New guy, 1993 300D first diesel - Page 2 - PeachParts Mercedes-Benz Forum

Mxfrank · #16 03-09-2014, 10:09 AM

Quote:

Originally Posted by shertex

You can crank longer than 15 seconds with your car....30 seconds is perfectly safe from everything I've read. IF the filter is filled or almost filled with fuel, you should not need repeated cranking cycles. It will catch then die; when you crank after that it will catch, sputter a bit, then be fine.

Read all you like, 15 seconds is a long time. My actual experience was being stuck in the middle of Pennsylvania for two days waiting for a new starter. Patience wins the day. A full tank also helps priming.

One thing you want to check is the pressure sense takeoff on the left side of the intake manifold. this is a pipe connection with a small rubber hose attached to it. The pipe connection becomes plugged with soot, and this prevents the turbo from engaging.

Drago · #17 03-09-2014, 05:54 PM

I changed the filters, full of black soot. fuel flow from tank seems ok. I put the filter in position and used a funnel and filled with BioD. it started right up it's not as rough but still smelly. I'm betting I got a dribbledick fuel injector. hopefully running the fuel injector cleaner and running B50 thru it may keep it running well enough until I get new injectors.

Drago · #18 03-10-2014, 07:51 PM

well I changed the filters and got good flow. starts quick and the idle smoothed a little. acceleration still sucks. ran it up and down the highway for a half hour at 70-80MPH. still has the rough idle, stinky exhaust, black smoke when you hit the pedal. gonna change the injectors this week.

Maxbumpo · #19 03-12-2014, 01:09 PM

Future diesel posts - use the Diesel forum: Diesel Discussion - PeachParts Mercedes ShopForum

Generally a rough idle is caused by incomplete combustion. If you get black smoke on heavy acceleration, you may simply have a lot of carbon build-up in the pre-chambers. Driving the car hard using quality clean fuel will help. Search the Diesel forum for "Italian Tune-up". There is also a product from Lubro-moly called "Diesel Purge", add a can to your next tank of fuel.

If none of these help, then perhaps you've got an injector issue. Service life seems to be about 100k miles. There is a heat shield under each injector which is one-time use so you need to replace these if you pull/replace the injectors. Rebuilt Bosch injectors are a great value, but the pressure spec for new injectors is a 10 bar range. In order to get a smooth idle, the injector pressures should all fall in a 5 bar range, and if you want a REALLY smooth idle, a 3 bar range.

There may be a Bosch service center near you that can test, clean, rebuild if necessary and set the pressures. Last time I did this, several years ago, they charged $25 per injector, took a couple days. Last time I purchased rebuilt injectors they were $75 each.

Garrett12 · #20 03-12-2014, 03:20 PM

vstech · #21 03-12-2014, 09:04 PM

Air filter? Catalytic converter? Idle shake on this motor is often the motor mounts, if you can't fit a pencil between the frame and the mount edge, it's bad!