Gerald Morris
Senior Member
Now C-body Moparians, we can hopefully conclude this series inspired by the overheating problem in our otherwise EXCELLENT barn find, Gertrude!
Nearly 54 years have passed since this car's engine had daylight fall upon its pistons! After patient, painful attempts to correct a rapidly worsening overheating problem, I finally was compelled by circumstance to do a risky, unpleasant operation on this engine and open the cylinders to daylight in hope of finding WHAT has been driving the running temperature of this otherwise SUPERBLY PRESERVED old machine to a level which assures destruction. To wit: the Old Virgin started running a DEADLY FEVER, and ONLY SURGERY might cure it! So, I've diddled Dear Gertrude, who will be a spinster no longer. Now, let us pray I can effect her Cure.
Prognosis: Gertrude's engine shows REMARKABLE preservation and maintenance. It runs extremely well, having passed the rigors of the City of Tucson's Emissions test with a level less than HALF that allowed by the City. The car accelerates most satisfactorily once at a normal operating temperature. Here lies the Problem. After warmup to ~190 F, the thermostat opens, momentarily cooling the engine with a flood of cooler coolant from the radiator, but then the already rapid ascent of coolant temperature, instead of abating, increases exponentially, reaching an unsafe level (over 230F) in 10 minutes, and pressurized boiling point (~250F) in less than 20 minutes. The operating range of this engine has fallen to less than two miles, and was decreasing with every run. A liquid sealant was introduced to the coolant to utterly NO avail. Other common overheating remedies such as adjusting timing, introducing a pusher fan, enriching the idle mixture all availed nothing, with the overheating worsening with every run cycle.
Only opening the cylinders offered any hope of finding and correcting the Problem.
Gertrude's Constipated Coolant Ports, Even Numbered Cylinders
Attend to the red circled regions in the graphic above: The first coolant port, as coolant circulation ideally was designed to flow in the cylinder heads, channeling coolant between cylinders 2 and 4, is TOTALLY BLOCKED WITH CARBON BLACK!!! Recall how the spark plug from Cylinder 4 has been found twice fouled, and is the ONLY spark plug in this engine thus compromised. I expected a head gasket leak, which, I thank the Lord, doesn't exist, BUT, with a blocked coolant port, even the superbly preserved steel shim gasket shown below would be eventually doomed, if the block or head didn't crack first.
So, as regrettable though it is to disturb the cylinder head seal, the severe escalation in overheating warranted investigation and remedy. A conventional (Blue Devil) organic acid cooling system flush had been implemented several weeks earlier, which cleared the radiator of accumulated scale, but clearly couldn't dissolve the non-polar carbon black deposits blocking the coolant ports on the cylinder head. There was no more time or margin for further experiment. The problem had to be solved immediately, by direct mechanical opening.
First head port TOTALLY BLOCKED!
Some trickle through middle port possible still, just....
Back head port also still capable of a TRICKLE, but no more!
Suffice to say, I'm not surprised now that the block below this head would get as much as 20 degrees Fahrenheit hotter than the rest of the engine! There were several cups of coolant STILL IN THE HEAD DESPITE MY SHOP VACUUMING OUT THE BLOCK OF COOLANT BEFORE OPENING THE BLOCK! Most of this spilled into the cylinders, which I QUICKLY VACUUMED OUT, but we planned to drain the crank case oil after this little surgery regardless.
I'll open the odd numbered cylinders after sunrise today. We want to make DAMNED SURE no other nasty little surprises in coolant FLOW await us!
This engine REALLY IS in EXCELLENT CONDITION, given its age! It runs VERY nicely too, sans thumping cylinders from stuck lifters and such. With God's help and St. Joe's intercession, we hope to clean off the mating surfaces of block and head, then install the FelPro gaskets I bought as part of a head set over a year prior, mindful of the need of a valve job for Mathilda then.
I'll use the rest of that head set too I imagine, except the valve stem condoms. That can wait for now.
Pray for us. We need to get Gertrude on the street ASAP!
Nearly 54 years have passed since this car's engine had daylight fall upon its pistons! After patient, painful attempts to correct a rapidly worsening overheating problem, I finally was compelled by circumstance to do a risky, unpleasant operation on this engine and open the cylinders to daylight in hope of finding WHAT has been driving the running temperature of this otherwise SUPERBLY PRESERVED old machine to a level which assures destruction. To wit: the Old Virgin started running a DEADLY FEVER, and ONLY SURGERY might cure it! So, I've diddled Dear Gertrude, who will be a spinster no longer. Now, let us pray I can effect her Cure.
Prognosis: Gertrude's engine shows REMARKABLE preservation and maintenance. It runs extremely well, having passed the rigors of the City of Tucson's Emissions test with a level less than HALF that allowed by the City. The car accelerates most satisfactorily once at a normal operating temperature. Here lies the Problem. After warmup to ~190 F, the thermostat opens, momentarily cooling the engine with a flood of cooler coolant from the radiator, but then the already rapid ascent of coolant temperature, instead of abating, increases exponentially, reaching an unsafe level (over 230F) in 10 minutes, and pressurized boiling point (~250F) in less than 20 minutes. The operating range of this engine has fallen to less than two miles, and was decreasing with every run. A liquid sealant was introduced to the coolant to utterly NO avail. Other common overheating remedies such as adjusting timing, introducing a pusher fan, enriching the idle mixture all availed nothing, with the overheating worsening with every run cycle.
Only opening the cylinders offered any hope of finding and correcting the Problem.
Gertrude's Constipated Coolant Ports, Even Numbered Cylinders
Attend to the red circled regions in the graphic above: The first coolant port, as coolant circulation ideally was designed to flow in the cylinder heads, channeling coolant between cylinders 2 and 4, is TOTALLY BLOCKED WITH CARBON BLACK!!! Recall how the spark plug from Cylinder 4 has been found twice fouled, and is the ONLY spark plug in this engine thus compromised. I expected a head gasket leak, which, I thank the Lord, doesn't exist, BUT, with a blocked coolant port, even the superbly preserved steel shim gasket shown below would be eventually doomed, if the block or head didn't crack first.
So, as regrettable though it is to disturb the cylinder head seal, the severe escalation in overheating warranted investigation and remedy. A conventional (Blue Devil) organic acid cooling system flush had been implemented several weeks earlier, which cleared the radiator of accumulated scale, but clearly couldn't dissolve the non-polar carbon black deposits blocking the coolant ports on the cylinder head. There was no more time or margin for further experiment. The problem had to be solved immediately, by direct mechanical opening.
First head port TOTALLY BLOCKED!
Some trickle through middle port possible still, just....
Back head port also still capable of a TRICKLE, but no more!
Suffice to say, I'm not surprised now that the block below this head would get as much as 20 degrees Fahrenheit hotter than the rest of the engine! There were several cups of coolant STILL IN THE HEAD DESPITE MY SHOP VACUUMING OUT THE BLOCK OF COOLANT BEFORE OPENING THE BLOCK! Most of this spilled into the cylinders, which I QUICKLY VACUUMED OUT, but we planned to drain the crank case oil after this little surgery regardless.
I'll open the odd numbered cylinders after sunrise today. We want to make DAMNED SURE no other nasty little surprises in coolant FLOW await us!
This engine REALLY IS in EXCELLENT CONDITION, given its age! It runs VERY nicely too, sans thumping cylinders from stuck lifters and such. With God's help and St. Joe's intercession, we hope to clean off the mating surfaces of block and head, then install the FelPro gaskets I bought as part of a head set over a year prior, mindful of the need of a valve job for Mathilda then.
I'll use the rest of that head set too I imagine, except the valve stem condoms. That can wait for now.
Pray for us. We need to get Gertrude on the street ASAP!