Planning on doing a diesel purge on my 98 E300TD, and the easiest way to do it is through the inlet and return fuel line according to this video

https://www.youtube.com/watch?v=AG5OpAOLvdI

.....question is, what's the hose size? It "looks" like it's 3/4" but that's due to me eyeballing it...and Im not accurate when it comes to that.

Anyone know?

The return line to tank is 8mm internal id ,and the line in to fuel heater is 10mm internal id.
So 3/8 and 5/16.

IMO this is an easier, less spillage, quicker way to do a DP on an om606. You do need a preheater to prefilter fuel line to make it work,

https://www.youtube.com/watch?v=1u2ZMenlxA8

my issue was I had the rear elevated to make priming the new filter I installed after purge, all DP how to's suggest putting a new main filter on. Fuel flows very well with an elevated rear so you have to plug off the main feed line coming from the tank in the OP's linked video or get out a bucket to catch the spillage.

__________________
Treetops
06 E320 CDI 127K Miles
87 300TD 231K Miles

99 E300 269K Miles-Sold

Awesome, thanks for the suggestion. I'll buy some hoses this upcoming Tuesday, or Monday if they're open.

I'm told not to poo open the fuel line if I have more than half tank. I have less than a quarter left...It's right before the fuel light comes on.

But yes, just to be sure, I'll cork it.

I will report back after I do it.

Reporting in:

I did the purge. The fuel lines you recommended worked perfect. ACE hardware did not have the coupler to attach the clear hoses to the fuel lines, so I juryrigged a deep socket 8mm socket as a coupler for the inlet fuel line, and simply shoved the 3/8 hose into the return fuel line. Worked perfect.

After 3-4 minutes, the return fuel became dirty very fast. The purge was originally clear with a very slightly pinkish ting, but very soon it became the color of brown mud. I ran it until it was almost empty (used two cans of purge). I will buy a new prefilter and main filter tomorrow when the parts department opens.

Engine runs noticeably smoother. It sounds the same as before, but smoother now. From the driver seat, it's just like being in a regular gasser. If you rolled up the window, you'd never know it was a diesel.

Time will tell if I have power or better mpg.