Cooling Issue

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mopowers

mopowers

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I'm having trouble keeping my 340 cool when stopped at a light. It runs right at and doesn't get above 190* while cruising, but will creep up steadily to 210, 220 and further etc while stopped. I have a 22" champion 3-row radiator with sealed factory shroud and 17" clutch fan with Hayden shorter thermostatic clutch. Considering the ambient temps are only about 65-70, I want to get this fixed before the hot temps come.

Considering it cools when cruising (the temp gauge even cycles as the thermostat opens and closes), the radiator is fine, right? That just leaves a potential air flow or water flow issue, right? I do have a factory fixed fan I can try, but would rather stick with the clutch fan. Could my parts store water pump not be up to the task? What do you folks think? I'm wondering if buying a high flow water pump and thermostat may cure this issue.

Oh yeah, I'm running 60/40 distilled water/coolant mix and it's got plenty of ignition timing in it. Thanks!
 
If you try the solid mount fan, it might answer all your questions. Maybe the fan clutch is failing. Do you have the spring in the lower hose? How about the seal that seals the hood to the radiator?
 
furyus2 said:
If you try the solid mount fan, it might answer all your questions. Maybe the fan clutch is failing. Do you have the spring in the lower hose? How about the seal that seals the hood to the radiator?
Click to expand...

The clutch is brand new, so I hope it's not failing. Is there a way to test it?

Yes, there is a spring in the lower hose and yes there is a seal on the hood (front and back)
 
did you recently change something
did it just start happening
has it always happened
 
I had a similar issue. filled up the radiator ran it until the thermostat opened. installed the radiator cap. without the valve open in can cause an air pocket. Not 100% but worth a look.
 
I didn't see anything about a fan shroud and those have everything to do with that problem.
As a matter of fact that exact scenario is exactly what they are for. (to flow air over the entire radiator surface like it does when the car is moving)
 
skep419 said:
I had a similar issue. filled up the radiator ran it until the thermostat opened. installed the radiator cap. without the valve open in can cause an air pocket. Not 100% but worth a look.
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Sorry, but you lost me with the incoherent sentence. How would I verify whether or not there is an air pocket? I've driven the can quite a bit. I would think any air pocket would have would itself out by now.

TrailBeast said:
I didn't see anything about a fan shroud and those have everything to do with that problem.
As a matter of fact that exact scenario is exactly what they are for. (to flow air over the entire radiator surface like it does when the car is moving)
Click to expand...

I have a factory style shroud sealed very closely to the radiator tanks. This is the reason why I added the extensions to the shroud. Thanks for the help.

Picture0310171304_1.jpg
 
Whenever I change my coolant,I always put my 73 Dart up on my metal car ramps for 2 reasons....one to aid in draining system through petcock and more importantly to elevate the car nose to get air bubbles out of the system as car is warming up with new coolant in and rad cap is off....it works for me every time. Try it and see if it solves your problem...Good Luck 318MG
 
mopowers said:
Sorry, but you lost me with the incoherent sentence. How would I verify whether or not there is an air pocket? I've driven the can quite a bit. I would think any air pocket would have would itself out by now.



I have a factory style shroud sealed very closely to the radiator tanks. This is the reason why I added the extensions to the shroud. Thanks for the help.

View attachment 1715026549
Click to expand...
Can't tell how close your fan blades are in the shroud, but some people put a spacer in between the fan blade to move it closer to the rad. But that is wrong because the blades should just be at the outside edge of the shroud. Hard to tell in your picture.
 
are your fan blades half in the shroud and half out for maxium cooling performance. This placement prevents the fan from acting like an air block and lets the heat and air escape from the radiator cavity.
 
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318MoparGuy said:
Whenever I change my coolant,I always put my 73 Dart up on my metal car ramps for 2 reasons....one to aid in draining system through petcock and more importantly to elevate the car nose to get air bubbles out of the system as car is warming up with new coolant in and rad cap is off....it works for me every time. Try it and see if it solves your problem...Good Luck 318MG
Click to expand...

My thermostat has a bleed hole in it. Wouldn't this allow any air pocket to bleed out?

fatoldguy said:
Can't tell how close your fan blades are in the shroud, but some people put a spacer in between the fan blade to move it closer to the rad. But that is wrong because the blades should just be at the outside edge of the shroud. Hard to tell in your picture.
Click to expand...

d1970 said:
are your fan blades half in the shroud and half out for maxium cooling performance. This placement prevents the fan from acting like an air block and lets the heat and air escape from the radiator cavity.
Click to expand...

Since I've taken the pictures below, I've added (4) 1/4" spacers between the fan and clutch to bring the fan back as far as possible. Now, the fan is pretty close to 50/50 in/out of the shroud. It should be close enough to work. I may just have to mount the fixed fan on and see how it cools. I'd hate to have to do that though. The shitty part is that the radiator needs to come out in order to change fans because it's so close.

Picture0310171621_1.jpg


Picture0310171622_1.jpg
 
I think you are going to have better luck with it now, as you would be surprised how much air comes off the tips of the fan.
With the fan deep inside the shroud all that air coming off the fan tips blows out against the inside of the shroud instead of out of it and therefore pulling more air volume through the radiator.
Was going to ask you about the depth and idle RPM's both. :D
 
Based on my first attempt after resurrection, the thermostat I used had a bleeder and it was a issue. I thought I had it covered from new radiator, fan shroud and all with factory style parts.

That fancy t-stat with bleeder sucked!!!

Put a high flow 185 stat from Milodon in and it made all the difference! Don't skimp on the cheap part that is often overlooked.
 
TrailBeast said:
I think you are going to have better luck with it now, as you would be surprised how much air comes off the tips of the fan.
With the fan deep inside the shroud all that air coming off the fan tips blows out against the inside of the shroud instead of out of it and therefore pulling more air volume through the radiator.
Was going to ask you about the depth and idle RPM's both. :D
Click to expand...

It already has been moved back 1/4" from the pictures and is still having issues. That's why I'm asking you folks. Thanks though!

1968FormulaS340 said:
Google "how to test a fan clutch". Everything else looks good to me.
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I will. Thanks! I though the only way to test them was to make sure they're snug (which this one is).

1969383S said:
Based on my first attempt after resurrection, the thermostat I used had a bleeder and it was a issue. I thought I had it covered from new radiator, fan shroud and all with factory style parts.

That fancy t-stat with bleeder sucked!!!

Put a high flow 185 stat from Milodon in and it made all the difference! Don't skimp on the cheap part that is often overlooked.
Click to expand...

I may try that. Do you happen to have a part number? Is this it?
 
For you, I think the only thing left is the anti-cavitation plate that comes on the Hi-flo pumps.And these pumps should be accompanied by a hi-flo stat.
Everything else looks pretty good. Well except I run a 7-blade oem fan.And,I assume you have a stand alone oil-cooler on the tranny. If not, what does she do in neutral? Otherwise you seem to have the bases covered.
considering it cools when cruising (the temp gauge even cycles as the thermostat opens and closes), the radiator is fine, right? That just leaves a potential air flow or water flow issue,
Click to expand...
But this statement has me concerned. Under steady state conditions you shouldn't be seeing the water temp going up and down.The stat just does not work that fast! What I would do is grab an old stat and cut everything off it so that you are left with just the restrictor. Install that and roadtest it.
Without the temperature regulation of those guts, now the temp will run differently with different loads and speeds, but stopped and at idle, with a good fan and pump, the water temp should actually fall.If it doesn't rev it up to 1000 rpm and watch the gauge. If the temp does not fall, either buy or build a hi-flo pump.(The anti-cav plate used to be sold separately). If buying, I have a 16 year old Milodon hi-flo pump,and matching stat, still in action; so of course I recommend them.
My 360 runs 14* idle timing. It has a 276/286/110 cam in it and a 750DP on an AG with unwrapped TTIs. It runs a rock-solid 205*.It idles at 750.I hear the thermostatic clutch kick in occasionally, after a hard run, but mostly it's pretty quiet.And since I like to rev the berries off it, I run an underdrive crank pulley and an overdrive alternator pulley. in an effort to keep the belt on. I have never yet thrown a belt.
I run a restrictor in my bypass hose too. My theory was, that after the stat opens this forces the water to go to the rad. If you notice, the later intakes have a bigger bypass system. I choked mine down to the old size . It seems to work.
Your rad size should be fine. I run a 26" A/C rad from a 73 Swinger 318, in a resized core-support. Yeah it's old, and it is only a 2-row.I guess she's pushing 44 this year. Yours looks all shiny and new. I imagine her calling out to that 340;"common big boy, show me what you got!"
 
AJ/FormS said:
For you, I think the only thing left is the anti-cavitation plate that comes on the Hi-flo pumps.And these pumps should be accompanied by a hi-flo stat.
Everything else looks pretty good. Well except I run a 7-blade oem fan.And,I assume you have a stand alone oil-cooler on the tranny. If not, what does she do in neutral? Otherwise you seem to have the bases covered.
Click to expand...

Do they make a 17" OEM 7-blade fan? The fan I have is an aftermarket 6-blade 17" piece. I can't run an 18" fan due to the fan shroud I have being from a '67 a-body. I do have a stand alone oil-cooler (B&M stacked plate style). The trans fluid also flows through the radiator though. Should I not have it flow through the radiator?

AJ/FormS said:
But this statement has me concerned. Under steady state conditions you shouldn't be seeing the water temp going up and down.The stat just does not work that fast! What I would do is grab an old stat and cut everything off it so that you are left with just the restrictor. Install that and roadtest it.
Click to expand...

Thats a good idea.

AJ/FormS said:
Without the temperature regulation of those guts, now the temp will run differently with different loads and speeds, but stopped and at idle, with a good fan and pump, the water temp should actually fall.If it doesn't rev it up to 1000 rpm and watch the gauge. If the temp does not fall, either buy or build a hi-flo pump.(The anti-cav plate used to be sold separately). If buying, I have a 16 year old Milodon hi-flo pump,and matching stat, still in action; so of course I recommend them.
My 360 runs 14* idle timing. It has a 276/286/110 cam in it and a 750DP on an AG with unwrapped TTIs. It runs a rock-solid 205*.It idles at 750.I hear the thermostatic clutch kick in occasionally, after a hard run, but mostly it's pretty quiet.And since I like to rev the berries off it, I run an underdrive crank pulley and an overdrive alternator pulley. in an effort to keep the belt on. I have never yet thrown a belt.
I run a restrictor in my bypass hose too. My theory was, that after the stat opens this forces the water to go to the rad. If you notice, the later intakes have a bigger bypass system. I choked mine down to the old size . It seems to work.
Your rad size should be fine. I run a 26" A/C rad from a 73 Swinger 318, in a resized core-support. Yeah it's old, and it is only a 2-row.I guess she's pushing 44 this year. Yours looks all shiny and new. I imagine her calling out to that 340;"common big boy, show me what you got!"
Click to expand...

If I buy a new hi-flow thermostat, what temp should I go with? 195? 180?
 
To test the fan clutch,you will have to get the engine good and warm.
Install the restrictor in the water-neck,and block the rad 100% with a cardboard plug, except right in front of the the fan clutch cut a hole about 4 or 5 inches in diameter. Bring the shop waterhose over, just in case.Then with the tranny in Park,and the engine idling, grab your IR gun, and periodically shoot the top rad-tank below the liquid line. When the clutch kicks in you will hear it roar;shoot the tank now!And pull the cardboard out right away.This is the fan's preset cut-in temp.It should be higher than the thermostat setting and lower than about 220*. I like lower than 210.
If this does not occur at or below 220* pull the cardboard out now! If the temperature continues to rise,rev the engine up to 1000 rpm. If that fails to bring the temp down within a few seconds,then dribble some running water over the front of the rad or hit it with a fine water mist, until the water comes down to under 200 and then shut it off.
Now order up a new clutch.But before you do, call up Hayden and ask them if the way yours is working ,is no good. Of course you could install a direct-drive fan, and then you would know. Between the gutted stat and a direct-drive fan, and the anti-cavitation plate,your problems should be over.This removes all the variables. If that works, then you can reintroduce the stat, and then a new clutch, one by one.I have heard many fan-clutches roar on cold engines, but they usually settle down in a minute or two, as the bi-metalic spring adjusts. That just tells you the parts are operational.
As to stat selection; The stat sets the minimum water temp.
I like to run mine hot, cuz I have it in my head that hot is fast and hot makes better fuel efficiency and hot makes more mpgs. So I run a 195, that appears to be defective, cuz she runs 205; and I'm all excited about that. If your engine has a history of running a little too hot you might want to run a little cooler,say 180 or so, just so you can catch a heating trend on the gauge. Once the cooling system has been bugged out, and you can trust it, then you can move up. As long as she's warmer than 160; that's too slow for me. I mean low,lol.
As to the fan
if you have a 6-blade I would keep it for now. IMO a 6-blade 17 incher with a shroud is better than a 7-blade 17 or 18 incher, with no shroud.
I think you will find your issue in the clutch, or the pump, or the stat.or some combination.
 
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Low RPM overheating is lack of air flow. On the highway is lack of water flow. You should be looking for something reducing air flow at idle.
 
Thanks for the input guys. I think I'll try it without a thermostat first since that's free. I'll also test the clutch, but considering it's new, that'll probably check out fine. I'm guessing I'll probably just end up with the fixed fan. I just don't think I'm getting the air flow I need.
 
mopowers said:
Thanks for the input guys. I think I'll try it without a thermostat first since that's free. I'll also test the clutch, but considering it's new, that'll probably check out fine. I'm guessing I'll probably just end up with the fixed fan. I just don't think I'm getting the air flow I need.
Click to expand...
What's your engines idle speed?
 
318MoparGuy said:
Whenever I change my coolant,I always put my 73 Dart up on my metal car ramps for 2 reasons....one to aid in draining system through petcock and more importantly to elevate the car nose to get air bubbles out of the system as car is warming up with new coolant in and rad cap is off....it works for me every time. Try it and see if it solves your problem...Good Luck 318MG
Click to expand...
------------BINGO ! That and a 1/16" hole in the thermostat. some do 1/8" .
 
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