Problem with my son's car... The car started fine Friday morning and when he attempted to start it again 3-4 hours later, it would not start. We worked on it briefly Friday afternoon and we discovered the #3 glow plug to be bad. Thought that would do it so we replaced it with a brand new Bosch GP, but still no dice. We quit for the day as it was too cold out to continue. We brought the car home today from where it had been parked and worked on it some more... There was some crap floating around in the prefilter...looked like oil or something equally viscous. Changed the prefilter and purged the fuel filter. Vented air from the system in the usual manner. Attempted to start, but still no go. I'm sure this is one of those times when the fix will be something completely stupid, but I'm honestly at a loss for now. due to the cold weather, my son has been using #1 diesel and has had no problems before now. One thing I did notice is that when I disconnected the hose from the fuel supply line to the prefilter, nothing flows from the supply line. I've never worked on this car, but when I change the filters and run Diesel Purge through my 300SD, the fuel flowing from the supply line connected to the hose feeding the prefilter is always an issue and must be plugged. So I thought it was odd that there was no evidence of fuel flowing from the supply line under nominal pressure. In addition, when operating the primer pump, it appears that fuel is flowing back into the prefilter, even though I can see fuel flowing from the fuel filter housing outlet when I loosen the fuel line there and operate the primer pump.

Any thoughts from the experts...?

Thanks in advance...

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-Ken Harris
1984 Mercedes 300SD
2001 VW Passat 1.8T
2004 Harley Davidson FLHRSI
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Der Dieselfanatiker

There is a screen in the tank that can blind over. Unscrew the large hex where the fuel supply line screws into. Make sure the tank is as mt as possible. Unscrew the hex and the screen comes out with it. Clean it and re-install. I don't remember the hex size.

Typically the car just gets slower and slower and then will not run when this screen blinds over.

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Jim

I have seen this a few times with my father in law's car, and at least once he had the vent system plugged so bad the fuel filler cap could hardly be removed. Try seeing if removing the filler cap makes the fuel flow, and check to see that the tank is not below the connection point you are breaking at the in-line filter. Depending on the tank level, and the specifics of the parking spot you are in, a low level in the tank can result in no flow, and then, once you have broken the connection and let air in, no amount of priming will help. You have to either get more fuel in the tank or turn the car around so the tank is higher than the break point.

Also, is the car a manual or an automatic? Manuals will start with a push in almost any circumstances if the glow plugs work and fuel is flowing.

Good luck and I hope this helps. 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)

The same thing happened to me last month on my 420SEL. It drove me crazy. I disconnected the battery over night and plugged it back in and it started. Not sure if I flooded it out or the alarm somehow diabled it from starting since the vacuum for my locks doesnt work. Let me know if it works.

Mary

Well, we finally got some decent weather and got back to this...

I'm still somewhat baffled. So far, we've completely removed the fuel tank and replaced the tank strainer, which really didn't look to bad. It was certainly not bad enough to prevent fuel flow, but we changed it anyway. In addition, inspection of the tank did not reveal an algae problem or even appear to be very dirty. We did find that the vent line was clogged, but I did not suspect this to be the only problem since I had previously attempted to start it with the gas cap removed. So, while I was able to clear the vent line, the card still did not start. We now have fuel flow and although we cleared the air from the fuel lines and are getting fuel to the injectors it still continues to turn over without ever firing. While checking the glowplugs, one of the terminals on the presumably original Hella GP relay came off with the GP connector, so we replaced it as well as all four glowplugs; suspecting a faulty relay. As far as I can tell, we are getting glow as per normal. I can remove the oil cap and see the camshaft turning when turning over the starter. I am once again at a loss...

Is it possible that the timing chain failed and slipped a link, resulting in fuel delivery being completely out of whack? Also, can the vacuum switch on the end of the IP fail in such a way as to exhibit these symptoms?

Additional background that may or not be relevent... Several weeks prior to this car simply deciding to not start, we had changed the fuel injectors. It ran a little differently upon doing so, perhaps a little less smoothly. I discounted this, however, to be the result of the new injectors being much tighter in terms of where they popped at relevant to the old IP. In any event, it appeared to run relatively well, and at least it ran. Shortly after changing the injectors, I realized that I had forgotten to replace the heat shields. So during the course of troubleshooting this problem, I removed the injectors and replaced the heat shields without incident. I thought it possible that there was a problem with the new injectors and toyed around with the idea of putting the originals back in and/or taking the new (rebuilt) injectors to the local diesel shop for comprehensive testing. I ask this remotely, because I suspect the symptoms would be different if one or more injectors were failing in some way. Finally, I think it is important to note that this problem manifested without warning and there wasn't a gradual change of any kind that culminated in the car simply resuing to fire. I suspect this is a key symptom and that I will be smacking myself in the side of the head when we finally get to the bottom of it.

As always, your assistance is greatly appreciated...

-Ken

__________________
-Ken Harris
1984 Mercedes 300SD
2001 VW Passat 1.8T
2004 Harley Davidson FLHRSI
-----------------------------
Der Dieselfanatiker

the only thing i can think is maybe the glows arent working. do you see heat when they are supposed to be glowing? there is a way to test them electrically in place and someone else will have to tell you how.

also you have may have washed all the oil off the cylinder walls and perhaps now are down on compression.

pulling it may get it started. then after running it for a while try starting it.

i think it would be hard for the pump to slip on the chain. its not built like the typical us made vehicle in which this is pretty easy when they are worn.

good luck.

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Tom:

We have checked each GP for proper resistance from connection terminal to case, continuity to the GP relay, and proper voltage at each plug with the relay closed. The only thing we haven't done with the preglow is to actually observe them glowing. (Perhaps we should've done this first ). I will try removing all injectors and observing for glow in each of the cylinders. This seems to me to be the easier method than removing each of the glow plugs.

I had not considered the possibility of low compression due to the absence of oil on the cylinder walls. I assume you are talking about trying to pull-start the car and would be interested in trying this in lieu of taking down the battery, since it is now brand new. I had heard that these cars could be pull/push-started in spite of the auto tranny, but do not know the procedure and have been unable to find it when searching previous threads. Also, would a recent rebuild on the tranny have any bearing on the ability to do this?

Finally, what are your thoughts on my idea about the IP vacuum shut-off switch being stuck in the "off" position?

Thanks,
-Ken

__________________
-Ken Harris
1984 Mercedes 300SD
2001 VW Passat 1.8T
2004 Harley Davidson FLHRSI
-----------------------------
Der Dieselfanatiker

IF I remember correctly...
pull the vaccum hose lose from the shutoff switch on the rear of the I.P.
EVERYTHING ELSE in perfect running order ...it should start.

Hand primer pump leaking badley? Perhaps letting air in when closed? Loosen an injector line fuel coming out? But what I am suspecting from your description is the larger fuel filter. It does not cost that much to sub it anyways and even if not the problem you are left with an emergency spare. On these cars that is always a wise thing. The reason I think it might be that filter is when you were pumping you thought you were observing more than normal back flow into the secondary filter.Perhaps pumping up more pressure than normally required that cannot reach the relief return valve? So it appears to back flow a bit more? If primary filter was not blocked I think fuel would go through pumps relief valve to return line and you would not observe the back flow. Just some thoughts. Perhaps wrong. Change the filter first. You have to eliminate it pretty well anyways before proceeding. Not absolutly sure if purging the filter would do it depending on what it may have been collecting. I guess you might also remove the hose and see what if anything is coming past the return valve when pumping. Fuel, fuel with a lot of air, no fuel at all? Just put a short line from the return valve into a small container with a little fluid in it. I would also consider warming up the block with the block heater if you can. It might ease a stubborn first restart a little.