Coolant Header Tank

[DJT]

There has been much discussion over the years about the design of the Stag cooiling system and its inherent faults. One of these faults is the poor position of the overflow bottle. Several attempts have been made to supply a suitable header tank, the most elaborate is the custom-made tank in Michael Heathcote's Car.

Today I spent some time in a breaker's yard looking under the bonnetsof the wrecks to try and find something suitable. One possible solution is the one fitted toa 1996Volvo V90 (picture attached). This mounts on a bracket similar to that for the Stag washer bottle, but in the Volvo this is welded to the suspension turret. With minimal work this could be removed and fitted to the Stag LH turret. The Volvo tank has two outlets - both visible in the photo. One, about 3/4" diameter, from the bottom, plumbs into the cooling system down at the side of the engine. The other, about 3/8" diameter from the top runs to the top of the radiator. There is also a low-level switch fitted. The pressure cap is marked 150 Kpa, which converts to 21.7 PSI.

Any thoughts about this being fitted to a Stag? Anyone want to give it a go?

Dave

[seaside bill]

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Dave

A very timely post. I've beenscouring Ebay for a suitable header tank and have just got one for £5 from a Volvo 850 T5 - it hasn't arrived yet. From the picture I thought it might do for the job, and your observations confirm this. Added bonus is it comes with a low water level sensor. It'll need a good clean up and some sort of mounting bracket made up, but I'll let you know how I get on.

[DJT]

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Hi, Bill,

Yes, that looks very much like the same thing. The 850 T5 is of about the same vintage - from the time when Volvo designers couldn't work without a ruler - typical Volvo breeze block.

Let us know how you plumb it in and how effective it is.

Dave

[philers]

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Although I am Stagless at the moment, I seem to remember on my last Stag (20 years ago) a spare place in the warning cluster which I believe was an over heating warning light that was disconnected. Could the low coolent level warning be wired there?

Just a thought

Phil

[Stagdad]

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Bill /Dave

Iguess the feed from the tank would be spiced into the top hose (Tank would want to be higher than top hose).how are you guys going to do that?

I found this as a neat but expensive fitting.



http://www.revotec.com/Self-Seal.htm

Or i would proberbly use plumbing fittings.

Steve

PS


Just got this off ebay http://cgi.ebay.co.uk/ws/eBayISAPI.d...:IT&ih=013

[seaside bill]

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Steve

Thanks for the info on the Revotec fitting - it's potentially a neat solution.

It's not an ideal a set up, but as long as the coolant level is higher than the water pump it should stop a meltdown situation - the low coolant level sensor will provide a warning that all is not well.


Phil, I wasn't aware of the redundant warning light, but I think I'll go for something more visible like the seatbelt warning light or wire in a very obvious, bright flashingLED or even a buzzer.

[Stagdad]

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It would be nice to fit an LED inside the temp gauge.like the older cars had for things like high beam .

[mjheathcote]

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seaside bill wrote:

Phil, I wasn't aware of the redundant warning light, but I think I'll go for something more visible like the seatbelt warning light or wire in a very obvious, bright flashingLED or even a buzzer.

I have my low level warning light beneath the switch for the heated rear window, that was originally used for a tow bar repeater light. My seatbelt warning light is now redundant following new seat belts. This position is ideal IMHO and I am looking for a suitable light for this position.

Cheers,

Mike.

[seaside bill]

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I've just noticed that somebodywith a Stag interest from Reading(anybody we know?) hasjust bought a Merc W124 expansion tankfrom Ebay -I was also looking at that as a possible solution.

[Hantsdave]

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Picking up the suggestion about a redundant warning light in the round cluster, I have just looked at a brand new (NOS) unit I bought from the states and there is no vacant sector.

Going round from the 1 o'clock positon it is IGN, FUEL, RIGHT INDICATOR, H BRAKE, CHOKE, LEFT INDICATOR, OIL, BEAM.

With adding things like warning lights there are so many options out there on eBay now and with a bit of doggedness you can find lights and switches to match the original Stag spec. A water level warning light would be a brilliant addition and it needn't look like some tacky retro bolt on bit either.

With these Volvo tanks you chaps are considering is there likely to be an issue with pressure? Do Volvo provide a range of caps that are compatible with the Stag engine requirements?

Dave.

[stustag]

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I have just spent the last 30mins trawling trough the tech reports to find out about the issue with the overflow bottle but could find nothing!

What is the problem with it? What do I need to look for? I am on my third Stag and have never had any problems with overheating or the coolant system.

Stuart

[monstag265]

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Stuart

I have owned a total of six stags, one in particular for 8 years andlike you have never had any overheating problems.All were standardincluding the overflow bottles so dont worry.Dont fix what aint broke.Some of these mods to the cooling system really do work and a lot of time and effort has gone in to them,but yours sounds fine.

Jon

[DJT]

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Hantsdave wrote:

Picking up the suggestion about a redundant warning light in the round cluster, I have just looked at a brand new (NOS) unit I bought from the states and there is no vacant sector.

Going round from the 1 o'clock positon it is IGN, FUEL, RIGHT INDICATOR, H BRAKE, CHOKE, LEFT INDICATOR, OIL, BEAM.

With these Volvo tanks you chaps are considering is there likely to be an issue with pressure? Do Volvo provide a range of caps that are compatible with the Stag engine requirements?

Dave.

Dave,

The water temp warning light was for the very early Stags and soon deleted. The early warning clusters had white printing on the lens and the warnings, from the 12 o'clock position, were: INDICATORS, BEAM, IGN, FUEL, H BRAKE, CHOKE, TEMP, OIL.

As for pressure, the Volvo cap is marked 150 Kpa, which is 21.7 psi. The Stag system is 20 psi, unless you have a very early one, in which case it was 13 psi with a different radiator, overflow bottle, inlet manifold andthermostat. I wouldn't have thought this would make much difference to a sound system, other than lowering the boiling point another few degrees. Thewater hoses in the Volvo I was looking at didn't seemto bereinforced.

Dave

[DJT]

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stustag wrote:

I have just spent the last 30mins trawling trough the tech reports to find out about the issue with the overflow bottle but could find nothing!

What is the problem with it? What do I need to look for? I am on my third Stag and have never had any problems with overheating or the coolant system.

Stuart

Hi, Stuart,

No, I don't have any problem with overheating either (apart from when the water pump went earlier this year :X).

The reason I started this post is that I know some do have marginal systems and, by installing a proper header tank that doesn't rely on the cooling fluid to draw a vaccum to keep the system topped up, a better margin of safety is introduced.

Various options for tanks have been considered in the past, and this Volvo one looked just the job for anyone considering going this way.

If I was to fit one, I think I would cut the top hose and usesuitable copper plumbing fittings to make a reducing T-piece. This could then be painted satin black and wouldn't look out of place.

The warning light could be fitted anywhere, but I would prefer a buzzer behind the dash. This wouldn't involve altering any of the instruments or existing lights. They only cost about £1-50 and can be ty-wrapped almost anywhere out of sight. I already have one for the indicators (how many times have you left these on when driving with the roof down?) and oneas a lights-on warning.

Dave

[Sheepdip]

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No, I don't have any problem with overheating either (apart from when the water pump went earlier this year

What happened Dave and what was the result (I have a vested interest)?

Re header tanks, I started a link on this a while ago. Some people use TR7 tank but it looks ugly. Isaw one in a scrapyard (but didn't buy) from a Mondeo or Maestro that looked like it would fit, had2 pipes - more importantly could fit Stag pressure cap.

Re is it nescessary? Possibly not but with one expensive engine failure behind me I'd like more peace of mind and info on whats happening under the bonnet.