Mk 1 Gs300

[Keith Bowler]

Can anyone advise me why my GS is overheating?

I had a new rad fitted a few months back and all has been fine with a steady running temperature at the two bar mark until today when out on a short run the temp guage went very quickly up to one bar below the red mark. When I stopped steam started pouring from the expansion tank where there was a gurgling noise like a kettle boiling and appears now to be empty.

Before I empty my wallet and get someone to look at it is there anything I can do to search the fault myself first?

Any help in diagnosing or fixing likely problem would be helpful.

Thanks - Keith

[kevinsgs300]

hi keith.

sounds like to me you have a head gasket problem.

[dave1]

It may be connected to having new rad fitted.......possibly hose worked loose and leaking? Hopefully that's all it is and nothing more serious.

[Keith Bowler]

Had a good look around rad, hoses and expansion bottle and no signs of any coolant loss though it has been going somewhere so at present I suspect HGF but there are none of the tel tale signs of water in the oil from what I can see. When looking at oil filler cap and smelling oil etc, the oil looks and smells fine.

I must confess that I had not checked the water level in the rad after the new rad was fitted but then there was never any indication that anything was amiss as far as what the temperature guage was telling me and the expension bottle level had not altered until today.

If it is HGF does anyone know what I can expect to have to pay, I am just due a cambelt change new plugs etc so may be able to kill two jobs at once.

Keith

[steve2006]

If you have a friendly MOT tester ask him to stick the exhaust gas probe into the expansion tank with the engine running ( not into the water) as this should detect any exhaust gases in the cooling system confirming HGF but TBH with the system pressurising to the extent you describe I would say it is HGF but there again check the thermostat is opening using the jug of boiled water method.

[Steve]

i was gonna suggest what Steve2006 suggested first

[Keith Bowler]

Thanks for the feedback.

Seems that there was a small leak at a union on the gearbox cooler part of the rad which was causing air/water leak thus reducing pressure in system causing it to boil at a lower temp. Very difficult to detect without constantly checkeing level in rad by removing rad cap which I never thought of doing as there was no visible signs of a leak or other tell tale signs.

I must say I really only check the coolant level in the expansion tank but in future will keep an eye on the level in the actual rad.

All fixed now and Toyota guy who does my repairs reckons the head gasket seems to be ok and that they only really go when engine is allowed to persitently overheat with guage in the red.

[JGS 300]

Hey,

check for a air lock. gs300's mk1 are hard to bleed coz the hose at the back of the engine is higher than the rad.

this can cause a loss of water and bubbling in the expansion bottle go to a proper garage and get a coolant change this cured my problem.