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Newts

Coolant Levels

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I've only been driving the car about once a week since being made redundant and got used to topping up the header tank in the boot which normally drops to the bottom of the tank. I was wondering where the water was going, but the car kept working with no issues so I assumed a minor leak somewhere.

Went to top up the other day and the tank was completely full and had even overflowed a bit.

The car still maintains temp as normal and there is no change in oil level

Anybody got any ideas ? :santa:

Edited by Newts

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I had the same problem and it was caused by rust on the bottom of the header tank. although it looked solid was very porous when under pressure..... I found it when I stuck a finger through the bottom of the tank whilst investigating.....

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I found that to ensure the right level of coolant was in the car and prevented the need from constant topping you should fill the coolant header tank then also put coolant in the expansion tank. IIRC I half filled this as well. It sounds like you've just topped up to much coolant that has been pushed out to the expansion tank - which has then been drawn back into the cooling system once it cooled.

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Thanks for the comments guys

The tank in the engine bay has been replaced with an ali one and on one occasion when I lost water and got a low water light on the dashboard I topped that up, only to find a personal pond in the boot. To check whats happening I have the drain pipe going into a plastic container currently so I see what has been expelled. The levels are still up and down which is a little hard to understand :(

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Hi!

Just wondering how you got on, as mine seems to be doing the same thing?

Does not look like the Cylinder Head Gasket has gone, but every time it heats up the cooling system is pushing the coolant into the

expansion bottle,until it overflows. It does not seem to return afterwards (presumably because it is lower).

There is no over pressure in the cooling system when running cold only when it heats up and especially immediately after stopping the car,

Strange!

Thanks

Kenny

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Just a thought guys, the cap on the canister in the engine bay has no pressure spring there is no resistance to pushing water into the header tank in the boot. The header tank cap has pressure relief spring in it 13 PSI or there abouts, don't quote me, the natural cool level in the header for mine is actually about half way from the "mark" to the bottom of the tank if I top the tank up to the mark it just pushes it out again.

Also check for air in the system, I believe there is a bleed technique but I'm not familiar with it. And the condition of the radiator.

Roger

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Hi!

Just wondering how you got on, as mine seems to be doing the same thing?

Does not look like the Cylinder Head Gasket has gone, but every time it heats up the cooling system is pushing the coolant into the

expansion bottle,until it overflows. It does not seem to return afterwards (presumably because it is lower).

There is no over pressure in the cooling system when running cold only when it heats up and especially immediately after stopping the car,

Strange!

Thanks

Kenny

Now the warmer weather is here, my 88 Turbo appears to be doing the same thing. When the system is hot, coolant is being pushed out of the engine bay mounted header tank, into the plastic expansion tank and then overflows onto the ground. When the engine has cooled down, the white plastic expansion tank is full and the header tank in the engine bay is almost empty, I sometimes get a low coolant light. The coolant doesn't seem to be getting drawn back from the expanion tank to the header tank when it all cools down for some reason.

The Service manual sates that the white plastic bottle should have a 15psi pressure cap fitted, and the black header tank should have a blanking cap. I have read some threads here though that suggest the pressure cap should be on the header tank which is quite confusing.

Today somebody told me when stopped at traffic lights that coolant was dribbling from the rear of the car, when I got home it was still dribbling and stopped about 10 minutes after I got home. Again the expansion tank was full, and the header tank was very low when it all cooled down. I will replace the pressure cap and see if it cures the problem.

Edited by stevem

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The 15psi cap goes onto the expansion tank and the plain cap onto the header tank. You should not be able to overfill with coolant as the system finds it's own level. If the coolant is not being drawn back into the header tank then check for leaks as it sound like air is possibly getting drawing into the header tank rather than coolant being drawn back from the expansion tank during cooling down.

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Re the caps on the expansion and header tanks

From what I have seen, some designs have the sprung cap on the expansion tank and a plain cap on the header tank and some have the plain cap on the expansion tank and the sprung cap on the header tank.

S4s's have the sprung cap on the header tank which is opposite to what is being discussed here.

So anyone reading this take care as designs do change....

Glyn

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Re the caps on the expansion and header tanks

From what I have seen, some designs have the sprung cap on the expansion tank and a plain cap on the header tank and some have the plain cap on the expansion tank and the sprung cap on the header tank.

S4s's have the sprung cap on the header tank which is opposite to what is being discussed here.

So anyone reading this take care as designs do change....

Glyn

I am still having this coolant expansion problem and have tried the caps both ways round ! Only on hot days ( 30 + ) that involve a fairly long drive, the coolant is pushed out of the header tank into the expansion tank, about a pint / half litre, but doesn't get sucked back in when the system cools down. I have checked all the hoses and clips for leaks but can't find anything. I syphon the excess out when required and put it back into the header tank again.

On cool days or short journeys it doesn't seem to happen as the coolant doesn't get so hot and stays in the header tank/system. With regard to the temperaure gauge readings - on cooler days the temp gauge is a steady 80-85, on hot days it reads 90-95 with the fans kicking in if I get stuck in traffic. No overheating as such though, it never gets to 100 as the fans bring the temp down from 95-ish very quickly.

The system has been flushed out and new coolant added, it's been 'burped' on a very steep hill and both the 16psi recovery cap and blanking caps are new. Thermostat has been tested and works ( you can actually see the temp gauge drop from 80 to 75 for a short while when it opens) and the radiator fins are clear of debris. Any other ideas ?

Most coolant recovery systems seem to have the pressure cap on the main header tank and the blank cap on the plastic expansion bottle, the Lotus service manual and owners manual quote the reverse. Either way, it doesn't seem to make any difference.

Edited by stevem

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Had similar problems some years ago but before I had the Esprit. It turned out to be a weak spring on the cap allowing water to escape under very low pressure. Replace the caps - should not be that expensive and then you will know for certain if its something more serious.

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I too had a similar issue with my S4. I checked the hoses, radiators, water pump, header tank, and expansion tank with video scope at standstill cold and at running hot. Replaced the blanking cap and the pressure cap. Still same thing...loss of coolant...

Discovered the mystery for me when after a long drive...reason for not finding a physical leak was that the antifreeze was being boiled off the heat shield. The turbo coolant feed tube had chafed against the heat shield resulting in the following:post-4361-125950609384_thumb.jpg

I repaired temporarily whilst awaiting for the new part. Since then all levels have stayed normal

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