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Overheating problem big block?

mattsmopars

mattsmopars

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Alright I have a 65 coronet wagon. It originally had a 361 BB engine in it with 65,000 original miles when i bought it. I got it running with the original engine, did a tune up, valve job, head gaskets, hoses, belts, water pump,thermostat, cleaned the radiator and so on. Drove it around quite a bit last summer even towed it to the mopar nats and drove it to the show with no overheating issues whatsoever. Then last year in late September I was going to drive it about 1 hour to a local mopar show. While going down the interstate it got hot on me. The best way I can describe how and when the car would get hot is if you ran it at 2000 rpms or above. Under that it was drivable and would stay cool. If you ran it hard or kept the RPM up it would overheat rather quick. So the engine was using quite a bit of oil and was smoking , so I had a rebuilt 383 short block laying around. So needless to say I used it and a fresh set of 915 heads for a new engine for the wagon. The only 2 items that are the same from the cooling system are the radiator and the water pump that was new when I first got it running. Well after 7 min. of run time at around 2000 RPM with the new engine installed it was getting toward the Hot mark so I had to shut it down. Seems to be the same issue as I was having before? So I pulled the new thermostat and tested it on the stove and all seems to be well there. I also pulled the new water pump, and noticed that besides the impeller having more blades it is the opposite direction to an original water pump that I had laying around. I will post a picture of the back of both water pumps. Both are facing up in the same manner. The one on the right is the new one and the left is the original. I hate to be so long winded, but i just can't figure it out. I have also removed the radiator for another trip to the radiator shop. Please let me know what you think. Matt
 

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The 6 blade pump is for a/c and max cooling,the blade configuration is not relevant,still does the same thing.The six blade pump circulates water slower and keeps in the radiator longer for better cooling..
 
If it is doing the same overheating on two different engines I would have to say your radiator is the problem.
 
Just curious- is your temp gauge the original? How accurate is it? Hate to see you spend more money (like I did) when it was a bad temp gauge...jmho
 
1st-temp gauge, a remote single one is cheap, re; big jim. 2nd- a new thermostat, brand name, is cheap. 3rd- don't go back to the same rad shop. re; g.m.79. the reason for the new thermostat is, unless you were checking the water temp on the boiling pot to know what temp it opened you really don't know. .02 cents
 
once the engine is Hot ,and after shutting the engine off,feel around the radiator to see if there are any "cool" spots indicating a restriction.I know you stated that the radiator is or was new,but when these cars sit for periods of time,scales or rust from inside the engine will break loose and clog a brand new rad quickly. just my experience . . . . . . ::sign13:
 
I have the radiator out , and I am taking it to the shop this morning. The lower hose is new and has a spring in it. The thermostat is a Brand new 180 degree, and not the cheap type. I checked it last night on the stove with a thermometer in water and it opens at around 175 degrees.
So far the radiator is the only thing that I can think of that could be the problem.
Thanks to ALL for the suggestions, it helps to have more than one person thinking on the subject.
 
Good luck ..... i just solved my overheating issue .. had the same water pump as you ( the right one ) ... replaced with a mancini aluminum high flow and housing .... flushed the radiator out .... what a difference ... on a 90 degree day am now running at 175-180 ...
 
65-440 said:
Good luck ..... i just solved my overheating issue .. had the same water pump as you ( the right one ) ... replaced with a mancini aluminum high flow and housing .... flushed the radiator out .... what a difference ... on a 90 degree day am now running at 175-180 ...
Click to expand...

Do you think it had more to do with the flushing out of the radiator or the change to the Aluminium water pump and housing?
Thanks, Matt
 
If the problem was on two different engines your problem lies in the radiator! not the water pump and housing.
 
greenmonsta79 said:
If the problem was on two different engines your problem lies in the radiator! not the water pump and housing.
Click to expand...

Yeah, That is what i was thinking as well. The only thing that is hard to understand is the fact I had ran it for about a year with the old engine and had no overheating issue. It just sort of happened all at once?
Matt
 
mattsmopars said:
Do you think it had more to do with the flushing out of the radiator or the change to the Aluminium water pump and housing?
Thanks, Matt
Click to expand...
That's one of the problems when people more than one change at a time. Ya just never know what was causing the problem. Same things happen in drag racing....
 
"That's one of the problems when people more than one change at a time. Ya just never know what was causing the problem"

-- fortunatley for me i KNOW how to repair cars .....

i know the problem was in the radiator, was not holding enough fluid. flushed it out 2 times, now holds 2 gallons ..... when i took the water pump off to inspect the impeller, saw that big void behind the fins ... decided to go ahead and upgrade to an all aluminum, high flow setup .... and for $160 i thinks its well worth it !
 
Here a few other things to check.
Does your car have a fan shroud?
Is your fan installed correctly? If it blowing in the wrong direction it won't cool. Should be blow toward the engine, not out.
Are you anti-freeze and what type, and what freezing point? too much water will weaken it ablity, wrong type will cause corrosion inside the radiator and hearter core.
 
Just this summer I had an issue with my 95 Ram radiator. I could hold my hand against the lower 1/3rd of it at operating temperature. But could not touch the upper 2/3rds of the rad. You cant tell me that it cooled the water that much, so I think the bottom of of it is clogged. Might want to try an I.R. laser thermometer [$25 at harbor freight] to look for cool, or hot spots in the radiator.
 
Well, I went over to the radiator shop to pick the radiator up again. He said that it was stoped up, and had to be rodded out. I also come to find out they did not rod it out the last time as they were supposed to, it just got flushed out. So i have the thermostat housing and water pump back together , and i hope to get the radiator back in it this week.
Thanks, Matt
 
Good, I knew it was the radiator! Now go do some burnouts in the wagon and post pics!!!!
 
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