Discovery II TD5 coolant pressurised

geoff edwards · Jul 1, 2017

Simon098 said:
The fan doesn't do much work when on the motorways, so although this is an issue, I don't think it's the underlying one. Have you taken the radiator off and run a hose through it? You should get a good flow. Probably better to fill it from the bottom and see how much overflows. Short of knowing what the cooling efficiency of the TD5 radiator should be (which someone like neilly or sierrafery may know?) so you can measure inlet and outlet temperature to tell you if the radiator is working correctly.

Thanks Simon098 I did need a new radiator and had one fitted, I thought I had mentioned that. I don't think the new fan is working properly. I read every post I came across trying to get an understanding of how the viscous fan work. That's why I was puzzled that the fan could be spun really easily after getting home with the engine overheating. The engine was very hot, so why wasn't the fan stiff to operate? Perhaps there was no water left in the radiator so the fan went into a cold engine mode?

Thor1950 · Jul 1, 2017

geoff edwards said:
Thanks Simon098 I did need a new radiator and had one fitted, I thought I had mentioned that. I don't think the new fan is working properly. I read every post I came across trying to get an understanding of how the viscous fan work. That's why I was puzzled that the fan could be spun really easily after getting home with the engine overheating. The engine was very hot, so why wasn't the fan stiff to operate? Perhaps there was no water left in the radiator so the fan went into a cold engine mode?

Hopefully you had the engine turned off when you spun the fan

Simon098 · Jul 1, 2017

Hopefully this explains it for you.

geoff edwards · Jul 1, 2017

Thor1950 said:
Hopefully you had the engine turned off when you spun the fan

LOL

geoff edwards · Jul 1, 2017

Simon098 said:
Hopefully this explains it for you.

Thanks Simon I had found a good explanation on this forum that was linked to from one of the other 4x4 forum sites. So my explanation is that the fan free wheeled as the radiator had lost so much fluid that it was cold so the valve had closed.

Simon098 · Jul 1, 2017

geoff edwards said:
Thanks Simon I had found a good explanation on this forum that was linked to form one of the other 4x4 forums. So my explanation is that the fan free wheeled as the radiator had lost so much fluid that it was cold so the valve had closed.

More annoyingly, as you may have noticed... The temperature sensor sits at the top of the coolant system, so if it runs dry, the sensor still reports as being normal temperature on the instrument cluster.

Simon098 · Jul 1, 2017

Thor1950 said:
Hopefully you had the engine turned off when you spun the fan

As mentioned earlier, I'm sure a newspaper or magazine was used.

geoff edwards · Jul 1, 2017

I have had a chat with my garage and it looks like I need to bite the bullet and get the head gasket/and cylinder head checked for a leak to the exhaust ports.

sierrafery · Jul 1, 2017

Simon098 said:
More annoyingly, as you may have noticed... The temperature sensor sits at the top of the coolant system, so if it runs dry, the sensor still reports as being normal temperature on the instrument cluster.

not at all, that's a false myth... the sensor will work on steam and temperature transfer through it's body too... if it runs low on coolant the gauge will go to red without any doubt

Bobdog · Jul 1, 2017

geoff edwards said:
I have had a chat with my garage and it looks like I need to bite the bullet and get the head gasket/and cylinder head checked for a leak to the exhaust ports.

Just had a good read through this thread. I had similar symptoms. (Mine was popping top hoses) all linked to a cracked head. If you have overpressure and you are losing coolant then either head gasket or cracked head is the answer. Not what you want to hear but neither did i!
Oh, and the fan doesn't have a "cold mode" it is operated by the engine revs and a viscous fluid inside it. It can't tell how hot or cold your coolant is and also, you can happily run a TD5 with no fan at all.

geoff edwards · Jul 1, 2017

Bobdog said:
Just had a good read through this thread. I had similar symptoms. (Mine was popping top hoses) all linked to a cracked head. If you have overpressure and you are losing coolant then either head gasket or cracked head is the answer. Not what you want to hear but neither did i!
Oh, and the fan doesn't have a "cold mode" it is operated by the engine revs and a viscous fluid inside it. It can't tell how hot or cold your coolant is and also, you can happily run a TD5 with no fan at all.

Thanks Bobdog for having a good read through the post. But my system is no longer subject to pressurisation in the coolant system as it appears that the cap although only 10 months old (I replaced it after having trouble after I had bought the car) had failed and would not release pressure into the overflow system. My hoses had split, possibly due to old age and some oil in the system, but also the extra pressure due to the cap not operating properly. Factors: pump not working as it should, radiator clogged and to be verified; a crack in the head allowing the coolant (one litre every five miles) to leak into the exhaust port. Repairs: new pump, four hoses, new radiator. I agree from what I have read that the car does not seem to need a fan, except under arduous conditions. However the fan was the last item to be checked. As I have mentioned, there is no evidence of a failed head gasket unless it can fail and let coolant enter the exhaust system. There is no coolant in the oil, no oil in the coolant and no exhaust gas in the coolant, all there is, is a loss of coolant, with no leaking hoses. Otherwise the car is fine.

When I first bought the car on driving it away from the garage where I bought it the fuel line split, 30 miles away down the M5. The AA took the car back to the garage and ferried me home. The fault was rectified but I still had trouble with overheating and the head gasket was replaced under warranty. I don't think the garaqe carried out its 131! checks on the car's condition before releasing it for sale.

Bobdog · Jul 1, 2017

geoff edwards said:
Thanks Bobdog for having a good read through the post. But my system is no longer subject to pressurisation in the coolant system as it appears that the cap although only 10 months old (I replaced it after having trouble after I had bought the car) had failed and would not release pressure into the overflow system. My hoses had split, possibly due to old age and some oil in the system, but also the extra pressure due to the cap not operating properly. Factors: pump not working as it should, radiator clogged and to be verified; a crack in the head allowing the coolant (one litre every five miles) to leak into the exhaust port. Repairs: new pump, four hoses, new radiator. I agree from what I have read that the car does not seem to need a fan, except under arduous conditions. However the fan was the last item to be checked. As I have mentioned, there is no evidence of a failed head gasket unless it can fail and let coolant enter the exhaust system. There is no coolant in the oil, no oil in the coolant and no exhaust gas in the coolant, all there is, is a loss of coolant, with no leaking hoses. Otherwise the car is fine.

When I first bought the car on driving it away from the garage where I bought it the fuel line split, 30 miles away down the M5. The AA took the car back to the garage and ferried me home. The fault was rectified but I still had trouble with overheating and the head gasket was replaced under warranty. I don't think the garaqe carried out its 131! checks on the car's condition before releasing it for sale.

So, if you think everything else is fine and you just have a leak somewhere, have you checked the hoses to the heater matrix? Also, have you (or anyone else) cleaned off the corrosion on the top hose connection to the head? They do corrode and make a poor seal. You can usually find coolant leaks due to the orangey-pink residue left by the OAT coolant

Bobdog · Jul 1, 2017

In fact, check all hose clamps. The garage who did my head gasket left the thermostat clamp off!

geoff edwards · Jul 1, 2017

Bobdog said:
So, if you think everything else is fine and you just have a leak somewhere, have you checked the hoses to the heater matrix? Also, have you (or anyone else) cleaned off the corrosion on the top hose connection to the head? They do corrode and make a poor seal. You can usually find coolant leaks due to the orangey-pink residue left by the OAT coolant

Thanks Bobdog. I did of course check for leaks in the heater matrix and elsewhere. In fact I have carried out a dye test utilising an ultra violet torch that I thought I had mentioned. The coolant loss is one litre per 5 miles. A round trip of 64 miles used 12 litres of coolant! I am not joking when I suggest that an expansion tank extension to 20 litres would be useful! The alternative is scrap the car or be prepared to spend hundreds of pounds on repair work, that might not work anyway.

Land Rover state that the cylinder head should not be skimmed. so what is the official solution? to scrap the head and buy a new one? From Spain as they have produced a better head?

Bobdog · Jul 1, 2017

geoff edwards said:
Thanks Bobdog. I did of course check for leaks in the heater matrix and elsewhere. In fact I have carried out a dye test utilising an ultra violet torch that I thought I had mentioned. The coolant loss is one litre per 5 miles. A round trip of 64 miles used 12 litres of coolant! I am not joking when I suggest that an expansion tank extension to 20 litres would be useful! The alternative is scrap the car or be prepared to spend hundreds of pounds on repair work, that might not work anyway.

Well if you're losing that much coolant and there are no leaks, then it has to be through the head or the gasket.

geoff edwards · Jul 1, 2017

do you mean that the head gasket could develop a break that would allow the coolant to enter the exhaust system?

sierrafery · Jul 2, 2017

geoff edwards said:
do you mean that the head gasket could develop a break that would allow the coolant to enter the exhaust system?

i dunno what the man means but i can tell you for sure that it can leak indirectly thrpough the combustion chamber....happened to me that's why i have a shiny new AMC head now as mine leaked through the first inlet port just that the leak was slow as 0.5 L/day

Bobdog · Jul 2, 2017

sierrafery said:
i dunno what the man means but i can tell you for sure that it can leak indirectly thrpough the combustion chamber....happened to me that's why i have a shiny new AMC head now as mine leaked through the first inlet port just that the leak was slow as 0.5 L/day

I meant exactly what you said. I thought that was obvious

Ian M in France · Jul 2, 2017

Hi had same problem with mine but not as bad, tighten head bolts and problem went away I also had other problems with leak in the rad a little time after but that might have been part of the problem the coolant system on the td5 is a pain. I think with the amount of coolant you are loosing it must be the head but might be a good idea to tighten head bolts as you never know and it is not too difficuilt to do

geoff edwards · Jul 2, 2017

Ian M in France said:
Hi had same problem with mine but not as bad, tighten head bolts and problem went away I also had other problems with leak in the rad a little time after but that might have been part of the problem the coolant system on the td5 is a pain. I think with the amount of coolant you are loosing it must be the head but might be a good idea to tighten head bolts as you never know and it is not too difficuilt to do

Thanks Ian I have read that the bolts could loosen as well see: http://forum.landrovernet.com/showthread.php/207836-TD5-Cylinder-Head-Questions
The chap also fitted steel dowels on his 10p engine and I have read that steel dowels could crack the head. I mentioned this to my garage a long time ago and the mechanic said that its not necessary to try to tighten the bolts. To me it would seem obvious that if the gasket can be compressed it could stop any leaks. When the head gasket was replaced last year under warranty perhaps they reused the head bolts and this is not recommended as they can stretch.

Discovery II TD5 coolant pressurised

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