Hi folks,

As I am wrapping up the body and suspension works this month, I am moving onto learning about the engine components going forward. As I've had this nagging whirring/pulsing issue going on with the stop lever, going to do a biodiesel (or possibly wvo), and also after examining a few fuel hoses, I decided that I am going to replace all the fuel lines and filters. I plan on placing an order with McMaster or some other online shop tomorrow, so I'd like to make sure I order enough and the right kind of hoses, so my apologies for the newb questions. First, I took a picture of the engine bay and labeled what I believe are the fuel delivery lines:



I have the rear axle dropped right now, so I am going to replace the return and supply lines (4 hoses total) back there. Those are pretty straight forward.

Questions:

1) Regarding the three plastic lines coming off the fuel filter, what is that material made of? Its obviously some sort of plastic. And second, I tried to wiggle these hoses to see if they were loose, but they are tighter than all hell. How does one get these things off?

2) Is the return line correctly labeled?

3) Is the supply line correctly labeled? Or is the line going into the pre-filter the supply line?

4) From the pre-filter, there is a hose going to some component. That component has 2 (maybe 3---i can't recall right now) hoses coming off of it. What is the name of that component? Is it some kind of fuel thermostat?

Thanks to all for any help.

Bob

Attached Thumbnails

 

"Prefilter2" is the fuel thermostat and unknown 1/2 are to/from the fuel heater.

Well you might want to wash up your engine bay with a hose and some soap, make everything nice and clean. I havent dealt with the 60x series too much so i couldnt help ya there.

__________________
Have you ever noticed that anybody driving slower than you is an idiot, and anyone going faster than you is a maniac?

As long as they would add one additional commandment for you to keep thy religion to thyself.
George Carlin (Wonder where he is now..)

1981 240d (engine donor 1983 240d) recently rebuilt engine hurray! - No more.. fought a tree and the tree won.

pearl black 1983 240d 4speed (Converted!@$$%) atleast the tranny was rebuilt.

They come off (and are replaced) fitting and all.

The supply and return lines are correctly labeled.

__________________

"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

thanks, gents. so i assume I got them all properly identified?

also, anyone know the material type for those 3 plastic hoses?

The plastic lines are sold by MB with fittings. They are not formed but they become rigid over time. I read that you can replace with fuel hose and clamps.

The fuel lines between the thermostat and the heating element in the head are formed - they have specific MB part numbers rather than bulk hose reference. I've had no problem replacing them with bulk hose.

Sixto
87 300D

problem gents: I decided NOT to go under the car last night to do some work. instead, i decided to change out the fuel hoses. I replaced all the aforementioned fuel hoses except the return line (its not the same diameter as the other hoses) and the hard plastic fuel lines (same reason).

I pulled the fuel line from the fuel heater (the one that has 3 lines going into/out of). near the front of the fuel heater is a plastic part that is held in with a snap ring. that thing has been slow dripping ever since I pulled the hose. I put some kitty litter on the garage floor this morning and im going to check again for a leak puddle when i get back. if there's a leak, then i imagine i will have to replace it.

so my question is, is that plastic part replaceable? I'm guessing yes, or otherwise, that snap ring is just for decoration. Or is it not? Or, are these leaks a normal thing when removing these hoses?

thanks,
bob

If you remove the circlip that holds the plastic part in you'll find there is an O-ring in there that has probably gotten hard. Your tugging just loosened up the old seal so now it's leaking. You might be able to source a new O-ring at a good hardware store but it's probably metric so the dealer would be more certain. In a pinch you can just bypass the heater until you get the parts you need.

__________________
LRG
1987 300D Turbo 175K
2006 Toyota Prius, efficent but no soul
1985 300 TDT(130K miles of trouble free motoring)now sold

LRG,

awesome advice, thank you. I'll check it out

bob

Sorry my reply is a bit late, but I would use clear polyurethane hose to replace your hoses. If you try to run biodiesel and/or WVO through standard Autozone hose, it will deteriorate fairly quickly. The clear hose is also great for troubleshooting air leaks. McMaster.com sells it.

__________________
1987 Mercedes 300D ~200K (Greasecar & Biodiesel)
1993 Ford F-250 7.3 IDI diesel 165K (Biodiesel)
1996 Thomas/International Bus with DT466 engine

The dealer sells individual parts for the fuel thermostat (it's not a heater) should the need arise.

Sixto
87 300D

Dan,

No worries, i bought BD resistant hoses from Vulcan performance which were recommended by many members here and on biodiesel.infopop.cc. If i do have trouble w/ air leaks, I'll take your advice.

Sixto: thanks for the scoop. Good to know. I"m going to dive under the car right now

Bob

damn that sucked. took me a whole hr!

theres hardly any room to get that snap ring plier in there. learn from me: jack up the car and go from the bottom.

remove the snap ring and the spring inside the thermometer will push the plastic piece out. i did my insepction and its fine, even the rubber ring that's attached to the plastic piece. i tried to fit a harbor freight viton o-rings i bought, but they did not work b/c they are round shaped like a donut whereas the oem o-ring is shaped more like a tire. i'll save them for the BD processor.

anyways, long story short, its all good. but if you have to do this and you have big hands, id advise jacking up the car, remove the hoses, and remove the two bolts that fasten it and then work it in a bench vise

Attached Thumbnails

   

ok so i got home a little earlier than expected, so i fired her up. firstly, the new engine mounts rock. i cannot begin to tell you all how much of a difference the car feels when you have new engine mounts. no side to side vibrating, not as noisy, etc. solid is the best way to describe it. i also did the trans mount bushing too.

so bad news: it is indeed that plastic piece and/or the rubber ring that is leaking. it was quite a heavy drip when i looked inside the engine bay. perhaps this is truly the primary reason for the obnoxious noxious diesel smell in my car. the smaller hose was cracked in places as mentioned above as were the injector return lines, so i know that contributed too. but this probably is the real reason.

time to order more parts >:|

I had no idea you could buy replacement parts for the fuel thermostat from the dealer. I was told I had to buy a whole new unit as mine was leaking, and went I went to mess with it the plastic end broke off at the nipple. It was a pricey little part, too. Like $130, and the new one has silly plastic nipple as well.

I wonder if you could just delete that whole fuel preheater, I mean is it really necessary this side of the arctic circle? It would also remove a bunch of clutter in the engine bay. I dont think the older models were blessed with this, were they?

__________________
Paul
Benz-less
I need an SDL !