300sdl long crank - PeachParts Mercedes-Benz Forum

Hoffman · #1 03-04-2009, 05:53 PM

ok so ive been reading alot of post and just cant seem to pin down my problem. i know its fuel related, i believe its losing its prime casue if i crank it for about 45 seconds and hold it to the floor it usally would start but its been getting worse. i took the injectors out and had them all popped all between 1900-1950psi. i pinched the injection pump bypass hose and didnt help. changed fuel filters. before i checked the injectors i cracked all the lines and it took about 10 seconds of cranking to get fuel out of them. what are the injector check valves? i cant see just one of those casueing my problem but it seems to have progresivly gotton worse as the fuel tank got low its almost empty now if that helps. any advise on where to go next? thanks, chris

mplafleur · #2 03-04-2009, 08:55 PM

It could be a number of things glow plug related.

Have you checked your glow plugs? Disconnect the glow plug harness which is the black rectangular box behind the driver headlight. Then take an ohm meter and measure the resistance of each glow plug, between the tip of the glow plug and ground, which could be the block, valve cover, or one of the valve cover nuts. They should all measure less than 1 ohm.

Brian Carlton · #3 03-04-2009, 09:29 PM

Next time, prior to starting it, remove the fuel filler cap. See what it does when you try to start.

Hoffman · #4 03-04-2009, 09:38 PM

i went back out and rechecked my glow pugs. only 1 ohmed under 1 when i checked them 3 weeks ago when i first started having the problem all of them where at 1.6-.6 i guess i thought under 2 was good but i guess when they start to go they go in a hurry ill get me some glow pugs and retest.

Brian Carlton · #5 03-04-2009, 09:59 PM

Quote:

Originally Posted by Hoffman

all of them where at 1.6-.6

Since there is no punctuation in the response, it's a bit difficult to tell what you have. However, if I'm correct in concluding that the plugs all check at between .6 ohms and 1.6 ohms, the plugs are not your problem.

Check to see if you have voltage at one of the plugs when you turn the key to the #2 position.

What's your exact starting procedure?

sixto · #6 03-04-2009, 11:54 PM

Any problems with how the engine runs once it's running?

Sixto
87 300D

mplafleur · #7 03-05-2009, 07:00 AM

Quote:

Originally Posted by Hoffman

i went back out and rechecked my glow pugs. only 1 ohmed under 1 when i checked them 3 weeks ago when i first started having the problem all of them where at 1.6-.6 i guess i thought under 2 was good but i guess when they start to go they go in a hurry ill get me some glow pugs and retest.

You know now that your meter is capable of measuring good glow plugs at around .6 ohms. The ones measuring 1.6 will only flow 1/3 the current of your best plugs and I suppose would be much cooler. I'd replace any that are over 1 ohm as a start.

Hoffman · #8 03-05-2009, 07:33 AM

sorry about the confusing post 1 was at .6 the rest 1000 plus ohms last night. when i checked 3 weeks ago they were all .6-1.6 ohms. i guess when they fail they go in a hurry.

Brian Carlton · #9 03-05-2009, 09:23 AM

Quote:

Originally Posted by Hoffman

sorry about the confusing post 1 was at .6 the rest 1000 plus ohms last night. when i checked 3 weeks ago they were all .6-1.6 ohms. i guess when they fail they go in a hurry.

That's your issue.

What's the brand of glow plug? Anything other than Bosch or Beru are worthless.

mplafleur · #10 03-05-2009, 01:58 PM

I just bought a set of Berus for my SDL on eBay for less than $7 a piece.

Hoffman · #11 03-06-2009, 07:32 AM

i got a set of new bosch plugs and installed last night and it fired right up!! now im just waiting on my injector hea shields since i had them out and tested. i also turned my alda while i ws messing around and man what a diffeernce, it dosnt start pullin hard when boost comes in, its smooth now. thanks!!