I understand the above,

I want to eliminate the three o-rings related to the pre-filter built-in to the housing. One from the fuel heater, one at the top of the pre-filter and the one at the bottom of the pre-filter.

The plastic pre-filters for 8mm fuel line have a very small opening, smaller than 8mm. That is the flow restriction I'm concerned about. I found a larger capacity pre-filter with 3/8" connections that I want to put in-line before the lift pump. I don't need a fuel heater in Texas and I don't want the o-rings.

I find it difficult to believe Mercedes has done a lot of things that weren't really good engineering. Why have ' marginal ", it's fairly easy not to have that. Why have bio-degradable wiring, especially when there was already a history of failure for that type wire.

I have nothing but good memories of my 78 CD. I'm trying to reduce the future problems with my 95 E300D. Not that much to do, just takes a little time now. Things like removing old grease, lubing slides, using 'better' when available.

I want to have a car I look forward to having and not be concerned about stupid little repeating failures.

My question was on how to convert from 5/16" to 3/8" with minimal clamps and other failure points.

I do regret buying the E300D because of the wiring issues, weak o-rings, evaporator location and a few other armadillos. I didn't do my research because of my previous love affair with the 78cd. I would have sold it fairly quickly but it is low mileage and exceptionally clean. Rear seat had never been used. Front seats covered with sheep skin put on when the car was new. Always garaged. Now I want to make it reliable.

Best car in my history of cars was the 95-99 Olds Aurora. Rock solid smooth good performance up to 200,000 miles then overheating. Just buy one, put on Michelin tires and use Mobil 1, no worries. I owned five of them, better than the four BMW's before that.