2.5V6 coolant and fan woes - Page 4

T-Cut · 16th September 2016, 10:55

Quote:

Originally Posted by Forestgreen

A few days and 100 miles later, with engine cold (I always check at least 24hrs after last drive) there's a hiss of air as I unscrew the coolant cap and the header is now empty again......

So back to the start of the discussion. There's really only one explanation for it and I suspect you already know what it is.

TC

Forestgreen · 25th September 2016, 15:55

Quote:

Originally Posted by T-Cut

There's really only one explanation for it and I suspect you already know what it is.

TC

Head gasket? Cracked cylinder head? What tests could confirm that in a 2.5 V6?

There are a couple of tests I haven't done - ultraviolet dye to look for external leaks, and is it called a compression test where you remove each spark plug to check for HGF? Are there any other tests I should do before I am forced to either change the engine or scrap what is otherwise a very tidy car? I just topped up 800 mls having driven 150 miles this week starting with the coolant at the maximum reading on a cold engine. Having changed the cambelts and water pump two months ago I'm very reluctant to scrap the car but I cannot limit my driving to short distances.

For the record the oil cap was cleaned about a month ago and this morning there was a small amount of gloop on it:

I put a few drops of oil onto absorbant paper and left for an hour. It looks pretty clear to me:

If all else fails, how quickly could I get an engine swap arranged, and how confident should I be that a replaced engine will be of good enough quality?

SD1too · 25th September 2016, 18:36

Quote:

Originally Posted by Forestgreen

Head gasket? Cracked cylinder head?

David; you can convince yourself of this if you like but the evidence is not there.

Loosing coolant does not equal head gasket failure, or a cracked head. That's just people looking for drama.
The KV6 has MLS gaskets. They're the type supplied to prevent future 1.8 K series head gasket failure. So why do you think they would fail on a V6?

Quote:

Are there any other tests I should do ...

Yes:

Activate the instrument pack digital display of actual coolant temperature as you drive. It should be in the low nineties, but rise to 100 when in stationary traffic.
Does the slow speed fan start at 100 and reduce the temperature to 96? You must check this as your previous posts describing slow and fast speeds as equal volume suggests that there's a fault here.
Is there any coolant leakage in the 'V'? You say not.
Is there mayonnaise on the dipstick or in the expansion tank? A little bit on the oil filler cap does not mean HGF.
With the engine at normal running temperature, is the bottom radiator hose hot to the touch?
When Gavin bled the system, did he drain it first, including the cylinder block drain tap? Did he raise the expansion tank during filling? Did he complete the bleeding and replace the screw before starting the engine? If you're not sure about any of these, you may still have an air lock and that may force coolant out of the system leaving no trace. This sounds very likely when your water pump was recently replaced.

Quote:

... how confident should I be that a replaced engine will be of good enough quality?

Not confident at all. It's crazy to even consider this! If you systematically go through all the possibilities you will eventually find the problem. That's the way forward. Please begin by answering the six questions I have posted above and I will do my best to help.

Simon

Forestgreen · 25th September 2016, 19:59

Hi Simon,

I really appreciate advice on the forum - I actually contacted Jules to see about him taking a look and it was his suggestion that the gasket might have blown or block might be cracked or porous for which the solution would be steel seal or a new engine. Hence why I want to ensure I've eliminated all other options before going down such a dramatic route. As I need a reliable car for my busy job I haven't got heaps of time to visit different mechanics to try different ideas but I do want to get to the bottom of it as the alternative would be a new car!

1. Activate the instrument pack digital display of actual coolant temperature as you drive. It should be in the low nineties, but rise to 100 when in stationary traffic.

Correct - normally goes up to about 102 in stationary traffic then comes down to 93 (except yesterday when it went up to 108 at the end of a motorway run when I was expecting I'd have to to have to top up).

2. Does the slow speed fan start at 100 and reduce the temperature to 96? You must check this as your previous posts describing slow and fast speeds as equal volume suggests that there's a fault here.

Yes.

3. Is there any coolant leakage in the 'V'? You say not.

No.

4. Is there mayonnaise on the dipstick or in the expansion tank? A little bit on the oil filler cap does not mean HGF.

No - just a little bit of slime which I gather is normal for city driving.

5. With the engine at normal running temperature, is the bottom radiator hose hot to the touch?

Putting my hand into a running engine sounds dangerous! Is it accessible?

6. When Gavin bled the system, did he drain it first, including the cylinder block drain tap? Did he raise the expansion tank during filling? Did he complete the bleeding and replace the screw before starting the engine? If you're not sure about any of these, you may still have an air lock and that may force coolant out of the system leaving no trace. This sounds very likely when your water pump was recently replaced.

He assures me he did everything to the letter, and he drove the car quite a while after changing and found nothing amiss. Having put probably 5 litres of coolant into the engine since the water pump change and found that if the car overheats I need to add 1.5 litres to get the coolant back to maxium, I can't believe I could have driven out the workshop with a couple of litres of coolant in the system without the engine blowing up if I've put in five litres since the pump was changed and the whole system only takes seven. However, if you are suggesting that an air bubble can somehow force coolant out (but from where?), then it makes sense as to why draining and filling again might cure what seems to be a leak (waiting to visit Tom to show me what to do).

If you think coolant is leaking from somewhere other than block or gasket, presumably an ultraviolet dye would show where it's coming from or being blown off from (pump, thermostat housing or coolant valve? If so shouldn't that be the next step?

Many thanks for all suggestions.

T-Cut · 25th September 2016, 22:20

You said there's always residual pressure released from the stone cold cooling system. I'd strongly suggest doing the residual pressure test properly and make a conclusion on that if possible.

Test Method
With engine stone cold, check and adjust coolant level as necessary. Ensure it's at the standard MAX mark at the bottom of the fins in the header tank.

Drive the car normally for the day, covering whatever mileage you normally cover - it should be at least 10 miles with mixed slow and fast driving.

Without touching anything, park up and leave the car overnight.

Next day, open the coolant filler cap and note if there's any release of pressure. There shouldn't be anything audible. (The typical day to day variation in atmospheric pressure and temperature doesn't cause anything audible).

If there is indeed residual pressure, it has to be explained.

TC

SD1too · 25th September 2016, 23:24

Many thanks David for your swift and clear replies to the questions I asked.

Quote:

Originally Posted by Forestgreen

... except yesterday when it went up to 108 at the end of a motorway run...

Right, well straight away there's something wrong here. You say that the fan starts running at 100°C, which is correct, so it's failing to cool the engine. This could be because the thermostat isn't opening properly or that your oil cooler is partially blocked. Both these can happen to the KV6. I'd like to know how the bottom radiator hose feels for temperature. It's the one containing the bleed screw. Provided that the engine is at running temperature you can stop it running before you carry out the test if you prefer. It should feel very hot, almost the same as the top hose. If it's cool, there's a problem.

Don't, whatever you do, put anything with the word 'seal' into your engine. There is a real danger that it will bung up parts which are supposed to be free moving, causing you even more problems. Using those products amount to 'papering over the cracks'.

You, or a previous owner or garage, hasn't already done this I take it?

Simon

Forestgreen · 25th September 2016, 23:56

T-cut, yes several times I've topped the engine up to the maximum line cold (ie first thing in the morning having not driven it the day before), driven it, left it overnight and checked the levels. They are down (as I've said) but there is always a hissing as I open the coolant cap. Not sure if that represents air entering a vacuum, or whether there is a residual high pressure in the header tank.

SD1 - I've never added any sealant in the five years I've owned the car. Can't speak for previous owners as I bought it with a coolant leak (thermostat). Jules said steel seal was the only sealant he'd suggest putting in a V6.

When I said the engine temperature display reached 108, that was only momentarily and whilst accelorating up a hill the end of the journey. Most of the time it sat at 93 when the engine wasn't under load, and never went beyond 103 when idling at traffic lights. As I had lost nearly a litre of coolant by the time it shot up to 108 it didn't surprise me. As far as we can work out the fan is behaving OK - it certainly comes on in the demist test and when triggered by T4 so Terry thought it was something of a red herring.

SD1too · 26th September 2016, 08:05

Quote:

Originally Posted by Forestgreen

When I said the engine temperature display reached 108, that was only momentarily ..

It doesn't matter. It should never reach 108°.

Quote:

... and never went beyond 103 when idling at traffic lights.

It shouldn't do that either. As soon as it reaches 100° the fan should start and bring the temperature down to 96° in about one minute.

Your engine is overheating. It's losing coolant because you either have an undetected leak or it's being ejected through the expansion tank cap. You need to find the cause of the overheating. I've told you where to start; with checking the temperature of the bottom radiator hose. Stop speculating about head gasket failure and cracked blocks and don't put Steel Seal in the engine no matter who tells you to! That is not the way to find out what is wrong and effect a permanent repair.

Edit: I've just thought of another test you can do. With the engine cold remove the expansion tank cap and ensure that the level is no higher than the 'max' marker insdie the tank. Now start the engine and watch the level. Is it bubbling? Does it rise up towards the neck of the tank?
You should also see a steady stream of coolant entering the tank neck from the small diameter cylinder head bleed hose. If you don't, there's air in the system.

Simon

T-Cut · 26th September 2016, 11:19

Quote:

Originally Posted by Forestgreen

- - - but there is always a hissing as I open the coolant cap. Not sure if that represents air entering a vacuum, or whether there is a residual high pressure in the header tank.

It's pressure being released. The pressure cap incorporates a hair spring vacuum valve that allows air in as necessary. The slightest vacuum will open it. The only way the cooling system pressure can be higher than atmospheric after it's cooled down is from exhaust gas. This and the regular loss of coolant doesn't bode too well I'm afraid.

TC

p2roverman · 26th September 2016, 11:25

An annoying continual coolant loss on my KV6 was found to be a pinhole in the rubber hose to the heater. Where it passes the battery box it should be supported in a hook. Mine wasn't and had dropped and rubbed against the suspension mount.

Such leaks can be only be found when the engine is running with the system up to working pressure.

25th September 2016, 19:59	#34
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	Hi Simon, I really appreciate advice on the forum - I actually contacted Jules to see about him taking a look and it was his suggestion that the gasket might have blown or block might be cracked or porous for which the solution would be steel seal or a new engine. Hence why I want to ensure I've eliminated all other options before going down such a dramatic route. As I need a reliable car for my busy job I haven't got heaps of time to visit different mechanics to try different ideas but I do want to get to the bottom of it as the alternative would be a new car! 1. Activate the instrument pack digital display of actual coolant temperature as you drive. It should be in the low nineties, but rise to 100 when in stationary traffic. Correct - normally goes up to about 102 in stationary traffic then comes down to 93 (except yesterday when it went up to 108 at the end of a motorway run when I was expecting I'd have to to have to top up). 2. Does the slow speed fan start at 100 and reduce the temperature to 96? You must check this as your previous posts describing slow and fast speeds as equal volume suggests that there's a fault here. Yes. 3. Is there any coolant leakage in the 'V'? You say not. No. 4. Is there mayonnaise on the dipstick or in the expansion tank? A little bit on the oil filler cap does not mean HGF. No - just a little bit of slime which I gather is normal for city driving. 5. With the engine at normal running temperature, is the bottom radiator hose hot to the touch? Putting my hand into a running engine sounds dangerous! Is it accessible? 6. When Gavin bled the system, did he drain it first, including the cylinder block drain tap? Did he raise the expansion tank during filling? Did he complete the bleeding and replace the screw before starting the engine? If you're not sure about any of these, you may still have an air lock and that may force coolant out of the system leaving no trace. This sounds very likely when your water pump was recently replaced. He assures me he did everything to the letter, and he drove the car quite a while after changing and found nothing amiss. Having put probably 5 litres of coolant into the engine since the water pump change and found that if the car overheats I need to add 1.5 litres to get the coolant back to maxium, I can't believe I could have driven out the workshop with a couple of litres of coolant in the system without the engine blowing up if I've put in five litres since the pump was changed and the whole system only takes seven. However, if you are suggesting that an air bubble can somehow force coolant out (but from where?), then it makes sense as to why draining and filling again might cure what seems to be a leak (waiting to visit Tom to show me what to do). If you think coolant is leaking from somewhere other than block or gasket, presumably an ultraviolet dye would show where it's coming from or being blown off from (pump, thermostat housing or coolant valve? If so shouldn't that be the next step? Many thanks for all suggestions.

25th September 2016, 22:20	#35
T-Cut This is my second home Rover75 and Mreg Corsa. Join Date: Nov 2006 Location: Sumweer onat mote o'dust (Sagin) Posts: 21,753 Thanks: 341 Thanked 3,660 Times in 2,924 Posts	You said there's always residual pressure released from the stone cold cooling system. I'd strongly suggest doing the residual pressure test properly and make a conclusion on that if possible. Test Method With engine stone cold, check and adjust coolant level as necessary. Ensure it's at the standard MAX mark at the bottom of the fins in the header tank. Drive the car normally for the day, covering whatever mileage you normally cover - it should be at least 10 miles with mixed slow and fast driving. Without touching anything, park up and leave the car overnight. Next day, open the coolant filler cap and note if there's any release of pressure. There shouldn't be anything audible. (The typical day to day variation in atmospheric pressure and temperature doesn't cause anything audible). If there is indeed residual pressure, it has to be explained. TC

25th September 2016, 23:56	#37
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	T-cut, yes several times I've topped the engine up to the maximum line cold (ie first thing in the morning having not driven it the day before), driven it, left it overnight and checked the levels. They are down (as I've said) but there is always a hissing as I open the coolant cap. Not sure if that represents air entering a vacuum, or whether there is a residual high pressure in the header tank. SD1 - I've never added any sealant in the five years I've owned the car. Can't speak for previous owners as I bought it with a coolant leak (thermostat). Jules said steel seal was the only sealant he'd suggest putting in a V6. When I said the engine temperature display reached 108, that was only momentarily and whilst accelorating up a hill the end of the journey. Most of the time it sat at 93 when the engine wasn't under load, and never went beyond 103 when idling at traffic lights. As I had lost nearly a litre of coolant by the time it shot up to 108 it didn't surprise me. As far as we can work out the fan is behaving OK - it certainly comes on in the demist test and when triggered by T4 so Terry thought it was something of a red herring.

26th September 2016, 11:25	#40
p2roverman Gets stuck in Rover 75 Connie Tourer & Connie SE Saloon & Club SE Tourer Join Date: Sep 2014 Location: Leeds Posts: 975 Thanks: 199 Thanked 71 Times in 59 Posts	An annoying continual coolant loss on my KV6 was found to be a pinhole in the rubber hose to the heater. Where it passes the battery box it should be supported in a hook. Mine wasn't and had dropped and rubbed against the suspension mount. Such leaks can be only be found when the engine is running with the system up to working pressure.