Header tank

steve b · Post by **steve b** » Mon Oct 08, 2007 10:16 pm

Now I'm pretty sure this has been covered before BUT what outlet/inlets should be on a header tank,I'm having a tank made which is about 1.5ltr capacity, with a stant cap(18-22lbs) a outlet on the bottom of the tank 16mm, do I need any more?
sorry forgot to say its a rv8 in a capri with, when funds allow a webber 500 and edlebrock manifold, with a cosworth radiator with the inlet via the old temp switch hole at the bottom and a kenlowe swich to the cosworth twin fans in the top hose.
If it needs a inlet to it were from?possibly from the thermostat housing?

Is the tank just a way of filling the system or does it did to be in a type of loop, dont want to end up with a load of trapped wind!

sorry to sound dumb but dont want to shell out money and it not work.

cheers. steve

ps forgot to say if pics would help I will try and get some up.

Post by **katanaman** » Mon Oct 08, 2007 10:27 pm

you would be well advised to include a small pipe high up the header tank to the highest point in the cooling system. This will help purge air out the system that otherwise could get stuck. Mine is on the top rad hose at the top of the bend which is as high as it gets on my install.

Paul B · Post by **Paul B** » Tue Oct 09, 2007 2:55 am

katanaman wrote:you would be well advised to include a small pipe high up the header tank to the highest point in the cooling system. This will help purge air out the system that otherwise could get stuck. Mine is on the top rad hose at the top of the bend which is as high as it gets on my install.

What he said.

How are you going to fill the sytem Steve, via a cap on the rad or through your header tank?

ChrisJC · Post by **ChrisJC** » Tue Oct 09, 2007 7:38 am

So this is a header tank (as opposed to an expansion tank), and so it will be higher than the top of the rad?

Chris.

steve b · Post by **steve b** » Tue Oct 09, 2007 8:40 pm

I will be filling the system from the header tank cos the rad doesnt have a cap and it will be a good few inches above the top hose.
could it be a good idea to run a hose from the thermostat bypass to the top end of the tank as Katanaman says? but that would be 16mm the same as the bottom outlet! not a small hose.Or is size not important!
cheers steve

ChrisJC · Post by **ChrisJC** » Tue Oct 09, 2007 8:56 pm

My Sherpa V8 has a header tank. There's a big (5/8ths bore) pipe from the bottom of the header tank into the bottom hose. Then there's a small (probably 1/4 bore) vent pipe from the top of the radiator to the middle of the header tank to make filling quicker.

Chris.

Post by **katanaman** » Wed Oct 10, 2007 8:00 am

the stat bypass is far too big.

steve b · Post by **steve b** » Wed Oct 10, 2007 8:51 pm

Thank again lads I think it would be a good idea to get my mate to put a smaller pipe near the top of the tank about 8mm me thinks and then find some were to plumb it in on top of the rad or somewere afterwards, or just blank it off gives me the choice either way. just out of interest which cars came with out the stat bypass P5,P6,SD1??

cheers again steve

Ian Anderson · Post by **Ian Anderson** » Thu Oct 11, 2007 8:51 am

I'm not convinced re the "near the top" bit

I would expect all entries to the header to be covered in water all the time - or you could get air drawn back in on cool down etc.

The feed back from rad is good idea but let the air "bubble through" and the pope will always be full

Then again I could be wrong - been wrong many times before!

Ian

Post by **katanaman** » Thu Oct 11, 2007 10:49 am

Ian Anderson wrote:I'm not convinced re the "near the top" bit

I would expect all entries to the header to be covered in water all the time - or you could get air drawn back in on cool down etc.

The feed back from rad is good idea but let the air "bubble through" and the pope will always be full

Then again I could be wrong - been wrong many times before!

Ian

That is why its supposed to be small bore.
It should be from the highest point of the cooling circuit as well which on the rover is usually the bend on the top hose. Generally on a rover install the rad will be full but the top hose could end up with a fair bit air in it as there is no real way for it to purge. As to position on the header, it should be under pressure so cant draw back. This is the way virtually every modern car is plumbed. If you look at the header tanks, although it might be a 1/4 bore pipe or larger the tank has a reducer to something more like 1/8. Its only intended to move air although when purged and running there will be a small stream of coolant.

steve b · Post by **steve b** » Mon Oct 29, 2007 9:48 pm

Got tank today ,well chuffed hope it works.

steve b · Post by **steve b** » Mon Oct 29, 2007 10:10 pm

Well that didnt work, how do you get pics with post?

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Post by **katanaman** » Mon Oct 29, 2007 10:21 pm

you didnt put a url to the pic between the tags as in imgwww.mypic.com/pic.jpg/img but properly formatted with brackets and all that.