I'm new to this forum so I thought I would give this a try.

My wife has had this 240D for years now and we think it needs a fuel filter change. She hasn't changed it (them) in at least 4-5 years. No surprise but it's not running well right now. Low power. I gave it a shot and changed the primary and secondary fuel filters but I can't seem to get all the air out of the new line. (I'm guessing that's all it is). Here'e why:

The original fuel filter(I think it's the primary. The small one that take a 90 degree turn) was slightly smaller and you couldn't see through it. The new one is "just" slightly larger around and clear. I can see the fuel coming through when I pump but I can't pump it enough to get "all" the air out. The fuel starts coming out of the pump shaft.

I tried losening the large filter in case there was an air pocket that wasn't allowing the fuel to move but fuel comes out the large filter so it "appears" full. I was told to try to remove one of the injectors and pump it or turn it over and try to force the air through and out one of the injectors. Still no luck. I "think" I can identify the injectors. They seem to be the metal tubes coming from the fuel distribution device to the head. It just won't turn over. (It fires and tries but it sounds like no fuel is getting there.)

I am not a mechanic and ony change oil and small things like that.

One note: When I first tried it the car ran for a few seconds then died. I'm assuming it was using the fuel still left in the lines from the filters to the block.

I tried to search the forum and I can't seem to find the exact fit when somebody describes fuel filters.

Any help out there?

= you need a new primer pump. if fuel can get out air can get in!

Scooter, fuel coming out of the pump shaft means you need a new primer pump because if fuel comes out air can get in, Get a new style black Bosch pump.
Try filling your secondary filter[the large spin on} with fuel before installing it. Less pumping needed to purge and fill.

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1981 240D 143k 4 spd manual -SOLD

2004 VW Jetta TDI 5 speed 300k -still driven daily

Make sure there are no fuel leaks throughout the system. There does seem to be fuel in the spin on filter, many will fill it with fuel before installing it, I do. In my case I pump the primary filter maybe twice, fires right up.
Also make sure the primer pump handle is tightened down, just turn it clockwise, when it's in the down position, as in tightening anything else. New style pumps are just a button, no locking or unlocking required.

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83 SD

84 CD

IS SCREWING the primer down that important,i have forgoten once or twice and still been able to get my motor 617 to fire without any noticeble difference.I did tighten it up before i drove it though.........you could see the primer going up and down !

scooter,
It might help to spray a little wd40 in the air cleaner, it works like a cold start helper. You may need to crank a bit to get the air out of the injector lines. Hope your battery is well charged!
There are plenty of threads on here about the correct procedure to change your filters. 4 or 5 years must be nearly a record for not changing diesel filters!!

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Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving

It usually takes a lot of pumping on that hand pump to clear the air out. It is much more efficient than cranking the engine. Even if it leaks a bit. The problem is the engineer who specified that thin top and sharp edged "knurling" to improve grip was a sadist. If the pump is squirting Diesel out while you are operating it, you should consider replacing it. They are not expensive or that much trouble to replace.

The pump needs to operate reasonably quickly and continuously until you hear a slight buzzing sound. That is a little pressure relief valve in the system that is signaling the air is actually getting out of the pump area as you are now building pressure in the system. You can't build pressure, or much pressure, with air in there as air is compressible and the pump stroke volume is not that much. I usually continue to operate the hand pump until I have about 60 strokes of "buzzing." I have managed to do this with the unit leaking a bit. Once you screw the handle down solid, you should have nothing leaking out. If you still have a leak, you must replace the pump.

Changing the filters is messy and requires you run this priming routine. The priming is simpler, as others have noted, if you fill the big, screw on filter with Diesel first. I usually put a Diesel additive in the big filter before screwing it back on - like RedLine or one of the others as they are nearly all Diesel fuel anyway.

Good luck,

Jim

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Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)

If you're referring to the bubble in the primary filter, that doesn't go away. It also seems that its size may depend on the fuel level in the tank.

I'll second the comments about filling the primary before installing and getting a new primer pump (they're not expensive, and the old one is a possible source of air getting into the system)

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1982 240D, sold 9/17/2008
1987 300D TurboW124.133 - 603.960, 722.317 - Smoke Silver Metallic / Medium Red (702/177), acquired 8/15/2009
262,715 and counting

You actually have 2 Fuel Systems.
The Fuel Supply System.
And, the Fuel Injection System (the high pressure Fuel supplied to the Injectors).

You bleed the Air out of the Fuel Supply system by pumping on the Hand Primer as described in some of the Previous Posts.

If after changing the Filters you did not do an adequate job getting the Air out of the Fuel Supply System; Air gets into the Fuel Injection System.

This is the Hard Injector Fuel Lines between the Fuel Injection Pump and the Injectors. If you get Air in the Hard Lines the Air likes to compress a lot and move only a little. You can easily deaden a use Battery trying to clear the Air out of them.
The solution is to get a 17mm Wrench and loosen the Hard Line Nuts at the Injectors and crank the Engine until Fuel comes out from under the Nuts.
Loosening the Hardline Injector Nuts allows the Air to escape.

After the Fuel Comes out tighten the Nuts and attempt to start.

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84 300D, 82 Volvo 244Gl Diesel

Thanks guys!!!!! I had the same problem. This fixed it.

And for anyone else reading, I think it helps to hold the accelerator petal to the floor while cranking until it gets running good.

Robert
'83 240D 300k miles

Heh, would this be a quick and painless way to do a mini-diesel purge? Just fill the filter with the LubroMoly Diesel Purge stuff? Or would most of it get bypassed and go straight back to the tank?

Kurt

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- '79 240D - engine swap complete! Engine broken in! 28-31 mpg! Lovin' the ride!
- '86 190D (W201-126) - 2.5 NA engine, 5 speed, cloth interior, manual climate controls, 33-34 mpg (sold to forum member).

In my experience, the filter contents bypass to the tank too quickly. Especially at the $ for the diesel purge, I wouldn't do it that way. I have filled mine with Sea foam a couple times, and @ $6-$9 I really felt like I wasted it.

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'86 300 SDL '83 300D Astral Silver/Blue
354k miles.. 326k miles..

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