Overheating

[enjenjo]

67 Mustang, bone stock 71 302. New head gaskets, new three core radiator, new water pump new correct thermostat. Marginally overheats when idling, seriously overheats when driving, in about 5 miles from cold. This is a buddy of mine who is an ace mechanic. He is pulling his hair trying to fix this, and I have no more suggestions. Let me have some new input.

[Harry]

By chance you didn't put on a "new" water pump from a car with a serpentine belt?
They turn backwards.

[enjenjo]

By chance you didn't put on a "new" water pump from a car with a serpentine belt?
They turn backwards.

Checked that, not the case here.

[wayne petty]

does the square corners of the head gaskets stick out from under the front lower corners of both heads as i have diagramed





is there a bypass hose between the thermostat housing and the water pump???  without that working the engine will overheat as the thermostat is almost a foot from any heat source... if the coolant is not constantly circulating through the block up the back of the heads...  forward through the heads to the intake manifold coolant crossover... through the bypass and around again until the coolant captured in the engine builds enough heat to open the thermostat... where cooler water is cycled into the engine.. the coolant in the radiator can come to almost a complete stop so the air flow can cool it in the radiator..


how fast does it build cooling system pressure..?  tiny combustion leak.??

does he have a infrared temp gun.. to wave around the motor see the actual temps....
wave it back and forth across the tubes of the radiator.. if you find cold ones where others are hot.. the cold ones are clogged...



did i ever mention my modification of a cylinder leak down test using a compression tester hose with the valve core removed...  hooked to shop air.. after  carefully positioning the crank using a remote starter switch for each cylinder at TDC compression..   the radiator cap off..  cooling system topped up...    any change in coolant level when you apply shop air to the combustion chamber with the valves closed... will show a leaking cylinder..

i even did this one time with the rocker arms off... at Bottom dead center.. checking for a cracked cylinder wall....  and found one...  and i don't think i caused it with just compressed air at 125 PSI...

its a great test to show customers... air into the cylinders. bubbles from the radiator.. a sure sign of a leak....  and narrowing it down to the individual cylinders..

[DRD57]

combustion leaking into the cooling system.

plugged/over restrictive exhaust.

vacuum advance diaphragm leaking vacuum.

[Digger]

Weak lower hose sucking shut at highway speed?

[DrJ]

Any of the above, and maybe timing mechanical and/or vacuum advances not advancing or maybe set retarded?
Even new thermostats can be bad, has/was it tested before installation?

[UGLY OLDS]

This sounds crazy .......Is the fan installed with the blades pointing in the correct direction   ( IE : Is the fan pulling air through the radiator?)

Possibly a thermostat installed backwards ??

 Please don't ask me how I know about these things  ......... :oops:  :oops:



Bob ......

[Crosley.In.AZ]

This sounds crazy .......Is the fan installed with the blades pointing in the correct direction   ( IE : Is the fan pulling air through the radiator?)

Possibly a thermostat installed backwards ??

 Please don't ask me how I know about these things  ......... :oops:  :oops:

Bob ......

not crazy.  back in the mid 1980's a customer came back into the shop on a monday after he picked up his Nova on friday.

He tells us the rebuilt  transmission is causing the engine to run 'hot' .  We open the hood, the shop manager goes for the dip stick to check fluid level of the trans.  I notice a new water pump and belts.

i ask the Nova owner about the pump.  "Yep" new water pump and belts on saturday.

I then tell the Nova owner he installed the flex fan backwards and I walk away as the shop manager was able to handle it from there.