Outer Limits 4x4 Board

Right

I'm trying to eliminate all the cheaper stuff to fix the intermittent heating problem i have.

i have heard that capilliary temp guages are more accurate then electronic ones. Apparently they are a mercury type guage similar to a thermometer that runs up a tube to the guage. is this a Speco gauge? where could i get one and how much in Brisbane.

The truck (1 HZ) intermittently heats up. doesn't particularly have any set time or conditions for this, sometimes rockcrawling, sometimes on highway, sometimes idling. The engine still runs cool as per normal when driving down a hill as you'd expect, and still runs marginally warmer with air con as you'd expect.

I suspected a head gasket a while ago, as there were bubbles in the water, but that seemed to have stopped some months back. Now, i fill the top tank and overflow, go for a run and when i get back the water has been blown out the overflow and half way down the top tank but then sits there forever. as soon as i refill it, it will blow half the top tank water out and and then happily sit at that level again.

the thermostat is only 12 months old
coolant is new 40% mix
Rad is rebuilt 24 months ago
brand new pump (buggered seal during service and replacing belts 4 months ago )
new rad cap 12 months ago.
no water in oil
no moisture in exhaust
havn't done an exhaust gas colour change test in coolant yet.
rad is clean of mud and shyte
spotties in front of rad, but was never a prob before

gonna try a decent guage to see if this will give me a better idea of what is happening.

any ideas?

Pleeze pleeze pleeze pleeze don't let it be the head

to me it sounds like you have a massive air lock, this will cause excess coolant to overflow into the catch tank. (air expands more than water when hot.)

have fun.

so how exzaccary would you get rid of said air lock.

are there air bleed/purge nipples? also try to fill on a good slope with the front up high. is the motor higher than the radiator when on level ground?

also are you getting coolant flow? pull the rad cap off when cold and run the mtr untill the thermo opens up, you should see (a change) water moving,

pull the thermo out and put it in just boiled water, watch it open up - or not.

have you pulled the plugs? any nice and shiny?

Hey,

you have a 1HZ just like myself. When I first purchased it, it had overheating problems occasionally just like you have. It ended up being the viscous fan clutch. Cooling system was full of water, no leaks etc etc... I haven't seen you mention this part and its condition.. maybe thats it?

Also, I dont recall them having a bleeding valve as the rad is higher than the engine.

thanks for your ideas. i will try locking up the viscous fan or pricing a newish one.

rockcrawler31 wrote:thanks for your ideas. i will try locking up the viscous fan or pricing a newish one.

Try Repco, it was under $200 from memory, and Toyota was double that.

Since I've changed it, temp has stayed a whisker under half.

Just a note, when you drain the cooling system, on the LHS of the engine, not far from the fuel pump is a plug you undo to let the coolant out of the engine.

I've had similar probs before, popeye is right most probably air lock problem. Took me ages to get rid of it but try moving the hoses around and giving them a good squeeze (with gloves on) when hot.

Good luck it is a pain in the rear

From my experience having had a 1hz troopy for 12 years it is unlikely to be an airlock IF you are opening the heater when refilling, leave the heater on for the first full heat/cold cycle, which will ensure all air is out if the cap is ok.
Check that the vent tube from the rad cap to overflow bottle isn't blocked (BTDT on a repaired radiator, causes your exact symptoms).
If all checks out ok i'd put some more silicone in the fluid coupling (available from your friendly Tojo dealer) , not necessary to replace coupling unless it has leaks, just top up, common problem.

right.

didn't open the heater when doing my pump, and hasn't been opened since either.

thanks for the tip on the return tube, silicone top up and drain plug.

ta all.