The mystery of the disappearing coolant

Christopher · 9th October 2007, 08:27

As some of you may know I have been noticing the coolant level dropping in my 1.8 dropping for a while now - with me having to top-up frequently. At Holker Hall I was convinced that it might be just me overfilling the header tank (although it had always been at that "high" level before). Since Holker Hall I have not topped up and just observed the level - it has steadily gone down - the idea would be that it would stabilise at or just above the MAX level. To my dismay this morning the level was below the max and close to the min!! :SHOCKED:

I am not a happy bunny

There appears to be no obvious leak - I am constantly on the look out for stains and the like. Oil filler cap appears clear, car runs OK ...

SO ... what next?? It is clearly not just me overfilling, the coolant is going somewhere ... but where?!?

So what do I do next??

pondweed · 9th October 2007, 08:49

buy a bottle of gin and celebrate impending 1.8 doom?
or put the purchase price of the above towards the "Garage fund"?
sorry not to be more positive...

BUT, aaah

have you checked the expansion cap, or a nice cheap hose, is not faulty first?

Christopher · 9th October 2007, 08:50

waay to be positive pondweed!!

Expansion cap (and header tank) have both been replaced (for a different reason) ... as for hose, which one?!

Tom Collins · 9th October 2007, 09:04

I had 2 hoses replaced. Not sure which though. Just before the head gasket went.

What about the inlet manifold gasket? That's what did for me.

Christopher · 9th October 2007, 09:12

Quote:

Originally Posted by collit

I had 2 hoses replaced. Not sure which though. Just before the head gasket went.

What about the inlet manifold gasket? That's what did for me.

Thanks Collit - I will collate a list of possible suspects, but cannot really do any of this myself ... the system has been pressure-tested with no apparent leaks too BTW.

Departed · 9th October 2007, 12:04

Once had a Rover 827 like this. The water pump seal would leak when cool, but not when hot. So when cold, no pressure equalled no leak, when hot, no leak even under pressure.

Maybe the same thing?

BTW still have the replacement water pump for the 827, even though the car is long gone.

sworks · 9th October 2007, 18:09

most common things are inlet manifold gasket as allready said - these were modified and the colour changed from black to green. If this leaks it is generally when stood over night and is fine when running. The water pumps are prone too, have a look around the bottom pulley for signs of leaking as it can generally be seen here

Christopher · 9th October 2007, 18:11

Quote:

Originally Posted by sworks

most common things are inlet manifold gasket as allready said - these were modified and the colour changed from black to green. If this leaks it is generally when stood over night and is fine when running. The water pumps are prone too, have a look around the bottom pulley for signs of leaking as it can generally be seen here

Thanks - I will take a look. I remember you telling me about the inlet manifold gasket now - although there is nothing I personally can do about it. Looks like I will have to go to my local dealer.

Fraser Mitchell · 9th October 2007, 21:54

The failed inlet manifold gasket on the wife's 25 showed itself initially as a very small damp patch underneath the car overnight. This got steadily worse until you could see the coolant creeping round the RH side of the block at the head gasket. I initially thought it was HGF, (and was worried as this had been done not 6 months previously).

Searching around at night with a mirror and a torch showed the coolant creeping down from the manifild gasket. New gasket and hey presto, end of coolant loss !

Water pump usually shows up as a puddle under the car.

If its HGF there are normally other symptoms like oil in the coolant, if it's blown at the cylinder head oil feed, or excessive pressure in the coolant if a cylinder is venting into the coolant. This is usually not released overnight. Normally when the engine cools overnight the coolant water vapour that has displaced the air causes a slight vacuum and the expansion tank cap allows atmospheric pressure back into the tank ready for the cycle to start all over again. Withe excess coolant pressure this can prevent a return to normal atmospheric pressure on cooling. I had this type of failure on an Jag XK engine with a cracked block which failed the HG

So if there is definitely pressure in the expansion tank at cold you could have HGF.

9th October 2007, 08:27	#1
Christopher Owners Club Director Rover 75 V6 Copperleaf Red, MG ZTT 190+ Lagoon & Early MGF Join Date: Oct 2006 Location: Rugby Posts: 9,287 Thanks: 105 Thanked 343 Times in 81 Posts	The mystery of the disappearing coolant As some of you may know I have been noticing the coolant level dropping in my 1.8 dropping for a while now - with me having to top-up frequently. At Holker Hall I was convinced that it might be just me overfilling the header tank (although it had always been at that "high" level before). Since Holker Hall I have not topped up and just observed the level - it has steadily gone down - the idea would be that it would stabilise at or just above the MAX level. To my dismay this morning the level was below the max and close to the min!! :SHOCKED: I am not a happy bunny There appears to be no obvious leak - I am constantly on the look out for stains and the like. Oil filler cap appears clear, car runs OK ... SO ... what next?? It is clearly not just me overfilling, the coolant is going somewhere ... but where?!? So what do I do next?? __________________ Christopher in banana veritas

9th October 2007, 08:50	#3
Christopher Owners Club Director Rover 75 V6 Copperleaf Red, MG ZTT 190+ Lagoon & Early MGF Join Date: Oct 2006 Location: Rugby Posts: 9,287 Thanks: 105 Thanked 343 Times in 81 Posts	waay to be positive pondweed!! Expansion cap (and header tank) have both been replaced (for a different reason) ... as for hose, which one?! __________________ Christopher in banana veritas

9th October 2007, 09:04	#4
Tom Collins Posted a thing or two Mondeo 2.0 cdti Ghia Auto Join Date: Jan 2007 Location: Leicester Posts: 1,731 Thanks: 0 Thanked 0 Times in 0 Posts	I had 2 hoses replaced. Not sure which though. Just before the head gasket went. What about the inlet manifold gasket? That's what did for me. __________________ In vino veritas [SIGPIC][/SIGPIC] Does Magna Carta mean nothing to you? Did she die in vain?

9th October 2007, 18:09	#7
sworks Been absent for a while… Rover 75 Tourer, Classic mini Cooper S, Abarth 595 competizione, MG TF and a Hyundai Tucson PHEV Join Date: Feb 2007 Location: Cumbria Posts: 13,065 Thanks: 1,033 Thanked 1,686 Times in 1,040 Posts	most common things are inlet manifold gasket as allready said - these were modified and the colour changed from black to green. If this leaks it is generally when stood over night and is fine when running. The water pumps are prone too, have a look around the bottom pulley for signs of leaking as it can generally be seen here __________________ ................................................. 'Marmite' Possibly one of the most famous 75 tourers produced! left the production line as the last of only Three Rover 75 tourers produced in Trophy Yellow. 48 hours later Longbridge closed. The last sold ordered 75 Tourer. Paid for by the Phoenix Four and handed over by John Towers to the Warwickshire Northampton Air ambulance service as a Rapid Response vehicle

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9th October 2007, 08:49	#2
pondweed This is my second home Waiter, Waiter! I seem to have a Roomster in my drive... Join Date: Nov 2006 Location: Sussex Posts: 3,268 Thanks: 0 Thanked 1 Time in 1 Post	buy a bottle of gin and celebrate impending 1.8 doom? or put the purchase price of the above towards the "Garage fund"? sorry not to be more positive... BUT, aaah have you checked the expansion cap, or a nice cheap hose, is not faulty first?

9th October 2007, 12:04	#6
Departed Retired -- Join Date: Jan 2007 Location: -- Posts: 3,785 Thanks: 0 Thanked 4 Times in 4 Posts	Once had a Rover 827 like this. The water pump seal would leak when cool, but not when hot. So when cold, no pressure equalled no leak, when hot, no leak even under pressure. Maybe the same thing? BTW still have the replacement water pump for the 827, even though the car is long gone.

9th October 2007, 21:54	#9
Fraser Mitchell Gets stuck in Rover 75 2.5 V6 Club Auto Join Date: Feb 2007 Location: Crewe Posts: 898 Thanks: 0 Thanked 0 Times in 0 Posts	The failed inlet manifold gasket on the wife's 25 showed itself initially as a very small damp patch underneath the car overnight. This got steadily worse until you could see the coolant creeping round the RH side of the block at the head gasket. I initially thought it was HGF, (and was worried as this had been done not 6 months previously). Searching around at night with a mirror and a torch showed the coolant creeping down from the manifild gasket. New gasket and hey presto, end of coolant loss ! Water pump usually shows up as a puddle under the car. If its HGF there are normally other symptoms like oil in the coolant, if it's blown at the cylinder head oil feed, or excessive pressure in the coolant if a cylinder is venting into the coolant. This is usually not released overnight. Normally when the engine cools overnight the coolant water vapour that has displaced the air causes a slight vacuum and the expansion tank cap allows atmospheric pressure back into the tank ready for the cycle to start all over again. Withe excess coolant pressure this can prevent a return to normal atmospheric pressure on cooling. I had this type of failure on an Jag XK engine with a cracked block which failed the HG So if there is definitely pressure in the expansion tank at cold you could have HGF.