My 300 SDL has been a a great car to me but recently, its been having a hard time starting. Heres the 411...usually, it starts right up after 3 revolutions but recently, especially when not run for 30 min or so...its like it aint getting fuel...I have to pump the throttle a little for it to stay running...like it just doesnt wanna run! Its KINDA intermittent but it did it twice tonight...and once when it had only been sitting for an hour after being driven 20 minutes. Once its running though...no power loss, no sputtering, no hesitation, nothing!!! I was debating maybe bad glow plugs or clogged filters but what does it sound like to you? If you need more info, just ask me to divulge a little more! Could it be bad fuel!? I was going to rule that out because it runs GREAT once I keep it running but Im an amateur.

Brian Carlton, if youre seeing this...youre the man!

You've got an air leak somewhere or a failed check valve. Air leaks are notoriously difficult to find..........but, look carefully over all hoses from the primary to the IP and try to find the slightest hint of fuel. That's your air leak.

With regard to the check valve, before starting the engine, pinch the return hose from the IP to the secondary filter with a pair of vice grips. See if it starts faster if you do that. Obviously, remove the clamp immediately upon start.

I will assume you have proven the Glow Plugs here and that your cranking is fast enough to support good compression.

Here is a good way to verify your fuel delivery and check valve......

Stroke the primer pump. If all is well (no air in system, good check valve etc.) you will hear a chirp from the check valve with each stroke.

Make sure the lift pump is operational by disconnecting cigar return hose and cranking.

Next prove the high pressure fuel delivery by opening the nuts at the injectors and seeing fuel being expelled when you crank.

Make sure your air supply is ok...probably is.

Next look to Injectors and compression.

Next try running from a small container of fuel (eliminates any possible air ingress issues on all plumbing and tank).

I have put some steps down but you can rearrange the order if you like.

__________________
Dionysius

I havent proven the glow plugs are bad yet...Ive read a number of things on here that would suggest that its the plugs.

It starts very rough BUT when running, its absolutely normal.

Do glow plugs just all of a sudden go bad!?

Ive owned the car since October but dont know when the plugs were changed last...

What's the cranking time when dead cold? Usually, a 603 won't start at all without glow plugs unless it's very warm outside and you crank it for awhile.

All very good suggestions, but his engine (603) doesn't have a primer pump or the cigar hose-style return line.

__________________
1998 E300 +310,000K
1996 E300 +460,000K

Thanks. I am not familiar with the 603. I only have 616 and 617. Which engine is it and what models??

If I want to avoid the infamous "rod bender" which engine is that...the 603 or another one??

__________________
Dionysius

Later models -- the 3.5 liter versions.

__________________
1998 E300 +310,000K
1996 E300 +460,000K

603.961 is six cylinders, not a rod bender. Found in 300SDL and 300D post-86 cars.

603.anythingelse is six cylinders with a rod bending issue. Comes in anything that says 350 and any w140.

__________________


~Michael S.~
Past cars:

1986 300SDL
1987 300SDL
1982 240D
1982 300SD


Current:

1987 300SDL

just my .02 says glow plugs

__________________
commercial fisherman diesel in my blood in my boats trucks and Dear old Dad has had me drivin them since i got my first license in 1968
1986 300 SDL 427654
1999 Chevy Crew Cab Dually 225423
1986 300 SDL 287000 Dad's
1987 190 Turbo 158000 Mom's (my inheritance)

I was thinking glow plugs, until Brian piped up... if his pinching the line test makes no difference on your cold engine, follow www.dieselgiant.com glowplug repair procedures... if you find bad ones with his test, you would do well to purchase a crossover tube gasket... unless you have tiny hands.

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

well my SDL had no bad glow plugs one day started fine. Next day it started hard (10F) glow plug light still lit . Two days later no glow plug light very hard start (20F). New glow plugs all was well again

__________________
commercial fisherman diesel in my blood in my boats trucks and Dear old Dad has had me drivin them since i got my first license in 1968
1986 300 SDL 427654
1999 Chevy Crew Cab Dually 225423
1986 300 SDL 287000 Dad's
1987 190 Turbo 158000 Mom's (my inheritance)

Well, I took Brian Carltons advice and checked the fuel lines for leaks...I found a cracked fuel line at one end of my inline fuel filter but the REAL kicker was when I replaced all the fuel lines attached to the inline filter...

I poured the diesel out of the filter and GUNK GUNK GUNK...it was like lake bottom slime! The filter element was GONE! I found a great lawnmower filter at OReillys for 1.99 with 5/16" fittings and replaced it.

I tested the glow plugs resitance last nite too...from the actual relay plug...all tested under 1 ohm with the highest reaching .7, I assume thats about normal but I didnt actually pull the plugs to watch them light up...I didnt wanna deal with reaming the holes out or working under that bulky intake manifold on the 603 motor.

I had to take drastic action...last night when I left work was the WORST start ever! I cranked the engine and it wanted to start but kept spittin and sputtering! I gently applied throttle while cranking and it kicked over but it was idling ROUGH and you should have seen the smoke out the back! It filled the parking lot! I tried accelerating up a hill and she hesitated a little but when she got to temps...everything was just great!

I hope this repair I did was the culprit...air seemed like the most probably cause but I was also debating water in the fuel...and after checking the filter...gunk. I dont want another start up like last nights!

Lawnmower filters............

Did you pull the secondary filter and change it yet? Please don't go to O'Reillys for Briggs and Stratton parts...........

Perhaps Im reaping what I sow...it seemed to work fine as a filter as I watched it idling in my driveway...so I took it to work! I checked the filter before I went in and it looked like someone had taken the actual paper element and twisted and crunched it! Im not sure whether its from volatile chemical reaction (added seafoam and diesel supplement to the gas tank), if it wont work with diesel fuel, or if the fuel pressure was the culprit in crushing the element. At any rate what do you think it could be and what am I doing wrong and how can I fix it!?