How.much coolant flow is too much? Still hot

[oldcarnut]

Short version is new 4 core radiator, water wetter additive, large fan in a shroud half way in, +pusher fan, extreme duty thermo clutch fan and lots of air flow, external oil cooler, ac condenser, new thermostat, spring in the lower hose, and temps go up quickly faster I drive and cool down at idle.  220 in 5 miles today mid high 90s temp outside. Watching flow with cap off and at 195 degree, the water flow is very fast at idle so I can only imagine how fast it's going at speed so thinking maybe this is the culprit. Not really much steam vapor. Perhaps the flow is too fast to cool properly.  Air flow through the nose opening will pull paper/rag right out your hand into the screen.  What should the coolant flow look like at idle.  Mine is like a water hose turned on at least half to 3/4 way on like mini rapids.  Number on pump is BH362

[b5blue]

  After adding Classic Air A/C I played hell sorting out cooling having lost my big flex fan due to the added belt. Fixing ended up with factory direct drive fan w shroud and Mildon 180* high flow T stat. (I have a spring in my lower hose also.) I'm in central FL. so heat is a beast.

[justcruisin]

The flow should be noticeable at idle but not ripping through, there should be a noticeable increase in flow when you bring the revs up. A high flow thermostat is a good idea, no thermostat is not a good idea. If the flow is too fast you can get pockets of water that get trapped and don't move well, so they heat up. A high flow factory style pump should include a cavitation plate.

Sounds like you have a good set up, with a high flow thermostat you should be good to go. Generally over heating while the car is traveling at speed points to a restriction problem and not an air flow problem. It would seem that as you have good flow the coolant is not restricted, so the problem may be due to a build up in the block not allowing the coolant to reach everywhere. Do you know your oil temps, is this a fresh build?

[b5blue]

Thinking back I had a Cherokee that drove me nuts only to find it was the sender for the gauge that was screwing things up. Have you double checked temps?   

[oldcarnut]

Thanks for the inputs.  I have a good flow thermo and drilled a 1/8" bypass hole in the face to allow air bubbles to escape and as a fail safe.  I double checked the temps and they seem to be in agreement.  I made this video on youtube of it idling at 190 degrees and towards the end a light throttle rev.  See what ya think.  
https://youtu.be/6qheRXWclag
When I looked at it when it was closer to 205 it flowed at idle about what it was doing at the end of the video

[Bronzedodge]

I went through a similar problem on my 69.  Idle, around town was fine.   At speeds over 55 mph it would run hotter and hotter.  Axle is only 3.55.   I found an old '67 Mopar high flow thermostat, 180*.    That cured it.  It looks just like the new high flow ones - the opening is 1.5", vs 1" on all the standard ones.

[justcruisin]

I doubt your problem is excessive flow, the thermostat provides a restriction to flow, it wont flow any more than what the thermostat will pass, it doesn't seem excessive to me but if you think it is, you could fit a fixed orifice plate or standard thermostat in place of the thermostat to reduce flow, doubt it will solve your issue. Your cooling system seems adequate. I would be checking your timing and tune up, exhaust for restrictions etc and insuring all is OK, proceed from there as previously suggested.

[Bronzedodge]

BTW - as stated by others, excessive flow is rarely a problem.  Measure the opening on the thermostat. 

[charger Downunder]

Time to take out your thermostat and buy a new high flow one place them both in a pot and boil them up and watch them open up and see the difference.

[b5blue]

I would test the fan clutch, odd problem.

[oldcarnut]

 I will recheck timing but it was reset with the new Firecore setup.  Pretty sure thermostat is good.  It's the third one I've done experimenting with different temps and boiling them.first for operation.  It's also a high flow.  I can feel and here the clutch fan kickin in.  It's pulling a lot of air. Hence plenty of air going through, extra 16" push fan set at 190 over the external oil cooler and ac condenser.  Kinda running out of options.  It would.be nice to know the block internals but the motor was built before I got it. Exhaust is stock hp manifolds and and new ultraflow mufflers

[c00nhunterjoe]

What rpm are you cruising at when it starts overheating at cruise after 5 minutes? Duplicate that rpm in your driveway for 5 minutes and see what the temp does.

[bakerhillpins]

large fan in a shroud half way in, +pusher fan,

So you have a 2nd pushing fan hanging on the front of the radiator?? 

If so I'm going to suggest that's the problem. The speed of the engine driven fan vs the pusher is going to vary and at some point they are going to interfere with each other and reduce air flow.

[justcruisin]

In my experience a fan in front of the radiator combined with an engine driven fan is not a problem. Although I can't say that if you are having over heating issues at speed that both fans working at once isn't going to cause an issue Extra air flow with fans shouldn't be required at speed, so I wouldn't think it was your problem. In your case anything is worth a go, if you have the front fan going at speed might be worth removing it to try.

On my own car I have an engine driven clutch fan combined with a front mounted electric fan, 180 high flow stat, car runs at 170-180 at speed,depending on outside temp. Electric is on a 190 thermo switch, cycles off and on in stop go traffic, never comes on at speed.

A 4 core radiator is around 3" thick and does require good air flow to push the heat out of the core, however, at speed that shouldn't be a problem.

[c00nhunterjoe]

Production cars and trucks have been using mechanical pullers with electric pushers for years.

[bakerhillpins]

Production cars and trucks have been using mechanical pullers with electric pushers for years.

I don't dispute that but those setups were engineered by the MFG. Most of the information I've read says that push/pull setups don't really make any significant difference to pull setups anyway.

[oldcarnut]

The push fan was added afterwards in an attempt to help the overheating issue. When the push fan is not on, the pull fan sucks enough to make the push fan turn by just the air pulling thru it. The radiator is a 3 core so i mis-stated it as a 4 core
I'll reverify the timing and as much as I hate to do it, pull off the water pump to take a look at it and see what I got. I appreciate the feedback so keep it coming.  Hopefully I'll get it cured

[oldcarnut]

What rpm are you cruising at when it starts overheating at cruise after 5 minutes? Duplicate that rpm in your driveway for 5 minutes and see what the temp does.

Rear is only 3:55s on 255/60 tires. Nothing abnormally high on the rpms but I don't remember specifically.  I only get up to 45mph before it starts climbing.

[bakerhillpins]

The push fan was added afterwards in an attempt to help the overheating issue. When the push fan is not on, the pull fan sucks enough to make the push fan turn by just the air pulling thru it. The radiator is a 3 core so i mis-stated it as a 4 core
I'll reverify the timing and as much as I hate to do it, pull off the water pump to take a look at it and see what I got. I appreciate the feedback so keep it coming.  Hopefully I'll get it cured

Since we are spitballing here.. I had an overheating/engine racing problem 2 yrs ago. Would only show up on really hot days (90+) and only after I drove the car for a few miles. The idle would jump up 3-400 or so RPM and I would overheat. I sprayed around the base of the carb when it was cool but didn't get any RPM change and didn't feel like risking something with a hot engine. After pissing around with a variety of different things it turned out that the carb wasn't torqued down and after a certain temp the expansion in the bolts would open up a gap between the intake and the carb.

[justcruisin]

Prior to getting into the engine I would be exhausting all other possibilities, as well as your timing I would be looking at your tune up as previously said. Running lean can have an effect, pull a plug or two after a run and have a look. Better still, when it gets hot - switch off and have a look then, even better, fit a wide band A/F gauge.

[Challenger340]

Is there any valid imput to thinking about a "time" thing ? as in the coolant is travelling so fast at higher rpm's in doesn't have time to release it's heat to air the rad ? or is the extra BTU's being burned at highway speeds simply too much for the cooling system to handle ?
You could try running the engine at 2,800 rpm, or whatever rpm you cruise on the highway at while parked stationary, and see what it does for temps ? That may answer some questions regarding the highway speed airflow factor in the equation.
If it still heats up at highway rpm's while sitting still parked, IMO, it may suggest you are realizing NO benefit from the highway speed(60 mph) airflow ?

[c00nhunterjoe]

Is there any valid imput to thinking about a "time" thing ? as in the coolant is travelling so fast at higher rpm's in doesn't have time to release it's heat to air the rad ? or is the extra BTU's being burned at highway speeds simply too much for the cooling system to handle ?
You could try running the engine at 2,800 rpm, or whatever rpm you cruise on the highway at while parked stationary, and see what it does for temps ? That may answer some questions regarding the highway speed airflow factor in the equation.
If it still heats up at highway rpm's while sitting still parked, IMO, it may suggest you are realizing NO benefit from the highway speed(60 mph) airflow ?

De ja vu.

[bakerhillpins]

Is there any valid imput to thinking about a "time" thing ? as in the coolant is travelling so fast at higher rpm's in doesn't have time to release it's heat to air the rad ? or is the extra BTU's being burned at highway speeds simply too much for the cooling system to handle ?
You could try running the engine at 2,800 rpm, or whatever rpm you cruise on the highway at while parked stationary, and see what it does for temps ? That may answer some questions regarding the highway speed airflow factor in the equation.
If it still heats up at highway rpm's while sitting still parked, IMO, it may suggest you are realizing NO benefit from the highway speed(60 mph) airflow ?

I can't see how sitting in one place and tacking up isn't going to do anything but overheat the car even if the cooling system is working properly. The system is designed to draw air through at low RPMs and use flow at speed. This is the same situation that occurs when doing burnouts or on the dynos where they have to setup fans or shoot water into the rad.

WRT the water moving too fast, I can't see that either. The limiting factor is airflow. The pump is only designed to move a fixed amount of water (pressure/flow) and the only result of spinning it faster is cavitation which will reduce flow. https://www.flowcontrolnetwork.com/qa-pump-cavitation-diagnosis-control/

[oldcarnut]

I'm still messing with this after letting it sit since last post.  I took the pump out and it looked fine.  Does anyone have a link or something that shows what the diameter of pulleys should be for stock ac vs non. I would like to know what crank size went with what pump size and blade config. Current one is an 8 and I know the AC is 6 but I'd like to verify correct pulleys to make sure my combo isn't correct.  Most posts I pulled up where all about the pump

[c00nhunterjoe]

Did you do the test that several of us said to try before taking it apart?