You mentioned that you installed "NAPA" glow plugs. However, NAPA is just a retailer. Did you happen to notice the manufacturer of the plug? Certain plugs don't have a good reputation and, if you've got such plugs, you really need to perform a resistance check of the plugs...........now.

Compression could be an issue if you leave the vehicle out in the cold and try to start it. But, if it's got a block heater and is inside a relatively warm garage..........we can dispense with that possibility.

So, that leaves the issue of fuel. You questioned the condition of the fuel at this new station..........and, therefore, it's time to pull the secondary fuel filter and carefully pour off the contents. Look for contamination and/or water. The filter will collect some of the water, but, if the problem is massive.........water will pass to the IP and prevent a start.

How far did you drive the vehicle after filling up at this "questionable" station? If it's more than 10 miles, fuel is not likely the issue.

Which brings us back to glow plugs...................

Bosch - I was not aware they sold any others.



Block Heater, yes. Heated Garage, no.

Holiday does not have a great rep in these parts. I prefer not to use their fuel, but had allowed the tank to get to a level that prevented me from going much further - not empty, but less than 1/4.

About 45 miles.

Indeed it does. I will pull the plugs and check the resistance. I should be able to hit them with 12 volts and see if they glow as well, while they are out. #4 and #5 are a real pain to get to without significant disassembly - which is why I have not replaced those. I do have replacements for them.

__________________
That's All I Got
Joshua Coder
Green Isle, MN
------------------
1980 300SD Turbo In a 1974 Ford SuperCab Pickup
1964 Parts Car

you should be able to measure the resistance in the car, no need to pull them. pulling them and putting 12V to them is the only SURE way to know if they are working though...
you want to have approx .6 ohms of resistance on a cold good glow plug.

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

I agree.

To test the plugs in the vehicle, pull the connector from the side of the glow plug relay. There will be five sockets in the connector........one for each glow plug. Put one probe in the socket and the other to battery ground. Make sure the meter is reading ohms on a very low scale. You're looking for values of .6-1.3 ohms. If you're on a 1K scale, your readings will be meaningless. Any reading of infinity indicates a bad plug.

Since you have this manual setup, I think you need to give the glow plugs more time. If you run them for 15/20 seconds and then no more power too them, I don't think you are getting them hot enough. Mine, with the automatic hookup, glow for 70 seconds before the relay shuts off. On these cold mornings, 10 to 20 F, with the block heater, I have difficulty in getting it running. So, I give it 60 seconds, then recycle the switch and give it another, at least 20 seconds. That is what it takes. These Mercedes with indirect injection are not easy starters, but given care and precaution, they will start. You also need fuel and compression.

__________________
Junqueyardjim
Christianity, if false, is of no importance, and if true, of infinite importance. The only thing it cannot be is moderately important. C.S. Lewis



1983 Mercedes W123 240D 4 Speed 285,000 on the road with a 617 turbo, beautiful butter yellow, license plate # 83 240D INDIANA

2003 Jaguar Type X, AWD. beautiful, good mileage,
Mom's car, but I won't let her drive it!

Some are not easy starters. But, I attribute this to valves. The SD would give some trouble when the temperature dropped below 15F. Had to crank for 20-30 seconds.

After the valve job, the SD starts at 0F............in one second. It also has 205K on the clock.

So, the issue is not with IDI..........it's with compression...........and the compression is compromised by old valves.

There is clue that shouldn't be overlooked. The glow plugs from cylinders 4 and 5, per the post above, have not been checked or changed because of difficulty getting to them. Two bad plugs can make starting a lot more challenging, given the likely accumulation of other less than optimum conditions that is normal with an older machine like this one.

The keys to starting are compression, glow plugs, and fuel delivery. There are several conditions that affect compression, but other than valves there is really only cranking speed (especially in cold weather) that is part of normal wear and tear, and that an owner can readily address. Cranking speed in cold weather is critical because an otherwise healthy engine will leak away more of the compression given the longer time to reach TDC, and the heat generated by that compression is very readily absorbed by the cold block. So, the Diesel compression ignition temperature is never reached. Cranking speed is affected by the battery health and robustness (brand new undersized batteries won't run glow plugs and crank at the right speed), the starter and the engine oil. This is one of the main reasons I use Mobil 1 (Delvac 1, actually) engine oil.

Glow plugs are well covered in this thread, and having two potentially bum plugs is really putting the starting function on the battery and starter, and engine oil side of the equation. Probably not likely to generate a good outcome.

Fuel delivery is also discussed but is affected by fuel quality, contamination with water and other gunk, injector nozzle condition, air tight connections throughout the system and, at low temperatures especially, the condition of the filters and fuel. Diesel will precipitate wax at around 14 degrees F without any additives (usually Kerosene, but plain gas at up to about 30% per your manual is acceptable in a pinch), which clogs the filters and you don't get fuel.

Seems you have lots of advice. I would do the resistance check of your plugs, especially those two old ones. Good luck, Jim

__________________
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)

He doeesn't have a relay. Check the resistance at each plug. Negative to the block, positive to the connector end of the plug.

__________________
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

Alright, I pulled all 5 plugs and found two that were DOA. In the interest of full disclosure, these two were not changed out last time I changed plugs (Around 11/07). I tested all five and they glow strong.

I pulled the fuel filter and did not find anything that "looked" suspicious - no water, sediment. I am going to replace the fuel filter tonight, just because I have not done that yet.

I pulled the air filter and replaced - the old one looked fine.

Vacuum is present and accounted for.

I still am unable to get her to start. I will try this evening after replacing the fuel filter. The only thing I can think of is that perhaps there is enough fuel getting through the filter to allow a fire or two and then it is sucked dry.

The firing seems very "off". In that I mean, this motor has historically started and idled smooth. Now, when it does fire - it is very rough, as though it is only hitting on a few cylinders.

Anyone have any more ideas?

__________________
That's All I Got
Joshua Coder
Green Isle, MN
------------------
1980 300SD Turbo In a 1974 Ford SuperCab Pickup
1964 Parts Car

Did you pump the primer pump at least 50 times after you changed the secondary?

I did not change the filter yet, though I did remove the old filter and inspect for contaminants. I did not "prime" anything.

I was just speaking with a guy at work here, he drives a TDI Jetta, who says he has a bear of a time restarting if he does not fill the new filter with fuel, after a filter change.

I will add a bit of kerosene to the tank and see if that helps at all. The fuel seems good (fluid - not waxy), from my untrained eyes.

I may pull the injectors and see that they are not plugged or obstructed. Anything in particular that I should be careful of, or pay specific attention to?

__________________
That's All I Got
Joshua Coder
Green Isle, MN
------------------
1980 300SD Turbo In a 1974 Ford SuperCab Pickup
1964 Parts Car

If you removed the secondary filter and failed to fill it with fuel...........you'll need to pump the primer pump about 250 times.........otherwise it will never start.

If you removed the secondary filter and filled it with fuel...........you'll need to pump the primer pump 20 times.........or so.........to help get a start quickly.

You can forget about the kerosene and the injectors..........they are not the problem here.

10-4 on the fuel. I will fill the filter with fuel and prime the snot out of the thing.

So I know, what does the primer look like and where do I look for it?

For the money, should I replace the primer pump while I am under the hood?

FEI (For Everyone’s Info) I had not messed with the fuel filters, prior to this vehicle not starting. This weekend was the first I have checked/messed with/replaced. So I do not believe that lack of "priming" is the root cause.

__________________
That's All I Got
Joshua Coder
Green Isle, MN
------------------
1980 300SD Turbo In a 1974 Ford SuperCab Pickup
1964 Parts Car

The primer, if original, is attached to the fuel pump. Follow the fuel line to the fuel pump and look for a white plastic device. Unscrew the know and the piston will pull out and allow you to pump fuel. If you have the new model primer, it will be a black plastic device. You just press down on the top plunger to force fuel into the system.

If the primer doesn't leak, you don't need to replace it. Conversely, if it does leak........you do.

Two bad glow plugs could give you starting problems. Fixing the glow plugs and draining the secondary (and not refilling it) will give you severe (impossible) starting problems.

I am curious about how you managed to try to start the machine after removing the old filter and before you installed the new filter.

The issue you are struggling with, it seems, is that once you open the system up, you get air all over the inside of the fuel system. The system is designed to operate "solid" with fuel, meaning no bubbles of air. None. The reason is the injection pump is a very low displacement (it meters out the fuel per power stroke to each cylinder, which is to say a very small amount of fuel) and air in the system on the high pressure side equal to a significant fraction of the amount of fuel being injected will waste most of the pump's stroke as it compresses, and then you get that much too little fuel in that stroke. When the pump tries to suck the next stoke full of fuel from the tank, well, the first thing that happens is the air bubble expands to fill the volume. You get the picture.

The system is designed to actually clear the air by pumping it back to the tank, but in very small volumes per engine revolution, equal to the volume of the fuel that would have been pumped if there had been no air, at the given throttle position. This, however, is a very inefficient means to pump air out of the system with the engine being turned over by the starter, so, on early Diesels they equipped the injection pump with a hand operated priming pump. It is on the forward end of the injection pump and has a knurled plastic edged disc on top. I have seen them black and white. The person who designed the knurling on the knob was a sadist. The edges are sharp, and the amount of hand stroking this pump needs to clear the system typically results in blisters and torn skin. Do yourself a favor, and use a rag over it. They can also be too tightly screwed down and that makes for another painful experience. Use a suitably sized pair of pliers if the unit won't unscrew readily by hand. And, while pumping they leak fuel. At least every one I have used does. I believe the leaking fuel is good as it keeps air out while you are pumping. When you finish, screw the top back down, firmly but not so tight it won't unscrew next time. If it leaks in the screwed down position, replace it with one of the new style pumps.

Good luck, and note that even after you prime the system with the hand pump, it often takes a few tries to get the engine to fire up. Some air may be inside the injectors and you can't get that out with the priming pump, especially if you tried to start it when it was full of air. Once it starts, let it run for a while and it should return to its old habit of starting and idling smoothly.

Jim



PS: To be clear, your original problem was likely the two bad glow plugs. But, once you opened the fuel system and let air in there, you were not going to start until all the air was removed, or almost all the air was removed. Once it starts, the engine runs like crap until it purges "all" the air out and the fuel system on the high pressure side is "solid" with fuel again.

__________________
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)