340 coolant temperature

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cadboy

cadboy

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Need some help on what is happening on my 68 Barracuda with 340.

It runs good at idle and upto 2000rpm and temp shows 160 on dial and just below centre on original guage.

When above 2000 to 3000rpm then temp goes up to 190 and between centre to High on the gauge.

The car has alu radiator with two electric fans and funnel, fans come on as soon as ignition is on.

I have tried to 3300rpm and temp goes above 190, so I stopped.

Any advice on what to look for and check, the car came as it is and I have just started using it.

 
195 is optimum temperture. 220 is not overheating.
 
Check your lower rad hose to see if its collapsing when the rpm is increased impeding flow? Something fast to check with a buddy. Also check if its got a spring initmor not while your at it.

I'd also address why the fans come on at ignition and stay on. They should thermostatically controlled to come on at a certain temp or manual controlled with a switch. If they are on all the time and the car is reaching 160 operating temp at idle the your stat is working ok.

Good luck! That's a nice rad and fan set up. Wonder if the prev owner had the same issue and threw that monster at the problem hoping it would cure it via shotgun method. You'll get it sorted. Seems to be a flow related issue to me.

Good luck!
 
Check the lower radiator hose to see if you can crush it with your hand. It is supposed to have a spring in it to prevent collapse under suction pressure. If the hose collapses, it will starve the water pump and drive up temperatures.
 
Wow Beatnik, great minds think alike! Though you beat me to the punch.

Cad boy, with such a beautiful engine bay, get rid of that corrugated upper radiator hose! Buy a nice molded hose and use original factory style clamps for a nicer appearance.
 
160 is running cold. 190 is normal.

The only problem you have is that someone convinced you, falsely, that 190 - 200 is hot.
 
Thanks guys you are experts in your Mopars.

I will check the bottom hose and I sort of knew 160 was cold and 190 was normal (as I had googled it) but it is the way it goes up quickly between 160 and 190+ when revs goes above 2000.

I hope there was no issue before I bought the car as the engine was done last year (so I was told) and it looks good.
 
cadboy said:
I will check the bottom hose and I sort of knew 160 was cold and 190 was normal (as I had googled it) but it is the way it goes up quickly between 160 and 190+ when revs goes above 2000.
Click to expand...


Check the bottom hose by manually operating the throttle on the carb while watching the bottom hose.. When you rev it quickly see if the bottom hose appears to be collapsing.

IF you find this to be the problem you can make a spring for the hose with a wire coat hanger. Simply coil it around a round object that is close to or a tad smaller than the ID of the hose. Stretch it to fit and put it in the hose and reassemble.
 
As an added thought. 160 is not "cold" .....it may have a 160 stat in it which yes is the lower end of temperature. I run 180 stats typically but 195 is quite normal too. The 160's are not my fav but that's because of thermal efficiency etc which is a whole other subject.....

But I still say your issue is flow related and I suspect a collapsed lower hose...

Good luck let us know what you find
 
Another thing.....wasn't somebody recently having an overheating problem that was related to those electric fans' giant aluminum "shroud" impeding normal air flow through the radiator? I believe there was.....

IMAG0042_zpsedeb0737.jpg
 
I would ditch those cheap flex hoses and get some better ones, make sure there is a spring inside as well. I wonder if that shroud is hurting the cooling as well, it definitely blocks air passing through it that could help it cool more. What kind of water pump are you running? Maybe upgrade to a higer flow pump, like a Flowkooler.

Strange that some cars have heating issues, mine cools great, I have a built 70 340 in my Valiant. I am running a 1966 Mopar 22" rad with a high flow efficiency 2 core installed, no shroud, a stock 4-blade steel fan, Flowkooler water pump and 190 thermostat, my car never gets above 200 and that's even while being stuck in traffic on a humid 98 degree day.....I hope you get it figured out!
 
I have checked the bottom hose and I can NOT squeeze it and it looks like spring inside.
The top hose however I can squeeze very easy, also the one from water pump to engine.

I ran the engine (without moving the car) let it reach 160 and then rev it to 4000 and within 5 minutes the temp was 210 and I could see overflow from rad.
Let it idle then temp start coming back down, but not as quickly as it went up.

There must be a flow or cooling problem.
How do I check water pump, I can feel the rad getting warm and hot all over, so i assume that means water is going around.

If it is cooling then the fans are not doing the work the should.

Any help/advice is appreciated.
 
Should get rid of the flex hose on the top and definately the one on the bottom and get factory style hoses.

What temp Thermostat do you have?
 
74DartSwinger360 said:
Should get rid of the flex hose on the top and definately the one on the bottom and get factory style hoses.

What temp Thermostat do you have?
Click to expand...

Please direct me to the factory style hoses.

I am not sure what the Thermostat is but I have a 180 waiting to be fitted when I find out the overheating issue.

I am planning to flush the system and change Thermostat (and any other items on the cooling system).
 
cadboy said:
I have checked the bottom hose and I can NOT squeeze it and it looks like spring inside.
The top hose however I can squeeze very easy, also the one from water pump to engine.

I ran the engine (without moving the car) let it reach 160 and then rev it to 4000 and within 5 minutes the temp was 210 and I could see overflow from rad.
Let it idle then temp start coming back down, but not as quickly as it went up.

There must be a flow or cooling problem.
How do I check water pump, I can feel the rad getting warm and hot all over, so i assume that means water is going around.

If it is cooling then the fans are not doing the work the should.

Any help/advice is appreciated.
Click to expand...

4,000 RPM with the car at a standstill for 5 minutes!?
And it only reached 210*F?

Based on what I've read in this thread, your cooling system sounds fine. I would cut some circular breather holes in the shroud to let the radiator breath a little better in the areas further away from the fans, but it sounds like your system is working fine. My car would DEFINITELY overheat sitting in place at that RPM for that long.

Just my $0.02.

-Mike
 
Everybody already told you to dump the hoses but flex hoses also limit coolant flow.
The corrugation causes a lot of disruption of fluid flow direction, so it slows the coolant down in the hoses.
They are smaller ID than normal ones also.
Electrics are cool, but nothing works like a clutch fan and shroud.

I run electrics in AZ by the way.:)
 
stupid question but are your fans sucking or pushing air and are they set up on a thermostat?
 
Hmmm I say flow issue still if its will climb to 210 then slowly come back,down.

Dumb question but did you check the fluid level? Take cap off when cold and check the let it get up to temp and see if you can see fluid movement thru the rad. Straight water or 50/50mix? Test your coolant maybe it's old and crappy. Drain and fill w straight water and retest. Also check you cap. Correct lbs of pressure? Sealing correctly? Beyond that if you see minimal flow throught the top of the rad maybe a new water pump as mentioned or there are clogged water passages in the block which would be worst case scenario after all else fails I'd say

Keep us posted....
 
When was the last time you spent a day in sweltering heat, not 5 minutes on a freeway at 4000 rpm? I could honestly say never

It seems to me your cooling system is working well, yet if you want to do something, change the top hose and as someone else said, open that shroud up with some holes, preferably when it's off the radiator :)
 
I built a similar setup for my big block. running duel 14" fans. the fans are sealed to the radiator and i have holes for air to pass thru during high speed cruising. when my fan controller was working the first fan would come on at 175 and 2nd fan come on at 185. it would cool the engine down to 170 instantly and cycle off. my set up worked very well in bumper to bumper traffic for over an hour in 80* temps.





 
Beatnik said:
Hmmm I say flow issue still if its will climb to 210 then slowly come back,down.

Dumb question but did you check the fluid level? Take cap off when cold and check the let it get up to temp and see if you can see fluid movement thru the rad. Straight water or 50/50mix? Test your coolant maybe it's old and crappy. Drain and fill w straight water and retest. Also check you cap. Correct lbs of pressure? Sealing correctly? Beyond that if you see minimal flow throught the top of the rad maybe a new water pump as mentioned or there are clogged water passages in the block which would be worst case scenario after all else fails I'd say

Keep us posted....
Click to expand...

I checked the level and it looks okay, not sure how old the coolant is, but it is not water only.
I could see coolant moving on the top when engine was running cold.

The rad system was new put in early 2012, when engine was changed.

I will flush the system out and try test again.

Thanks.
 
HotLines said:
When was the last time you spent a day in sweltering heat, not 5 minutes on a freeway at 4000 rpm? I could honestly say never

It seems to me your cooling system is working well, yet if you want to do something, change the top hose and as someone else said, open that shroud up with some holes, preferably when it's off the radiator :)
Click to expand...

It was doing the same when I drove it first time and around 2000rpm was okay and when speeding more than 45 with revs up above 2000 then temp went up.
So I don't think it is that much different with car moving or not.

I have to open the shroud as you say and test again.
:cheers:
 
younggun2.0 said:
I built a similar setup for my big block. running duel 14" fans. the fans are sealed to the radiator and i have holes for air to pass thru during high speed cruising. when my fan controller was working the first fan would come on at 175 and 2nd fan come on at 185. it would cool the engine down to 170 instantly and cycle off. my set up worked very well in bumper to bumper traffic for over an hour in 80* temps.

Click to expand...

Now this is what I would call a very nice set up, could you send me the information on how to set the two fans to work this way please,
I like this it's cool.
 
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