Thread: How Hot is too Hot?

Hi All,

Some advise please.
Plastic resovoir bottle on Disco had minor split causing water to escape under pressure. While up in the hills in Perth (we do have some) and noticed water leaking from front
Tempreature guage was reading slightly higher than halfway and headed to nearest garage
By time reached garage tempreture guage up to 3/4, switched off engine,
purchased distilled water,started engine and filled resovoir bottle.
Heard a bit of clanning comming from waterpump which sounded ominous.
and motor did seem hot
Tempreture dropped back to normal, got halfway back to home and tempreture up again so pulled over and purchased more distilled water and repeated procedure.
Purchased new replacement bottle and cap fitted to unit refilled fluid.
Now the problem, Running vehicle tempreture gets halfway switch off engine and pressure builds up and water leaks from cap in resovoir bottle.
Took Disco to radiator repairer and they flushed radiator checked thermostat and waterpump all OK. Said pressure was building up and may have head gasket problem
Also said to put old cap from original bottle back on as new cap may be faulty.
Replaced cap (with old one) and drove Disco to local mechanic reached normal tempreture on guage and when pulled up no build up of pressure or water loss. Mechanic who checked motor for headgasket leak using a tool with fluid that changes colour for presence of gases in water no change to fluid in vile. Next test put 300mm long tube on extension screwed to resovior bottle and filled bottle to max and filled tube halfway. Checked no air in bottle or tube and ran engine. water in tube remained same level, no build up of pressure noticed and motor runs sweet as ever
BUT drived it twice now short distances and tempreture guage has risen higher than normal and have ad to pull over and allow to cool down

Question 1: Don't see any bleeder valve for air in system do they have
one, could there be air still in system.
Question 2: Could we have overheated motor more than the guage
showed as we were mindfull of not letting it get over hot
as guage only ever got to 3/4 high.
Question 3: Whats the cost to replace head gaskets if its done through a
mechanic?
Question 4: Besides pulling heads off is there any other definitive test to
check for blown head gasket?

Your thoughts would be appreciated

Cheers

Baggy

Just a basic question - you did buy the right type of radiator cap? It's just that you mentioned that the problem was kinda fixed when you put the old cap back on?

Is your air-con on when it overheats, or not?

Did they replace the thermostat, or did they just say that it was Ok? Most places that I know just replace them anyway, you may as well if you have it off and looking at it for the sakes of $10. Unless it is brand new.

Building up pressure doesn't necessarily mean head gasket problems. The thermostat can cause it, or excessive **** through the coolant system (but the flush should've fixed that), or blockage in the radiator (usually means a re-core).

If the mechanic has done a die test etc, then he should've picked up on any problems with the head gasket if there was any. It kinda normally stands on like dogs nuts when one goes.

When you say that it gets hotter than normal - what exactly are you meaning? That it gets up to 3/4 on the gauge or similar?

Is this occuring when the vehicle is under load - another words when going up hills or in traffic? Does it do it when coasting up a highway? Does the temp gauge come down when heading down hills etc?