losing coolant again!!!!!!!!!!!!!!!!

[Buckle]

Hi all,

I have a `93 2.4 surf SSR-X which started dumping about .5 to 1ltr of coolant into the expansion tank about a month ago.Replaced the coolant filler cap and all seemed well for a while. Now its started doing it again. Took out the thermostat and tested it - it wasn`t opening until 97 deg C - so cut the middle out and refitted the outer ring so seal would fit in housing. On the next drive the temp gauge went up to half way mark after driving for a couple of miles, which I thought was odd with the `stat removed, continued to drive for another 60 or so miles. The engine did not overheat at all andd heaters were hot when tried. Still found coolant had dumped into the expansion tank, about .5 ltr. Engine is not exhibiting any headgasket sympyoms. Checked flow thru rad and all seems ok there. Every time I drive it between .5 and 1 ltr of coolant gets dumped into the expansion tank and i`m starting to clutch at straws.
The cooling system does not seem to over pressurise, viscous fan coupling is ok, electric cooling fans are working. The new cap is genuine Toyota and has a three way seal type arangement to allow the cooling sytem to draw coolant back into the rad from the expansion tank but it doesn`t seem to be doing this - has anyone had a dodgey cap before?
Any one got any better ideas ?
Help!
Eddy.

[Dazza]

This may be quite normal, you see water expands when hot. What the expansion tank is for is to collect the expanded water. As the engine warms coolant expands into the expansion tank and will fill it from the min line to max line, then when left to cool it will be drawn back into the engine. I would check that the expansion tank level is on min when cold go for a drive check level in tank when engine hot shouldn't be above max, then let the engine cool completely and look at the tank again to check level has dropped back to min. It's a bit strange to get so hot so quick without a thermostate maybe a fan fault.

[marky]

The head gaskets dont seam to go on the 2.4 no one has had a gasket go as its the head that cracks near the valves

[Dazza]

Duh, didn't read your write up very well did I. Maybe you have a slight air leak on the pipe going to the header tank, so as it cools rather than bringing coolant back it brings air, are you loosing more coolant than whats not returning?

[kevb]

has the hose that dips into the header tank and is attached to the header tank cap come off.this would stop coolant being drawn back into main system.

[poppy986]

Had the same problem on my 91,2.4.
It was the thermostat,I'm now on the third one in three years.
Although you took the oldone out,give it a try they are
cheap enough even just to eliminate it out of the picture
Cheers Chris

[Haydn Callow]

This topic is worth a read if you arhttp://www.hiluxsurf.co.uk/showthread.php?t=42464&highlig ht=fitting+coolant+alarme having to top up your coolant

[SoundsDigital]

As the engine warms coolant expands into the expansion tank and will fill it from the min line to max line, then when left to cool it will be drawn back into the engine.

I van see where you are coming from, but I find when I top mine up it pushes a bit of water into the expansion tank but when it cools, rather than draw it back, it simply compresses the top hose as the filler cap stops the water being drawn back into the engine. How is the water supposed to get drawn back past the filler cap into the engine?