Coolant mystery....<again>!

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Dhammadad

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Apologies first of all as I know this is an Old Chestnut but I have trawled through the forums and can't see a similar issue.

2001 TD5 Auto

Bled system, as per RAVE and all seemed ok. Drives well and heats up as expected.....heater works perfectly and no coolant loss when stop and check. Drove it HARD last night including some demanding hills. Stopped to check and no leaks (visible anyway) and coolant level remained constant at filler line. Drove home and checked again. All good.

Got up this morning and coolant level dropped by an inch. No visible leaks though.

No yogurt in oil and no smoke when starting or driving.

No loss in power and nothing else to report......

Just to reiterate I am pretty damn confident that the system has been vled correctly with no air trapped and no 'waterfall' noise when starting or running......got me beat!

Any ideas?

Cheers!
 
I had a coolant loss mystery on my TD5 90 last year. Like you I had coolant level dropping without obvious cause. Turns out it was the hose from the heat exchanger/fuel cooler to the water pump (I think).. It was rubbing on the chassis and had a micro hole in it. It would blow out coolant when hot but when the engine was off, nothing. I only spotted it when the hole got slightly bigger and there was a small pool of coolant under the engine. Even then I couldn't find the source straight away as the hole was touching the chassis and the coolant was seeping along the chassis before dripping on the floor.
 
Over night loss will be the difference between hot and cold surely! Is it continuing to drop over the following nights?
When I had the td5 coolant issue we all dread I was getting a pressurised coolant system at first. Hard pipes very quickly.
Later had the small pipe under the manifold go, due to the pressure probably.
Then heater intermittently working and loss of fluids.
Took head off put steel dowels in and new gasket (reused everything else) and its been perfect ever since.
You could get a test on the coolant to see if any chemicals are present.
To be fair my coolant was a rusty colour when mine diagnosed itself.
 
Dhammadad said:
Bled system, as per RAVE and all seemed ok.
Click to expand...
The bleeding procedure from RAVE is incomplete and in most cases there is still air in the system in the bypass circuit, as you drove it hard the residual air was dislodged that's why the level dropped IMO. Also it's normal for the level to drop a bit when the system cools down that's why it's named ''expansion" tank. Top up the fluid and see next time and dont be stressed untill then

it's not mentioned but additional to RAVE you have to undo partially the bleed screw with running engine, keep it rev'd above 1500rpm untill no bubbles are coming out then tighten the screw, that's needed cos the mechanical bypass flow valve in the thermostat opens only at 1500 rpm when the flow is harder so at idle it's closed and air can be trapped before or after it. Other important thing is to tighten the tank's cap to maximum possible eventually if you know it's old would be a good move to put a new one cos the pressure valve in it gets "tired" in time
 
sierrafery said:
The bleeding procedure from RAVE is incomplete and in most cases there is still air in the system in the bypass circuit, as you drove it hard the residual air was dislodged that's why the level dropped IMO. Also it's normal for the level to drop a bit when the system cools down that's why it's named ''expansion" tank. Top up the fluid and see next time and dont be stressed untill then

it's not mentioned but additional to RAVE you have to undo partially the bleed screw with running engine, keep it rev'd above 1500rpm untill no bubbles are coming out then tighten the screw, that's needed cos the mechanical bypass flow valve in the thermostat opens only at 1500 rpm when the flow is harder so at idle it's closed and air can be trapped before or after it. Other important thing is to tighten the tank's cap to maximum possible eventually if you know it's old would be a good move to put a new one cos the pressure valve in it gets "tired" in time
Click to expand...

My cooling system has been bang on now for months after following the sierrafery procedure - I had bled the system as per RAVE after a fuel cooler seal issue and obviously still had some air in the system. Of course, the expansion tank is filled to the level mark when the system is cool - it will go slightly above this mark when engine has reached operating temperature only to drop back again once cooled. I originally had leaking from the fuel cooler after the engine had cooled down overnight - seems to be a common problem, especially from the front end of the fuel cooler.
 
tilly2 said:
Was the coolant leak visible at the fuel cooler ?
Click to expand...
Yes, small puddle under the engine in the morning. With the pink/orange OAT coolant, also clearly visible (coolant precipitates) on the top of the driver's side engine mount, where it would also pool (directly below the front of the fuel cooler). New viton o-ring and new clamp fixed it for good.
 
Intestinalworm said:
Yes, small puddle under the engine in the morning. With the pink/orange OAT coolant, also clearly visible (coolant precipitates) on the top of the driver's side engine mount, where it would also pool (directly below the front of the fuel cooler). New viton o-ring and new clamp fixed it for good.
Click to expand...

I saw a bit there too....can you elaborate on how you fixed it - apart from the bleeding procedure? "viton o-ring and new clamp"?

Thanks....
 
Fuel cooler is a small shell-and-tube heat exchanger - this is a thread you might want to read:

https://www.landyzone.co.uk/land-rover/fuel-cooler-leaking-again-and-heater-not-working.365241/

I did this job twice! Not hard, just a little bit fiddly - second time around it was quick and easy and I made sure it was a nice seal (used a narrow band worm drive clamp)!

No need to do the seal at the back of the engine as there was no leak there - that would be trickier to do in any case and likely would necessitate removing the fuel cooler.
 
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