hi everyone,
i have had my van for 6yrs(4x4 masterace)and with 4 kids+2dogs i could not of picked anything better to do the job.
but over the years i have had my fair share of problems,i just had a new head fitted(£1400.00) about 4 weeks back and i had both rads recored(£340.00)this week,the bottom rad was blocked and was leaking slowly which would explain why i was always topping up the rads and also explain why my head cracked twice,i feel it mot important to make sure the cooling system is the number job because if you let those leaks go unchecked and keep telling yourself you can always keep topping it up you will damage the head as you will get over heating at the top of the engine.
i now come to my question,have i got an expandion tank or not ? i feel it only got a overflow bottle,should the cooling system always keep itself topped up by itself,i have been checking my rad water level and found that every morning i put 400ml of water in the main rad neck,i understand the water gets hot and expands into the overflow tube into the plastic bottle but i cannot understand how the cooling system sucks it back up as the rad cap spring would work against the flow?is it a sealed system with no expand/bottle as the bottle jut look like the same as a window washer bottle,i cannot see how it could take any form of pressure as the lid got no real seal.
would be very greatful for any information on the matter,regards

- (#8971) dennis, 6 Jun 03 1:31

look carefully at the rad cap, there's a little valve in the middle of it to let the water back in. As the coolant in the system cools, it contracts, and sucks the balance out of the expansion tank.
Are you using an OEM Toyota rad cap? Pattern caps have a spring- loaded vacuum valve, the Toyota one has a plastic "float" and it's WAY more efficient at letting the system recuperate. It costs a tenner, but could save you the price of a head...

- (#8972) david miller, 6 Jun 03 1:50

Dennis

I think we've all had a crack at this subject over time. Various mods have been made ranging from using waterless coolant and electric fans to increasing the flow through the thermostat. All the threads covering the subject should be easily found on AceAnswers including how the expansion bottle syphoning works. The main thing I would point out is that the proper Toyota rad cap plays a very important part in all this and worth the extra expense over the non OEM versions available from local factors. Part number should also be on AceAnswers. Have a read at all the threads then decide for yourself what applies to your condition.

- (#8973) Ian Dunse, 6 Jun 03 1:55

Dennis. I commented on this in a previous posting and, 12/18 months ago, on my 4x4 Masterace, because I was finding irregular levels (at the filler neck), decided to fully overhaul the system. You mention "should the cooling system keep topped up by itself". Definitely, yes. Mine does, with the very occasional top up (in the expansion tank) due to evaporation etc. However, the expansion tank is not sealed and it's filler cap is not airtight.
What MUST be airtight are the small bore delivery/suction hose (to the tank), the rad/filler cap, and all the connections between the rad/filler cap and the expansion bottle. Also, the level of coolant, in the expansion tank, must never be low enough to uncover the bottom of the suction tube which is fitted on the underside of the cap, and extends almost to the bottonm of this tank. This hose is often overlooked and any pin prick/fracture/hardening of this hose will destroy it's ability to lift the coolant back to the main system If you pay particular attention to these,replacing any suspect hoses, plus the better type of genuine Toyota rad cap, your days of adding that 400ml of coolant every day, will be over. I should be a bit upset (I am paranoid about my cooling system) if I had to top up at the rad/filler neck. I do check it, most regularly, but, it rarely alters. Also I think,,an often overlooked point is the condition of the "seat" for the rad cap. If it has any dents or fractures, even a new cap cannot operate effectively. The motto is "between the rad cap and bottle, keep air out and coolant in"

- (#8974) John Davis, 6 Jun 03 2:32

The suction tube is more likely to go soft. So soft that when under suction it just seals itself. So don't think that as it's bendy it's ok, it should be quite stiff. Some other Toyota models have a solid tube as part of the cap.

- (#8975) Clive, 6 Jun 03 4:09

many thanks,david,ian,john&clive.
i now understand that the bottle is a expansion bottle and the way it works,which now made me contact my local dealership and paid £19.86 for T16401-63010,i also took the ex/bottle out and gave it a good wash + i checked the small pipe from cap to rad neck and all seems to be air tight,i will over the next week keep a very close eye on water level and once i am confident i will make sure i check water and oil level every week
i am hoping the cooling level will now be ok.
i will keep you all updated over the next 2/3 weeks
many thanks guys for your fast replies.
the 2 weeks the van was off the road was hell for us it so easy for the whole famly to jump in the van,it times like that,that makes it easier to pay the money out on the repairs.

- (#8976) dennis, 6 Jun 03 14:50

Just another point Dennis, whenever the rad/filler cap is removed, ie, for checking the level at the filler neck, some air is introduced and the discharge/suction hose assembly has to overcome this on it's next warm up/cool down cycle. I now only check the level, at the filler neck, infrequently. As long as the coolant, in the expansion tank, shows a high level, with a hot engine, and a low level with a cold one, it's reasonable to expect that all is well. Cleaning the tank thoroughly, as you have done, helps a great deal here

- (#8977) John Davis, 6 Jun 03 15:03

thanks john,
i was always fearful that if i kept undoing the rad cap i might break the rubber seal so i am going to find a way to mark the outside of the ex-bottle when cold and also when hot and will see how i cope,i am wondering if you can buy a new ex-bottle from the main dealerhip,to me it would be worth it after the money i have just forked out,
ha anyone got a part number for a expansion bottle for a 1991 masterace 4x4 2ct,

- (#8978) dennis, 7 Jun 03 11:03

16470-64030

- (#8979) david miller, 7 Jun 03 11:30

many thanks david,
i will contact my dealership and order one,i did try and wash my ex-tank the other day but its still very hard to see the level,i also checked the water level this morning and level about 2/3inch below rad cap,so why i am going to order ex-tank i might as well renew tube that links rad cap to bottle,any way it only took a egg cup full to top it up,once i fit a new ex-bottle i will then mark the bottle and use the marks as to how well the cooling system is operating and avoid any damage to the rad cap seals,i will keep you all informed on the situation,many thanks

- (#8980) dennis, 7 Jun 03 17:57

Dennis, that's normal- there's always a (small) amount of air right at the top of the filler...

- (#8981) david miller, 8 Jun 03 2:58

What you are all refering to as expansion tank is actualy a overflow tank, an a expansion tank is a tank with a radiator cap instaled in it, and is used to obtain the highest point of your cooling system

- (#10132) TORVIK, 26 Jul 03 14:02

Well thank- you Mr Smartypants. The normal terminology in the UK for a tank connected to a cooling system where liquid of expansion goes is "expansion tank". A non- pressurised expansion tank at that ;)

- (#10133) david miller, 27 Jul 03 3:04

re- i only occasionally check level at filler neck.
i found in the past when i had a leak ,that the expansion tank wasn't draining. on cool down air was being drawn through hole in rad, reducing the vacuum to draw coolant from expansion tank. i ended up needing a litre of water in system, but expansion tank was full.
i now always check filler level and tank level at same time.
- (#10134) eddie arrowsmith, 27 Jul 03 14:33