cooling issues

-
6

66dartgt

Well-Known Member
Joined
Jan 11, 2006
Messages
815
Reaction score
13
Location
chgo suburbs
I posted on moparts about the problems Im having with my 66, if anyone happened to read it.

The engine is a freshly overhauled 060 318, 9:1 compression ratio, mp 268/272 .455 cam, shortie headers, running a 600 cfm carb., 302 heads pocket ported with 1.88/1.60 valves. It has maybe 4-5 hours running time on it. It has a 180 robertshaw thermostat (that is verified to be working correctly), 8 blade 4 3/8 inch impeller with an anti cavitation plate. Stock 22 inch radiator, recored with a "high efficiency" 2 row core, stock shroud, 7 blade 17 inch thermal clutch fan. New hoses, heater core etc. 50/50 coolant water mix.

Engine runs at 220F whether driving or idling. I checked the inlet and outlet temps on the radiator, 215-220 in, 195 out. Obviously the radiator isnt cutting it.

My question is: would trying various sized restrictors in place of the thermostat tell me much ? Or am I pissing my time away. My thought is that maybe the water pump is pushing the coolant thru the radiator too fast ?

I am leaning towards that not being the case, but if anyone has any thoughts about my next move I'd appreciate hearing about it.

Right now I am thinking a new Aluminum radiator is the way to go.
 
66dartgt said:
I posted on moparts about the problems Im having with my 66, if anyone happened to read it.

The engine is a freshly overhauled 060 318, 9:1 compression ratio, mp 268/272 .455 cam, shortie headers, running a 600 cfm carb., 302 heads pocket ported with 1.88/1.60 valves. It has maybe 4-5 hours running time on it. It has a 180 robertshaw thermostat (that is verified to be working correctly), 8 blade 4 3/8 inch impeller with an anti cavitation plate. Stock 22 inch radiator, recored with a "high efficiency" 2 row core, stock shroud, 7 blade 17 inch thermal clutch fan. New hoses, heater core etc. 50/50 coolant water mix.

Engine runs at 220F whether driving or idling. I checked the inlet and outlet temps on the radiator, 215-220 in, 195 out. Obviously the radiator isnt cutting it.

My question is: would trying various sized restrictors in place of the thermostat tell me much ? Or am I pissing my time away. My thought is that maybe the water pump is pushing the coolant thru the radiator too fast ?

I am leaning towards that not being the case, but if anyone has any thoughts about my next move I'd appreciate hearing about it.

Right now I am thinking a new Aluminum radiator is the way to go.
Click to expand...

What do ya mean when you say "high efffiency 2 core". Are the fins beween the tubes packed so dense that the air can't get through. Before I would go buying an expensive aluminum rad. I'd install a stock pump, because yes you maybe pumping the coolant through the rad faster than the time it takes for the coolant to be cooled by the rad.

terry
 
I'd thought about the pump too, but the previous engine (dead stock 318 2bbl) had an 8 blade pump as well, with the old radiator core, and had no issues cooling it, no shroud and using a 4 blade solid drive fan.

The core that's in it has more tubes per inch than the standard style. According to the radiator shop its more efficient that way. I trust them as I have used them many times over the years and had excellent results. This time is a different story.

The pump that's on it is stock, except for the cavitation plate. The only other option would be a 6 blade smaller impeller AC pump, which is not what is supposed to be on the engine with the size pulleys it has on it, which are factory correct for the larger impeller pump.

If I understand this correctly: in effect if you put in a restrictor in the thermostat housing you can slow the flow rate, without changing the pump.
In theory it sounds cheaper and faster to swap restrictors than it does pumps.
 
Calculate the expected temperature drop (inlet temp - ambient temp) * radiator efficiency = xx degrees

Lets say that inlet temp is 220 and the ambient temp is 90 and the rad efficiency is 50 percent, that would be 65 degree drop at best from inlet temp to outlet temp.
Think outside the box, put a c-clamp on the upper hose....that will restrict the flow :)

Maybe the old radiator was "restricting" the flow enough for it to cool down by the time it made it to the outlet, or maybe the fan clutch is bad??
 
I had the same problem with my 440 engine in my coronet with the stock radiator. ( I know a B body )
I changed the radiator to the aluminum one it maxes out at 190. It still is running a little hotter when I stop.

Does the car have AC? If yes try pulling off the ac condenser.
 
Does it stay rock steady at 220? Even in traffic? Or does it heat up if sitting around...

Check your fan clutch, is it operating correctly? Maybe it's new, I dont think you said one way or the other.

What is your radiator flowing in gpm? Any good shop will flow test it when they rebuild it or simply check it. If they never flow tested it, you dont know what your flowing, rebuilt or not...and it could be an issue. You want a min. of 20-22 gpm.

I blamed my Autozone parts store special radiator for my cooling issue and it turned out to flow 35gpm! Put a shroud on, and a 180 stat in and my issue was solved. Since you already have both a shroud and 180 stat, I'm wondering if your rad is not flowing what you think it is? Pull and and have it checked. If anything it's a cheap/easy variable to eliminate...
 
1st off a new tight engine does run a little wrmer, also being slightly modified from a stock engine and a worn one at that will require more cooling capacity. IE larger radiator, better desgin, more air movement, water flow etc.

Have you thought about adding a radiator expansion tank to maybe just add some more fluid capacity? Just a thought, may the added capacity would help smoe, but I think a larger raidiator that holds more and has more cooling area gains the best in terms of effectiveness..

I was just thinking maybe without spending a lot more $$$ you could add someting like this and it may be enough to increase the capacity to solve your problem?
http://www.pitstopusa.com/detail.aspx?ID=8876
MOROSO ALUMINUM COOLING SYSTEM EXPANSION TANK

Anyone use something like this and did it help?
 
Interesting thoughts. I don't have the top tank filled all the way when its running as I am worried about it overflowing, with the thermometer stuck in the cap. But even still I cant imagine its going to hold much more than 1 additional quart. I'll give it a shot, later this week. On a business trip now.

I'm also going to try clamping the upper hose down with some wood working clamps to see what if anything that does, (player1up's suggestion), to restrict the flow.

I do have an expansion tank on the thing, but I have not had the system completely filled so that it spills into the thing. Again, something to try when I top off the radiator.

The coolant flow thru the radiator looks pretty fast to me. Water is churning around in there pretty well. The clutch on the fan is working. It pulls lots of air.

I've pretty much convinced myself its the radiator cooling capacity and not much else. When you have good flow, and 220 at the top and 195 at the bottom it seems as though the thing just cant handle the cooling needs of the engine.

I will putz around with the radiator shop later this week and see what they have to say. Problem is - I don't think there is room to install a three row core with these tanks. If that's the case then its new radiator time.
 
Have it flow checked. That will tell you alot. Just looking at it move isnt going to tell you much I dont think. It worries me that your shop didnt flow test it first and foremost before rebuilding it! If you can, be there when they do it and see for yourself. If it's flowing less than 20-22gpm, then your new re-core job isnt working like it should.

Also, have you tried running a stock 6-blade fixed fan (no clutch). Just another easy variable to eliminate. If it pulls more air, and helps things, you know your clutch fan is not pulling enough.

Let us know how it comes out!
 
Well, its been a while since I posted on this issue, and I learned some things. Since this car isn't gonna get driven much more this year (it was 38 F this morning), I can afford to be very deliberate before spending money. Sometimes procrastination is your best friend, that and a memory.

I had forgotten I had a 69 A body 3 row radiator in the attic. I dug it out and inspected it. Its ugly but the core tubes look clean. I put some saniflush in the thing and let it set, then flushed it with clean water and installed it. While cleaning it I repaired the busted plastic shroud, (learned how to weld plastic) and fixed that up.

Installed the whole mess with the little 7 blade 17" clutch fan from the stock 66 set up. It improved somewhat to maxing at around 215F.

After fumbling around with unrelated house projects for a few weeks I decided to try a larger 6 blade 18" flex fan I had laying around, last weekend.

Interesting - it now holds temps at around 195 with extended idling and up and down from 900 rpm to 2000 rpm for 45 minutes sitting in the garage. I have concluded the problem is air flow - I talked to flexalite today and asked them difference in air flow for the 6 blade flex and their new 7 blade (both 18") fans - the 7 blade will pull 15% more air. I still dont understand why the clutch fan worked so poorly, the clutch is a new thermal type, but obviously the fan wasnt up to the task, probably due to its overall diameter and blade pitch.

So I ordered a 7 blade flex a lite fan today. Will install that this weekend and see what happens. I suspect this will solve the problem. Next I have to decide whether to monkey with the 66 radiator and this new fan or just get the 69 radiator recored and fixed up. Decisions decisions.

Knowing my detail (read anal) nature I'll try it both ways ! LOL. Problem is the damned 66 radiator shroud doesnt sit centered on the fan hub, and the opening in the shroud is 19.25" or so, meaning the 18 inch fan may hit the edge of the shroud = bad.

Well, at least I seem to have gotten on to something that makes sense and is resolving the problem.

I'll futz with this thing some more and see what happens. Probably you'll see another post from me in November ! Haha.
 
Running hot when driving is not a fan blade issue. Ram air goes through the cooling fins then. And some shrouds don't sit centered for some reason.
 
Hi Tom thanks for the thoughts. The overheating issue occurred whether moving or not. I figure an acid test is running it in the garage, which is what I have been doing. Weather has not been conducive to driving. Its a convertable and the top needs work.

Anyway, I put the new 18" 7 blade fan on it. Results ? 180-185 F whether running at idle or 2000 rpm for extended periods of time. I think I've got it licked !
 
You must log in or register to reply here.
-

Back
Top