350 SDL Fuel Injector Replacement & Rough Idle? - PeachParts Mercedes-Benz Forum

ezrider · #1 11-18-2002, 04:20 PM

I have a 1991 350 SDL with 145K miles and a rough idle and injector knock condition. This occurred after the seals on top of the injector pump to the injector lines were replaced. Shop says the problem is not a result of the seal replacement.

I went to the "experts" on fuel injection in my area (Tampa Bay) and they said the injector pump and injectors should be replaced.

Strange thing is that on occassion it runs fine without the rough idle and knock, it is however always rough and noisy with injector knock before it warms up.

Would replacing all the injectors be a first good step in attacking this problem? I think the injectors are in the $30-40 range each to replace?

Thank you.

turnne1 · #2 11-19-2002, 10:49 AM

Sell it!?....lol

I think he should go a little further investigation before he makes such a drastic move

actually since the car has made it to this mileage ...most likely he won't have any problems...most had problems in less than 100K or right around there

Warren
1992 300SD 151K
Columbus Ohio

turnne1 · #3 11-19-2002, 11:19 AM

Actually what I am suggesting is that he take it to an experienced mechanic...who has experience with this car..and then make a decision

and to add to this 3.5 litre debate(that comes up constantly) ...I always find it interesting that most of the people that talk badly about this engine(and the 140 chasis also)...have never owned one...and still give advice!!..lol

reminds me of those stories that get told through several people and by the time it passes a few ears gets "bigger and bigger" and is more heresay than anything else

Warren
1992 300SD 151K
Columbus Ohio

turnne1 · #4 11-19-2002, 11:38 AM

Quote:

Stick to the facts not opinion

interesting statement there.....and I think that one must understand what are facts and what might be rumors

asking someone for an expert opinion who has never owned one or is not a certified MB tech leaves some doubt in regard to opinions...don't you agree?

in looking at the persons in this group....there are very few 3.5 liter diesel owners,140 owners,210 owners....but it seems that the opinions fly about these vehicles..many very bad...

Warren
1992 300SD 151K
Columbus Ohio

turnne1 · #5 11-19-2002, 11:56 AM

ok...I will have to chack that one out...because its been my observance that opinions rendered are not from owners of the specific cars thay are commenting on..

as for my personal its was not a rebuild..it was a complete long block replacement at the the MB dealer...BUT its is important to note that of the 22K in repairs that my car has has in the last 3 years(90%) warranty that there were many other issues than the engine...including a $5100 climate control,evap etc etc visit

tank..I have owned a 126 in the past and yes the car was more reliable than the 140...but didn't offer near the driving experience,,ride,creature comforts/updates,safety features and in my opinion looks of the newer car...and guess what if wallet allowed I would probably be a candidate for the new S class....it doesn't feel as substantial as the 140....but it drives head and shoulders better and has many updates in regards to safety and creature comforts

so for about the next year I will chugging along in the old 92 SD

after that I may be in the market

Warren
1992 300SD 151K
Columbus Ohio

mplafleur · #6 11-19-2002, 12:12 PM

Warren,

Doesn't your '92 have the dreaded 6cyl of which we speak?

Also, It sounds like you've owned both a 126 and a 140. How do they compare? I just bought a 126 (300SDL) but I have to get it shipped out here, then rebuild the motor.

rdanz · #7 11-19-2002, 01:09 PM

Have you had your timing chain checked?

gsxr · #8 11-19-2002, 01:34 PM

Sheesh, isn't anyone going to actually HELP the poor guy instead of bashing his car? If I understand correctly, the problem started after the "seals" on the top of the pump were replaced. I'm assuming delivery valve seals. There is a VERY specific method for torquing down the barrels after replacing those seals, it is only found in the TDM (Tech Data Manual). Something like torquing to spec, releasing, torqueing again, releasing, then doing it a third time (can't remember exactly). If this is not done BY THE BOOK you can get problems similar to what was described. There was a recent post detailing this procedure on the MBZ.org diesel list, but I don't think the archives are back up yet since the server crash.

BTW, the metal lines only need replacing if they crack or break, so I'm guessing you have the braided-cover rubber return lines replaced. (?)

If the above is NOT the problem, I'd check motor mounts, timing chain stretch, and IP timing before replacing the injectors. Next up would probably be new injectors BUT a new set must be calibrated (all set to the same "pop" pressure) on a test bench, so buy them from a diesel shop that will do that before they install them (or give them to you to install). If you can get them matched to less than 3 bar variance, you should have a smoooooth idle. I would NOT replace or rebuild the IP ($1000+!) unless you have significant proof that it is indeed bad! That is very unlikely... but it would "fix" the problem if the original shop didn't torque down the delivery barrels properly!

Now, as to Tank's ranting, I agree that the OM603.97x was flawed. I also try to dissaude people from buying cars with those engines. HOWEVER, if someone already OWNS the car and obviously likes it, we should try to help the guy and not tell him to "sell his POS!" The 90-95 S-class diesels are nice cars (especially the 140), and some of the engines DO survive without bent rods... just my $0.02!

Regards,

turnne1 · #9 11-19-2002, 01:43 PM

Quote:

Have you had your timing chain checked?

huh?....not sure if that question was meant for me

Quote:

Doesn't your '92 have the dreaded 6cyl of which we speak?

if you mean the 3.5...yes and the the complete long block was replaced at the MB dealer(under warranty) at about 100K

Yes I used to own a 126(85 300SD) and also a 124 (92 300D 2.5)

honestly, of the 3(including the 140) the 124 was probably the best of the the lot if lowest overall maintenance was the main criteria for buying a car.....bought the car at 75K and sold it at 208K...and spent $700 in that three years in repairs(excluding tires,glow plugs,filters)

stephenson · #10 11-19-2002, 02:10 PM

I love my 126 with 603.970, but would have preferred to have the same car with a more historically reliable engine.

I have heard some stories of these engines going for 200K plus, but many other stories of them trashing themselves very early (40-60K even).

I am gonna go for the 200K brass ring and see if I get lucky ... after taking apart the intake system and finding and cleaning out the gunk from the combination of the EGR and the crankcase ventilation, I continue to hope for long term reliability.

The 603.970's torque is far better off the line in driveability than 3L's, but likely not much difference at cruising speeds.

unkl300d · #11 03-27-2003, 01:45 PM

Well, browsing the classifieds ., there is a 1991 350SD
READS: "120K,exc. cond. engine smokes $4000

My friend has a '92 S350D. Relatively low milage and his engine went south (bent rods) about 1.5 yrs ago. He ended up having the dealer rebuild the engine, way over $10K!!!!

So, I am tempted to look at this car because of the price, but I am aware that the engine can be a bomb.

Yup, nice car but 'holy smokes'!!!!!!!!

stephenson · #12 03-27-2003, 02:03 PM

With a $12K engine replacement bill and a car value of about $10-12K in most areas (some a bit higher) ... the value of the car is actually in parts that could be sold off.

Terrible thought ...

On the other hand, if the car was pristine and could be had for less than $1K, a new engine would give you a GREAT long term ride.

Mine has been a wonderful car ... course, I would be of a different mind if it had bent a rod!

unkl300d · #13 03-27-2003, 02:18 PM

I called up. It burns oil due to "piston ring problems".
I may go look at it out of curiosity. It is at his mechanic's
shop.

I'll offer $800.

stephenson · #14 03-27-2003, 02:27 PM

That would be about my top offer - and, then only if the interior and body are really nice - maybe not perfect, but really nice.

Do a search on this site for the problem and you will find a link to a site where the problem is beat up in detail ... take a copy ... or refer the owner to the site.

Sad thing for such a nice car to have such a bad engine.

It is piston ring problem ... but, only in the sense that the piston rings are likely still round and the cylinders aren't.

No way there is an unrelated oil burning problem, unless the oil was never changed.

Good luck.

gsxr · #15 03-27-2003, 02:39 PM

Piston rings my eye! It has bent rods, which caused the cylinder walls to get out of round (oval shaped). To fix this, you need to have the cylinders sleeved and install new rods, and possibly new pistons. BIG job. Probably cheaper to buy a used motor and install that. If you find a good 3.5L motor that hasn't failed yet, just replace the rods with the new updated type (before the old ones bend!) and the engine will last forever.

Option two is to buy an OM603.96x, the 3.0L version from a 1986/87 diesel and install that instead. Power will be slightly less but you won't have the bottom end flaw. Used 603 motors are in the $1500-$2500 range nowadays, I believe...

Regards,