1985 Mercedes 300d Engine died while driving - PeachParts Mercedes-Benz Forum

KnightOwl · #1 03-04-2010, 02:42 AM

So on the 1985 Mercedes 300d turbo diesel . Its a every day driver. Just pulled into the neighborhood and before i can make it to my house the Mercedes stalls and dies. Tried to crank the engine and it wouldn't start. I just came off a 20 mile run.

Next day i checked the lift pump for diesel, all seemed flowing good. I sprayed a bunch of starting fueled into the air intake and also removed my air filter and it still wouldn't start. I replaced the lift pump thinking maybe it wasn't getting enough fuel pressure and also primed it bunch of times. Still nothing. Check the fuses and everything seems good..

Can it be the CPS fail? How do i test that?

Any ideas what the problem might be?> Very strange. Any help, thanks ahead of time.

pawoSD · #2 03-04-2010, 06:57 AM

You replaced the lift pump before you tried replacing the two fuel filters or cleaning the tank strainer??

Check the filters and tank strainer! And STOP with the starting fluid! Explosive vapor + hot glow plugs = BOOM

snookwhaler · #3 03-04-2010, 09:15 AM

Good advice. Use WD40 if you feel you "have to use a starting fluid". Never use ether.

Is your primer pump the older style (white one)? If so, be sure the o-ring is seating properly against the pump body.

You can reverse the supply and return lines to clear the screen in a pinch. Or just blow compressed air through the supply line in a burst.

When was the last time you replaced the fuel filters? The primary should be changed every oil change and the secondary can go about 3 times as long if you do not have any biological fuel related problems.

kerry · #4 03-04-2010, 09:20 AM

What's CPS?
While you shouldn't be using ether unless you unplug the glow plugs (even then it is dicey), the fact that it won't fire on ether is odd. It is also odd that it quit running as you were driving. Usually that is a result of not getting fuel. Any chance this car has been running on WVO?
Crack an injector hard line and turn the engine over to see if it is getting fuel to the injectors and then report back.

KnightOwl · #5 03-04-2010, 11:30 AM

Reason why my old man replaced the fuel pump was because he just replaced the fuel filter like 4-5 months ago (only drives this car to work and back) (30 miles a day). I for example told him not to replace it because i thought i saw enough fuel coming when we cranked it and had the fuel line unscrewed by filter bolt. But he had a spare from his other Mercedes so he gave it a try.

No this thing doesn't run WVO and never did, i wish though. When done properly it can actually prolife the engine if the oil is de-water and clean correctly with the correct system installed.

As side WVO, what concerns me is it will not even fire for a second on starting flulid. This starting fluid is made for gas and diesel einges so it should be safe to use unless the company of starting fluid wants to get suid by happy sue people. Thanks for the W40 tip though

Someone mention the tank area? There is another filter their?

KnightOwl · #6 03-04-2010, 12:03 PM

Spoke with Whunter on the phone. Gave me a lot of pointers where to start and how to clean the tank filter. I will give it a shot this weekend with my old man and get back with you guys with results.

I appreciate the phone conversation, really thanks a bunch fella's for YOUR TIME, like i said we will give an update later if fixed or not.

whunter · #7 03-04-2010, 01:15 PM

Location: Washington state.
Inner city low speed driving 20 miles per day, roughly three years.

* Primer pump is the spring loaded black piston style.
* 2-3 years no valve adjustment.
* Fuel filters replaced October 2009.
* Battery run down, re-charging NOW.

Diagnostic advice:

** Adjust the valves, install a NEW valve cover gasket...
** Remove fuel fill cap, disconnect clear fuel filter, and blow 15-20 psi air through fuel line to clear (possible) plugged tank strainer.
** Replace the fuel filters, pre-filling with ATF.
** Pump the primer 100 strokes.

#1. Glow until you hear the relay clunk (turn off).
#2. Try to start, cranking a maximum of 30 seconds.
#3. Wait 15 minutes, to allow the starter to cool down.
#4. Repeat as needed.

He will be using a heavy 100 AMP battery charger..

Have a great day..

Diesel911 · #8 03-04-2010, 11:22 AM

Trouble shooting by replacing parts is expensive (unless you have a parts car), labor intensive and sometimes creates more problems for you.

As previously stated loosen the Fuel Injection Line nuts and deterring if you are getting fuel or not.
If you are not getting Fuel from there and your Engine cranking speed is good; next is the Filter change. (Fill the Spin-on Filter with Fuel and start pumping on your hand primer until you hear a buzzing or squishing sound coming from the Fuel Injection Pump.)

If still no Fuel; make sure you have at leas 1/2 tank or more of Fuel and exchange the Fuel Inlet hose with the Fuel Outlet hose (Cigar Hose). And, start pumping on the Hand Primer again. This will bypass your Fuel Tank Screen incase it is plugged.

The other way is to run a longer Fuel Inlet Hose to a container with clean Diesel Fuel and Hand Prime again.

Again leave the Nuts on the Fuel Injection Lines at the Injector loose until you see fuel coming out while you are cranking the Engine before you tighten the Nuts.

layback40 · #9 04-16-2010, 10:25 PM

Very unlikely that the IP has failed like that. blow & suck air (mouth pressure in & out of the shut off diaphragm on the IP, it may be stuck.
Is there fuel coming back through the return line when you crank the motor?
There is a lot more diagnostics to do before the IP gets the blame.

Best you get your dads mechanical friend to have a read of your thread before he makes decisions. Some of the others who have commented on here are very experienced diesel specialists. If your dads friend is experienced with diesel Mercedes, chances are he would of at least heard of 1 or 2 of them!

leathermang · #10 04-17-2010, 04:17 PM

Just set the valves... they need to be right for a compression test anyway... that is not something used to find that the valves are not set properly... a feeler gauge does that...then try the spray..
see if that causes it to run temporarily ....
Then start on the liquid fuel available to the engine...
Are you going to be charged for the compression test ?

I am not saying you don't have other problems... I am just saying that the logical and cheapest way to proceed is to make sure the valves are set properly... and then get some fuel in by spraying...
then report back to us...
other things could have happened ... and we can sort it out... but it does not make sense to not be sure the valves are set properly before doing the other stuff....

leathermang · #11 04-17-2010, 04:27 PM

Knight Owl.
check your PM's...
either go to the user control panel..
or click ' your notifications' upper right on page

KnightOwl · #12 04-17-2010, 04:38 PM

Thanks for the quick update. I am trying to convince him to do a valve check but he is being stubborn. I think i have a better chance of making him do a compresson test and if the compression test turns out weak (which i think will be) then it will force him to do the valves check. I mean i understand his pain, this engine shows no life whats so ever so i can understand that he doesn't want to spend the time on the valves yet he is ready to buy a new injector pump lol.

Can anyone explain if the injector fuel line should be spraying fuel if you remove the line that connects to the plugs while cranking?

leathermang · #13 04-17-2010, 04:40 PM

Whose car is this ?
Who is paying for whatever is happening to the car labor and parts wise ?

WHo's pain are were talking about you feeling ?

leathermang · #14 04-17-2010, 04:44 PM

Read Your PM's....

kerry · #15 04-17-2010, 04:55 PM

Yes, there should be fuel coming out of the hard injector lines when cranking. There is a long thread on here by a guy in Louisiana (?) who had an SD with similar symptoms. It was a failure in the timing device on the end of the IP. He figured out that his IP was not turning. Before you go down that route, you need to confirm that your shut off valve on the back of the IP is not activated. Pull off the brown vacuum line and crank it over and see if you get fuel.
I agree that you should get some action with starting fluid or WD40 into the intake but it wasn't clear to me how much you were spraying at what location when you were using the stuff.
A compression test only takes a half hour or so and personally I would run a compression test before adjusting the valves if for no other reason, just to find out what effect the valve adjustment had.

300SD woes Injection Pump Timing device