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Old 11th May 2019, 15:38   #1
Mr Toad
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Hi Guys,

Here we go again. It was six years ago that I last removed the heads after a cambelt failure and seized tensioner. A few months ago had a thermostat leak which I repaired (plastic rubbish). I was considering fitting Kaisers metal thermostat but I have been away and then noticed water loss and mayo when removing oil filler cap.
My questions are as follows:-

1. When I took the heads off last time the car had not overheated therefore I just used the latest MLS gasket. However I have read on the forums that if the heads have not been skimmed you should not use the MLS gasket and use an original gasket or composite gasket. All the suppliers have the MLS gasket although DMGRS supply them but have no stock at the moment. As the car has not overheated I intend just to remove the heads and replace the gaskets. Anyone got any views and if I should go the composite gasket route where can they be obtained?

2. Haynes reckons that you have to remove the inlet camshaft sprocket but I can't see why this should be necessary. Is it?

Appreciate any views .

Martin
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Old 11th May 2019, 16:43   #2
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I would examine the heads carefully. If flat and not corroded, I would not skim. You don't need to remove the sprockets off the cams. You can remove the cam belt and lift the head off as is.

Well, let me put it this way. I have just done this on a K4 engine, and I cannot see any reason why this should not also apply to the KV6.
As for the head gaskets, I think the original gasket for the V6 is always multilayer metal!

The mayo should not be taken as coming from HGF, that is only one of three (four?) possibilities.
You can easily get mayo from leaking inlet gaskets and indeed also from a leaking oil cooler, and maybe (?) even if the internal ventilation system is not maintained and blocked.
I would not jump to conclusions based on what you have stated here.

As for the thermostat! well................, what can I say
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Old 11th May 2019, 16:45   #3
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Hi Martin,

My first thought is, have you considered a faulty oil cooler?

You said you were away before noticing mayo under the oil filler cap. How long have you been away and how much mayo is there? Could it be the result of condensation forming over a period when the car lay idle?

Regarding head gasket type, the KV6 uses only MLS. The elastomer type applies to the four cylinder K series.

If I were you I wouldn't embark on any major work until you have a positive diagnosis. For example, either temporarily by-pass the oil cooler or remove the RH bank cam cover to check for mayo there.

If you do decide to lift a cylinder head then the inlet camshaft sprocket wheel will have to be loosened in order properly to refit the timing belt so your second question therefore doesn't arise.

Simon
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Old 12th May 2019, 12:39   #4
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Thanks for the responses. The car is running perfectly except it is loosing about 150ml of water a week. I suppose the best course is to carry out a compression check in the first instance and I will keep you posted.

Martin
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Old 12th May 2019, 13:18   #5
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I don't think that would be the first option. 150ml per week is not a lot. I don't think any compression test would pick that up.
Except perhaps a compression of the cooling system!

I would check the outer spark plugs for signs of water, by-pass the oil cooler, and keep a weary eye on the V for leaks from the plastic brigade.

Then see if that helps.

Don't forget you can leak water from the water pump as well! That will show near the crankshaft pulley. Look for colour change, not necessarily wetness!
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Old 12th May 2019, 17:44   #6
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Thanks Kaiser. How do I bypass the oil cooler please?

Martin
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Old 12th May 2019, 17:55   #7
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You disconnect the two rubber hoses going to and from the cooler and connect them together with a fitting fitting! (a pipe and a couple of hose clamps)
That way you lead the water past the cooler, and you can see if the leak stops. Drive it for a while until you are secure that it makes a difference.
If it does, chances are good that you have found the culprit.
If not, you can reconnect it and look for alternatives. Or leave it off. Chances are good that it will develop a leak in due course.
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Old 12th May 2019, 19:25   #8
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...and then of course there’s the possibility that it could be the inlet manifold gaskets that have given up.
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Old 13th May 2019, 09:57   #9
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Thanks for the responses so far. I will check the plugs first and then by pass the oil cooler. Will keep you posted.

Martin
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Old 13th May 2019, 21:03   #10
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Plugs seem to be fine. No external leaks apart from a small leak into the V from the coolant sensor but not anything like the 150ml a week. So it looks like either the oil cooler or the inlet manifold gaskets. So far as the oil cooler is concerned there is no leak and the car has only covered about 60,000 miles so I doubt that is the culprit. So that leaves the inlet manifold gaskets which were replaced about six months ago when the thermostat was leaking again. I know I torqued down the manifold nuts correctly, is it likely that one or both could be leaking?

Martin
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