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Coolant Overflowing


Guest Roy P

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I have a 12 plate Zero with a crated black top zetec and a raceline water rail. When I returned from a 15 mile medium speed run yesterday there was a lot of water on the road where I backed into my drive. The water appears to be coming from under the radiator cap on the front of the water rail. I would like any opinions on why this is happening and why any excess water does not go down the overflow pipe. Also what is the canister that the overflow pipe goes in to for, the canister is approximately 40 mm dia and 250 mm tall and exits to atmosphere, surly it is too small to be an expansion chamber. Another question, there appears to be a sensor just below the radiator cap, but if this is the temperature sensor how can that work correctly when my water level is always below that sensor?


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Is the cap seated properly? It should lock down tight when it is turned against the stops. I had one that didn't and that leaked so I put an extra rubber seal in so that it was tight against the cap. The overflow bottle is just that when the water expands and there isn't enough room for it the rad cap allows some to flow in to the bottle. When the water cools it will suck it back as long as you haven't taken the rad cap off. Does sound a bit small though. Is the sensor for the temp gauge or the fan? Some people clip the fan sensor to the rad fins and tune it to come on at the correct temperature rather than plumb it into the pipe work.

I'm no zetec expert but my money is on the rad cap. No doubt someone will correct me!

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Don't think that will work as an expansion tank, if the outlet of the rad isn't in the water it can't suck it back in.

Has the rad cap got two rubber seals, usually need a second seal on top.

Just for reference 6 litres of water will expand to 6.26l going from 20 to 100 degrees, got that off a plumbing web site when I was dealing with an air lock on my 2B.

Edited by Jez Morton
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Guest 2b cruising

Sounds like you have a spit and suck system with expansion tank type rad cap.

If the overflow pipe is directed to the bottle, it's spit and suck.

If so, it sounds like you have an expansion type rad cap which gives free flow to the expansion bottle. What you actually need in this case would be a pressurised rad cap. One seal in the cap and one seal at the bottom of the spring and inlet valve assembly.

You woul need around about 15 psi cap.

As said, this is only if it's a spit and suck system.

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The raceline water rail does seem to produce problems. In your installation you had room to use the standard zetec thermostat housing which works on millions of standard installations in ford cars but it can be difficult to retrofit as the bolts are long.

As above a proper seal in the rim needed, not the metal sprung plate. The spit and suck tank should have one short tube and one that goes almost to the bottom of the overflow tank. The latter is the one that joins to the stat housing, the short one vents to ground. A hole in the stat is needed to allow air bleed and a little circulation to activate the thermostat opening. 3 or 4mm hole should be enough.

I sold on my raceline rail and reverted to the standard zetec housing.

 

Nigel

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To all who made suggestions, many thanks,


I had a good look at the top of the water rail and the aluminum casting was not flat, I have gently filed it flatter and then made a thin plastic gasket to fit in the cap to seal against the top of the water rail housing.


My theory is that when the engine gets a bit hotter than normal, i.e. when reversing into my drive, the cap blows and the water takes the line of least resistance, that is instead of going down into the overflow tank it blows out the top of the casting under the radiator cap.


Should the cap have two seals, one on the end of the spring at the bottom of the housing and one just under the cap, it seems logical to me unless i am missing something. Several of you have said I should have two seals but where do you get a cap like that from


Will road test as soon as I can.


Roy


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All coolant problems now sorted, thanks, new correct cap on order, can someone give me a clue as to how much anti freeze I need for a Zetec with a standard GBS radiator,

 

Thanks

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Guest 2b cruising

Richard is correct.

If a good quality undiluted a/f is used, 50/50 with water is good for general use in this country.

Usually works out to around 18' below c.

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