Header Tank (Stagweber)

[sujitroy]

I'm working on Stag no.2 and taking care of the plumbing. I'm bridging the left head to the right head.
The question is the kit came with a T . One end of the tee feeds into the heater return pipe, another end goes into the top feed into the thermostat cover and the third end goes into the header tank.
I have a Mk1 with early manifold. When the car is running, I'm assuming water is being sucked into the engine from the top, (radiator bottom hose and heater return pipe. What prevents water being sucked into the engine from the header tank?
Sujit

[Swifty75]

I’m wondering that at the moment Sujit. If it does then it bypasses the radiator. I took the radiator plug off to look at the water flow. When you rev the engine there is a lot of pull on the water, so at higher revs you could get water bypassing the radiator. This is the same with the bypass hose on the mk1 though as it never shuts.

Neil

[trunt]

Normally there are 2 connections, top and bottom. The top connection should be a small diameter hose which would restrict the amount of flow, it’s as high as possible and near the outlet of the engine water(thermostat) If it’s not then a restriction may be in order? The bottom is in the draw side of the pump and is usually larger for topping off. In operation there is a little flow.

You say the tee taps into the header tank, from the thermostat? If it’s on the heater hose then I think it’s from the pump?? where does the other hose from the header tank go? teeing into the heater pipe whilst easy is probably not the best solution, adding connections in the radiator itself seems to be more efficient.

Terry

[richardthestag]

After I found exactly that, i.e. hot running at speed I simply blanked off the feed to the HT from the top of the Rad. Instant improvement

It is now a high level expansion tank with a gravity feed, that has to be better than the original that relied heavily on vacuum

Alas the reed switch is all wrong and doesn't allow for sufficient head of air above the coolant. so the low coolant light I fitted constantly flickers until the coolant pressurises.

It is on it's way out of my engine bay to be replaced with something else that might work better

[sujitroy]

Normally there are 2 connections, top and bottom. The top connection should be a small diameter hose which would restrict the amount of flow, it’s as high as possible and near the outlet of the engine water(thermostat) If it’s not then a restriction may be in order? The bottom is in the draw side of the pump and is usually larger for topping off. In operation there is a little flow.

You say the tee taps into the header tank, from the thermostat? If it’s on the heater hose then I think it’s from the pump?? where does the other hose from the header tank go? teeing into the heater pipe whilst easy is probably not the best solution, adding connections in the radiator itself seems to be more efficient.

Terry

Here's the pipe set up. (return from heater and supply form header tank goes into small inlet in thermostat cover. Yes. There is a 2nd small connection at the top of the tank. This goes into the top radiator hose.

[trunt]

OK, yes you are confusing the pump cover with the thermostat.. heater return goes to the pump cover where it is sucked in by the pump.

.. again put a restriction in the hose to the top hose if you feel the flow is too much, that hose is just to bleed air. The other one is used when you fill it up so I would leave that alone.

I have a 5/8" tap lowish on the radiator and a 1/4" on the radiator filler neck. soldered them in myself using pex connectors.

Terry

[sujitroy]

After I found exactly that, i.e. hot running at speed I simply blanked off the feed to the HT from the top of the Rad. Instant improvement

It is now a high level expansion tank with a gravity feed, that has to be better than the original that relied heavily on vacuum

Alas the reed switch is all wrong and doesn't allow for sufficient head of air above the coolant. so the low coolant light I fitted constantly flickers until the coolant pressurises.

It is on it's way out of my engine bay to be replaced with something else that might work better

Hi, I have a mk1 radiator. Are you saying I should not cut the top radiator hose and add the tee and I should blank off the top small connection in the header tank? Isn't this essentially the standard set up for a Mk2? The only difference is the reservoir is above the water pump and not below.

Someone posted a fix for a low fuel light. Maybe add that thing to the circuit.

Sujit

[sujitroy]

I email Chris Spain and he got back to me. Here's what he said

A simple header tank holds a reserve of coolant that will flow through an outlet, into the engine until it is full. Provided there are no leaks then no more coolant will flow because there is nowhere for it to go.


The action of the pump is to circulate coolant through the radiator, heater and back to the pump. It circulates because it is part a closed circuit.


The plumbing arrangement we use on the stagweber tank also has a return inlet which does allow a small amount of coolant to be circulated as this helps to bleed out any air, and mixes in any additives. The coolant is drawn from the tank into the pump inlet, and returned to the tank via the top connection at the filler boss (or in some cases the radiator top hose). We fit a restrictor in the small tank return hose to limit the flow.

I asked him a followup question as to whether I can block of the return. He says there is a chance of air accumulating in the top radiator pipe,

In the kit he provides, comes a restriction device which I forgot to add in my circuit, he says not critical but does help. As Terry mentions it for air to bleed. In my case I added a T in the top hose. I may block it off with a bleed screw and see if there is any difference.

Sujit

[richardthestag]

Ok so my facts based on first hand experience

When I bought my Thomas mk1 HT from stagweber it included,at additional cost, an adaptor that allowed me to splice a T piece into the top hose and add a 10mm feed pipe to the top of my header tank.

I believe that the top hose T, rather than a dog leg off the top of the mk2 rad, was root cause to my hot running issue at motorway speed. My defence is that once I blocked the 10mm feed to the HT my hot running issue was resolved.

I believe that the water pump was drawing "some" coolant from the header tank, which was being replenished by the 10mm feed. On a cooling system that most believe to be marginal at best, is this a great idea? Just beware of running the HT plumbing in this way!

Other than that the only real issue with Thomas aside from that the pressure cap didn't seat properly was that the reed switch was too high and caused the low level warning to flicker before the cooling system pressurised. I did the whole delay switch thing and the warning still comes on when cold. PLUS more importantly, when my cooling system is compromised do I really want to wait 10 seconds before I get a chance to think about finding a safe way to the hard shoulder? What actually is the point of the slow early warning system?

So onto Chris' comments above. I looked and found his vid on youtube https://youtu.be/XVBiDLUo_1Q you can see that the feed is now from the top of the rad, I hope this now slows the coolant bypass from the radiator, maybe this is what Chris is referring to. But is that reed switch below the top level of the rad and maybe an inch above the waterpump? Who has one, any comment on that?

Range Rover classic (I know, I have another lover and Stag knows)
Header tank is installed to the output side of the rad, the feed is from the hose just above the bottom stub on the radiator (rather than above the waterpump)
The return feed to the HT is at the top of the matrix directly above the bottom hose (rather than before coolant gets a chance to even go through the Rad matrix)
Because of this I can see no way as to how the waterpump might draw coolant from anywhere other than through the radiator,

Other header tank installations looked at would appear to match the above basic principles

High level expansion tank that does away with reliance upon a having a perfectly sealed system to provide a vacuum to top up the radiator on cooling, and comes with the added benefit of warning when the expansion bottle level is low is where I am going with this.

[Dieter H. Marschall]

I would recommend to ask Chris Spain (Stagweber) and to build in a low level sensor with an alarm. Good luck, Dieter.

[Neil Egerton]

I have (I think) successfully installed a Stagweber tank in my Mk2 this week, but I am unsure of how to connect the buzzer to the fuse box. Does anyone have any advice?

[sujitroy]

I simply ran a line from the back of the clock. purple wire. and for LH Stags it's on that side of the car. it live all the time. but because of a battery drain problem I always disconnect the battery at night. When water moved around it triggers. I suggested adding a delay circuit but someone pointed out that delay but that delay may be long and your car overheats

[Bakdraft007]

Hi Sujit,

I fitted my Stagwebber a few months back. I have a Mk1 and the plumbing I did was nothing like yours.

The tank came with a T which goes from the return from the Thermostat housing to the top hose of the radiator with a smaller diameter hose to the Stagweber tank. see the photo.

The return from the stagweber tank is meant to go to the bottom hose of the radiator. However, as I have a Mk1 radiator I removed the drain tap at the bottom of the radiator and chose there. Because of the size of the hose needed there i fitted an even smaller restrictor to the T hose which you can see in the photo. The small restrictor is 6mm. This allows air to escape, but very limited flow to the tank. It all works fine.

IMG_2862.jpg



The above photo shows the T and additional restrictor

[Bakdraft007]

I have (I think) successfully installed a Stagweber tank in my Mk2 this week, but I am unsure of how to connect the buzzer to the fuse box. Does anyone have any advice?

I have a Mk1 so I did not use a buzzer, I used the 'Temp' indicator segment on the dashboard cluster. This is not on the Mk2. For a power source, I used the Fuel cuttout supply as it located close to the tank.

Dave

[richardthestag]

looks like it would work and I see no way that the pump would draw from it rather than the rad.

Surely though all you have created is a high level expansion tank with low level warning - set level with the top of the water pump. and incorporated an air bleed.