Coolant level in expansion tank.

[The Lang-Shankit Scunner]

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

I would hesitate to trust the expansion bottle all the time, as when mine went to a constant level for more than 2 weeks it turned out to be a blocked expansion bottle supply pipe! I was down 2 litres as it was leaking at the back. Others have reported a cap problem, and sometimes the thermostat can jam and not pull water back in. I would def go with Tony on this one, as his knowledge of these vehicles is far superior to most of the members, with it being his profession.

The cap is spring loaded with a return valve in it, therefore the water is designed to push past it when warm and expands, thus causing the level to rise a little in the expansion tank, and when the water gets cold its molecular structure tightens and shrinks, causing less water to be in the expansion bottle. Hence the name EXPANSION.

The only sure way to know your rad is full is via the cap!!!!!

[NiftyNev]

I would hesitate to trust the expansion bottle all the time, as when mine went to a constant level for more than 2 weeks it turned out to be a blocked expansion bottle supply pipe! I was down 2 litres as it was leaking at the back.

If that is the case then checking the level in the expansion tank when hot would have shown you there was a problem. It only takes a minute to do this and is an early indication of problems if the level does not rise by the correct amount. Just because you failed to see a problem does not mean that the method of checking via expansion tank is flawed.

Others have reported a cap problem, and sometimes the thermostat can jam and not pull water back in.

Same as above. Radiator cap problems can just as easily be detected through operation of the expansion tank. The thermostat itself will not prevent coolant being drawn back into the cooling system even if stuck closed. It will however cause overheating and along with that a host of other problems.

I would def go with Tony on this one, as his knowledge of these vehicles is far superior to most of the members, with it being his profession.

So are you saying I am wrong? If so then show me where.

The cap is spring loaded with a return valve in it, therefore the water is designed to push past it when warm and expands, thus causing the level to rise a little in the expansion tank, and when the water gets cold its molecular structure tightens and shrinks, causing less water to be in the expansion bottle. Hence the name EXPANSION.

Yes, heating the coolant in the engine causes a pressure buildup. This pressure then opens the rad cap at a set pressure and allows excess coolant to escape to the expansion tank. Once thie coolant reaches operating temperature then the radiator cap will close again. As the engine cools then coolant is drawn back into the cooling system via the return valve. The reason it's a pressurised system is because it raises the boiling point of the coolant. Without pressure it will boil at a lower temperature. I know how a cooling system works.

The only sure way to know your rad is full is via the cap!!!!!

Before the days of expansion tanks then I would agree but cooling systems have come a long way so you are wrong. I have been checking cooling systems via the expansion tanks for longer than I can remember and find it very reliable and an early indication of problems. I will say it again.If you need to remove the radiator cap to check and top up your cooling system then you have problems that should have been picked up through checking the expansion tank. I will continue doing it this way because it works even if you don't think so.

Nev

[SimonT]

Thanks for the help. I have just replaced the rad cap but I have yet to try the Surf with the new cap. My Surf has the rear heater fitted and the cooling system was flushed through before rebuild. The new thermostat is a cooler one I think, I will have to check with my mechanic. I would be incredibly surprised and annoyed if it is the new head, as it has only 300 miles since it was first fitted and 40 miles since it was taken off and pressure tested. The thing is apart from the expansion tank problem the car runs beautifully.
Simon.

[NiftyNev]

Thanks for the help. I have just replaced the rad cap but I have yet to try the Surf with the new cap. My Surf has the rear heater fitted and the cooling system was flushed through before rebuild. The new thermostat is a cooler one I think, I will have to check with my mechanic. I would be incredibly surprised and annoyed if it is the new head, as it has only 300 miles since it was first fitted and 40 miles since it was taken off and pressure tested. The thing is apart from the expansion tank problem the car runs beautifully.
Simon.

Hope you sort it out soon. Fingers crossed it's as simple as the cap. I would check on the thermostat as running a cooler one is not recommended and is usually done to try and mask other problems. As for the engine running fine, then this is not unusual, as a cracked head sometimes has little effect on anything but the cooling system until something goes bang.

Nev

[SimonT]

Hope you sort it out soon. Fingers crossed it's as simple as the cap. I would check on the thermostat as running a cooler one is not recommended and is usually done to try and mask other problems. As for the engine running fine, then this is not unusual, as a cracked head sometimes has little effect on anything but the cooling system until something goes bang.

Nev

I hope it is the cap as a new head, two sets of bolts two gaskets, two thermostats and a rad cap plus labour has become very expensive. I will change the thermostat to standard. Thanks for the advice. Toyota themselves have been as much use as a chocolate fireguard.

Cheers, Simon.

[The Lang-Shankit Scunner]

If that is the case then checking the level in the expansion tank when hot would have shown you there was a problem. It only takes a minute to do this and is an early indication of problems if the level does not rise by the correct amount. Just because you failed to see a problem does not mean that the method of checking via expansion tank is flawed.



Same as above. Radiator cap problems can just as easily be detected through operation of the expansion tank. The thermostat itself will not prevent coolant being drawn back into the cooling system even if stuck closed. It will however cause overheating and along with that a host of other problems.



So are you saying I am wrong? If so then show me where.



Yes, heating the coolant in the engine causes a pressure buildup. This pressure then opens the rad cap at a set pressure and allows excess coolant to escape to the expansion tank. Once thie coolant reaches operating temperature then the radiator cap will close again. As the engine cools then coolant is drawn back into the cooling system via the return valve. The reason it's a pressurised system is because it raises the boiling point of the coolant. Without pressure it will boil at a lower temperature. I know how a cooling system works.



Before the days of expansion tanks then I would agree but cooling systems have come a long way so you are wrong. I have been checking cooling systems via the expansion tanks for longer than I can remember and find it very reliable and an early indication of problems. I will say it again.If you need to remove the radiator cap to check and top up your cooling system then you have problems that should have been picked up through checking the expansion tank. I will continue doing it this way because it works even if you don't think so.

Nev

The purpose of this posting is to give as much info as possible, as you will have noticed, i never made any reference to people being right or wrong! All I did was say I would hesitate that way because of my own personal experience (although little). Freedom of expression by way of help then leaves a person with some decisions to make.
Not everyone will agree, but not everyone is wrong. I personally take advice from the ones I know work on surfs for a living, and a hobby.
Im glad to make your aquaintance, and hope we can be of help to oneanother as time goes on.
Have a good day and happy Surfing

[SimonT]

Well just tried it with the new rad cap and checked it after 8 miles. Coolant levels still well up and coming out. I turned round and on my way back the gauge crept up above half then went back down to below half. I checked the level when I got home and the coolant level had dropped down in the tank by almost 2" which it didn't do until the engine was off and cooling down.
I think I've had enough now and may put it for sale for a couple of grand as it needs a couple of bits on the body but it has great ICE. It stands me at £4k.

[Rob]

I think getting the coolant tested for exhaust gases is the first thing that needs to be done, as Tony said. At least you'll be able to rule the head job in or out.
After that, I reckon its likely to be down to a blockage somewhere or the water pump (i know you said it was fine!). Assuming the new 'stat is good and that the rad cap appears to be doing its job.

[TonyN]

Its a valid point, if you own or work on these motors you'll do it how ever works for you. Nev has enough personal and 'read about on the net' experiance to know what he is talking about.
But I personally don't trust the average 2.4 anymore than I can throw it across a field! I like to know what the level is in the motor, not relying on the cap to be working properly or small unnoticed leaks to robbing it of coolant slowly, while the expansion tank level stays the same.
Its just an opinion, read the Toyota handbook, and it'll tell you to check the level in the expansion tank.....

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

[chrisinflight]

Interesting thread! I`ve always checked via rad-cap and never needs topping up that way but am concerned by checking too regularly the cap seals will wear and leak. I also check the exp. tank and top up about a cupful every couple of months. As for the main problem- I sympathise with you as it sounds like you`ve been messed about and that issue of the garage not checking the system is full is very poor.

[SimonT]

What also really peed me off is that when the head was returned to me it had a big dent in it by an oil gallery and because the garage left the head on the workshop floor for 8 days without checking it mean't that I could not take it up with the couriers or the supplier hence a repair to the head and a second pressure test to ensure no damage had been done. Garages response was, "we did not do it It's not our fault." Total expenditure on the head and ancillaries comes to £1311.00 and it is still goosed. At the moment I really hate this vehicle.
Simon.

[The Lang-Shankit Scunner]

What also really peed me off is that when the head was returned to me it had a big dent in it by an oil gallery and because the garage left the head on the workshop floor for 8 days without checking it mean't that I could not take it up with the couriers or the supplier hence a repair to the head and a second pressure test to ensure no damage had been done. Garages response was, "we did not do it It's not our fault." Total expenditure on the head and ancillaries comes to £1311.00 and it is still goosed. At the moment I really hate this vehicle.
Simon.

Hate the circumstances, the vehicle is only behaving the way incorrect fitment has made it. Whenits done you will be ecstatically happy with her. Ive never been more happy with a car, and theres always been something to fix on her.
sympathise with your predicament though, hope it sorts for you.

[stormforce]

i have spent nearly £600 on mine this month alone on repairs and i still won't get rid of the truck.It is frustrating when you spend all that money and the truck is still not right.

[NiftyNev]

Im glad to make your aquaintance, and hope we can be of help to oneanother as time goes on.

Same here and thanks for the PM. Apologies to you and the other members. My post was a little over the top.

Nev

[The Lang-Shankit Scunner]

Same here and thanks for the PM. Apologies to you and the other members. My post was a little over the top.

Nev

And ill watch out for my opinions being with little foundation.

We better be careful the pic of eric estrada doesnt come up.

cheers fella