300sdl .... injectors or injection pump? - PeachParts Mercedes-Benz Forum

jonschwenke · #1 09-29-2013, 07:53 PM

Hey all. Thanks for all your help in the past.

1987 300sdl
I recently bought this car cheaply with the intention of fixing it up for a family vehicle.

Very rough idle and noisy clacking. Lots of smoke at startup. Idle and smoke improve somewhat after engine is warm. New filters (both). Fresh fuel. Fuel filler cap off, replaced injector return lines

I have pulled the fuel supply and return lines and run a mixed bottle of veg oil and seafoam. After a few minutes everything quieted down and smoothed out. almost perfect. Occasional clacking / knocking / nailing from #3.( DIAGNOSED BY CRACKING THE INJECTOR LINE AT THE IP - NOISE STOPS) So I figure the injectors are the problem, not the pump, not the timing, and now I've cleaned them out due to the nicely running engine before me.

However, after the car is back on diesel fuel the symptoms return. I have switched supply and return lines to eliminate possibility of clogged fuel screen. I also bypassed the fuel heater setup and ran the supply straight into the lift pump. No change.

So, my question is this. Is there any simple way to determine from these findings if the injection pump or injectors are at fault? How can I tell which is at fault? Is there something else to check that I'm missing? I once had a mechanic tell me about a jetta that would only run on vegetable oil because the injection pump was so worn it would not handle the thinner diesel fuel properly. Is that possible? What say you guys? Any easy way to tell for certain where the issue lies? If not, what's the best approach here? I don't want to jump and replace the injectors if the IP is bad.

Thanks again.

ichris93 · #2 09-29-2013, 07:57 PM

Quote:

Originally Posted by jonschwenke

Hey all. Thanks for all your help in the past.

1987 300sdl
I recently bought this car cheaply with the intention of fixing it up for a family vehicle.

Very rough idle and noisy clacking. Lots of smoke at startup. Idle and smoke improve somewhat after engine is warm. New filters (both). Fresh fuel. Fuel filler cap off, replaced injector return lines

I have pulled the fuel supply and return lines and run a mixed bottle of veg oil and seafoam. After a few minutes everything quieted down and smoothed out. almost perfect. Occasional clacking / knocking / nailing from #3.( DIAGNOSED BY CRACKING THE INJECTOR LINE AT THE IP - NOISE STOPS) So I figure the injectors are the problem, not the pump, not the timing, and now I've cleaned them out due to the nicely running engine before me.

However, after the car is back on diesel fuel the symptoms return. I have switched supply and return lines to eliminate possibility of clogged fuel screen. I also bypassed the fuel heater setup and ran the supply straight into the lift pump. No change.

So, my question is this. Is there any simple way to determine from these findings if the injection pump or injectors are at fault? How can I tell which is at fault? Is there something else to check that I'm missing? I once had a mechanic tell me about a jetta that would only run on vegetable oil because the injection pump was so worn it would not handle the thinner diesel fuel properly. Is that possible? What say you guys? Any easy way to tell for certain where the issue lies? If not, what's the best approach here? I don't want to jump and replace the injectors if the IP is bad.

Thanks again.

How many miles are on the injectors? I would recommend replacing them and have them balanced.

Have you done a valve adjustment?

barry12345 · #3 09-29-2013, 08:00 PM

Swap the number three injector with another one. See if the problem moved With the change. Or not. Your model has hydraulic lifters so no adjustment.

jonschwenke · #4 09-29-2013, 08:36 PM

Barry,
I can do that, but now that is not the only noise maker. It was on the veg oil seafoam mix though. On diesel there are several injectors clapping, but then again I'm not sure it's the injectors or poor fuel delivery from the ip. I assume I'll need to replace the injectors at some point, but I want to rule out the ip. Any ideas?

ichris93 · #5 09-29-2013, 08:46 PM

Quote:

Originally Posted by jonschwenke

Barry,
I can do that, but now that is not the only noise maker. It was on the veg oil seafoam mix though. On diesel there are several injectors clapping, but then again I'm not sure it's the injectors or poor fuel delivery from the ip. I assume I'll need to replace the injectors at some point, but I want to rule out the ip. Any ideas?

Not sure you can rule out the IP without replacing the injectors. Replacing injectors is kind of a maintenance thing. So are valve adjustments.

Diesel911 · #6 09-29-2013, 08:55 PM

Is the IP leaking at the Top and could there be any Air Leaks in the Fuel inlet?

The higher cetane of the veg oil and seafoam mix quiets down even normal Diesel Fuel Knock.

Some people have had their Fuel Injection Pumps damaged due to WVO to the extent that they would no longer work on Diesel Fuel.

Isn't it also possible for defective Valve Lifters to stick until the Engine warms up?

jonschwenke · #7 09-29-2013, 09:16 PM

Quote:

Originally Posted by Diesel911

Is the IP leaking at the Top and could there be any Air Leaks in the Fuel inlet?

The higher cetane of the veg oil and seafoam mix quiets down even normal Diesel Fuel Knock.

Some people have had their Fuel Injection Pumps damaged due to WVO to the extent that they would no longer work on Diesel Fuel.

Isn't it also possible for defective Valve Lifters to stick until the Engine warms up?

The ip does not appear to be leaking from the top.
Air leak is possible, I'll run the same test w straight diesel in a bottle to compare apples.
I have no history on the car, so wvo damaged pump is a possibility.
I have no ideas about the valve lifters. How would I check for that? Thanks for the ideas.

jonschwenke · #8 09-29-2013, 09:20 PM

Quote:

Originally Posted by ichris93

Not sure you can rule out the IP without replacing the injectors. Replacing injectors is kind of a maintenance thing. So are valve adjustments.

I don't believe this om603 engine requires valve adjustments. I think the hydraulic lifters take care of that....

Agreed on injector replacement. Hoping to rule out ip issues before replacing injectors, but unless someone had a suggestion for that I may have to.
Thanks.

ichris93 · #9 09-29-2013, 09:24 PM

Quote:

Originally Posted by jonschwenke

I don't believe this om603 engine requires valve adjustments. I think the hydraulic lifters take care of that....

Agreed on injector replacement. Hoping to rule out ip issues before replacing injectors, but unless someone had a suggestion for that I may have to.
Thanks.

Sorry, forgot it had a OM603 engine. I don't know anything about those!

Are the injectors the same as an OM61x engine? There is a forum member who replaces injectors and balances them, at least for the OM61X motors.

jonschwenke · #10 09-30-2013, 01:18 AM

Quote:

Originally Posted by ichris93

Sorry, forgot it had a OM603 engine. I don't know anything about those!

Are the injectors the same as an OM61x engine? There is a forum member who replaces injectors and balances them, at least for the OM61X motors.

I think the nozzles might be the same, but the injectors housing is not. Feel free to enlighten me on this anyone.

ah-kay · #11 09-30-2013, 01:38 AM

Quote:

Originally Posted by jonschwenke

I think the nozzles might be the same, but the injectors housing is not. Feel free to enlighten me on this anyone.

The nozzle are NOT the same between OM61X (DN0SD240) and OM603 (DN0SD265) injector.

Check compression which is free, before replacing anything. I always find compression # gives me a lot of info.