The V8 Owners Forum -

My Range rover has a buggy body and due to that it would appear that the expansion tank has been mounted lower than originally. In it's new position it is lower than the radiator top hose.



It feels like a fair bit of air is trapped in the top hose and I have no way of bleeding it. I thought about getting an in-line fan sensor housing and using a bolt to blank the hole and give me a point to bleed the hose.

In my searching I found this in the USA
http://jagsthatrun.com/Pages/Parts_Cool ... Glass.html
It has the in-line bleed valve along with a sight glass to check for any air. Seems like a good idea to me or am I missing something?

Can anybody recommend anything suitable to enable me to bleed my top hose ?

Looks like a useful device. Although I'd prefer a screwdriver etc operated bleed valve.

Looking at the photo some more. If the air pocket is just over half way up the hose, you would only be able to see coolant and not know the air is there anyway.

Has anybody got any links to anything suitable in the UK ?

I made a fitting with a bike tyre valve in it. I just (carefully) push it in with an allen key until coolant comes out.

Car builder?
http://www.carbuildersolutions.com/uk/b ... with-bleed

Probably got other sizes give them a call

Ian

You need to tweak the system if the highest point is not the header tank. Air will always collect at the bleed point and you'll always be bleeding it.

What you need is an expansion bottle, which you can mount anywhere you like. This is what I did with my Landie.

That 'thing' in the top hose you can buy, I didn't realise and made my own. Basically, the magic is in the rad cap. It has the normal pressure seal, and another perfect seal under the cap itself. Therefore any excess pressure will blow out of the little pipe to the expansion tank. When the system cools, because the small pipe goes to the bottom of the expansion tank, it will draw in coolant.
The system self primes, and always keeps it topped up.

Chris.

Ian Anderson wrote:Car builder?
http://www.carbuildersolutions.com/uk/b ... with-bleed

Probably got other sizes give them a call

Ian

Works a treat too. I've also got the same as their in-line housing on page 310 of catalogue and has a code #INT32

richardpope50 wrote:

Ian Anderson wrote:Car builder?
http://www.carbuildersolutions.com/uk/b ... with-bleed

Probably got other sizes give them a call

Ian

Works a treat too. I've also got the same as their in-line housing on page 310 of catalogue and has a code #INT32

Have you got a temperature sensor in it ?

ChrisJC wrote:You need to tweak the system if the highest point is not the header tank. Air will always collect at the bleed point and you'll always be bleeding it.

What you need is an expansion bottle, which you can mount anywhere you like. This is what I did with my Landie.

That 'thing' in the top hose you can buy, I didn't realise and made my own. Basically, the magic is in the rad cap. It has the normal pressure seal, and another perfect seal under the cap itself. Therefore any excess pressure will blow out of the little pipe to the expansion tank. When the system cools, because the small pipe goes to the bottom of the expansion tank, it will draw in coolant.
The system self primes, and always keeps it topped up.

Chris.

Sounds good. Is this the same as you made?
http://www.demon-tweeks.co.uk/motorspor ... ck-adaptor

I bought mine from the web as I wanted it in blue and were much cheaper however came with naff jubilee clips.

As you can see, I used the original tap to put in a pipe to my header tank and added a new tap to fit an otter switch controlling my fan. For the latter I bought some cheap taps.



I've removed the swirl pot since this photo but it shows my header tank on the left. I cannot position it higher but it is just (only just) higher than top of engine but seems to work OK.



I have been told that I should have taken a pipe from the outlet* just to the right of the ECU water temp sender and almost under the air intake and near N0 1 injector to a new inlet in the top of the header tank, then another pipe from bottom rad hose to bottom inlet of header tank. That way it should keep everything air free.

*You can just see this rubber hose to the right of the brown ECU sensor. My engine came with a short rubber hose from this outlet but plugged with a bolt. I can only assume TVR did this or was it a standard Disco RV8 feature?

I've now replaced this bolt with a fuel pipe on/off valve making it easy to bleed air out and indeed fill the last bit of coolant into engine.

Make sure the small pipe to the header tank is restricted, only needs to have a small 1mm hole to bleed the air. If not it will become a radiator bypass and will effect cooling


edit: My comment refers to a header tank and not an expansion tank

The Saint wrote: Sounds good. Is this the same as you made?
http://www.demon-tweeks.co.uk/motorspor ... ck-adaptor

Yes. Exactly. I wish I'd known about those when I machined up mine!

You do need to make sure the rad cap is one with the two seals as well, otherwise the expansion fluid will piss out of the rad cap rather than run along the pipe to the expansion tank.

Chris.

ChrisJC wrote:

The Saint wrote: Sounds good. Is this the same as you made?
http://www.demon-tweeks.co.uk/motorspor ... ck-adaptor

Yes. Exactly. I wish I'd known about those when I machined up mine!

You do need to make sure the rad cap is one with the two seals as well, otherwise the expansion fluid will piss out of the rad cap rather than run along the pipe to the expansion tank.

Chris.

Isn't it the other way round?, caps without the secondary seal wont be able to allow fluid to be drawn back into the engine from the tank? Or am I missing something here?

Denis247 wrote: Isn't it the other way round?, caps without the secondary seal wont be able to allow fluid to be drawn back into the engine from the tank? Or am I missing something here?

You do need the two seals.

So the 'normal' seal that all rad caps have is the one with a spring so it opens when the working pressure of the cap is reached. Then air (or coolant) passes this seal into the chamber which is effectively the neck part, sealed at the top by the rad cap and second seal. The only way out for the coolant is along the small overflow pipe to the expansion tank. When the system cools down, it forms a vacuum in the cooling system, which draws coolant from the expansion tank. If the top seal on the rad cap is missing, this vacuum will just draw in air.




Chris.

From what I understand there are two different solutions to my problem, being shown here. Both a lot more complicated than I first envisaged but self bleeding would make it worth the extra work.
Can anybody tell me which solution is best for my needs ?