Very mysterious coolant leak V6

martinstranden · 31st May 2017, 20:15

Hi.

I am having a problem with my 75 2.0 V6...

After driving the car and opening the bonnet I can see that water has been pouring out of the "overflow" tube on the expansion tank. I can also hear the water boiling inside the tank for a minute after stopping the motor.

After about 5 rides, I have to add about 1 litre of water/coolant mixture.

- I have tried replacing the coolant filler cap with 2 new ones.

- I was having the idea that the head gasket may be off, leaking exhaust into the water creating overpressure that comes out of the tube.... So I replaced the motor oil today and it looks as it was brand new.

- Oil level is steady at max.

- Water/coolant also looks fine.

- If I let the car rest for 12 hours, I can still feel pressure on the hoses and a satisfying "hiss" when I open the expansion tank cap.

- Water pump replaced 4 months ago.

- Radiator replaced 3 months ago.

- Coolant fan replaced with a Revotech improved fan 2 months ago. (Speeds work fine).

- Temperature is steady at 9 o-clock. Never goes over that.

- Removed inlet manifoil today to closely inspect the entire block for head gasket failure symptoms.. Looks fine.

- No sign of water leaks anywhere. No wet carpet.

- I am pretty certain that over filling is not the issue, as the expansion tank is completely empty after 5 rides.

- Bled the entire coolant system with haynes method several times.

What am I missing out? :-( :-( :-(

Lord of Hog · 1st June 2017, 06:47

The temperature gauge sitting at the halfway point tells you nothing other than that the temperature is somewhere between 75 and 140. Try running the diagnostic just to see what your temperature actually is.

Secondly, when you drained the system did you note how much came out? There are threads on here regarding about 3 litres staying in the system if you drain it using anything other than a high pressure air line, but that still leaves around 5 litres to come out.

If you're absolutely sure you don't have a leak (and I assume you'd done all the obvious things like check the thermostat housing and removed the undertray) then the alternative is that you have a blockage causing your coolant to over heat and vent through the expansion chamber. If your interior heater doesn't work then that's probably the culprit. If a previous owner was overly fond of RadWeld or similar products that could also be the culprit.

kaiser · 2nd June 2017, 14:24

75 to 115 degrees. No reason to start introducing erronous info.

SD1too · 2nd June 2017, 15:09

The first thing to do Martin is to activate the instrument pack diagnostics to find out the exact maximum temperature which the coolant is reaching.

Can you confirm that you followed the Haynes bleeding method exactly, not missing out any operations? Did you raise the expansion tank?

As Lord of Hog says, could anyone have added the dreaded K-Seal to your cooling system?

Simon

martinstranden · 4th June 2017, 18:15

Thanks for the massive response guys :-)

Just a little update!

Since I decided to take the inlet manifold out in order to get a very detailed inspection inside the "V" I figured out that I could do the "VIS-Removal" mod while I had it off.

There has been alot to do at work now, but I have managed to get the inlet manifold properly cleaned and the plastic flaps inside removed.

The store is closed now until tuesday, so I won´t get the car back together until then :-( Need to get some gasket-on-tube in order to get the manifold closed up.

By the way, this is a little off topic but I will try anyway: I managed to break the two rear mounts on the inlet manifold :-( Will it be enough with the 4 bolts at the front?

I have also talked with the previous (and only) owner and he has confirmed that rad-weld has never been put into the car :-)

+ I have purchased a vacuum filler the other day. So when I get the car back together I will try and see if there are any air pockets with it.

Does anyone know if I have to tap all the water out of the car before I use the vacuum filler? Or can I just put it on and it will "suck" air pockets out?

And at last, I can confirm that the heater works fine on both sides.

kaiser · 4th June 2017, 19:01

The bolts will hold the manifold, no problems.
As for vacuum filling, I can't see any problems leaving whatever is in the cooling system and just fill as an addition.

Let us know how it goes.

And, have you opened the manifold and removed the flaps? If so, make sure it is air tight when assembled.

Oh, and let us know about the performance as well

martinstranden · 13th June 2017, 13:51

Ok an update.

Decided to change the gasket on the transmission valve cover so the repair took a little longer than expected.

Tried to take the car to work today, and the performance is just as good as before I took out the VIS valves.

But I got a MAJOR problem after 30kilometers. The engine overheated!

Temperature was between 95-100C and then within 30 seconds it went up to 125C!!!

Foolishly of me I opened the coolant cap and burned my arm so badly that I had to go the the hospital... :-P

Refilled it with water and it was steady between 95-100C until suddenly it spiked up to 120C again.

The last run I had was with defroster ON and temperature setting on HIGH....

I noticed that the hose under the radiator was cold, but the one on top of the radiator was very hot....

What am I missing guys?

Is it a broken head gasket with exhaust leaking into my coolant or is it the thermostat?

SD1too · 13th June 2017, 14:32

Quote:

Originally Posted by martinstranden

I noticed that the hose under the radiator was cold, but the one on top of the radiator was very hot....is it the thermostat?

Yes.

Simon

martinstranden · 13th June 2017, 15:17

Quote:

Originally Posted by SD1too

Yes.

Simon

So you think I should buy a new thermostat?

I am like very close to putting "Bar´s Leak" into it as every mechanic at work sais it has to be the head gasket....

martinstranden · 13th June 2017, 16:16

New thermostat on its way from rimmerbros..

31st May 2017, 20:15	#1
martinstranden Newbie Rover 75 2.0 V6 Auto Join Date: Oct 2016 Location: Skreia Posts: 27 Thanks: 0 Thanked 0 Times in 0 Posts	Very mysterious coolant leak V6 Hi. I am having a problem with my 75 2.0 V6... After driving the car and opening the bonnet I can see that water has been pouring out of the "overflow" tube on the expansion tank. I can also hear the water boiling inside the tank for a minute after stopping the motor. After about 5 rides, I have to add about 1 litre of water/coolant mixture. - I have tried replacing the coolant filler cap with 2 new ones. - I was having the idea that the head gasket may be off, leaking exhaust into the water creating overpressure that comes out of the tube.... So I replaced the motor oil today and it looks as it was brand new. - Oil level is steady at max. - Water/coolant also looks fine. - If I let the car rest for 12 hours, I can still feel pressure on the hoses and a satisfying "hiss" when I open the expansion tank cap. - Water pump replaced 4 months ago. - Radiator replaced 3 months ago. - Coolant fan replaced with a Revotech improved fan 2 months ago. (Speeds work fine). - Temperature is steady at 9 o-clock. Never goes over that. - Removed inlet manifoil today to closely inspect the entire block for head gasket failure symptoms.. Looks fine. - No sign of water leaks anywhere. No wet carpet. - I am pretty certain that over filling is not the issue, as the expansion tank is completely empty after 5 rides. - Bled the entire coolant system with haynes method several times. What am I missing out? :-( :-( :-(

1st June 2017, 06:47	#2
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	The temperature gauge sitting at the halfway point tells you nothing other than that the temperature is somewhere between 75 and 140. Try running the diagnostic just to see what your temperature actually is. Secondly, when you drained the system did you note how much came out? There are threads on here regarding about 3 litres staying in the system if you drain it using anything other than a high pressure air line, but that still leaves around 5 litres to come out. If you're absolutely sure you don't have a leak (and I assume you'd done all the obvious things like check the thermostat housing and removed the undertray) then the alternative is that you have a blockage causing your coolant to over heat and vent through the expansion chamber. If your interior heater doesn't work then that's probably the culprit. If a previous owner was overly fond of RadWeld or similar products that could also be the culprit. __________________ Conformity is not morality. Consensus is not truth.

2nd June 2017, 14:24	#3
kaiser This is my second home 75 Tourer 2.5 Auto, 1.8T, 75V8ZT Join Date: Jun 2007 Location: Johannesburg ZA Posts: 6,200 Thanks: 1 Thanked 859 Times in 613 Posts	75 to 115 degrees. No reason to start introducing erronous info. __________________ Worth his V8 in gold

2nd June 2017, 15:09	#4
SD1too Doesn't do things by halves Rover 75 2.5 Connoisseur Auto (1999) Dealer launch model. Join Date: Mar 2007 Location: Former Middlesex Posts: 20,533 Thanks: 1,587 Thanked 3,749 Times in 3,181 Posts	The first thing to do Martin is to activate the instrument pack diagnostics to find out the exact maximum temperature which the coolant is reaching. Can you confirm that you followed the Haynes bleeding method exactly, not missing out any operations? Did you raise the expansion tank? As Lord of Hog says, could anyone have added the dreaded K-Seal to your cooling system? Simon __________________ "Whatever is rightly done, however humble, is noble." Sir Henry Royce. Last edited by SD1too; 2nd June 2017 at 15:11..

4th June 2017, 18:15	#5
martinstranden Newbie Rover 75 2.0 V6 Auto Join Date: Oct 2016 Location: Skreia Posts: 27 Thanks: 0 Thanked 0 Times in 0 Posts	An update Thanks for the massive response guys :-) Just a little update! Since I decided to take the inlet manifold out in order to get a very detailed inspection inside the "V" I figured out that I could do the "VIS-Removal" mod while I had it off. There has been alot to do at work now, but I have managed to get the inlet manifold properly cleaned and the plastic flaps inside removed. The store is closed now until tuesday, so I won´t get the car back together until then :-( Need to get some gasket-on-tube in order to get the manifold closed up. By the way, this is a little off topic but I will try anyway: I managed to break the two rear mounts on the inlet manifold :-( Will it be enough with the 4 bolts at the front? I have also talked with the previous (and only) owner and he has confirmed that rad-weld has never been put into the car :-) + I have purchased a vacuum filler the other day. So when I get the car back together I will try and see if there are any air pockets with it. Does anyone know if I have to tap all the water out of the car before I use the vacuum filler? Or can I just put it on and it will "suck" air pockets out? And at last, I can confirm that the heater works fine on both sides. Last edited by martinstranden; 4th June 2017 at 18:16.. Reason: Misspelling

4th June 2017, 19:01	#6
kaiser This is my second home 75 Tourer 2.5 Auto, 1.8T, 75V8ZT Join Date: Jun 2007 Location: Johannesburg ZA Posts: 6,200 Thanks: 1 Thanked 859 Times in 613 Posts	The bolts will hold the manifold, no problems. As for vacuum filling, I can't see any problems leaving whatever is in the cooling system and just fill as an addition. Let us know how it goes. And, have you opened the manifold and removed the flaps? If so, make sure it is air tight when assembled. Oh, and let us know about the performance as well __________________ Worth his V8 in gold

13th June 2017, 13:51	#7
martinstranden Newbie Rover 75 2.0 V6 Auto Join Date: Oct 2016 Location: Skreia Posts: 27 Thanks: 0 Thanked 0 Times in 0 Posts	Update Ok an update. Decided to change the gasket on the transmission valve cover so the repair took a little longer than expected. Tried to take the car to work today, and the performance is just as good as before I took out the VIS valves. But I got a MAJOR problem after 30kilometers. The engine overheated! Temperature was between 95-100C and then within 30 seconds it went up to 125C!!! Foolishly of me I opened the coolant cap and burned my arm so badly that I had to go the the hospital... :-P Refilled it with water and it was steady between 95-100C until suddenly it spiked up to 120C again. The last run I had was with defroster ON and temperature setting on HIGH.... I noticed that the hose under the radiator was cold, but the one on top of the radiator was very hot.... What am I missing guys? Is it a broken head gasket with exhaust leaking into my coolant or is it the thermostat? Last edited by martinstranden; 13th June 2017 at 14:17..

13th June 2017, 16:16	#10
martinstranden Newbie Rover 75 2.0 V6 Auto Join Date: Oct 2016 Location: Skreia Posts: 27 Thanks: 0 Thanked 0 Times in 0 Posts	Ordered New thermostat on its way from rimmerbros..