Anybody know.....what I should do?

Get over your fascination with tractor engines and buy a gasser.

 

Ha ha. Diesel pwnes gasoline to the 8th power.

 

That is all part of the spin on fuel filter changing process. Crack the bolt, I think it's 21mm? at the top of the fuel filter. Then use the manual fuel pump and pump it until all the bubbles are out of the line and fuel leaks out the top of the bleed bolt as aforementioned. Crank the car with the pedal down on a fully charged battery and off you go.

I must say, the 300D W115 is the hardest diesel I have ever had to prime. It's quite frustrating actually.

 

Ha ha. Diesel pwnes gasoline to the 8th power.

Whatever gets you through those cold, dark nights, buddy.

 

That is all part of the spin on fuel filter changing process. Crack the bolt, I think it's 21mm? at the top of the fuel filter. Then use the manual fuel pump and pump it until all the bubbles are out of the line and fuel leaks out the top of the bleed bolt as aforementioned. Crank the car with the pedal down on a fully charged battery and off you go.

I must say, the 300D W115 is the hardest diesel I have ever had to prime. It's quite frustrating actually.

Are you talking about the bolt next to the one that I unscrew to take off the canister filter? I meant to try that one but it was getting dark and very very cold.

 

Are you talking about the bolt next to the one that I unscrew to take off the canister filter? I meant to try that one but it was getting dark and very very cold.

Yes that is the bolt. Loosen it and prime the fuel filter.

 

I found what I think was that purge pump today and pumped it about 300 times (seriously) The fuel in my clear lines moved around but didn't fill them. I got the engine to run after many failed starts but it sounded loud and I had to keep it revved up until it died minutes later. When I have the time I'll make sure I have no leaks in the lines, although I'm sure I tightened everything down.

 

You may have some air leaks in the lines but you may also be dislodging some bubbles as well. Is the primer pump giving some resistance or leaking excessively as the primer pumps do fail over time.

 

It's greasy but not dripping and there is resistance. How much do you usually have to pump it? I did it for several minutes at a time inbetween start attempts.

 

Pumping while getting someone else to crank the engine helps a little. I killed 3 batteries to get the engine primed once. I don't know what it is about that specific 300D motor.

 

Just out of curiousity when did you adjust valves last?

 

I don't know the last time the valves were adjusted, but I know it's long, long overdue. When I have more money...

 

The valve adjustment will help but if it ran before it will run now.

 

The valve adjustment will help but if it ran before it will run now.

Not necessarilly. Tight valves may be the key to his problem. The weather has just turned cold, and the lower the temp, the tighter the valves get. It can lead to lowered compression, and you need compression to make a compression ignition engine to fire. Those air molecules need to be compressed into a tight space to raise combustion temp to about 900 degrees F.

 

The engine is not likely going to drop compression that much in 2 days and it was clear that the engine was running fine before he changed the fuel lines. There's likely air in the lines and it is just a pain to get it reprimed. I highly doubt the valves will become so tight that it will not fire unless the GP's aren't working, the fuel isn't gelled up and or the air is unusually cold.

Sako, are you getting some partial firing when it cranks or nothing at all? What's the air temp where you are?

Either way get the valves adjusted when you can.

 

The engine is not likely going to drop compression that much in 2 days and it was clear that the engine was running fine before he changed the fuel lines. There's likely air in the lines and it is just a pain to get it reprimed. I highly doubt the valves will become so tight that it will not fire unless the GP's aren't working, the fuel isn't gelled up and or the air is unusually cold.

Sako, are you getting some partial firing when it cranks or nothing at all? What's the air temp where you are?

Either way get the valves adjusted when you can.

Question? When does a light bulb burn out? It worked yesterday. When does a diesel engine reach the point when it doesn't start because of low compression? True story: A guy drives his SL to the grocery store, gets out of the car, goes into the store. He gets back in his car, starts it, puts it in drive and nothing happens. His transmission just quit worling just like the light bulb. I'm just saying we need to look at all the possibilities.

 

It still runs, it is clear to me that it is a fuel starvation issue. When it's being cranked while I am pumping the purge valve as fast as I can I can hear it firing but doesn't stay that way. 2 days ago I did get it to run for a minute. I'm going to warm up in here for a minute then go back outside to tinker more. And also I am now using ULSD since the bio was solidifying in the 35 degrees were having.

 

I just got back inside. I manually filled all the lines with an ear dropper w/diesel, some of them stayed full and others I could see the fuel flow away, back to the tank I presume. I replaced and filled the canister filter too. Finially got it to run and it idled but sounded like it was missing every couple of seconds. While it was idling I went to the back and poured 5 gallons of diesel in, when I took off the cap I heard air rush out so the tank was pressurized. Idled for about 7 minutes until what was in the canister filter ran out, then it got rough and died. I cannot get fuel to go to the clear fuel filter by pumping the purge valve. I see it come up from the tank but stop just short. Shouldn't the pump force fuel to go through the whole system?

 

I'm really confused here. Bio diesel shouldn't gel up any more than diesel and especially at 35 degrees unless you mean -35 degrees., and what is ULSD? The reason you can run biodiesel without altering the vehicle is because it is vegetable that has been chemically altered to retain the consistancy of diesel. If you want to use WVO or SVO, you need to install a single tank system or a dual tank system to heat the oil. You can also do a blend of 85% veg oil to 15% unleaded regular. This blend dowsn't require heating. You mentioned all the lines being clear. You should have only two or three clear lines. The rest should be steel. To bleed these systems all you need to do is pump the primer pump until you hear a squeaking sound. It is primed. If the engine doesn't start right away you will need to prime again. It is possible that the valves in your transfer pump are sticking which might be causing part of your problem. Transfer pumps seldom fail, but occasionally they do. Also I still think a valve adjust would help considerably. You know in the factory diagnostic manuals MB lists the order to check things for a particular complaint. There is a manual for gas and one for diesel. I'm home now and don't have my manuals handy, but Im telling you that check valve adjustment is one of the items on the list.

 

Well, biodiesel DOES gel. I don't know the exact temp, buty it was butter-ized so I stopped using it for now. Ultra Low Sulpher Diesel (15ppm) I already know about WVO, it's not a big concern to me at this point, neither is a valve adjustment until after the engine wants to run. My car retained all of it's stock metal lines, I only changed the rubber ones with vinyl (wrong material I know, but it works) Would the transfer pump be that thing with the black plastic purge valve on it?

 

I think I'm getting somewhere!

OK I went and got my hands dirty and learned a bit about how the fuel system is supposed to work. I now know that: Fuel is supposed to come from the tank, flow through an inline filter, then go somewhere at the bottom of the injection pump, get pumped back up into the canister filter and go back to the tank. Right? I'm still clueless as to what the red plastic line on top of the injection pump does.

What my car was actually doing: Well, nothing unless you pumped the purge valve very quickly, then fuel very slowly came up from the tank and barely made it into the inline filter. It would run if I kept the canister filter full, which had to be done by pouring it in through the top.

What I did: I bypassed the inline filter and red plastic line that makes the fuel go to the pump and back. I connected the line from the tank straight to the reciever underneath the purge valve and used the valve to pump fuel (which was much easier now with the shorter trip) directly into the canister filter.

What happened: The car ran continuously as long as I frequently pumped the purge valve. The idle would get rough as if running out of fuel if I didn't. A foamy mixture of air and fuel ( I could see it was now a B99/ULSD mix) flowed of the line at the top of the purge valve. This was the fuel feeding the engine, correct?

What else I learned: The nuts and possibly seals on the purge valve assembly seem too easy to loosen which causes fuel to slowly drip out. Perhaps running bio ate some rubber seals which are now letting in air?

My conclusion: The fuel pump is not doing it's job. I should have seals in the purge valve replaced with OEM/better quality parts, along with lots of other seals and hoses under the hood. Please correct me if I'm wrong. And if you've made it this far, THANK YOU THANK YOU THANK YOU. I would be permenantly up poo creek w/no paddle without the internet and the people who use it.

Here is a link to pictures and video:

http://s24.photobucket.com/albums/c39/SakoTGrimes/Mercedes fuel problem/

The first video shows what happens when I throttle up the engine. The line coming from the lower side of the injection pump spurts some fuel, mostly air.

In the second video you can see me pump the purge valve, which will fill the line from the tank to the canister filter. Shortly after I stop, the line empties, and you can see fuel and air coming out of the filter on it's way to...? I can't remember, but it goes back to where ever it was designed to, I didn't change it. I think it goes to the pump because as long as I used the purge valve to fill the canister it kept running.

The third video is a longer, poorly lit version of the Second. I threw it in there just in case.

 

Finially got to the mechanic while he was still open and he told me that it's probably just a clogged screen blocking the fuel pickup in the tank. Now I gotta get that huge ass hex bolt out and have fun with downpouring diesel. Anybody know what size it is? 19mm?

 

I think you're right it's 19mm or 22mm. I have never remembered to check it while it's on the lift. It's best to run the tank down first if possible or use a container to catch the fuel before removing the strainer.

I am glad it clearly wasn't a compression issue.

 

Definately not compression, I'd just sell it for parts if that were the case. I used a pump siphon to empty out as much of the tank as I could into a new diesel can today but I only got about 1 gallon (there's at least 10 more in there) and the stuff I sucked out was real dirty with lots of flakes, supporting the mechanic's idea of a clogged screen. Went to Harbor Freight but they didn't have any big hex keys. Any idea where else I should look? Working on a diesel is a real pain when it won't QUIT RAINING! Oh well, I'll be back out there tomorrow if I have time after work.

 

Are they black flakes or rust flakes? I get chunks of rust in my 300D fuel system which settle out in the prefilter. It was a San Diego car as far as I can tell so it probably got a fair share of salt spray.