300SDL Not Firing on All 6
 

Hello All,

'87 300SDL 202k

Last week she started to idle a little rough and got progressively worse. I thought it may be the injectors so I put in a rebuilt set and fired her up (I pop tested them and all were around 2000 PSI). NO CHANGE :mad:

So, I started her up and cracked open each injector line - the engine ran differently the second I turned the nuts on injectors 1 through 4. Injectors 5 and 6 made no difference. Fuel did leak out of 5 and 6.

I have only had the car a few months. It does not smoke and the engine temp has been stable in the 80-90 range.

More information if this helps. The previous owner said he had the delivery valve seals changed and new nozzles installed. The power level has never been what it should be - 16 second 0-60, but the car otherwise ran well and I thought I would take care of that after I got the heat/AC stuff done. Looks like the diesel gods have decided otherwise....

What do I check now?

Thanks!

Richard

Sounds to me like a compression test is in order.You could swap #5 & 6 injectors with two that are working like #1 & 2 and see if the problem moves with the injectors,i wouldnt bet on that, but its easy to do so give it a try.I am not familiar enough with that particular engine to know if it could be a head gasket blown between #5 & 6 and not affect the cooling system,there are engines where this can / does happen but i dont know if the 603 is one of them. My $.02 Don

He already replaced the injectors.

I agree, a compression test is the next test. If all is well with the compression test, and you feel good about your injector installation, it would indicate a problem with the IP, possibly delivery valves not sealing properly (fuel backflow) based on the PO's delivery valve seal job. Do you have a receipt for this work?

Since the sensible suggestions have been made, is the cam in good shape?

Sixto
87 300D

I've been here

Dollar to a donut,,,,,, bent connecting rod #6

Are 603s known for that?

Only the 3.5L I6 aka W126 model 350SDL G442(i think)model 350G W140 model S300-diesel S350-diesel

This is out of my '87 SDL.

http://img356.imageshack.us/img356/6730/bentrodmq9.jpg

Once in awhile, about as often as 617's put a rod threw the block.

If it hasn't run right since they did the delivery valves I would redo them first. Since thats the cheapest place to start. Also a compression test wouldn't hurt.

Any oil consumption?

603.97 rods bend along the other axis.

Sixto
87 300D

Oh right -- like your avatar, huh?

Have you a larger version of that? I'd like to see it.

Blue tank -- check all the simple stuff first -- delivery valves for sure, cam condition, etc... I very seriously doubt it's a bent rod.

First hit on a google image search of "bent connecting rod" -

http://kb-silvolite.com/article.php?action=read&A_id=54

Sixto
87 300D

Oh, I thought that might be a Mercedes-specific illustration from a tech bulletin you'd found during your research.

Nevermind.

No - no receipt of the work. Only his word that it was done. Worth about as much as what this is written on! :)

I'll get a compression tester in the next day or two and report back.

Thanks!

Richard