1978 300D Dead?.. - PeachParts Mercedes-Benz Forum

cooljjay · #1 12-30-2012, 04:11 PM

wondering if anyone has any thoughts on my current problem. I just came to Arizona from California in my 300d. The car was ran on wvo before I got it. I replaced everything from the tank to the injectors less then a year ago. I was having hard starts when I left Ca but she always started. Now she's dead as a door nail. The engine just cranks and cranks. I've got desperate and used ether and it won't even start on that. I've checked the glow plugs and relay as well as the battery plus checked the valves. I am at a loss as to why its not starting.

The only conclusion I can think of is the cold weather and attitude has something to do with it. It ran fine going 75mph here and the car has 155k on it. Thinking the wvo did the engine in early....thoughts???

kerry · #2 12-30-2012, 04:20 PM

Did you check for voltage and resistance of the plugs?

Govert · #3 12-30-2012, 04:46 PM

It needs fuel and compression.

What did you do to check the glow plugs? Are these the original loop glow plugs?

What were the valve clearances when you checked?

How many miles on the engine?

What did you replace in the fuel system? I assume the fuel filters and tank screen, but also the hand pump, pressure relief valve, lift pump valves? What do you hear when you use the hand pump? Do you hear the pressure relief valve opening? Any air bubbles visible in the fuel lines?

Arizona altitudes wouldn't prevent starting. How high are you?

BodhiBenz1987 · #4 12-30-2012, 05:09 PM

When you replaced parts of the fuel system, did you replace the little valves in the lift pump? Those can get gummed up and prevent fuel flow. When you pump with the hand primer, do you get a solid flow of fuel? Any bubbles?
I wouldn't assume the engine dead until you've ruled out fuel problems. You could always do a compression test, but since the engine is cold I'm not sure how useful the numbers would be.

kerry · #5 12-30-2012, 05:25 PM

Cold compression numbers are useful. A 0 would say a lot.

cooljjay · #6 12-30-2012, 06:48 PM

lets see glow plugs were upgraded to pencil style. I ohmed them as well as spark tested them. They are getting 10v. Attempted to start the car by appointing 12v directly to the plugs and no go.

valves are adjusted to spec.

the lift pump is the first generation and is different then the post 80s models. I thought this was the problem, I pulled the line at the spin on and pumped the primer and a good amount of fuel came out. I then cracked the lines and got fuel at each injector. I then undid the nut on top of the spin on didn't see any bubbles just fuel. There is a new tank screen plus primer and filters. Pressure relief spring was cleaned and adjusted not long ago.

engine has I think 155k but as usually the od wasn't working when I got the car.

what I was reading is that the oil may be too thick and the starter could be tired. It does have the original starter on it. I just don't want to put out the dough for a new starter and that's not the issue.

oh I also removed the vac line from the shut off incase that was the issue and no go.

I just don't understand why ether wouldn't work unless it is the start n oil causing the engine to turn to slow.

rscurtis · #7 12-30-2012, 08:28 PM

Try pull or push starting it to get it going and see what you have.

Ozarkdude · #8 12-30-2012, 09:53 PM

Starting fluid is a terrible thing to use on a diesel with prechambers, you can do catastrophic damage.

Crack the lines loose at the injectors and crank it over a few times.

Oops, see you already tried that.

So, hopefully its stiff cold oil and a slow turning engine, and maybe it saved your butt from blowing it up with ether?

I had a 300D that once cranked up at zero F dead cold, not plugged in overnight or preheated, but I never tried it again. It made so many awful noises in protest it was simply sad. That is the absolute coldest I ever tried starting a cold diesel, and after that attempt I have always plugged them in if its below 30F.

But that was with straight #1 diesel with some kerosene and gasoline added (there had previously been some extreme cold with -20F and colder). #2 diesel, or winter blend it wouldnt have worked. Straight #2 is good down to 35F or so, blended maybe will fire down to 20F or so. They might crank up at colder temps, but its a real risk of failure if its much colder.

Pull starting it might just be the trick to getting it going. Even a low compression diesel can get going that way sometimes.

vstech · #9 12-30-2012, 10:06 PM

... non working odo, but you think it's a 155K vehicle. ok.
while cranking, do you get ANY smoke out the exhaust?
can you get to a harbor freight and purchase a cheap (29.00) compression tester? that'll tell us what the motor is doing.
air filter?

dieselmania · #10 12-30-2012, 10:45 PM

Where in AZ are you?

cooljjay · #11 12-30-2012, 10:54 PM

agreed on either....I started with wd40 and as my anger grew I began using harsh chemicals...

the car was gummed up really really bad due to the previous owners attempted at wvo. So I am thinking that the oil has a lot to do with it, as the engine was full of carbon. I am also thinking the starter is tired thus as you say a slow cranking engine....and the cold is making it worse. My mom knows a local diesel guy so I am hoping when he gets back intown he can help before I throw money into something that isn't the problem.

well according to the paper work that came with the car it has 175k. I am in the middle of no where so getting a compression tester is a bit hard. The engine can't be to bad as I was getting 26mph on the way here. Air filter is clean. White smoke out the exhaust and it smells diesel like.

I'm in page, arizona

dieselmania · #12 12-30-2012, 11:07 PM

you couldn't be further away from me if you were still in Cali! You're not even close to anyone I know with tools! I do think however with the help of this forum you will figure it out.

cooljjay · #13 12-30-2012, 11:22 PM

Quote:

Originally Posted by dieselmania

you couldn't be further away from me if you were still in Cali! You're not even close to anyone I know with tools! I do think however with the help of this forum you will figure it out.

I know amazing huh? I may have to wait till warmer weather to use the car. Good thing I am just not out here for a vacation...