Ok to run at 160-180 coolant temps?

kerb12

Well-known member
My '66 200 used to always run hot, and when I was stuck in traffic I would start to really worry about overheating. Once I'd get moving, things would cool down again, but it was always a bit nerve wracking.

So I decided to redo my cooling, and put in an aluminum 2-row radiator, a 6-blade fan, a shroud, and an Edelbrock high flow 180 thermostat. Problem is, now it cools TOO well. When the outside temps are low and the coolant hits 180, the thermostat opens and within seconds my temp drops below 160 and then has to slowly come back up to 180. Then it drops again and keeps cycling like that. I never get above 180, and I spend a lot of time in the 160-170 range.

Now that the outside temps are higher, the drops aren't as bad and I stay mainly in the 170-180 range, but still never get above 180.

Is that ok for this engine? I thought operating temps were supposed to be more like 190-200. Do I need to switch to a higher temp thermostat?
 
first thing to remember is that if the cooling system is designed to operate at 180 degrees, then as long as the tstat opening point is below that, the system will operate at 180 degrees. step the temperature opening point up to 195 and the system will run at 195 degrees, the temp the tstat is designed to open at.

it sounds like your system is designed to run at 180 degrees, so stick a 195 degree tstat and be happy with the higher efficiency.
 
good Q Kerb.
I asked the Q a few yrs ago: "OK then, what would be a too cold engine? I know we want cool (more compressed, denser air) in the carb...how bout the water jacket?"
Never got too far on it. But I'm betting the answ is here...somewhere....I just can't.... :unsure:...find... :arg:...it with all this junk lying around :unsure::
 
rbohm, agreed that's what is supposed to happen, but I had a 180 thermostat before as well, and would hit 225 on hot days. My hope was that because of the other cooling upgrades my temps would stick in the 180-190 range, I didn't realize I would spend most of the time UNDER the thermostat opening temp.

If all I'm losing is some fuel efficiency, I don't mind. My only worry was that if I'm running for prolonged times at 20 or 30 degrees below the suggested operating temp that there would be some other damage being done (like oil not flowing correctly).
 
Hi, the engine as a whole runs more efficiently at over 195* It will have run cleaner inside and out. It will be less prone to condensation and sludge inside. The heater will perform better. What is happening is the radiator is doing such a good job that the cooling water from the lower radiator hose is closing the thermostat and the thermostat is cycling as the engine is never warming up.
So I see a few choices. Leave it alone and see what happens in the summer heat, change to a 195* thermostat, or put the original fan back on if it fits with the shroud or remove the shroud. My 66 Bronco never had a shroud and I haven't needed one.
Good luck
 
X2 You now have to much cooling system effecancy for your combo and the T Stat can't do its job of a quick warm up and maintaining the normal operating temp. If you don't care if the engines running temps are too low you might just put in a 160 T Stat and see if temp stabilizes at 170 to 180. If that doesn't work you could say goodby to a quick warm up and try no T State or gutting out a old T Stat center and running with just the other ring to see what temp you get. You could probably add more cylinder compression now to if you wanted also. Good luck :nod:
 
Ok thanks guys. I think I'll leave things as is for the summer months and then I'll put a 195 thermostat in the fall, and then just keep it in all the time.
 
as bubba and b ron noted, you have extra capacity in your cooling system now, so running a 195 tstat wont have an issue with temperature creep.
 
Have you considered an electronically controlled fan? With the extra cooling capacity it seems likely that it would only be needed in traffic, and because of that you would free up some horsepower.

I believe one of the episodes of Engine Masters (one of the free episodes on YouTube) indicated that a fan consumes much more horsepower than you might expect.
 
:unsure: You can also do a FREE fix very easily.Just take a piece of cardboard to get a proper size to block off part of the radiator,and when you find a happy medium,make another one out of some water proof material for a permanent fix.And make it removable.Soooooooooooo easy.
Diesel rigs do it all the time with shutters in the grille.Been doing it that way for decades.
Good luck.Have fun.Be safe.
Leo
 
An update, it's in the 80's here today in NJ and I took it for some rides. The first time I made no changes, and I would get the constant cycling with never reaching above 180. Every time the thermostat opened, I'd get an instant 20 degree drop. Then I took the fan shroud off and went for another ride. This time I still never went above 180, but once the cold fluid in the radiator cycled through the engine a few times, I stopped getting the drops and it stayed consistently at 170.

So one lesson learned - fan shrouds actually make a pretty huge difference.. much more then I expected. Even the cheap flimsy ones like I have. I'm going to leave it off to keep my temps consistent.

Now I think my next best step is to get a higher temp thermostat (190 or 195) and my temps should stay consistently there, and problem solved.


Soldmy66, I would definitely consider an electric, but every time I've looked in the past I couldn't find any that fit the 6 cyl aluminum radiators well. Are you running one? Or know of a good kit?

woodbutcher, ha I actually like that idea. I have some pieces of plexiglas laying around, I wonder if it could hold up to the temps. How would you mount it to the radiator though?
 
"...How would you mount it to the radiator..."
anyway U want. What...OH, I C stang
How bout behind grill in frnt of core support. How bout frnt of radiator, right on it? (I'd use the cardboard as it resists the heat better than the plastic at ur temps - may B no matter?).

"...couldn't find any that fit the 6 cyl aluminum radiators well...."
not sure what U have now (size). For awhile folks pulled the tempo/mercury ouda the junk yards.

U Go boy! I like the incremental approach U take to this testing process. Good 2C a true scientist @ wrk.
One more idea - today U can get pretty cheaply a hand-held infrared temp gauge. It would B interesting to measure the different levels of the radiator for temp, use the device as U go ahead w/this research...

https://shop.advanceautoparts.com/p/per ... lsrc=aw.ds

https://go.harborfreight.com/coupons/20 ... -36087822/

Happy day any x I can buy a new tool...
:eek:
 
Yes that is for sure that a fan shroud and or also using a fan with more the the stock 4 blades does work well to cool down a hotter running engine. Plexiglass would work fine since you all ready have it plus it's not going to get hot enough to hurt it. For a temp type mounting until you finalize the size there's always those handy dandy Zip Ties (better) or even Duck Tape will work for a short time. :nod:
 
kerb12":28sgii8w said:
Soldmy66, I would definitely consider an electric, but every time I've looked in the past I couldn't find any that fit the 6 cyl aluminum radiators well. Are you running one? Or know of a good kit?

I am not running one, although I used to on my 1957 Chevy Wagon w/ a Griffin Aluminum Radiator. I never had heating problems with my 1966 Mustang.

I believe some on this forum have used a fan from a Taurus, and others may have used on from a Volvo. Those were "re-purposed", and I believe there are threads.

When I used one, it was from Derale. https://derale.com/product-footer/electric-fans

They offer several different styles. Maybe someone on this forum has used them in a Mustang application.

Also, regarding woodbutcher's idea, there are a lot of guys on the ecomodder forum that do that, some of them almost completely. And it ctually reduces drag more than you might think. IIWIYS - and wanted to try that - after determining the correct size with cardboard - I would consider making a more permanent version using thin lexan or plexigas, held on with discrete zip ties. If there is a way to squeeze more from a gallon of gas - those boys have tried it (many times with great success). https://ecomodder.com/

The Engine Masters Episode #20 compared a fixed bladed fan (no clutch) vs no fan (in a dyno room) and the difference was 30 Hp. Sadly, you now have to subscribe to Motor Trend on demand to see that episode. If you are running a clutch fan, the difference will be much less, probably more like 5 HP to 10 Hp. Those are well intended guess-timates, based on a few things I've read. Perhaps someone on this forum has actual (or better) data.
 
You should keep in mind that the temp sensor on the small sixes is at the rear of the block. Coolant from the radiator flows from the water pump back through the block and around the cylinders. From the rear of the block, where the temp sensor is, it is then sent into the back of the head. The head is where most of the heat is generated. The coolant is probably picking up another 20 degrees of heat going through the head before it gets to the thermostat. You just can't see it at the gauge.
 
:unsure: Hi Kerb12.Mostly the ones that I have seen done are mounted to the core support in front of the radiator.
Usually,4 small bolts are used to secure the piece.The bolts are a permanent install.Either by welding or using a QUALITY epoxy.My personal preference for epoxy is Brownells "AcraGlass"
from Brownells in Iowa.They are a gunsmithing and firearms equipment supplier.Most have used wingnuts instead of nuts for ease of R&R.
Good luck.Have fun.Be safe.
Leo
 
Switched back from the 6 blade fan to the stock 4 blade today - surprisingly made very little difference. At this point I'm running stock except for an aluminum radiator and the high flow 180 thermostat.

viperwolf1, that's a very good point - I forgot to mention that I'm measuring at the water outlet. My stock cluster gauge meter is still connected to the port in the block, but I also have one of those Sunpro triple gauges and I ran that temp gauge to the water outlet since the gauge actually shows temps (instead of just "C" or "H" like the crappy stock one)

Out of curiosity I spent a little bit of time looking at electric fans again and found a Spal 16"fan (30100400) that might actually fit.. it's only 2" thick! I only have 2.25" clearance between my radiator and the pulley, so that's always been my limiting factor. It's still cutting it really close though.. but something to think about.
 
"...viperwolf1, that's a very good point - I for..."
he IS a bronk owner, showed up here recently (just a few posts'n gone) but runs a bent 8...

Not sure where U saw the Spal 30100400. Delrail (is that wrong spell?) is less money & hasa thermo switch'n mounts. The ford junk yrd one even better'n less $ plus a sensor/harnes...
 
Not sure that's a very good spot for the sender or that you will get an accurate engine temp reading unless you put the temp sender back behind the T-Stat at least in the center of the head. That also explains why you could tell when the T-Stat was opening and closeing. You could put a T fitting into that rear of head boss so you could have both of your gauge senders hooked up there and then you really will know what the true engine temp is. My bet is its going read temp somewhat higher too. :nod:
 
what's the H2O path bubs? I C it comes in (radiater) low out hi, hits the pump...how duz it go thru block, head? I C jackets in block, passages in head but what is the route?
 
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