Header /exspansion/ coolant collector tank?

After years of faithful service from the cooling system on my 22tc, all has gone wrong recently, the heater packing up as well as losing water everywhere! After replacing foam in the heater and a few hoses the repaired system was then good enough to make the rad let go! After further repair I now have a dry presurised system, however I cannot have the coolant level above 3 inches below the bottom of the rad filler neck or when the car is warmed up any fluid above this level is ejected. I am thinking it cant be right that some of the uppermost coolant tubes are not covered with coolant, yet a quick look on here tells me that it is! Although this seems to be comman I am not very comfortable with it and would like to secure a solution.

Firstly the rad cap spec on my car is 7lbs per square inch. I have read that a 10lb cap may cure the problem, however I have also read that fitting a cap of higher pressure than the system strains the system and is therfore not advisable. Any comments on this matter much appreciated, is anyone else running a 10lb cap on a 7lb system, are there any benifits, more importantly are there any consequences?!!

Secondly an additional coolant reservoir tank would seem to be an option. This is where I could use some help. I have heard there are two ways of doing this and would like to know which is best.

1 Replace the origional rad cap with a blanking cap also known as a zero pressure rated cap. Connect the radiator overflow outlet to a hose clipped pressure pipe feeding to the bottom of a secondry tank the same pressure rating as the origional radiator cap.

2 Leave the origional rad cap as is . Connect the radiator overflow outlet as before to a secondry tank with zero rated pressure.

I favour no 2 (a) because you dont have to purchase another rad cap and (b) you dont need to secure a specific pressure rated tank as its very easy to convert any pressure rated tank into a zero pressure one ! and therfore there should be more choice of tank.

Is this the right choice and if so does anyone know where to get some sort of kit from (tank/ tank top/ tubing hose clips fixing bracket etc )or is it just a cobble one together from ebay sort of thing.

As always any advice most welcome.
I have option 1 on my P5B & Bruiser (4 pot) & both radiators are always brim full. Cobbling one together from ebay sort of thing is what I also did. I have ADO16 brass tanks but the SD1plastic tanks look fine.
Well, first of all, the 3" below the filler neck scenario is indeed normal on both the V8 and 4 cylinder cars. And yes, I do agree that that seems very much less than ideal. Not least because it always tempts you to top the system up and if you keep doing this you gradually lose anti-freeze concentration (unless you top up with premixed anti-freeze - and that is beyond most peoples organisational abilities these days!). Plus, how do you judge when your car genuinly is losing coolant? And I do agree that increasing the radiator cap pressure is unwise - and in any case will have no effect on the phenomonen (unless, of course, the engine takes up the difference through balloning the hoses instead of expelling coolant!).

So a radiator header tank really is a seriously good idea.

You are correct in your analysis of the two possible methods of doing this. Except that, with your method no 2 you do still need a new radiator cap, because the cap needs a one way valve in it to alow coolant to be drawn back into the radiator as things cool and the level drops. These caps are normal on a lot of 80's Japanese cars, I've not seen one in this country for our type of radiator though.

So in this country the normal route to take is to fit a pressurised expansion tank as per your method no 1. Luckily an attractive and period tank is readily available. It was fitted to contemporary Land Rovers, SD1's, MGB's Dolomites, Stags etc etc! It even comes in two dimensionally identical versions, one in brass and the other in nylon. The latter allows you to see the coolant level without having to take the cap off, the latter can be polished up to look very bling in a smart engine bay.

A quick search of EBay revealed this one:


As a general rule the tank should be fitted as high as possible in the engine bay and as close as possible to the radiator outlet. I've not previously seen one fitted in a 4 cylinder engine bay, so perhaps other 4 cylinder owners might be able to help with a specific location?

Hope that helps.

It's my understanding that Land Rovers (Series 3 certainly) used method 2. There's a black plastic tank beside the radiator that's supposed to catch water then send it back to the rad, but isn't pressurised. In my experience it never really works.
I have method 1 in the 2000TC and it works a treat.


Well-Known Member
Mick, appearances are deceptive as they say.
What you see though a low analysis mobile phone photo is basically a clean cam cover and carb dashpots. The servo has been rebuilt (therefore also painted) a few months ago, and the inner wings were also painted at the recent front end repair. Below that, there is the usual dirt and grime of an everyday car.
In any case, if i remember correctly the undebonnet of your V8 looks far more better.
To set up a 1 litre expansion/recovery tank:

1.Buy a 7lb coolant recovery radiator cap. Take in non recovery radiator cap, and they can match up the right one. If you have a seal on the upper side of the cap, and well as where it sits on the inner radiator filler part, then you already have a recovery type.

2. Go to the supermarket. Buy a 1 litre bottle of orange juice. Drink the orange juice, and wash out the container.

3. Drill a hole through the lid of the bottle, about half inch diameter.

4. Slide some tubing with a clamp over the outlet of the radiator. About 8 inches long.

5. Then fit the bottle down by the battery. My car is series 1. Series 2 cars have a lot more room, although you will have to work out how to bracket it.

6. Slide the tubing into the bottle.

7. Secure the bottle with 2 cable ties, from the battery bracket.

8. Pour in coolant through the radiator filler. The bottle will fill through the overflow. Fill it about half full.