first step.

[TheBMan]

9 hours ago, MC1of80 said:

IF you have the type fan clutch like the one pictured in the 396.com add, you take a screwdriver or needle nose pliers and take the end of the spring where it is anchored on the outside and wind it tighter by 1 TURN and reanchor it. The fan clutch works way better. 

I have found IF using the "thermo" coupler type and you race the car or drive spiritedly they have a tendency to internally overheat quickly and freewheel rendering it useless. 

I happen to have mine off the car right now and am going to do this before reinstalling. Thanks Thomas!

[420ponies]

Also, on all my rebuilds, I use a .062" (1/16") drill bit and drill a hole in my thermostat ( on flat part of thermostat) , so if any air is in system, it will burp out air in system. I've been doing that since I was in N.C. back in '84. Works well.

[TheBMan]

54 minutes ago, 420ponies said:

Also, on all my rebuilds, I use a .062" (1/16") drill bit and drill a hole in my thermostat ( on flat part of thermostat) , so if any air is in system, it will burp out air in system. I've been doing that since I was in N.C. back in '84. Works well.

I've heard of others doing this with good results.

[MC1of80]

1 hour ago, 420ponies said:

Also, on all my rebuilds, I use a .062" (1/16") drill bit and drill a hole in my thermostat ( on flat part of thermostat) , so if any air is in system, it will burp out air in system. I've been doing that since I was in N.C. back in '84. Works well.

Lol I have been doing it with an 1/8" drill bit for like forever. Lol I actually forgot to add that to my post. Goooooood tip! 

[Jsd454]

Thank you all for the information.I just received the 7 blade fan with mounted clutch. Will get it installed soon and hopefully solve my heating issues. Will use the tips as well.