OM617 Hard Line Replacement - PeachParts Mercedes-Benz Forum

JHZR2 · #1 01-18-2013, 06:04 PM

Who has done this? Can I just replace the lines without the banjos, i.e. buy new tubing and install with a heat gun, or is it smartest to buy all new?

I have a slight hot only idle shake, and though there are never any bubbles, Im at the point where all I can do is throw parts because Ive gone through everything...

Thanks!

Diesel911 · #2 01-18-2013, 09:19 PM

I am not sure why but they call the Fuel Injection Lines Hard Lines on these forums.

You are speaking of the Plastic Lines.
Are you looking for the Inlet or the Outlet line?

If you don't care about seeing through them you can replace the Plastic lines with 1/4 inch Rubber Fuel Hose and clamps; I did that. That is the Cheapest way to go. If you want to do that heat the babed end just enough to soften the plastic and yank it off of the barb; careful the Banjo Fitting gets hot.

There is a thread somewhere where someone heated the tubing end and shoved it on the Barb. However, I believe He use Tygon Tubing.

The originals use Tecalan Tubing that I do not think is sold here. From My notes: the one I too off of my spare IP has: DIN-78878-PA-TECALAN-79 a arrow and a bunch of widely spaced 2 digit numbers?

When My Car had the hot shaking issue a Valve adjustment and replacing rebuilding the Injectors cured the bulk of it.
Motor and Transmission Mounts took away some more and finally the Rack Damper Screw took a little more away.

I also found I had a small Air Leak that showed up after the Engine was hot. The Fuel Inlet Hoses were to hard and inelastic to seal and for some reason when it was hot under the hood allowed Air to leak in.

The Plastic Lines are not on the Suction Side I don't see how they would cause the Hot Idle issue.

JHZR2 · #3 01-18-2013, 10:23 PM

yes, plastic lines, the transparent/translucent "main" ones.

Which one? Dont know. Ive replaced all the braided lines, valves are perfect, compression is high, injectors had nozzles replaced and were popped and balanced. Rack dampener doesnt help, and it is hot idle only. Super smooth cold. New MB mounts, shocks, shock mounts are all on the car, its still there. The car is wonderful at all other conditions but hot idle.

Diesel911 · #4 01-19-2013, 07:59 PM

All that leaves is uneven compression or something like a Valve not seating when hot that might show up with a Leak Back Test.

There is something else that may be related. In the manual the Oil Nozzles on the Turbo Engines need a certain minimum pressure (can't remember what it is) in order to spray. When the Engine and the Engine Oil is Cold on mine at idle the cold Oil pressure shoots up to 3 and stays there for quite awhile till the Engine starts getting warm and creeps down to about 1.5+ bar when the Engine us fully up to temp.

The point here is that when the Engine is cold there is enough Oil pressure for the Oil Spray Nozzles to work during cold idling. That would help seal the Piston/Ring/Cylinders.
When the Engine is hot at idle the Oil Spray Nozzles are not working because the Oil Pressure is too low; meaning no Oil is being sprayed up there to seal at idle.

Someone on one of the Forums concerning 240ds was speaking about some adjustment inside of the Fuel Injection pump that helped the idle control. Unfotunately if I have that in My notes I cannto find it.

When I was in Trade School they said that Governors have an adjustment called Governor Droop (no doubt a generic term). Adjusting the Governor Droop determines how fast the Governot responds to changes in speed or load.

That Guy did not use that term but that is I think similar to what He was speaking of.

If you go over to the Superturbodiesel forum the show pics of the backs of some Fuel Injection pumps and inside there was a Screw labled Idle (something). Other than the Title I am not clear what that adjustment actually does and I did not read enough of the thread to know what it does.
Apparently Superturbodiesel has changed names; I found the site with the pic
http://competitiondiesel.com/forums/showthread.php?t=142105

Skippy · #5 01-19-2013, 09:32 PM

Quote:

Originally Posted by JHZR2

yes, plastic lines, the transparent/translucent "main" ones.

Which one? Dont know. Ive replaced all the braided lines, valves are perfect, compression is high, injectors had nozzles replaced and were popped and balanced. Rack dampener doesnt help, and it is hot idle only. Super smooth cold. New MB mounts, shocks, shock mounts are all on the car, its still there. The car is wonderful at all other conditions but hot idle.

In your situation I would just ignore it.

JHZR2 · #6 01-20-2013, 10:34 AM

Quote:

Originally Posted by Skippy

In your situation I would just ignore it.

My 300CD is too nice otherwise to have such a thing bother me. Perhaps Im too sensitive/perfectionist... But if swapping a few parts lets me make it better, Im a happy guy!

Quote:

Originally Posted by Diesel911

All that leaves is uneven compression or something like a Valve not seating when hot that might show up with a Leak Back Test.

There is something else that may be related. In the manual the Oil Nozzles on the Turbo Engines need a certain minimum pressure (can't remember what it is) in order to spray.

Interesting thoughts. I will plan to do another valve adjustment perhaps in the spring and see what I get. Worth a shot anyway.

The oil pressure comment is interesting, Ive never done a hot compression or leakdown test...

funola · #7 01-20-2013, 11:08 AM

"I have a slight hot only idle shake, and though there are never any bubbles, Im at the point where all I can do is throw parts because Ive gone through everything..."

" Ive never done a hot compression or leakdown test..."

So you have not gone through everything. You're problem is hot idle, it makes sense to do a hot compression test.

JHZR2 · #8 01-20-2013, 11:54 AM

Oh I totally agree. I meant that all the obvious stuff like mounts, rack dampener, valves, etc has been done.

Any hints on a hot compression test? Is it as straightforward as it sounds? Do the same technique on a hot engine vs a cold one???

Thanks!

funola · #9 01-20-2013, 12:42 PM

Quote:

Originally Posted by JHZR2

Oh I totally agree. I meant that all the obvious stuff like mounts, rack dampener, valves, etc has been done.

Any hints on a hot compression test? Is it as straightforward as it sounds? Do the same technique on a hot engine vs a cold one???

Thanks!

Do it quick, before the engine cools off. Are you doing it through the glow plugs or injectors? Practice on a cold engine so you can be quicker when it's hot. If doing through glow plug holes, cut the wire lugs to make them come off faster (w/o having to remove the nuts). The hardest is #5 glow plug so make sure you have the right wrenches ready and practice.

JHZR2 · #10 01-20-2013, 01:05 PM

Ive done cold compression before, no big deal. Id just disconnect all of the GP leads in advance (plus the fuse/relay), and restart and let it idle to maintain heat, then wire the stop lever, and go at it.

The engine starts fine without glowing warm and even down to pretty cold ambient temperatures, so I could even run it for a little bit inbetween tests.

funola · #11 01-20-2013, 01:17 PM

Quote:

Originally Posted by JHZR2

Ive done cold compression before, no big deal. Id just disconnect all of the GP leads in advance (plus the fuse/relay), and restart and let it idle to maintain heat, then wire the stop lever, and go at it.

The engine starts fine without glowing warm and even down to pretty cold ambient temperatures, so I could even run it for a little bit inbetween tests.

You want all glow plugs out before starting the test so you will not be restarting it to warm up the engine. Do #1 and #5 first since they're the ones to cool off first. Rig up a remote start switch to save time and so that you can see the gauge as you crank.

edit:

I'd suggest doing a valve adjustment before the compression test.

JHZR2 · #12 01-20-2013, 01:53 PM

Thanks!

Ill have a helper to crank.

I did the cold one one at a time, because I could. Good tip on pulling all GPs.

Is there a reason why I couldnt/wouldnt want to leave the GPs in and then run the engine a bit inbetween?

Seems it would make the heat issue a non-issue and Id be pulling all he GPs at some point or other anyway.

Of course pulling ALL GPs makes valve adjustment easier when turning the engine by hand...

funola · #13 01-20-2013, 02:03 PM

The reason for removing all glow plugs or all injectors is for maximum cranking rpm for more accurate compression test.

edit: your valve adjustment should be a separate event from the compression test.

JHZR2 · #14 01-20-2013, 02:56 PM

Understood, thanks.

I did my cold compression test with the glow plugs in, thinking it would be more realistic in terms of forces on the crank and cams, and overall operational scenario.

When I free up some time all do all of this. Thanks again!