Right now I'm experimenting with a water/methanol VAPOR injection system on the '87 MB.
I'd used a simple bubbler jar on my old '87 Subaru gasser ('87 must have been a good year for cars, I ended up replacing one '87 with another) for water vapor injection - an instant coffee jar with tube fittings screwed into the lid, a length of hose and a bubbler attached to one that went to the bottom of the jar. A needle valve on the inlet controlled the flow of air into the jar and thru the bubbler, the outlet connected to the PCV hose and thus the intake manifold and engine vacuum which sucked air thru the bubbler.
Can't do that on a diesel - no engine vacuum. Instead of "sucking" air thru the bubbler, I needed a way to "blow" air thru the bubbler.
The '87 MB came with a factory closed CCV system - a 2 ft length of hard plastic 1/2" OD tubing, that ran from the valve cover down to it's own sleeve in the rubber air intake boot between the air filter and the turbo inlet. One of the first things I did after buying the beast was to replumb this CCV hose and install a Provent filter - after 20 years there was so much oil leaking out of that boot and the intake I initially thought the turbo drain pipe was leaking.
I had two possible sources of pressurized flow - tap off the intake manifold and use boost pressure, or use the flow from the CCV system itself - in both cases, the outlet of the bubbler would have tapped into the CCV hose downstream of the Provent going into the air intake boot.
Boost pressure with the old fixed Garrett turbo turned out to be a no go - the intake manifold turned out to actually be at a slight vacuum at idle and even when revved up in park, and runs with a temporary boost gauge showed that even at 55 to 60 mph it was only making 2 to 3 psi of boost at most - pretty much useless for anything other than high speed interstate driving as far as operating the bubbler.
But experimenting with the CCV hose showed that it had adequate flow and just enough pressure behind it, even at idle, to make a bubbler work well.
I used a 1/2 gallon plastic rubbermaid container from Wally World, and took care to make sure the fittings, hose, and bubbler fittings equaled or exceeded the diameter of the original CCV hose - definitely didn't want to end up blowing seals due to backpressure. In that regards, having the Provent installed upstream was a double blessing - not only removing the oil, but it's built-in vacuum and pressure relief valves would be an added measure of safety.
Got the bubbler jar constructed back on Sunday, and on Monday installed it, plumbing it in downstream of the outlet from the Provent, and it's outlet plumbed to the CCV hose sleeve in the air intake boot prior to the turbo.
For the fluid, I used a jug of washer fluid from Advance rated to -20 F - I'm guessing roughly 30% methanol - that cost roughly $2 for a gallon jug.
So far, I've only driven about 30 miles with it installed, in 2 or 3 short trips, nothing faster than 45 mph. No data on fuel economy yet - that will come next week when I'm back at work and put 200 miles on it - but so far on the short trips I've made, on the return leg with the engine warmed up it does seem much quieter and smoother, power delivery from a stop much more consistent. Only some real world testing will tell if this is true and that I'm not imagining a "placebo" effect.
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