Recommended inlet manifold sealant ?

[Mandrake]

Hi All,

I'm planning to have the inlet manifold out on my Xantia V6 again this weekend to swap over injectors, in the process I will have to replace the upper inlet manifold gasket again.

I am becoming suspicious that despite fitting a new gasket each time, I may still have a small vacuum leak on one or more inlet runners causing a mixture imbalance between cylinders. Perhaps due to warping of one of the manifold faces.

Every time I remove the gasket I find a significant amount of oil on the faces where the gasket sits, which was fitted dry, as in the photos in the below posting:

http://www.frenchcarforum.co.uk/forum/v ... 09#p372309" onclick="window.open(this.href);return false;

Another clue is that my ICV is nearly fully closed to achieve a hot idle (about 25% opening on the Lexia, where 20% is fully closed and 30-35% is normal) and that if I block the ICV supply hose the idle speed only falls from 650 to 560 rpm when it should nearly stall. I've so far been unable to find any other causes of vacuum leak.

So in an effort to rule out (or fix) a vacuum leak at the upper inlet manifold gasket, I want to try some sealant in addition to the gasket this time. The gasket is a cardboard type and both halves of the manifold are alloy.

Anything with silicone in it is ruled out as that is highly toxic for the oxygen sensor, also it needs to be something that doesn't set hard making it difficult to get apart again - I don't want to be scraping off half glued on bits of gasket next time I have the manifold off! So a sealant that will "let go" and not tear the gasket to bits on removal is a must. I just want something that will seal a bit better than the gasket alone if the manifold faces are not as flat as they should be.

Any recommendations ?

Also given its a cardboard gasket, is the torque of the mounting bolts critical to get a good seal ? Previously I've only ever tightened them "by feel" but now that I have a torque wrench if anyone knows the correct figure for the bolts either side of the gasket I'll make an effort to torque them correctly too.

[Hell Razor5543]

Simon, I hope this is of help;

http://worldtracker.org/media/library/C ... 357334.PDF" onclick="window.open(this.href);return false;

I have also heard of hermetite paste (various colours), and I have a recollection of my mother using some on her 504 estate when the head gasket needed replacing, but I cannot remember colour or application (well, it was 30 years ago!).

[Mandrake]

Thanks James,

I don't see inlet manifold tightening torques listed though. Also there are some curious errors on that page casting an eye over the specs - firing order 1-4-3-2 on a V6 ? Where did the other two cylinders go ?

Also, 1.8 litres of oil in a gearbox oil change ? (The Xantia V6 only came with an auto, which is 3.3 - 4 litres for a change) Those errors make me wary of trusting anything else on the page.

I've just remembered that I have seen the torque (and tightening order!) for the inlet manifold bolts in the Citroen service data in Docbackup - I'll see if I can find it tonight.

[Hell Razor5543]

I just noticed them myself, which suggests a 4 cylinder engine and a BE3/ML5T gearbox. Sorry to have wasted your time.

EDIT; Kept looking, and found this. It looks a lot more useful;

http://www.citroenkerho.fi/xantia/pdf/t ... 0ES9J4.pdf" onclick="window.open(this.href);return false;

EDIT2; you might need one of these as well;

http://www.ebay.co.uk/itm/1-2-TORQUE-AN ... 19e5740796" onclick="window.open(this.href);return false;

[isisalar]

Simon,
CT1 is the stuff you need:- " onclick="window.open(this.href);return false;
There is also a solvent/de greaser sold alongside called Multisolve which can be used for cleaning and removal. They are both fantastic products. Can use it on aquariums so shouldn't upset the sensors.
Cheers
Paul

[Peter.N.]

I use ordinary bathroom silicone sealant, if you apply a bead around the manifold and then leave it to set overnight you have virtually a rubber seal when you refit it. Never failed for me.

Peter

[Mandrake]

Thanks guys, but as I mentioned in my original post silicone based sealants can't be used on the intake manifold of a modern petrol engine as the silicone goes through the combustion process and contaminates/poisons the oxygen sensor. See the following:

http://www.lambdapower.co.uk/Diagnosis/ ... ex.asp#q19" onclick="window.open(this.href);return false;

On an old petrol engine without an oxygen sensor or a diesel engine (which has no oxygen sensor) it may be ok, but not for a modern petrol engine.

[Northern_Mike]

It's only going to get into the air stream if you apply it like a gorilla .
A thin bead is all that's needed. It shouldn't even squidge out to the edge of the gasket.

Sent from my GT-I9300 using Tapatalk

[Peter.N.]

Thanks guys, but as I mentioned in my original post silicone based sealants can't be used on the intake manifold of a modern petrol engine as the silicone goes through the combustion process and contaminates/poisons the oxygen sensor. See the following:

http://www.lambdapower.co.uk/Diagnosis/ ... ex.asp#q19" onclick="window.open(this.href);return false;

On an old petrol engine without an oxygen sensor or a diesel engine (which has no oxygen sensor) it may be ok, but not for a modern petrol engine.

Ah right, I have only run diesels for about the last 30 years, didn't know about that.

Peter

[dnsey]

I use blue Hylomar for most tings these days - it seems to have inhereted the mantle of red Hermetite.
If it's good enough for Rolls-Royce...

[myglaren]

I generally used Blue Hylomar too, but that was a few years back now.

[Mandrake]

This one ?

http://hylomar.com/hylo-wp/wp-content/u ... ssue_6.pdf" onclick="window.open(this.href);return false;

Looks like just what I'm after, fuel and heat resistant, no silicone content and not hard setting.

Where's the easiest place to buy some before the weekend ? Do any of the major hardware stores carry it on the shelf ?

[Xantidote]

I use blue Hylomar for most tings these days

When I originally read Simon's post, my immediate thought was also Blue Hylomar, but that's because I've used it over the years, and still have some in the garage. I thought there'd be a few more modern offerings, so kept mouth shut Blue Hylomar is supposed to be non-setting.

Main problem as I see it, is that Simon wants a sealant that is very easy to remove, both from the metal faces, and the gasket itself, the latter presumably to allow re-use of the gasket.

Edit: just seen last post, so Blue Hylomar is still manufactured - hope it works for you, Simon

[Mandrake]

No I don't want to reuse the gasket, they're supposed to be replaced every time you remove the inlet manifold.

What I don't want is a mess of torn lumps of cardboard gasket glued to the manifold that needs careful scraping and cleaning before refitting...

[Northern_Mike]

Probably Amazon

http://www.amazon.co.uk/Hylomar-HMMS00C ... ue+hylomar" onclick="window.open(this.href);return false;

If necessary, I have a prime account and can order it for you if you wish.