over heating shorty

[lancer]

Mate and I worked on a 1980 S3 shorty he has had for 25 years, it was overheating, did the head, new head gasket, new theromstat, new water pump, new temp sender unit, new temp gauge, new radiator cap, had the radiator overhauled and cleaned, did thetiming by a timing light and manually all perfect. Flushed the block. Runs ok when static but gets hot again on the road. At least it cools down quicker. SO WHAT THE...... any ideas.

[centy]

is it holding pressure?
if not look for the leak.
if heater fitted try blocking it off.
use a cleaner fluid to clean block incase a blockage in the block.
does it have a buypass from the pump or a release hole on the thermostat?
is the vacume advance working correctly?

did it start to overheat suddenly or was it a slow build up till it got to bad to drive.
ie sudden failure or slow build up.

[spambo]

had an old holden gemini once used to over heat only when driving but when idling would run cool would also cool down quick like you said,
we tried the radiator and thermostat, waterpump still did the same thing then out of frustration i revved the **** out of it and held the throttle flat, to my amasement the bottom radiator hose had sucked flat, totally collapsed when returned to idle the hose would pop back out, we put a spring in the hose so it coul not collapse he presto problem solved!

it might be worth checking this if you have not already,
good luck...

[JDNSW]

I would check for vacuum leaks in intake, leading to a weak mixture. Perhaps something to do with the crankcase ventilation system, or a leaking manifold gasket. (It does have the correct carburetter?).

Also, another suspect would be whether the distributor centrifugal and vacuum advance are working properly.

John

[mick88]

Probally not the case here but I know of a situation where a VL commodore kept running hot. Another guy suggested fitting a better earth strap between the body and the donk and the problem was rectified. Apparently it was using the water as an earth and this was increasing the engine temp.
Sounds an odd tale I know!

Cheers, Mick.