Question,which is better,the factory silicone sealer (the black stuff)or the loctite 5900 sealer This is for the notorios top timing chain/front cocer.Also where can I get this loctite 5900?

I bought the Mercedes oem, because the Loctite wasn't available where I live. Take a look at my thread that has pictures of the sealant and the job. Pages 4 and 5 might be of interest to you starting at post #51:

M103 Oil leak or burning?

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1989 300CE Astralsilber/Schwarz
1992 300CE Schwarz/Schwarz

I've used the Mercedes OE twice, seems to work okay. (But I thought it was the same as the Loctite?)

I believe I saw a thread here a few months ago that concluded that they were the same - except of course for price, which is several times higher for the MB version. I believe the Loctite is widely available for a few bucks.

FWIW, my MB mechanic and I use Permatex's "The Right Stuff".

It was been about 2-years now since we've used it, and NO LEAKS, and a M104-engine (C36).

:-) neil

used on my M103, works great, two years on top timing chain cover. About to use on my other MB also.

http://www.permatex.com/auto/autouh.asp?automotive=yes&f_call=get_item&item_no=25249


Robert

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89 300te 222,222
92 300e 190,000

Robert: is that the "blue" Hylomar ? If so, that stuff never hardens, correct ?

My understanding is that the top timing-chain cover needs Hylomar on the gasket, but a hardening substance (e.g., The Right Stuff) on the edges that is "blowout proof".

FWIW, "The Right Stuff" is now Mercedes approved, and "blowout proof".

http://www.permatex.com/products/prodidx.asp?automotive=yes&f_call=get_item&item_no=33694

Excerpt (note last sentence):
Return equipment to service immediately when you make leakproof gaskets in just one minute with the Right Stuff.® This latest elastomeric rubber gasket technology is blowout resistant and outperforms pre-cut gaskets. Specified on production lines by GM, Ford, Daimler-Chrysler and Mercedes-Benz. Temperature range -75°F to 450°F; (-60°C to 232°C) continuous, 500°F (260°C) intermittent; resists ATF, coolant, oil and other shop fluids.

Protects against leaks caused by vibration and thermal expansion.

:-) neil

Thank you for the correction, I thought it was okay to use the same compound all around. I've used the blue Hylomar before and it worked fine but maybe that was just luck. So you use The Right Stuff and Hylomar for this repair? Seems to me that they would get mixed together at the corners and that could cause problems. Have you tried using just The Right Stuff on the rubber U gasket and the metal flanges? The Hylomar does say it works on pressure flanges.

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89 300te 222,222
92 300e 190,000

No "Right Stuff" on the rubber "U'" gasket, however outside we also sealed it with Right Stuff and still no leaks.

:-) neil

I believe the Mercedes books asks for the U-gasket to be lubed with motor-oil, and the corners with the Mercedes gray sealant. Basically, I use blue Hylomar as a gasket dressing, and "The Right Stuff" in lieur of the Mercedes gray sealant.

:-) neil

How difficult is it to remove things that have been sealed with the Right Stuff? If that's the defacto replacement for the MB grey sealant then I should definately be using it. I've just had such good luck with smearing the Hylomar on the flanges and the rubber gasket that I'm a little hesitant to switch to just oil on the gasket and a good sealant. I did the U gasket about two years ago and about two months ago I did the timing chain, head gasket, etc. The Hylomar was no longer soft after two years but disassembly was not tough, and there was absolutely zero trace of any leaking.


Robert

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89 300te 222,222
92 300e 190,000