Overheating Engine (Part 4)

Q: Overheating Engine (Part 4)

Does anyone have any suggestions for an overheating engine? I have an overheating problem with my 1968 400. When idling it’s fine. Sits right about 180-190. As soon as the car starts to move it gets hot quickly. If I stop for a light or a stop sign it immediately drops back to 180 or so. The radiator has been cored. I’ve replaced the thermostat and the fan clutch. Any other suggestions?

A: The one thing I found out was, although my radiator looked good, it was about 30% clogged. I was using a stock clutch fan and shroud. After my radiator man cleaned it out, it would idle all day long without overheating.

A: You know I was thinking the same. My 1968 400 didnt overheat during its life here in Orlando,but it was in good mechanical shape. Even with the a/c on it didnt go above 220 if idled all day.

Heres a check list.

1. water pump make sure its the proper cast iron impeller

2. thermostat 180 F is fine 160 will work too,dont leave this out

3. check timing cover and waterpump baffles these must be in good order without pinholes,if not buy the stainless replacement.

4. check static timing and advance on distributor must be right on or motor WILL overheat

5. engine condition, clogged cooling passages will ruin a motor

6. heater core still intact and flowing good

7. radiator still flows fine no bent fins and mud inbetween fins,no loose fins

8. hoses must be fresh and wire installed in lower one

9. fan pulley and fan,proper one as factory installed,no gimic ones here.

10. a/c cars (not Brads) had smaller pulleys to speed up the air /water flow

11. proper fan shroud(OHC-6 didnt use one only a finger guard)

this check list will if followed lead to a happy and cooler car. The only exception to needing auxiliary fans is large cammed ultra hi compression,ultra low gears,hi stall speed converters.A stock motor if in good condition shouldnt overheat.

A: Take a look at your lower radiator hose, squeeze it. Does it have a metal spring inside of it? If you can squeeze it flat then chances are you don’t have a spring. The lower radiator hose is the suction side and when you rev the car up with no spring in the bottom hose then alot of times it sucks the hose closed. Like when you put your finger on the end of a straw and suck on the other end it flattens in the middle and that sounds like what could be going on. Also with the car idling put your hand if front of the air breather and feel the flow of air, now have someone in the car rev it up to about 2,500 rpm and see if there is a great big boost in the amount of airflow, sometimes a new clutch doesn’t necessarily mean a good one. With the type problem you have I would say it has something to do with rpms which is generally the fan clutch or the lower radiator hose.

A: My view is that a great many overheating problems are related to wrong timing or carb set too lean. Many of us are spending big money on fancy water pumps and big radiators when we really need to sort out the basics first.

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