I've actually got two related questions about my '87 300D:

1. How bad is it for the IP when you run it dry? The reason I ask is that with my WVO setup, I've recently been getting an air bubble that passes through when I switch over. Usually, the car loses power briefly and then recovers, but occasionally it dies completely, and needs to be cranked for a little bit to restart. To what extent is the IP lubricated by only the fuel? Any time I open the fuel system, there is a certain amount of cranking that happens, so I assume the IP is built to withstand some dry operation. But I'm not sure if there is a difference between just dry cranking, and dry running at speed. And yes, I do plan to find the air leak soon. I've ordered some clear fuel hose, which should aid greatly in isolating the problem area.

2. My second question is pretty ignorant, but here goes: What is the difference between direct injection and indirect injection? And which one does my car have?

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

1. Hmmm. I'm not sure of the answer but I'm curious to know because I go through the same thing when I change my WVO filter. It takes forever to get the air out and there is a lot of dry ip time.

2. The OM603 that your car has is indirectly injected (ID). That means that, instead of the fuel being directly injected into the combustion chamber, it is injected into what is called a prechamber, which aids in the mixing and heating of the fuel. Most older engines are ID, while almost all newer models are directly injected (DI). DI engines seem to get better mileage and are easier to start in cold weather.

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Seth

1984 300D 225K
1985 300D Donor body
1985 300D Turbo 165K. Totaled. Donor Engine. It runs!!!
1980 300SD 311K My New Baby.
1979 BMW 633csi 62K+++? Dead odo

I am not sure if the answer was clear enough for you. Direct injection means the fuel is injected right into the combustion chamber. There are or seem to be many inherent advantages to the system. The indirect injection is where the fuel goes into a precombustion chamber containing a glow plug and an injector nozzle in you case I believe. It flows out there into a cylinder. Edit: I just read the last post. Starting easier for me is an understatemet in cold weather on certain direct injection engines. I suspect the compression alone is higher in them. Some will start when good gas cars will not. Just unbelievable compared to our older engines.

In general its not good habit to run an IP dry all the time. I suspect this is more true for fuel lubricated IP's. Our are oil, different animals.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

hey Diesel Dan, the easiest thing to do is to fill the filter first with oil before installing it. Also not sure of your set up but i have a electric fuel pump on my engine and i just bleed the IP before starting it. Also you could bleed the IP with the hand pump by loosing the return fuel line on the back of the IP, or easier yet where the return line returns back to the fuel filter and then just pump away until oil starts to flow out of the return line.

I know running out of fuel on the 24 valve Cummins is VERY bad thing, not as much of a problem on the 12 valve Cummins and I've not heard of any problems with MBs 616/7 although , as was mentioned, it cant be real good for the IP.

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

Yep, thats what they taught us in truck driving school - that running an engine bone dry can really mess it up. Not just the IP but score the bores too. It's like without fuel the engine cranks and runs on steam.

I usually don't change fuel filters till I detect that slight hesitation on a long pull uphill. It would probably run for miles on the flat but thats when they get changed. On a boat with a cat or Jimmy fuel filters generally don't get changed (switched over) till they need too be (RPMs drop a little, skipper freaks) . I don't think this practice would be considered running outa fuel tho.

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

Stevo

I am curious. What kind of mileage are you getting with your '95 dodge ram with the 5spd & 5.9 Cummins? After I get my 82 300SD on the road again I'd like a diesel truck. Have heard a lot of pros and cons between the 12 valve & 24 valve and the mechanical injection vs. the common rail.

Thanks

Sedecrem

That's because the IP is lubricated by the fuel in the later 5.9's. There were a lot of problems with failing lift pump on those engines. People who know this put fuel pressure guages on their vehicles so they can monitor the continued flow of fuel to the pump.

Some direct injection engines are actually lower in compression than the 616/7 but they still start easier in cold weather without glowplugs. (CAT 3208 for example)

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

As I remember my 5.9 is 17:1, and as far as the later IPs, I know a fuel pressure guage is a "must" on those engines.


I towed a 240D on a dolly back from Seattle, 230 mls, and got 23 MPG for the round trip last time I checked it. I like the 12 valve Cummins, its noisy and it doesn't have the HP of the later engines but it meets my needs just fine.

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"