Diesel RVs: 10/07/18

[Attachment(s) from Nate included below]

The basic wastegate internals are lain out (Pic. 1) and reveal some details no one had ever mentioned to me before :

The diaphragm is directly screwed on to the inner end of the valve and the valve stem is hollow and has a vent hole 1/2 way down it this I assume helps keep it cool by passing pressurized boost air to be forced down it and out the wastegate exhaust port (Pic. 2) .

The adjuster access is only when the turbo is off the vehicle (! labor !) and so is pre adjusted by measuring the clearance of the tip of the valve to the lock nut (Pic. 3) . (4.5MM)

The valve has a slot in it to facilitate removing the diaphragm by simply holding the diaphragm and using a screw driver to unscrew the valve, this makes it easy, by the time the diaphragm is coming off the heavy internal spring isn't under much pressure .

The valve as you can see was heavily coked up along the stem and was a little bit stiff in it's unlubricated, ventilated guide so I wire brushed it until shiny and clean then used picks and chemicals to clean the air way in the middle of it as that was full of oily sludge .

The seating face of the valve clearly showed a good clean and shiny contact surface else I would have hand lapped it as this must have good seating or boost pressure, especially at low RPM's, would be lost .

Test fitting the valve showed it to easily slide in and out . the junked 1980 W116 300SD I got the good used diaphragms from had the valve stuck 1/2 way open by accumulated carbon and oil crud, I had to use a hammer to knock it out, I took it just in case I'd need another popoff valve .

As I re assembled all the nice clean and checked / tested parts I didn't re adjust the boost to the same lock nut measurement it had before because the valve hadn't been opening before at 20 # of boost, I was afraid to see how high it would go, I just winged it when I re assembled it and got 7.5 ~ 8 # of boost maximum, the engine responds nicely now but I want to go back in and raise the boost up to at least 10# when I'm lead footing it .

Later models also have an A.I.R. valve on the upper front of the cold (intake) side of the turbo with a single vacuum line connected to it, again no one could explain what it is for apart from 'it's a U.S. market thing for softer slush box shifts' ~ it turns out it dumps excess boost pressure back into the intake so the tranny doesn't make such abrupt up shifts, not a good thing whatsoever .

My A.I.R. valve had both a degraded (rotted from oil contamination) rubber diaphragm as well as totally gummed up and uneven sealing surface resulting in constant loss of low RPM boost as well as the spring and piston being gooey and stuck, simply cleaning it all up and replacing the rotten diaphragm made it all better, I didn't check to see if there's ever any vacuum to it yet as the tranny shifts well, the improvement to off idle throttle response is amazing .

All this took seven hours including breaks, the car is running fine and not leaking oil in spite of no new gaskets used at all .

Some times it still belches out a grey cloud of excess fuel smoke after a long stop light, I think an injector is drooling a little bit but am waiting for the fuel fungus to be 1,000 % gone before removing and testing them yet again, I've $pent far too much $ replacing nd cleaning injectors only to have them clog up with fungus again to rush that job now .

I ordered in some turbo / manifold mounting gasket kits and plan to soon install non E.G.R. manifolds and replace the various gaskets then .

Thank you for reading all this, I get a lot of good feed back and appreciate it as I'm always learning and teach my self new things even that I'm old, broken and retired .

-Nate

The essence of loyalty is reciprocity

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Attachment(s) from Nate | View attachments on the web

3 of 3 Photo(s)

WASTEGATE.INTERNALS[1].jpg

WASTEGATE.EXHAUST[1].jpg

WASTEGATE.10[1].jpg

Posted by: Nate <vwnate1@yahoo.com>

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Diesel RVs

[diesel_mercedes] Wastegate Service pt.2 [3 Attachments]

Re: [diesel_mercedes] Wagon 3rd Row Seat Belts

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