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Discussion Starter · #1 ·
Need informed opinions to this tech problem:

Friend’s 1976 RC 440
It had a tendency to run hot before we had it rebuilt SO THIS IS AN ONGOING PROBLEM, had it vatted and rebuilt and still runs hot. Heads were rebuilt also, with new springs and valves. Temp is fine as long as the outside temp is below 70 F roughly, but above that, the temp gauge keeps creeping up to over 210 F even at highway speeds. There is a mechanical temp gauge as well as the stock gauge. It does not boil over but it does dump coolant into the reserve tank after the engine is stopped.

Following is what we have done over the months:

1. swapped out two radiators (there is a fan shroud)(current radiator was infrared scanned and has a good temp drop between the top and bottom of the radiator)
2. new water pump
3. new thermostat (2 or 3) have even tried running it without one and this slows down the temp rise but does not stop it.
4. hoses not kinked, lower hose has spring
5. tried 2 different clutch fans, and a flex fan
6. set timing to 10 degrees advanced(could this be lower perhaps?)
7. checked the coolant, it is fine, checked the coolant for exhaust gases that might be heating it up, there were none found.

8. No vacuum leaks, vacuum is good and strong.

9. Not running lean.

I may have forgot to add something to the list above, but as I get input I will mention if we did it or not.

Thanks,
Mac
 

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Discussion Starter · #3 ·
I don't know if he has but I will find out. How much could that be backed off? I don't know what the total timing is.

Mac

Slanted_Mind said:
Have you tried backing your timing off? Any effects?

What is your total timing at?

-SM
 

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I would back it off in 2* increments to see if it has any effect. IIRC big blocks like total timing to be somewhere in the 32*-36* range, depending on the setup.

Do you know how much mechanical advance the dist is providing?

-SM
 

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Discussion Starter · #5 ·
I don't know on the mech advance question, but the distributor is stock.

Will probably try to back it off this weekend.

On the total timing, I recall that when we set the initial timing to 10* and we reconnected the vacuum advance, the timing did not increase over the initial 10*. Is this ok?

Mac

Slanted_Mind said:
I would back it off in 2* increments to see if it has any effect. IIRC big blocks like total timing to be somewhere in the 32*-36* range, depending on the setup.

Do you know how much mechanical advance the dist is providing?

-SM
 

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macario said:
I don't know on the mech advance question, but the distributor is stock.

Will probably try to back it off this weekend.

On the total timing, I recall that when we set the initial timing to 10* and we reconnected the vacuum advance, the timing did not increase over the initial 10*. Is this ok?

Mac
Yes, that is OK. Vacuum advance should not be doing anything at idle, it works under part throttle and cruise conditions to improve mileage. Vac advance should be disconnected and the vac advance port on the carb plugged when setting base timing though.

-SM
 

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Has the engine been previously rebuilt?? When it was rebuilt this last time; did they measure the bore to see if it had been bored out, or did they bore it even farther?
You mentioned trying several thermostats; what temperature were they; try a 180 deg stat.
How about the radiator cap, proper one & functioning?
Only other thing I could suggest would be to pressure test the cooling system.
 

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Have you checked the AC condensor or tranny cooler to see if they are blocked up? Do you have a shroud over the top and bottom of the radiator/condensor/tranny cooler so that air doesn't go over the radiator?
You could try going to dual 12 or 14" electric fans. You can also try "Water Wetter" or another additive that helps it grab heat out of the engine.
Are you using a 4 core radiator? With the big blocks it is basically mandatory....
 

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like dodge said about the four core radiator, is any thing blocking air flow into the radiator, does it move water with the thermostat open and the cap off,intake old or new maybe got some glog in it the intake caskets blocking the water ports im taking a wag on it all.
 

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Discussion Starter · #10 ·
AWYSEGUY: No, the engine had not been previously rebuilt, and there is a 180* stat in there now. Radiator cap has been replaced at least 2X - not the lever type either. Cooling system has been pressure tested as well.

DODGE8564: There is no tranny cooler on this rig we are talking about; Have not checked AC condenser as far as I know; Shroud is full surround but we could adjust the placment better as it is about an inch too high compared to the fan; Have tried water wetter to no effect; Yes, it is a 4 core rad; He does not want to go to electric fans unless that is the final solution.

MIKEK: Intake is the stock cast iron one, and when we rebuilt the engine it looked good underneath, all the galleries were clear; air flow to radiator is good, nothing in the way; Yes, water/coolant moves well or seems to as far as we can tell.

Mac
 
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You don't mention whether you're running a heater core. If so, are you getting proper flow thru the core? Is the heater blowing hot air?
 

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May consider going down farther.. see what a 160 degree does.. When I was running a big block.. It got plenty hot.. but only when I drove it without a cooling system.
Could there be an airlock in it somewhere? I wouldn't think so, with all you've done; just trying to make sure everything we can imagine gets suggested.
 

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Discussion Starter · #13 ·
The heater kicks ass when he turns it on. Winter and summer works great. Heater core is fine.

PrimerGrey said:
You don't mention whether you're running a heater core. If so, are you getting proper flow thru the core? Is the heater blowing hot air?
 

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Discussion Starter · #14 ·
We ran it without a stat and that only delayed the heating not stopped it so going to a 160* would probably not help.

Mac

awyseguy said:
May consider going down farther.. see what a 160 degree does.. When I was running a big block.. It got plenty hot.. but only when I drove it without a cooling system.
Could there be an airlock in it somewhere? I wouldn't think so, with all you've done; just trying to make sure everything we can imagine gets suggested.
 

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i know oyu said the water pump was new, but you might check it out anyway.

also, have you checked the hoses? made sure nothing is clogging them or that they arent collapsing?

and i know oyu visually inspected the manifold, but you might consider having it tanked as well

i would also check the water ports in the heads and might if all else fails consider having them tanked as well

eric
 

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Discussion Starter · #16 ·
The water pump we replaced with a new one and the old one has since gone into another vehicle and is working well so that tells me that the pump was not the problem.

Hoses are fine, no clog or collapsing.

Personally, if retarding the timing does not help this weekend then I will begin to suspect the heads and/or the intake manifold.

Mac

intenseimages said:
i know oyu said the water pump was new, but you might check it out anyway.

also, have you checked the hoses? made sure nothing is clogging them or that they arent collapsing?

and i know oyu visually inspected the manifold, but you might consider having it tanked as well

i would also check the water ports in the heads and might if all else fails consider having them tanked as well

eric
 
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Mac, the way you describe the heater leads me to think it's not a flow problem. The heater takes coolant from the top of the motor where it's the hottest, so if flow thru the heater core is good, flow thru the rest of the system should also be good. Were the heads checked for cracks?
 

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Discussion Starter · #18 ·
As far as I know the heads were magnafluxed for cracks and rebuilt but they could have missed clearing out a coolant gallery I guess.

I agree, I do not think it is a flow problem of the coolant.

PrimerGrey said:
Mac, the way you describe the heater leads me to think it's not a flow problem. The heater takes coolant from the top of the motor where it's the hottest, so if flow thru the heater core is good, flow thru the rest of the system should also be good. Were the heads checked for cracks?
 

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macario said:
AWYSEGUY: No, the engine had not been previously rebuilt, and there is a 180* stat in there now. Radiator cap has been replaced at least 2X - not the lever type either. Cooling system has been pressure tested as well.

DODGE8564: There is no tranny cooler on this rig we are talking about; Have not checked AC condenser as far as I know; Shroud is full surround but we could adjust the placment better as it is about an inch too high compared to the fan; Have tried water wetter to no effect; Yes, it is a 4 core rad; He does not want to go to electric fans unless that is the final solution.

MIKEK: Intake is the stock cast iron one, and when we rebuilt the engine it looked good underneath, all the galleries were clear; air flow to radiator is good, nothing in the way; Yes, water/coolant moves well or seems to as far as we can tell.

Mac
Water wetter will not lower your temps, but it helps keep the coolant from boiling and creating air pockets. It is just a band aid, but a friend of mine ran it and I think he said it ran hotter than before....
 

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What carb? Make sure you're not running too lean. Pull and check the heat range and condition of the plugs. We had a big block that would run hot if it was'nt full of oil. Have you tried an oil cooler? Sounds like you have covered most everything.

Skeeze
1988 RamCharger
318 FI
 
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