[kemp02]

I have myself a 84 sierra that keeps over heating, ive replaced the thermostate flushed out the radiator and the engine, but continues to overheat, so im at wites end and know idea what ro do next, any suggestions?

[royce]

when does it overheat?
do you lose any coolant?

did you have the rad cleaned by a shop or just hosed it out yourself?

[kemp02]

It can over heat after driving if for 2 hours hours on the highway on 5 min down the road, its so eradic but once its starts overheating it constintly will after that, i hosed it out myself and i just boils over and i gotta put like 2 litres back in it, and im currently stuxk in it 2 hours from home as we speak haha

[PORL]

Possibly blown/ cracked head. Just keep water handy and half remove to radiator cap, keep an eye on the temp gauge and nurse her home
Investigation / tests are required

[steve]

I had a sierra that over heated all the time... I got a new radiator cap and it fixed it.

[kemp02]

If i have a wrong radiator cap for my model will that effect it?

[upgarage]

yes it will affect it
check the radiator for cold spots. this will indicate a blockage

I just refurbed my cooling system with:
tridon high flow thermostat
new temp sender
reconditioned radiator
AU/BA falcon single thermo fan in stock shroud. removed standard fixed fan
toyota red coolant

thermo fan is brilliant for cooling. draw a bit of current but cools very fast

currently wired to a switch until i get my jaycar universal voltage switch in there

[kemp02]

okay, ill try having it tested and pressure tested, maniged to get home after a while, it seemed to sit 3 quaters of the way up cruising at 100, but didnt get any hotter for some reason....

[royce]

have a squiz at your fanbelt, make sure its correct tension and not worn, might be randomly slipping

Also something that happens on 1 litres that dont have an earth between body and negative battery terminal, when your lights are on or you have something high current operating, it upsets the voltage regulator for the gauges so the temp reads higher even though its not running hotter, a fat earth to the body sorts it out

[kemp02]

It definatlybreading right cos when it says its like halfway/three quarters its bubbling away, and i replaced the fan belt a week ago, and have checked tention twice since, when its ran from idle and left to sit, only the top of the radiator fets got and the bottem hose and the radiator stays cold, so im thinking possibly clogged radiator or new water pump needed?

[alexxx]

Get it properly flushed buddy. It's very hard to tell.

[shandy92]

alexxx wrote:

Get it properly flushed buddy. It's very hard to tell.

not really, get a temp gun. anything more than 15 or so deg difference in temperature (between top and bottom hose) will indicate a blocked radiator.....easy!

with a blocked rad, its actually cooling the coolant heaps because the coolant is staying in the rad for a long time. but its also staying in the block for to long which is what causes it to get hot. without thermal differential there is no cooling!

[sideways]

steve wrote:

I had a sierra that over heated all the time... I got a new radiator cap and it fixed it.

x2 when I bought the LJ it had a dead radiator cap. The spare I brought was a dud too. It'd spew all the water out into the overflow bottle and overheat every 15kms. That was a long 300km drive home.

Have you got a fan shroud? Is it a 1l or 1.3l?