Coolant level in expansion tank.

[SimonT]

Morning all. I have done a search for coolant levels in the expansion tank and it is quite confusing. Some say that the level when cold should be at the minimum mark and some say at the maximum mark. Can anyone clarify this please? I have had the Surf for six months and driven her for three weeks. The loveliest looking storage shed in South west Scotland.

Cheers, Simon.

[stormforce]

Morning all. I have done a search for coolant levels in the expansion tank and it is quite confusing. Some say that the level when cold should be at the minimum mark and some say at the maximum mark. Can anyone clarify this please? I have had the Surf for six months and driven her for three weeks. The loveliest looking storage shed in South west Scotland.

Cheers, Simon.

as long as the fluid is 2-3inches up the pipe inside the exspansion bottle when cold yoo will be ok

[NiftyNev]

Maximum when cold. This make it easier to keep track of the level and if drops below this then you start looking for leaks.

Nev

[The Lang-Shankit Scunner]

I go min when cold because the level rises, and would end up peein out the top. But whatever suits you, in a way that you can keep track.

[SimonT]

Thanks for the advice. Mine is just above the max mark and does lose some coolant. The head has just been re fitted and i think it is just getting rid of a bit of air. How much should the coolant expand by from cold to hot generally?
Cheers, Simon.

[NiftyNev]

I go min when cold because the level rises, and would end up peein out the top.

If it rises that much from the minimum mark and overflows then something is wrong. Expansion of the coolant should increase the level by no more than about 20 - 25mm.

Nev

[NiftyNev]

The head has just been re fitted and i think it is just getting rid of a bit of air.

Air is vented through the cap so will make no difference to coolant level. Excess pressure in the cooling system will however force more coolant out causing the overflow.

Nev

[SimonT]

Air is vented through the cap so will make no difference to coolant level. Excess pressure in the cooling system will however force more coolant out causing the overflow.

Nev

I am absolutely stumped then. This vehicle has had a brand new head, gasket, bolts, thermostat and radiator cap fitted. Cooling system has been flushed and filled properly. The head has also been pressured tested twice, long story. What else can be the problem? This is the most tempremental vehicle I have ever owned and I am rapidly losing patience with it. If anyone has any ideas I would really appreciate it. The water pump is also working. Other than that down the road she may go.

Cheers, Simon.

[TonyN]

You shouldn't be checking the coolant level by the expansion tank, always check it at the filler cap, when cold.

The expansion tank is just that, it gives the coolant somewhere to go when it gets hot enough to excede the capacity of the cooling system and rad cap valve rating. Then the motor can suck it back as the coolant cools so you arn't short or coolant next time.

The level in the expansion tank can vary up or down, I just keep a little in the bottem.

If the motor has passed a pressure test then you must have a small leak somewhere. Bare in mind the engine needs to be properly warm, small cracks in the head close up unless its properly hot, and won't show up when tested. I always use the 'sniffer' test, a liquid that changes colour when exhaust gas is present in the coolant. Sometimes it take 1/4 hour of engine running with the tester on it to show up.

Check the main crank pulley hasn't delamiated, if its slipping on its hub the pump won't be driving at the right speed compared to engine revs, so coolant won't be circulating properly. With it running look at the alternator bets where they go round the pulley on the crank, if they are 'floating' around compared to the other two belts, most likely you need new pulley.

[SimonT]

You shouldn't be checking the coolant level by the expansion tank, always check it at the filler cap, when cold.

The expansion tank is just that, it gives the coolant somewhere to go when it gets hot enough to excede the capacity of the cooling system and rad cap valve rating. Then the motor can suck it back as the coolant cools so you arn't short or coolant next time.

The level in the expansion tank can vary up or down, I just keep a little in the bottem.

If the motor has passed a pressure test then you must have a small leak somewhere. Bare in mind the engine needs to be properly warm, small cracks in the head close up unless its properly hot, and won't show up when tested. I always use the 'sniffer' test, a liquid that changes colour when exhaust gas is present in the coolant. Sometimes it take 1/4 hour of engine running with the tester on it to show up.

Check the main crank pulley hasn't delamiated, if its slipping on its hub the pump won't be driving at the right speed compared to engine revs, so coolant won't be circulating properly. With it running look at the alternator bets where they go round the pulley on the crank, if they are 'floating' around compared to the other two belts, most likely you need new pulley.

Thanks for the information I will get my mechanic to check it. When the head was put on originally the previous mechanic did not turn the heaters on when he filled the cooling system back up. The car ran great until I turned on the rear heater within minutes the temp gauge went up and it started boiling over in the expansion tank. The previous mechanic said the head was faulty so it was removed and returned to the company I bought it from who pressure tested it and said it was fine. My then mechanic insisted it wasn't so a mate of mine in England took it to a place he deals with for his Delica who also pressure tested it and said it was fine. The new mechanic put the Surf back together with a new gasket but used the original bolts as recommended by Toyota and the engine rebuild program he has. The car pressurised straight away. Redmans who pressure tested the head told me to replace the bolts. I did this and the car runs much better. The temp gauge stay below half, the hoses don't pressurise and there is no white smoke. All that happens is the coolant expands in the tank by almost three inches and throws a little out. The car has plenty of power and runs beautifully. I have bought a new rad cap but not had chance to run it yet and this morning I topped up the rad with about a pint. Sorry for the long post and thanks for any help you can give.

Cheers, Simon.

[Ricksurf]

Hiya mate,
Just a point I noticed:

Cylinder head bolts changed for new ones, but no mention of yet another head gasket (I believe they compress and only seal once).
Ask if it was changed (again)??

You seem to have checked most things visible in the engine bay, but have you checked the heater matrix (s) for pin hole leaks (damp carpet is a giveaway)

Hope this helps

[SimonT]

Hiya mate,
Just a point I noticed:

Cylinder head bolts changed for new ones, but no mention of yet another head gasket (I believe they compress and only seal once).
Ask if it was changed (again)??

You seem to have checked most things visible in the engine bay, but have you checked the heater matrix (s) for pin hole leaks (damp carpet is a giveaway)

Hope this helps

Thanks for the help . The gasket is also new. There are no signs of coolant/water on my drive or in the vehicle. I am hoping it is just too much in the expansion tank.

Simon.

[BUSHWHACKER]

Does yours have the rear heater fitted? the pipes sometimes block or become restricted causing air-locks in the cooling system. The pipes are independent of the rest of the heating circuit.

[NiftyNev]

You shouldn't be checking the coolant level by the expansion tank, always check it at the filler cap, when cold.

I disagree to a certain extent on this one. I believe it depends on how the cooling system is working. In the case of where the coolant remains at a constant level in the expansion tank when checked then there is no need to remove the rad cap. If the level changes then this is an indication of problems. I am lucky if I remove mine two or three times a year and this is just out of curiosity rather than for any other reason. I just like to have a look in there and check out the seals. Over a two year period I have added no more than a couple of hundred ml of coolant to my system and always via the expansion tank.

Now, if the coolant fills the expansion tank above the limit of its capacity and coolany is lost then this will result in a shortfall of coolant than needs to be sucked back into the cooling system to ensure it is full. In this case the cap will need to be removed to replace coolant in the engine and also top up the expansion tank. As I said before if the expansion tank level changes where there is more or less coolant than the level to which it was filled then something is wrong.

Nev

[NiftyNev]

All that happens is the coolant expands in the tank by almost three inches and throws a little out.

Three inches is way too much. You have a problem. This could be as simple as a faulty rad cap, a problem with water pump etc as Tony mentioned, a faulty head or head gasket or other reasons. I can't diagnose this from where I am so I suggest you get Tony to have a look at it for you if you can get it to him.

Nev