Overflowing expansion bottle

[DiveTruck]

Hi, This is my first mailing so please acceot my apologies for launching straight in with my own problem.

I'm totaly stumped with what's going on with my 1990 2.4TD manual Surf and am posting this in the hope that someone might have seen something similar. The problem is that when the engine is up to temperature (showing a normal reading on the temp guage) the expansion bottle fills all the way up and then overflows - I mean really pours coolant out of the breather pipe all over the road - 1.5 - 2 litres seems typical.

This has been going on for a while. I though I'd solved the problem when I changed the thermostat but the problem is back, and may in fact never have gone - I tried another new thermostat (genuie Toyota) and have changed the rad cap (spring pressure 88kPa) but its still happening.

The water pump was changed about 6 months ago after it failed and the coolant was really well flushed at that time. I keep a 30-50% antifreeze/water mix in the loop.

Now, the weird thing about what is happing is that the coolant only seems to overflow when I stop the vehicle or let it idle when the engine is hot. The fan is spinning OK I think. What comes out of the breather pipe from just below the rad cap seems to be a mixture of coolant and air 'spitting' from the pipe. There does not seem to be oil in the coolant and the exhaust is clear of smoke/steam.

I've got a bad feeling.........can anyone offer any advice?

[Silversurfer]

First thing to check for is an airlock - it's quite a common problem, particurlarly if the coolant has been changed, and is air generally trapped in the heater pipes. As the coolant gets hot and under the pressure of the coolant pump the air bubbles will compress. When you switch the engine off the compressed air will blow the coolant back into the expansion bottle.

Also do not fill the expansion bottle to the top. There should be a high and low level mark on the side of the bottle. At the most the expansion bottle should be no more than one third full as even without an airlock the coolant expands when hot and has to have somewhere to go - hence the expansion bottle. When the coolant cools down it should be sucked back into the radiator from the coolant bottle, which is the function of the correct radiator cap. Make sure that the tube on the inside of the expansion bottle is in the coolant at the bottom of the bottle in order that it can be drawn back into the radiator as the engine cools down.

Also make sure that both the front and rear heater controls are set to fully open when you change the coolant to help prevent air being trapped.

Have a look at the below link for a good way to get the air out of the cooling system:

http://www.allhead.com.au/cooling.html

[Silversurfer]

Just read your profile - I see you are a Physicist - Hope you don't think I am trying to teach you how to 'suck eggs'.

[cockybundoo]

Exactly the same thing happened to mine, expansion bottle maxed out even though the temperature gauge stayed dead center and there was no oil in the water.

If you took off the radiator cap and then started the engine when it was hot, coolant would spit out.
Unfortunately for me this was caused by the release of exhaust gas entering the coolant system due to a cracked head.

Some of the other signs I had was evidence of a white powder type substance near to the rad hoses and if you felt the main hose from the rad to the engine it felt as if it was going to explode due to the pressure.

Other than these the engine still ran really nice and there didn't appear to be any increase in fuel consumption.

I hope that this isn't what has happened to yours, but I thought I'd let you know.

Mike

[JimSuperSix]

I too had the same problem - the car ran fine with no overheating, but when switched off when hot loads of coolant poured out of expansion bottle .

It turned out that the head was cracked between the valves on cyliners 2,3 and 4. I got a replacement head from Stevo and fitted it along with a new rad cap and thermostat and a new water pump, and now (touch wood) it's working perfectly. The coolant level remains constant just below the rad cap when cold, and there have been no more leaks or overflows.

I sent my old head to Stevo for the replacement (I believe he strips off the valves, cams etc... to reuse) and I also sent him the viscous clutch from the main fan - he checked the fluid level and set it slightly tighter so it runs faster at a lower temperature, to cool the engine a bit better.

Finally, I ditched the aircon system (rad, pump and pipes) as a) the rad blocks the underside of the engine and b) the pump was making horrible sounds anyway.

[BUSHWHACKER]

Could be one of these reasons I reckon....

1. Blockage in the waterways somewhere.......Engine running, circulating o.k.
(airlock?)
2. Water pump problem..............not circulating very well until engine revved.

3. Another duff thermostat ?
Have you tried running the engine up to temp without it ?

p.s. Hope it's one of the above, much cheaper to put right than a new....you know what

[DiveTruck]

New cylinder head from Stevo

Thanks this is really helpful, when you say you got a bew head from 'Stevo' who do you mean? Have you got contact details and how much did the new head cost?

Cheers

I too had the same problem - the car ran fine with no overheating, but when switched off when hot loads of coolant poured out of expansion bottle .

It turned out that the head was cracked between the valves on cyliners 2,3 and 4. I got a replacement head from Stevo and fitted it along with a new rad cap and thermostat and a new water pump, and now (touch wood) it's working perfectly. The coolant level remains constant just below the rad cap when cold, and there have been no more leaks or overflows.

I sent my old head to Stevo for the replacement (I believe he strips off the valves, cams etc... to reuse) and I also sent him the viscous clutch from the main fan - he checked the fluid level and set it slightly tighter so it runs faster at a lower temperature, to cool the engine a bit better.

Finally, I ditched the aircon system (rad, pump and pipes) as a) the rad blocks the underside of the engine and b) the pump was making horrible sounds anyway.

[marky]

STEVOS details are in one of the links below.