I replaced the O-rings and copper washers on my W124. I did this job 18 years ago just perfectly, and then did the job again just yesterday.

I thought I put everything back pretty well. I put the fuel lines back on the delivery valves tight, but left the upper part of the fuel lines that go directly into the injectors just hand tight because I know the car has to expel the air when cranking. I know the car has to crank a while, I made note the last time I did this that the car might have to crank for 45 seconds. But I might have cranked for over a minute and the car got absolutely nowhere, not even sounding like it's ready to fire up. I had to stop to recharge my battery and will try again later today. Hopefully all it needs is another 15 seconds at this point, but there's no fuel at all coming out of the upper metal fuel lines. It seems to me 18 years ago that I left those loose and fuel and air bubbles came out, then you wait until nothing but diesel fuel comes out, then tighten them up for good.

I just wanted to ask, was it the upper part of the fuel lines that I was supposed to put on hand tight, or the lower part at the delivery valves? I think it's the upper but.....seems like something is not right. If nothing else, it seems like I should have gotten fuel coming out at the upper part after cranking for that long.

1991 300d, 258k

You want the fuel injection hard lines loose at the injectors in order to get the air out.

While you are cranking the engine are you getting fuel up to your spin on fuel filter?

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84 300D, 82 Volvo 244Gl Diesel

I assume when you say "spin on fuel", that you mean the spin on fuel filter. I don't know. I haven't checked. Since that was never drained to do this job, I feel no need to check it. It's probably full since it was never drained.

Yes, and thanks I went back and fixed it.

You can of course check or not check as you see fit. I was trying to see if your fuel supply/lift pump was working properly or if you were getting air coming out of the fuel filter housing.

If the valves are not holding when a car sits in particular with the front of the care higher than the read a valve that is no sealing allows the fuel to flow back down into the thank. If you opened the delivery valves a leak at the fuel supply/lift pump valves would have the fuel flowing back to the fuel tank and at the same time pulling air into the fuel supply system.

Find some threads on members who have rebuilt their fuel supply/lift pumps and see the symptoms they were dealing with.

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84 300D, 82 Volvo 244Gl Diesel

I recall filling the IP with diesel when the delivery valve was off. I only replaced two washers and seals on mine at the time. Before taking it back apart and doing this it would crank and crank. I think it was just pumping air until I filled the cylinder in the IP with diesel.

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Old Blue - '83 240D 6 speed manual trans, OM648
Green Machine - 2001 Europa G500
'87 300SDL Bought on Peachparts
'02 E320 4matic wagon

Patchouli Wagon - 2004 E500 - SOLD
333k mile 97 BMW 750il V12. - SOLD
The Californian - 85 300TD - SOLD
Daily Super Sedan - 03 Audi S8 - SOLD
Family Truckster - 2012 VW Touareg TDI - SOLD

Be really cautious when filling the IP with diesel directly. Not only are you putting unfiltered diesel into it, but you can easily introduce dirt from the surrounding area. If you're going to do this, clean everything spotless (which should already have been done) use a vet syringe and triple check the fuel you're using is ultra clean.

Inline 12v lift pumps are dirt cheap ($20) and are great to drop into your fuel line temporarily to resolve priming issues. In fact they will pass fuel fine even when not turned on due to their simple design, so they aren't bad to just leave installed.

I have them on multiple tractors, and one can turn hours of bleeding certain nightmare pumps (CAV rotary I'm looking at you) into a 5 minute affair.

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1993 300D 2.5L Turbo

I had to do that on my Volvo Diesel. It has a fuel injection pump like a VW Rabbit but no priming pump. I removed the fuel injecting pump to change a seal on the drive shaft. But it was just taking too long to get the fuel from the tank up front so I installed an Eletric fuel pump. It did the job.

I am addling this. CAV rotary pumps usually have a manual air bleed located in one of the 3 head locating bolts.

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84 300D, 82 Volvo 244Gl Diesel

I had to recharge the battery for a day and crank and crank and crank. Once again, the car didn't start but at least I got some diesel fuel coming out of the fuel lines at the injectors, so that's good.

The battery got worn down again so I'm having to recharge the battery and am hoping the car will start today.

I cranked the car today after charging the battery from yesterday. The car cranked for about 30 seconds but wouldn't start.

I know fuel was at least coming to the injectors because I purposely put those nuts on hand tight, then backed them off just a smidgeon.

After 30 seconds of cranking, I thought maybe the fuel lines were supposed to be on tighter. I hand tightend the fuel lines up, and the car started right away.

Another job done! I will have to re-do it again in another 18 years! Ha!!

Congratulations! I guess your IP must have drained right back. When getting it to start, you need to have the nuts tight enough to build pressure, or the injectors won't pop. These cars seem to be fine blowing a bit of air out on their own once they get going, but some other mechanical diesels you have to crack successive lines and get individual cylinders firing.

I should do my delivery valves and see if it quiets my idle clatter. But it needs to be above -20 during the day to even think about it. What a winter.

On the side discussion regarding CAV, all the CAVs I own are covered with bleed screws! The main issue with them I found was you could bleed forever with the hand primer, but if the tiniest bit of air got sucked back after the primer stroke, they won't fire. You had to do it like bleeding brakes, cracking the screw open and shut with every stroke, or have another guy crank the starter and wear it out.

With the electric pump I can just put a pan underneath, turn the pump on, crack each bleed in sequence and turn the key. Highly recommended.

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1993 300D 2.5L Turbo

I had previously mentioned that he is having a symptom of his fuel supply/lift pump disc valve seals leaking and the fuel going back towards the tank.

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84 300D, 82 Volvo 244Gl Diesel

It was just because I put the nuts on the upper lines just enough to where they started to catch, then I backed them off just a tiny bit so that they would spit fuel and air out. But turns out the "tiny bit" was too much, so I had to tighten them more, and then the car cranked right up.