Who really needs a wastegate hose?
 

...was doing a change out of the aircleaner support on Marlene the Wonder Wagon yesterday...discovered the almost ceramic-like qualities of the ancient wastegate hose when it literally shattered in my hand.

At 8:30pm, without a replacement and 85+ miles from the nearest MBZ dealer I figure: WTF, I have a boost gauge, if it gets too high, I'll back off of the loud pedal.

One thing: It definitely spools faster w/o a wastegate and, AFIK it doesn't make much over 15-16 psi boost at full chat. On a long grade you may get more but 180 mile round trip drive to Austin through the flatlands showed me a very controllable 7-12psi. It did clear out some old soot the first time it revved over 3500...

Should I leave it off?

Definately not. Use fuel or vacuum hose if you have to.

Tell me why.

Did you plug the hole on the compressor housing with anything? That might be why its not going over 12 psi.

If the boost never exceeds 16 psi and you've got a gauge to observe, you certainly don't need the wastegate.

I do find it surprising that the boost is only 16 psi, however. The turbo is known to push well over 20 psi if not checked by the wastegate. Are you sure the gauging is correct and without leaks?

On a related note, is there anything particularly special about this hose to make me spend 2x$20 (two cars)? I'm tempted to get some fuel hose...

Well, #1 it was designed to have it for a reason. This is not some emissions device that can be axed without negative effects. It prevents the turbo from overspeeding (grenading), restricting the exhuaust and excessive headgasket stress

That is VERY bad advice!!!

His trubo doesn't make more than 16psi because that just happens to be the overboost protection's 1.1bar setting and its probably doing the job Mercedes put it on there for.

I use fuel hose with no problems.....

I agree, fuel hose should be fine if you check it every few years.

Nuff said. Thanks.

My wastegate hose had a slit in it and my boost needle would easily peg at 20 psi. Fuel hose has been working fine for me.

What does the overboost do? I thought it just limited the boost pressure going to the ALDA...the compressor is still going to build "unlimited" pressure which goes right into the intake manifold, doesn't it?

I think it does just limit (by venting) the boost pressure to the ALDA, however, without that boost/alda enrichment, the engine will be down on power and not build much boost anyways...so it protects it in that way.

The expensive "Real" waste gate hose is made of silicon to resist the intense heat in the vicinity of the turbo/exhaust manifold. I need to replace mine soon too....its kinda spongy. Spark plug wires are also made of silicon rubber to protect them from heat.

if you have no wastegate protection, you are running on just the little electric overboost protection fuel cutout... assuming you never block that off. IF you have a boost gauge, AND you watch it all the time, the wastegate is unneeded, however, if you are watching the boost gauge all the time, it's kinda hard to drive... also, the alda overboost line is KNOWN to plug up and fail regularly, so if you run this way, I'd add remove/clean/reassemble the alda boost line and fittings banjo bolts to the maintenance schedule...

An obstruction in that line has the same affect as an activation of the overboost protection system; it prevents boost pressure from getting to the ALDA.

My wastegate spring must be out of adjustment, because I can go up to about 17 psi before the wastegate opens...however, when the hose had a slit in it, the boost needle would peg at 20psi. And I had the boost gauge reading from both before and after the electronic overboost protection thing (at different times) and the full boost pressure alway made it to the alda...maybe my overboost protection thing is broken.