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Silicone hoses for upper to lower intake?

Started by 3l33ter, 13 July 2015, 02:26 PM

3l33ter

The car in question is a 6.9. I will (hopefully!) be putting the engine back together soon, and I'm trying to leave no stone unturned. The rubber hoses that connect the upper and lower halves of the intake seem to be in OK condition, but at 160k miles and 38 years old, I'd like to replace them.

MB wants something ridiculous for those things. So instead, I want to buy a meter of silicone hose and cut my own pieces out of it. The o.d. on the manifold nipples is 50mm. I was wondering if I should get 50mm silicone hose, or 48mm? The original hoses don't really have a hose clamp on them, they just have what looks like a single plastic strap / tie wrap in the center. So I don't know if I should get the 48mm and stretch them on, or get the 50mm and use hose clamps, because 50mm hose on 50mm nipple alone might not seal. I have no experience with silicone hose so I don't know if "50mm" hose is actually 49.9mm, etc.

Oh yeah, and would silicone hoses be appropriate for this? I know that they're meant for vacuum and coolant, and some say that they shouldn't be used for oil, and there is oil vapor in the intake. But people use them on turbos, intercoolers, etc.
'75 280S
'77 6.9
'82 300TD

ptashek

It's more than just a piece of rubber hose, if this is the part you're talking about:
http://www.autohausaz.com/pn/1171400265

I've used those on my M117.986.
1993 "Pearl Blue" W124 280TE
1988 "Arctic White" W124 200T
1979 "Icon Gold" W116 450SE

TJ 450

It's a special size for the M100... considering the design of those parts, nothing else will suffice. You don't want to have to pull it off again, trust me. 8)

I'm going through this on my M117... I used URO ones, and they're falling apart already. I've got a genuine set on the way.

BTW, they are sandwiched between the upper and lower sections.

Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500

ptashek

TJ, just out of curiosity - is it the rubber that's failing, the plastic clamps, or both?
I wonder if URO are actually able to produce anything that fits, or lasts any time at all :-/
1993 "Pearl Blue" W124 280TE
1988 "Arctic White" W124 200T
1979 "Icon Gold" W116 450SE

marku

You can't use hose as the originals have a ridge on the inside to engage with the two halves. The ones on the earlier M117s are different from the later ones which are a very different design. The EPC and MB say the earlier ones don't exist but my original parts illustration does. The clearance between the two halves is greater using the new ones but not by much so probably doesn't make any difference only trouble you will have to replace them all if fitted with the earlier ones.
1974 450SE silver green/bamboo velour/green vinyl roof