Defender 200tdi loosing coolant

Hi all

Having coolant problems with my 200tdi defender engine. Have been loosing coolant for a while now and replaced the gasket between the thermostat housing and block, then after still leaking took it to my mechanic during the week who pressure tested it, found a few leaks which we fixed with new jubilee clips. We then depressurised the system and it held the pressure so assumed everything was grand. Took it for a long drive today however and she is still loosing coolant and had to stop multiple times to top up. The header tank is not pressuring only a tiny hiss when I open it also the oil seems perfectly normal not emulsified. Other points to note:

Radiator has not been replaced by me but looks like a fairly new aluminium one
Water pump replaced
Heater matrix replaced
Header tank replaced

Has anyone any ideas where my coolant could be going?

Thanks in advance

Get some UV dye To look for external leaks

could be going Into a cylinder, and exhaust symptoms?

What would be the symptoms of it leaking into a cylinder. Might get it pressure tested again to double check and rule an external leak out

Mine leaked into a cylinder I think. I had a coolant loss problem, with no external leaks, and swapping the head fixed it. The only symptom I had was an occasional lumpiness to the starting, which I put down to a small amount of water settling in the bore as it sat on a compression stroke.

Was the water in your oil or was it pressurising the coolant system then? Starting to panic now I'm having the same symptoms she sometimes sounds like she's not going to start then won't rev hard for a minute or 2. Generally after that she's fine however I went on a longer drive yesterday (150 miles+) and when I got close to home she started to idle real rough and would stall if left long enough. I thought the idle screw on the injector pump may have come loose however by the sound of things my problem could be much more serious

Simple thing first, where are you filling the coolant up to?

Some coolant leaks can be a right bugger to find.
If you think about it the 200 system is as simple as it gets, engine/rad/heater and some hoses joining the lot together.
The 200 heads can crack between the valve seats, though I have not seen once lose coolant because of it.


Ref the nearly cutting out
Is the fuel old?
Have you checked/changed the fuel filter?
Have you replaced the lift pump?

Filling the coolant up to half way in the header tank, basically just to the top of the we + shaped post as you look in.

Had it pressure tested and found a couple of hose clamps loose which I replaced and she then held the pressure, but she's still loosing coolant. Going to get it pressure tested again to double check.

Fuel is only a week old and was filled up from half the day I had the problem. Fuel filter was changed a couple of thousand miles ago tho might do it again to be sure. Lift pump has not been replaced so that might be an issue. How would I go about testing it?

Ryan_mag said:

Filling the coolant up to half way in the header tank, basically just to the top of the we + shaped post as you look in.

Had it pressure tested and found a couple of hose clamps loose which I replaced and she then held the pressure, but she's still loosing coolant. Going to get it pressure tested again to double check.

Fuel is only a week old and was filled up from half the day I had the problem. Fuel filter was changed a couple of thousand miles ago tho might do it again to be sure. Lift pump has not been replaced so that might be an issue. How would I go about testing it?

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Did you remove the plug in the top of the radiator when you filled up with water/coolant?

Got to ask -------- are you confident the filler cap is holding pressure ?

mick 1986 said:

Did you remove the plug in the top of the radiator when you filled up with water/coolant?

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I did originally however not since it started loosing water I've just been topping it up. What would be the correct procedure to bleed the coolant?

frog hopper said:

Got to ask -------- are you confident the filler cap is holding pressure ?

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Yea the expansion tank and cap are new as I wanted to rule this out

Thanks for all the replies so far!

Ryan_mag said:

Filling the coolant up to half way in the header tank, basically just to the top of the we + shaped post as you look in.

Had it pressure tested and found a couple of hose clamps loose which I replaced and she then held the pressure, but she's still loosing coolant. Going to get it pressure tested again to double check.

Fuel is only a week old and was filled up from half the day I had the problem. Fuel filter was changed a couple of thousand miles ago tho might do it again to be sure. Lift pump has not been replaced so that might be an issue. How would I go about testing it?

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Thats the corretc coolant level, I was checking just in case you were brimming it.

There has been lots of dodgy derv about in the south of england causing all sorts of filter issues, not sure where irish fuel comes from? but might be worth changing the filter just to be sure.

When you change the filter, if the old filter is not full thats a good sign the lift pump is on its way.

Ryan_mag said:

I did originally however not since it started loosing water I've just been topping it up. What would be the correct procedure to bleed the coolant?


Yea the expansion tank and cap are new as I wanted to rule this out

Thanks for all the replies so far!

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Personally, I remove the radiator plug every time I fill up with coolant. If the plug is out, and coolant is already at the top, it can’t have an airlock in the radiator.

mick 1986 said:

Personally, I remove the radiator plug every time I fill up with coolant. If the plug is out, and coolant is already at the top, it can’t have an airlock in the radiator.

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+1. Definitely the correct way to top up even if it’s a pain in the arse,

Ryan_mag said:

What would be the symptoms of it leaking into a cylinder. Might get it pressure tested again to double check and rule an external leak out

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white smoke out the exhaust

flat said:

white smoke out the exhaust

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This +1, and if there's coolant getting into the cylinder/s under combustion it will be quite noticeable

Ryan_mag said:

Was the water in your oil or was it pressurising the coolant system then? Starting to panic now I'm having the same symptoms she sometimes sounds like she's not going to start then won't rev hard for a minute or 2. Generally after that she's fine however I went on a longer drive yesterday (150 miles+) and when I got close to home she started to idle real rough and would stall if left long enough. I thought the idle screw on the injector pump may have come loose however by the sound of things my problem could be much more serious

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Mine showed no water in oil or oil in water, and no pressurisation of the cooling system. No smoke out of the exhaust either, I figured it was a very small leak. Over a journey of a few hundred miles it would drop maybe 1/2” in the header tank.

Retroanaconda said:

I figured it was a very small leak.

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where was the leak? this may help @Ryan_mag and others

lynall said:

Thats the corretc coolant level, I was checking just in case you were brimming it.

There has been lots of dodgy derv about in the south of england causing all sorts of filter issues, not sure where irish fuel comes from? but might be worth changing the filter just to be sure.

When you change the filter, if the old filter is not full thats a good sign the lift pump is on its way.

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I've ordered a fuel filter so will try that and report back

flat said:

white smoke out the exhaust

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There's a wee bit at times when starting but not noticeable when driving however was stuck in traffic only ticking over for about 45 mins at the weekend, and when I gave her a big rev there was a puff of white smoke.

Will pull the radiator cap out later and top the coolant up and see what happens

Ryan_mag said:

I've ordered a fuel filter so will try that and report back


There's a wee bit at times when starting but not noticeable when driving however was stuck in traffic only ticking over for about 45 mins at the weekend, and when I gave her a big rev there was a puff of white smoke.

Will pull the radiator cap out later and top the coolant up and see what happens

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Do not condemn it on the smoke colour just yet.
Injection pump timing slightly retarded can also make white smoke at cold start and long periods of ticking over.

yeah what lynall said, its jsut a potential symptom coupled with others as part of the bigger picture fault finding. I think you have coolant going into a cylinder though tbh.