I have on my newly built Rv8 a Radiator from a TX1 taxi and a header tank from a VW (the bulb type). The Header tank has a tiny little pipe on it that I neglected to cap on my first extended run of the engine (about 5-10 minutes). Towards the end of this run the engine was getting hot the cooling system pipes were warming up as expected. The radiator fan didn't kick in but then again the gauge said it hadn't reached the correct temp. The water level in the globe rose up quite alarmingly and all of a sudden hot water squirted out all over the drive. Should I cap this outlet or plumb it back into the system somewhere? There is a tiny outlet on the radiator it theoretically could go into.


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Description

mine has a smallbore pipe between there and the radiator,.. I guess if you leave the pipe on the header tank open, it will not be a pressurised system, unless there some sort of valve,.?

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Originally posted by HowardB
mine has a smallbore pipe between there and the radiator,.. I guess if you leave the pipe on the header tank open, it will not be a pressurised system, unless there some sort of valve,.?

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You should have a return back to the header tank on the rover V8, my Seight westy has a 6mm return to the top of the header tank.

You should have a return back to the header tank on the rover V8, my Seight westy has a 6mm return to the top of the header tank.

Fit a plain non pressure cap on the radiator and run a small hose from the outlet you have blanked off adjacent to your rad cap.

As long as your header tank is higher than the rad this should bleed off any trapped air in the system.

The cap on the VW header will be your pressure cap.

Let us know how you get on please. I have the same rad and am far from plumbing it up, any advise would be a great help.

I had a similar problem.
Is that Ball a pressurised ball?
Is there an overflow from above the presurised section of the rad cap on that header tank?

The RV8 holds a lot of water, and this needs to expand somewhere.

I had a pressurised cap with a double seal on my header tank, and a blank on the rad itself.
The overflow from the Rad (thin blue pipe into the top of my header tank) came from the rad overflow.
This would bleed air from the top of the rad to the header tank.

My Rad cap was off a Land Rover Series 3, 14 or 15Lb (from memory) had two rubber seals.
One on the normal sprung loaded tit, and another flat rubber seal just inside the top of the cap which sealed the cap to the top rim of the rad cap housing.
Then I fitted an overflow pipe to a non presurised water bottle (the coke type bottle in the pic)
The expansion pipe MUST go to the very bottom of the bottle for this to work.

Thus on expansion the water is expelled through the overflow, and into the non presurised bottle.
Then on cooling it would syyphon back into the header tank.
All this is done by having the cap with the extra seal in the very top of the cap, and by the pipe reaching the bottom of the overflow bottle.
I was going to change this for a posher bottle when could find one at a rally.

The thin blue pipe at the top of the header tank came from the overflow at the top of the rad. Where I had a blamking cap fitted (No sprung loaded tit in it) just a flat cap with flat rubber seal in it. This was for bleeding the air trapped in the top of the rad to the header tank.


Hope this helps..

Geoff


Overflow syphon

I was hoping you'd reply Geoff. I remember you had a setup to get round this issue. The Ball VW header tank has a pressure cap of unknown quantity. I don't think the outlet on the tank is above the pressure cap. I don't think the system got hot enough to blow the pressure cap anyway. The fan didn't kick in and the gauge never read above 80degrees and they are on separate sensors. The water level did rise from between the minimum and maximum level to above the outlet pipe quite quickly.

I'll have to check to see if the any of the outlet pipes are above the pressure caps.

I have the same radiator and header tank (not a coincidence - I copied yours!).

I have a return pipe going from the small pipe at the top of the header tank to the small pipe that comes out of the radiator just below the filler cap. Like yours, my pressure relief valve is the VW cap on the header tank rather than the radiator cap, which is just a seal, rather than the spring loaded pressure relief type.

You can see the start of the plumbing in this picture and just about where it connects to the radiator. The water in the header does expand quite a bit, which is normal. Not sure how much water your V8 takes, but when cold my header is about half full and there is plenty of expansion room for the volume my straight 6 takes.

Went for a run (about 15 miles) in the nice weather today and the temperature got to 91-92 degrees and stayed there. I need to do a longer run to be absolutely sure, but the cooling seems to work OK.

Just had a thought. If the volume in the header is rising really quickly, you may have air somewhere in your plumbing which is expanding a lot more than water does when it gets hot


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[Edited on 24/7/14 by SteveWallace]

NO problem Mr Irony.
I am still around, just no Kit car anymore.
I bought an empty 2001 Sprinter van and am filling it with foam and plywood, to make a Locost Motorhome.
I canst afford £30k (MIN) for anything new, or even nearly new, or even old!
So its Locostbuilders approach.

I pop in here from time to time as its such a good bunch of people.

Also I think 82 degrees is correct for a RV8. So you sound about right.

If its only going from Min to max when cold to hot, then that doesnt sound too bad.
Mine was using the same amount of water every time. Although my header tank didnt hold a lot.
Looked nice, but not a lot of capacity!

Hope you get sorted.
Last thing you want is to overheat the RV8 Ally block and heads.
That can get expensive.

Wish you all the best

Geoff