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Old 14th December 2019, 09:55   #11
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Another factor which is raised now and then is the effect of varying atmospheric pressure. Obviously, if the pressure cap is opened then sealed on a day when ambient pressure is 'high', a pressure difference will exist on a day when the air pressure is 'low'. So opening the sealed tank should release that excess air pressure. In reality, you'd be hard pushed to detect it by the usual 'hiss' sound unless the difference is very substantial. So, the other factor is exactly what the ambient pressure difference is likely to be required in practice.

A simple way to test this is by using several pop bottles with a similar volume to the airspace in the header tank ( several hundred mls). Polyester pop bottles are non-expandible, so behave like the header tank/cooling system. In practice, days with a significant air pressure difference are few and far between. To detect anything at all by ear, you need at least 20-30 millibars difference and preferably 30-40 mbar. I never got that scale of difference during the weeks I did the tests This was in UK, though other countries may experience wider fluctuations. So, unless you live in an area where the weather can change from clear bright skies to heavy thunderstorms overnight, in a regular manner, these tests require a lot of patience and record keeping.

Edit: To put this into context
20mbar = 0.3psi
30mbar = 0.4 psi
40mbar = 0.6 psi.


TC

Last edited by T-Cut; 14th December 2019 at 13:27..
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Old 14th December 2019, 15:49   #12
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Default Excess coolant from header tank

Hi folks, I had to start the car today in order to move it so I could use other vehicle. It was running for approx 5 minutes, I checked all the hoses and water pump and no leaks visable. I haven`t checked header tank as I would expect it to do the same as previous.Even though I had the head gasket done only 20 months ago, along with the cambelt and water pump and done 3 thousand miles since I feel it`s got to be repaired. It has to be one of the best cars I have owned apart from the obvious, and the large history file I have say`s this is the fourth time the HG has gone. I will get a garage local to me to diagnose fully and (hopefully) take on the task as I am unable to physically do it myself.I will get parts from DMGRS as many of us have used Mat for the parts we need to keep these cars on the road. Can anyone tell me what is the VVC engine when referred to regarding these cars? Thanks to everyone who has given advice on this issue it is much appreciated, Regards Paul
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Old 14th December 2019, 16:44   #13
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Good luck though it seems you have already made your mind up as to what the problem is.

Check for cross contamination of oil and water in the coolant and oil but don't think that if it's the pump, then it has to be the head gasket. Perhaps there is someone who is a member with the correct knowledge not too far from you who could have a look.

It might be worth you draining and refilling and follow the procedure that involves running it with the cap off to ensure all air is expelled.

Remember that several Land Rovers have the same engine and if you can't find Rover help, then LR experience is a good move.
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Old 14th December 2019, 16:46   #14
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Originally Posted by Ginger Teddy View Post
Can anyone tell me what is the VVC engine when referred to regarding these cars?

The Variable Valve Control version of the K-series wasn't fitted to the 75/ZT range, so there is no specfific connection. Some members have used the aluminium inlet manifold that was fitted to the VVC version to improve the reliability over the plastic one, but that's about it I think.


Info on what cars have the VVC engine can be found here: https://en.wikipedia.org/wiki/Rover_K-series_engine


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Old 14th December 2019, 17:03   #15
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I will get parts from DMGRS
Considering the history of your engine, I'd suggest you select the Payen BW750 head gasket or the lower cost equivalent. Both available from DMGRS: https://www.dmgrs.co.uk/collections/head-gasket-kits

There's an article on the DMGRS website that gives some advice on HG replacement.

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Old 14th December 2019, 17:37   #16
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Its exhaust gas passing through a failed head gasket into the coolant system hoses - if it is suspected that this is happening always worth a good sniff of the coolant tank - if it smells of exhaust fumes then that could point to HGF. On the debate of an audible hiss when opening a cold expansion tank my 1.8T is silent - i did have hiss a couple of years ago and swopped out the expansion tank cap and all has been OK since - saying that i swop out the expansion cap very 12 months or so.
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Old 14th December 2019, 19:01   #17
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Default Excess coolant from header tank

Hi, I did sniff the coolant tank when I eventually removed the cap and it just smelt of coolant and it looked as if it had just been added , showing nothing untoward. There is nothing on inside of oil cap and on checking the dipstick it is as you would normally expect it to be. And I always change header tank cap at every yearly service( which was march this year) as a precautionary measure as they are cheap enough and prevention is better than cure.So really I am not 100% it is the HG . When the HG went in april 2018( the only time in my ownership ) steam was coming from under the bonnet and on opening it up the steam was coming from a bolt where the turbo bolts on so I thought the turbo had failed and on speaking to the person who was recommended to me said it was the HG, the job was done and we have been ok until now. Apart from the header tank saga it hasn`t been anything like it was before, regards Paul
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Old 14th December 2019, 20:33   #18
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If you have doubts, try a fast pressurisation test. With the engine stone cold, open the header and check/adjust the coolant level. Replace cap. Start the engine and with your foot on the throttle, raise the turnover to around 3000rpm. Keep this going for around 30 seconds. Turn engine off. It will still be relatively cool, so remove the pressure cap and see if there's any pressure buildup. If coolant surges into the filler neck or actually overflows, you can be pretty sure the gasket's failed.

EDIT: Make that absolutely sure.

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Old 17th December 2019, 11:13   #19
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Default Excess coolant from header tank

Hi folks, I have just carried out the pressure test that TC suggested and this was the result. I removed cap and the coolant was halfway up to the neck ( no pressure and nothing overflowing )so I removed excess down to max mark, replaced cap and started engine and slowly built the revs to 3000 for 30 seconds as suggested, and switched engine off.Removed the cap and coolant level hadn`t changed.I tried the same again and with the same result , no change from the level I started the test with. I was already thinking of draining system and refilling as suggested by planenut ( fred ) before TC suggested this and because this was the easier of the two try this one first.There is no smoke from exhaust, again no mayo on oil cap and dipstick showing same as before when wiped with cloth just oil and sniffing in top of header tank you can just smell the coolant.So if the rain stops will try and get the coolant drained and renewed as might as well try everything I can, as the garage I use ( for other cars ) apart from MOT`s and fitting a full exhaust (dec 2018)have never worked on it and I don`t feel they would be keen ( I remember seeing an 03 model 75 in the workshop a few years ago and it had an electrical issue and there was no power and it was being cursed as it was being pushed out of the workshop and it was said they were rubbish cars ! ) so got to try everything I can before it goes into the hands of the people who do not understand them, Regards Paul
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Old 17th December 2019, 18:09   #20
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Hi folks, I have just carried out the pressure test that TC suggested and this was the result. I removed cap and the coolant was halfway up to the neck (no pressure and nothing overflowing)
That's not a good sign IMO. For a 30 second test on a cold engine, the coolant level should hardly move above the start point. It hasn't got warm enough to display thermal expansion and half way up the filler neck is a lot higher than expansion would create - even at 100C.

You might try the test again, but increasing the time to say a minute or more and see what the coolant level does. From earlier description, I'd expect some ejection of the cold/warmish coolant.

Quote:
so I removed excess down to max mark, replaced cap and started engine and slowly built the revs to 3000 for 30 seconds as suggested, and switched engine off.Removed the cap and coolant level hadn`t changed.I tried the same again and with the same result , no change from the level I started the test with.
Removing the 'excess' coolant simply makes the inventory too low. You started out at 'full' when cold, so that's the amount the system needs. By removing it you mitigate the effects you're trying to test. Unfortunately, this part of your test is meaningless. If you want to take it to the proper next stage. adjust level to full with engine cold and run the 60 to 90 second test as above and tell us the result.



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