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Hi all ,I am thinking of trying a sealed water system by having a vw overflow sphere mounted higher than the rad with a metal pipe welded on the thermostat housing then a rubber pipe going to the bottle which has two pipes ,so one in one out with the bottom one going in the rads bottom hose, I will need to block the overflow from the rad. ,my reason is on tick over it gets hot very quick ,my fan comes on so no problem but the guys who tuned my webers recommend I do it,

Any one done it ?

Regards

Nick

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That sounds ultra complicated Nick and it isn't going to help with your heat problem. All a sealed system does its allow the rad to be filled to the neck. It doesn't provide any more cooling than the standard system. Sounds as though either you have an air-lock, the thermostat isn't working properly, or your radiator needs flushing.

 

Many people have fitted a rather simpler sealed system than you describe. A forum search will find the discussions about that.

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I agree with Rob, sounds over complicated. After refilling, the standard setup always seems to expel any trapped air and replace it by drawing in coolant over several cycles of heating and cooling.

 

Nigel

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I have done a simple mod on my previous SP250 and my current 3a

 

Use an mgb ( yeah I know !!!! Mg stuff) expansion tank. It a nice Period brass tank with a low internal pipe.

 

Use a plain blanking cap on the rad

Use the overflow point to connect to the brass tank.

Put the pressure cap on the tank and the overflow pipe on the overflow of the same tank.

 

This is the type I use.

MGB / MG MIDGET EXPANSION TANK https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F231858963810

 

Basically stops expansion water being lost.

 

H

Edited by Hamish
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Any one done it ?

Regards

Nick

 

I did that a similar way on my TR4A, if wanted I can report.

But there is no improvement at all in cooling, and not needed.

 

The water pump is a monster, good for about 5.000 liter/h,

nothing flashes the system better than the water pump.

 

Do you use a bellows thermostat? I've seen that on a TR6 these days.

Then fit a "modern" one, one that was common in the 80-/90-ies, 71°C or 74°C

 

Cioa Marco

Edited by Z320
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Fit one of these and you can fill the engine and radiator to the brim.

https://www.ebay.co.uk/itm/MG-MIDGET-THERMOSTAT-HOUSING-1500-CARS/232712343231?epid=23005103220&hash=item362ebc8ebf:g:cgIAAOSwbDZaujNW

 

Used for many years to ensure a full radiator cooling system. They are available new also from MG Midget 1500 specialists.

Peter W

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"the car is just been rebuilt with Ali rad etc"

 

Why ? the alloy rads can't remove heat like the original copper ? that normally makes the car run hotter !

The modern alloy rads are often used when racing but that's purely because of the flow, not the heat exchanging qualities. I'm afraid that's a step backwards, try a search in the box for numerous posts and feeds on it.

 

Mick Richards

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Thx all , Hamish I use that system on my jag works very well , Pete that looks like a great idea ,the car is just been rebuilt with Ali rad etc so that part should be ok, will report back.

Regards

Nick

On my own car I have drilled and tapped the thermostat housing to 1/8" BSP

 

I simply fill the radiator to the brim with the plug removed, Then fit the radiator cap and loosely fit the bleed plug, start the engine and as it warms up the air is vented through the bleed plug. Nip up the plug when you are happy that only water is being expelled. Cheaper solution than a complete cover, if you do not charge for your time.

 

Plug https://www.ebay.co.uk/bhp/1-8-bsp-plug?clk_rvr_id=1542174590269&rmvSB=true

Tap to cut thread https://www.ebay.co.uk/bhp/1-8-bsp-tap

 

Peter W

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I just put an in line bleed valve in the top heater hose.

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Hi All

Oh dear I’m going to show my ignorance her so bear with me.

I thought the idea of the TR6 cooling system was that once filled, engine running and hot any pressure, above that allowed by the cap would push water out of the rad into the expansion bottle via the overflow pipe and any air expelled would bubble through water in the expansion bottle and on cooling water would be sucked back in as the overflow pipe was below the water level. Its not a completely sealed system as it will allow water out and in but kind of.

So is my understanding way off?

If it is I do have an excuse as my 72 Pi is in the garage in many many bits so is kind of not running. Lol

Keith

 

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Hi All

 

Oh dear I’m going to show my ignorance her so bear with me.

 

I thought the idea of the TR6 cooling system was that once filled, engine running and hot any pressure, above that allowed by the cap would push water out of the rad into the expansion bottle via the overflow pipe and any air expelled would bubble through water in the expansion bottle and on cooling water would be sucked back in as the overflow pipe was below the water level. Its not a completely sealed system as it will allow water out and in but kind of.

 

So is my understanding way off?

 

If it is I do have an excuse as my 72 Pi is in the garage in many many bits so is kind of not running. Lol

 

Keith

 

Perfect understanding

So long as the radiator filler cap is the highest point in the system. The heater tap may have something to say about that....

Peter W

 

On MGRV8 you fill the cooling system from a container on a ladder above the roof line of the car with a hose into the cooling system - or you get a nice airlock that stops the heater from working or cooks the manifolds. etc

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Allow me a different point of view:

 

The cooling system has to run with air in the system, 0.5 - 1.0 liter is needed on our TRs.

 

It does not matter where the air is, in the radiator, hoses or in a higher expansion bottle of a closed circut system.

 

With less air the pressure rises fast, water is pushed in the expansion bottle and cold sucked back - every time with fresh oxygene.

I drive my TR4A on purpose with 0.8 liter air in the radiator - and could do that without any overflow bottle.

I can also run the engine without any air in 10 minutes, and with 0.8 liter air the next moment again.

Believe it, I can do - and it makes no difference at all.

 

You sent Nick on a wrong way!

 

Ciao Marco

Edited by Z320
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Well - sorry, I did not tell you the truth!

 

I some situations I have got the impression cooling works a minimum better with air in the water.

And I have never got the impression cooling works better with the air seperated in the expansion bottle.

 

Sorry that inaccuracy.

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Story telling at the bonefire, each one the other one,

they sit in an "echo room" and like this stories to keep you on distance.

 

To be serious, ask yourself 3 questions:

 

If hot spots allow to form "air" in the engine, what is the benefit of such a "bottle" after the engine for the hot spot?

If 5.000 liter/h of coolant (or more) run through that tiny, cute bottle, what happens with anything that´s inside?

If boiling water (if there is boiling water) (=steam, not air) goes through the radiator, what happens there?

Edited by Z320
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Just a thought - has it got the original bellows stat or a modern one?

Fitting a modern one isn't a problem so long as you restrict the bi-pass hose.

 

The bi-pass hose allows water to circulate around the engine when the thermostat is closed. When the stat opens the bellows occludes the bi-pass so the water goes through the rad (to get cooled) Without the bellows the flow to the bi-pass remains unrestricted so hot water then returns directly to the engine without being cooled. The trick is to restrict the bi-pass hose so only a limited flow goes through it. (or use a bellows stat)

 

Ignore the above - thought I was in the TR4/4A forum!

 

If you are overheating it is unlikely the radiator is the cause which if in good nick is going to have ample cooling capacity whether it's alloy or not!

 

Again fitting a header tank won't improve cooling as such it just maintains the fluid level.

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