Where does the water go (2.5V6)?

Forestgreen · 16th May 2016, 20:52

Fresh from my recent broken driveshaft disaster I would really appreciate advice about a slow coolant leak that I've noticed in recent months.

Going back to last autumn Terry (TS Autos) replaced my thermostat (2.5V6 auto) as it turned out to have a slow leak resulting in an overheat warning and prompt pulling off the road for a top-up. He also replaced the radiator as he had noticed a few stains of coolant and advised it should be replaced. Apart from that I never really felt I had to top the coolant up much and didn't really keep a close eye on it. That changed when a few weeks ago the red overheat warning light came on and the thermometer needle suddenly shot from 9 o'clock which is its normal position, to midnight. I stopped right away and waited until the engine was completely cold before topping up with about 1.5 litres.

Since then I've been checking every week and finding that I have to pour in a small amount say 50-100ml at a time. So I took it back to Terry who had a very thorough look over the engine and said he couldn't see any possible cause of the leak, and he suggested that the water filler cap O-ring might be dodgy and thus be letting water evaporate off slowly. He fitted new O-rings to the cap. Also, as I can't easily read when the coolant is covering the "max" line I tend to slightly overfill the yellow plastic chamber, and he reassured me that I was probably just filling it a bit too much and it was finding its own level, so no need for me to be so paranoid. For the record, when I drive with on board diagnostics activated, the water temp runs at between 93 and 99 degrees Centigrade.

I waited a month before checking again - and had to top up with 500ml this time, which is rather a lot more than I would have expected if it was just supposed to blow off a small amount above the max line.

So I'll throw the question out to the knowledgeable forum and see if anyone can advise me further. Is it normal to have to check the water levels and top up once a month or more on a V6 (apart from the two leaking thermastats that I've had since buying the car, I've never had to top it up until recently). Where might water be leaking from if a thorough going over by an expert like Terry can't spot it?

One more thing - my cambelt is due another replacement in 2017, is it worth bringing that forward to this year and doing the water pump at the same time in case the water pump is starting to go?

motmann · 16th May 2016, 21:38

recently ive had two kv6 engines losing small amounts of water even after waterpump,belts, stat and pipework radiator etc, the problem in the end in both cases was the water temp sender in the "v" next to the stat housing, the sender was leaking between the plastic of the switch and the brass of the body.........

Jules · 16th May 2016, 21:51

What are you calling the max level?
A lot of owners overfill the header tanks.

Correct level is bottom of fins.............not the top. (see photo below)

Also RHS (driver's side) of radiator is favourite for slow leaks where the plastic end is crimped on.

Jules

Forestgreen · 16th May 2016, 22:04

Thanks Jules, helpful photo outlining the difficulty....

Open the cap (when engine is cold) and I can't see any water.

Add even a small amount via funnel and immediately as it drains away into the system the bottom of the header tank gets a bit of water on it, making it well nigh impossible to tell if it is somewhere between "min" and "max" or that it's wet from having just poured coolant on it. I do tend to fill to just above max so that I can be sure it isn't still draining away - but that wouldn't explain why if I do that every week I add 100ml and after a month without checking I had to pour in 500ml to reach that level!

Jules · 16th May 2016, 22:06

Have you checked the metal coolant rails to the oil cooler?

Corrosion here causes pinholes.

casperdog21 · 18th May 2016, 16:00

Jules makes a good point there as I had a problem with the oil cooler pipes on my v6 I was pleased it was spotted tiny hole on bend of pipe after giving it a good clean more holes came to light.

chris75 · 18th May 2016, 16:32

Quote:

Originally Posted by Forestgreen

Is it normal to have to check the water levels and top up once a month or more on a V6

No , it definitely isn't

I have had my v6 for nearly 12 years and apart from a broken thermostat assembly and a leaking water pump incidents , I don't have to top it up .
If you remove the engine undertray it will help you look for leaks ; a leaking waterpump tends to leave telltale drops of pink coolant hanging from the sump, and wet patches on the drive will confirm you have a leak and may pinpoint the location .

Forestgreen · 18th May 2016, 19:21

Thanks for these ideas - car will be going back to Terry for him to fiddle with the undertray at his leisure. I will post the cause once we sort it out so others can know for future reference.

Lord of Hog · 19th May 2016, 07:48

Can I just add that, after removing the undertray, give everything that is remotely damp or gungy down there a good blast with carb cleaner or suchlike so you're setting off from a defined "point zero" in your search. Water can make its way down and around an engine compartment from point of origin to point of visibility in such a circuitous fashion that you'd scarce believe it. Once you've done that take it for a nice drive then look again. I have a similar slow loss on my 2.5 and, although I'm just about certain it's the water pump, I'm still looking everywhere else in the increasingly vain hope that it's not

SD1too · 19th May 2016, 08:09

Quote:

Originally Posted by Lord of Hog

Water can make its way down and around an engine compartment from point of origin to point of visibility in such a circuitous fashion that you'd scarce believe it.

Very eloquently described too!

Simon

16th May 2016, 20:52	#1
Forestgreen Gets stuck in Rover 75 Connoisseur SE 2.5 V6 saloon Join Date: Dec 2011 Location: Birmingham Posts: 770 Thanks: 47 Thanked 105 Times in 54 Posts	Where does the water go (2.5V6)? Fresh from my recent broken driveshaft disaster I would really appreciate advice about a slow coolant leak that I've noticed in recent months. Going back to last autumn Terry (TS Autos) replaced my thermostat (2.5V6 auto) as it turned out to have a slow leak resulting in an overheat warning and prompt pulling off the road for a top-up. He also replaced the radiator as he had noticed a few stains of coolant and advised it should be replaced. Apart from that I never really felt I had to top the coolant up much and didn't really keep a close eye on it. That changed when a few weeks ago the red overheat warning light came on and the thermometer needle suddenly shot from 9 o'clock which is its normal position, to midnight. I stopped right away and waited until the engine was completely cold before topping up with about 1.5 litres. Since then I've been checking every week and finding that I have to pour in a small amount say 50-100ml at a time. So I took it back to Terry who had a very thorough look over the engine and said he couldn't see any possible cause of the leak, and he suggested that the water filler cap O-ring might be dodgy and thus be letting water evaporate off slowly. He fitted new O-rings to the cap. Also, as I can't easily read when the coolant is covering the "max" line I tend to slightly overfill the yellow plastic chamber, and he reassured me that I was probably just filling it a bit too much and it was finding its own level, so no need for me to be so paranoid. For the record, when I drive with on board diagnostics activated, the water temp runs at between 93 and 99 degrees Centigrade. I waited a month before checking again - and had to top up with 500ml this time, which is rather a lot more than I would have expected if it was just supposed to blow off a small amount above the max line. So I'll throw the question out to the knowledgeable forum and see if anyone can advise me further. Is it normal to have to check the water levels and top up once a month or more on a V6 (apart from the two leaking thermastats that I've had since buying the car, I've never had to top it up until recently). Where might water be leaking from if a thorough going over by an expert like Terry can't spot it? One more thing - my cambelt is due another replacement in 2017, is it worth bringing that forward to this year and doing the water pump at the same time in case the water pump is starting to go?

16th May 2016, 21:51	#3
Jules This is my second home ZT 260 SE Twilight and 10 other 75 ZT's :O Join Date: Jan 2007 Location: Conwy NORTH WALES Posts: 11,094 Thanks: 512 Thanked 1,116 Times in 763 Posts	What are you calling the max level? A lot of owners overfill the header tanks. Correct level is bottom of fins.............not the top. (see photo below) Also RHS (driver's side) of radiator is favourite for slow leaks where the plastic end is crimped on. Jules __________________ [SIGPIC][/SIGPIC] Newbies do now!! 1. Plenum drains..all 3 or 4 year dependent 2. Cooling fan..All speeds functioning 3. Bonnet cable divider block

16th May 2016, 22:06	#5
Jules This is my second home ZT 260 SE Twilight and 10 other 75 ZT's :O Join Date: Jan 2007 Location: Conwy NORTH WALES Posts: 11,094 Thanks: 512 Thanked 1,116 Times in 763 Posts	Have you checked the metal coolant rails to the oil cooler? Corrosion here causes pinholes. __________________ [SIGPIC][/SIGPIC] Newbies do now!! 1. Plenum drains..all 3 or 4 year dependent 2. Cooling fan..All speeds functioning 3. Bonnet cable divider block

19th May 2016, 07:48	#9
Lord of Hog Gets stuck in Rover 75 2.5 V6 in Wedgwood Blue Join Date: Dec 2015 Location: Felbridge, East Grinstead Posts: 982 Thanks: 250 Thanked 294 Times in 206 Posts	Can I just add that, after removing the undertray, give everything that is remotely damp or gungy down there a good blast with carb cleaner or suchlike so you're setting off from a defined "point zero" in your search. Water can make its way down and around an engine compartment from point of origin to point of visibility in such a circuitous fashion that you'd scarce believe it. Once you've done that take it for a nice drive then look again. I have a similar slow loss on my 2.5 and, although I'm just about certain it's the water pump, I'm still looking everywhere else in the increasingly vain hope that it's not __________________ Conformity is not morality. Consensus is not truth.

16th May 2016, 21:38	#2
motmann Loves to post Zt-t cdti 135 zt-t 120 Join Date: Dec 2012 Location: oldbury Posts: 412 Thanks: 10 Thanked 67 Times in 55 Posts	recently ive had two kv6 engines losing small amounts of water even after waterpump,belts, stat and pipework radiator etc, the problem in the end in both cases was the water temp sender in the "v" next to the stat housing, the sender was leaking between the plastic of the switch and the brass of the body.........

16th May 2016, 22:04	#4
Forestgreen Gets stuck in Rover 75 Connoisseur SE 2.5 V6 saloon Join Date: Dec 2011 Location: Birmingham Posts: 770 Thanks: 47 Thanked 105 Times in 54 Posts	Thanks Jules, helpful photo outlining the difficulty.... Open the cap (when engine is cold) and I can't see any water. Add even a small amount via funnel and immediately as it drains away into the system the bottom of the header tank gets a bit of water on it, making it well nigh impossible to tell if it is somewhere between "min" and "max" or that it's wet from having just poured coolant on it. I do tend to fill to just above max so that I can be sure it isn't still draining away - but that wouldn't explain why if I do that every week I add 100ml and after a month without checking I had to pour in 500ml to reach that level!

18th May 2016, 16:00	#6
casperdog21 Avid contributor rover 75 club se Join Date: Aug 2014 Location: sunderland Posts: 150 Thanks: 5 Thanked 5 Times in 5 Posts	Jules makes a good point there as I had a problem with the oil cooler pipes on my v6 I was pleased it was spotted tiny hole on bend of pipe after giving it a good clean more holes came to light.

18th May 2016, 19:21	#8
Forestgreen Gets stuck in Rover 75 Connoisseur SE 2.5 V6 saloon Join Date: Dec 2011 Location: Birmingham Posts: 770 Thanks: 47 Thanked 105 Times in 54 Posts	Thanks for these ideas - car will be going back to Terry for him to fiddle with the undertray at his leisure. I will post the cause once we sort it out so others can know for future reference.