Header tank (not again!)

[dripster]

I'm very hesitant posting this, as I know there seems to be a lot of opinions on this, but here goes...

I'm considering fitting a header tank and have got one from a TR7 (not pretty I know, but it gives me some comfort that it's a 'Triumph'). Now comes the problem of how to fit it.

My understanding having trawled through the previous posts on this is that the bottom, large connection should connect to the bottom of the radiator (or nearby) and the top smaller connection should attach to the top. Which is tricky to do neatly without modding the radiator.

The easy option would be to connect the bottom larger connector to the top hose and the top smaller connector to the overflow pipe (MK2 system). But I don't think this would do what I want?

The next easiest option is to connect the top larger smaller hose into a t-piece in the rad top hose, and then somehow fit a connector to where the temp switch for the electric fan is (low down on the near-side of the rad) and join this to the large, lower connector on the header tank. I guess then blank off the overflow?

If this latter case is the best way to go, anyone know if I can get an adaptor for the temp switch hole?!?

Cheers guys.

Ian

[Mark S]

imported post

Hi Ian,

I have the top hoseof the header tank connected to a stub soldered onto the filler neck of the rad (but you could tee into the top hose for the same effect). The bottom hose of the tank connects to the old expansion bottle connection on the rad.(Mk2 rad of course).

With the engine warm and the stat open so that the foot starts to close the by-pass, there is enough pressure across the rad to give a flow through the header tank, so trapping any air and keeping the top hose full at all times. This set up alsoallows the pressure cap to see the lowest pressure in the system, If you connect both hoses to the "top hose" side of the radiator the cap will effectively blow a little early especially at high revs.

Hope this helps.

Mark.

[Dave M]

imported post

Hi Mark

After recently loosing all my coolant due to core plug failure I would like to fit a suitableheader tank with a low level sensor, but have a few questions similar to what Ian is asking.

So using your set up there is no need for an additional tapping into the radiator for the return pipe, are there any advantages to adding the additional tapping or is the original overflow pipe sufficient?

Can not remember but does your tank have a standard type pressure cap as per the ones fitted to the original expansion bottle or does it have one of the modern type plastic caps. Does anyone know if the colours of the plastic caps are a way of identifying the pressure rating if in fact they are pressure caps?

I see someone on ebay is selling top hose tee adaptors that allow the fitting of a fan control switch, this could easily be adapted with a connector rather than the switch to be the take off for the top tank connection.

Dave

[Sheepdip]

imported post

Dave, I used a Volvo tank, connected the bottom outlet into the heater return pipe and the top pipe into the top of rad, replacing the filler plug with an adaptor (described elsewhere). I went for the heater pipe as lowest point I could tap into, as the tank has a sensor I wanted to ensure any coolant loss would completely empty the tank, not sure if it was in the top hose.

Anyway the cap sealing ring failed and blew my lovely hot stuff everywhere so temporarily removed, I will be tapping into the rad as a permananet fix tho.

The pressure cap I had was marked with pressure but I got a new one from a Volvo man which gave me the pressure on thepacket.

Paul

[Mark S]

imported post

Hi Dave,

My header tank is form a big Merc, and has a low level sensor and standard type pressure cap. I run a 15lb cap, mainly because the 20lb cap bought from a "good" supplier was absolute c**p and I already had an unused 15lb one originally bought for the Tiv .

As far as the tank bottom pipe is concerned, I looked atconnecting to the heater return but connected to the rad exp bottlepipe for convenience. This works very well. A larger connection to the bottom of the outlet side of the rad would be a better engineering solution, but there is no easy routefor the pipe.For the top header tank pipe, a top hose adaptor would do the same jobas a stub soldered on the neck of the rad with no permanant mods.

The disadvantage of my system is thatthe water needs a little help starting when filling from empty to clear the air lock in the pipe, but if you filled the rad throught the filling plug and started the engine it would self purge when the thermostat opened.

We went to Burton Agneson Sunday, Nice red and black Stags there but didn't have chance to speak to the owners. Unfortunately the show was in an un-mown cow field so crossed off the list for next year. Brigg Border Classic rally through the Wolds this Sunday and we're booked in for Lincoln next month so may see you there.

Mark.

[alan230752]

imported post

Mark S wrote:

Hi Ian,

I have the top hoseof the header tank connected to a stub soldered onto the filler neck of the rad (but you could tee into the top hose for the same effect). The bottom hose of the tank connects to the old expansion bottle connection on the rad. (Mk2 rad of course).

With the engine warm and the stat open so that the foot starts to close the by-pass, there is enough pressure across the rad to give a flow through the header tank, so trapping any air and keeping the top hose full at all times. This set up alsoallows the pressure cap to see the lowest pressure in the system, If you connect both hoses to the "top hose" side of the radiator the cap will effectively blow a little early especially at high revs.

Hope this helps.

Mark.

i have fitted tr7 header like you suggest(had it chromed and fitted rear bulkhead)

dont have level sensor or warning light,only ever topped it up twice,excluding annual flush

quote "The easy option would be to connect the bottom larger connector to the top hose and the top smaller connector to the overflow pipe (MK2 system). But I don't think this would do what I want?"



been on car over a year now,temp gauge always just below halfway

does not give me any problems

alan

[Mark S]

imported post

dripster wrote:

The easy option would be to connect the bottom larger connector to the top hose and the top smaller connector to the overflow pipe (MK2 system). But I don't think this would do what I want?

Quite right Alan, the pressure across the radiator would force the air out of the header tank back into the rad.

Mark.