Hey guys,

I bought my first Diesel Benz in 13 years, which is a LOT different than my old 83 240D 4spd that I used to have. There is a lot more stuff under the hood on this 300SD! It is in very nice Florida shape and has 165K+ on the clock.

OK, I have been reading on 3 or 4 different forums about the 603.971, turbos, EGRs, IPs, performance upgrades, etc. My background is in restoring classic Fords, Resto-Modding them and now my 92 is my new toy.

My car is in pretty good condition, but I have been finding all kinds of "landmines", the more I do and poke around.

My IP delivery valves are leaking, which I bought the O rings and socket and will be doing it soon.

I will need to upload my pics to photobucket so you can see some of my issues.

I was reading about EGRs, the pros/cons and decided to look at mine and saw that there was no tube from the bottom to the manifold! UGH! The manifold is capped, but the bottom of the EGR is just open! What is this doing? Is this why my turbo seems intermittent in operating? Sometimes it is just a DOG and others it kicks in and goes pretty well.

I replaced the oil filter, oil and fuel filters, all with Factory Mercedes parts and am running Mobil 1 0w-40 European oil. I put in a K&N air filter too. There are no drops on the driveway and the dipstick still reads 100% after 2 weeks of highway driving, 70 miles per day.

I need to get my pics loaded...

Replace that K&N filter with a decent paper one and you'll be filtering air far better. Your motor will thank you in a few hundred thousand miles. The only way K&N filters work optimally is if they are properly treated with oil. The oil becomes the particulate trap.
Then again, I'm partial to using oil to filter my intake air. Oil bath filters like on my 1972 220D are far better at catching particles than a dry mesh or open cell filter. The only issue is that most folks don't want to take the time to do the maintenance on them.

Phil Forrest

__________________
1972 220D "Trudy," named by a friend.

"The 220D sounds good... I suspect it is the only car that you need a calendar for, rather than a stopwatch, when doing acceleration tests."
Tom Abrahamsson

Hi Phil, thanks for the feedback.

I agree about the Oilbath Aircleaners! My old 67 F-100 still had its original on it and I kept it filled with 40 weight.

I agree with the K&N... I keep 'er well oiled! Do you oil your paper elements? What oil would you use on them?

Paper elements aren't designed to be oiled, will likely swell the fibers and restrict airflow.
The K&N are typically decent filters if properly oiled, but the paper ones your car came with originally flow plenty of air, last through normal to dusty conditions with plenty of capacity, and filter well. I don't mess with K&Ns, their best purpose is to make money from guys with "tuned" ricers and to sell replacement MAFs when they get oil in them.

I'm not sure about the open EGR, but I don't think that it opens without a vacuum signal so if yours is not hooked to a vacuum source it is likely not allowing air into the inlet. If it is, you're getting unfiltered air, that's all. Not totally sure about the '92 though, it might close with a vacuum signal like the 606 engines? Normal trick on the early ones is to put a BB in the rubber part of the vacuum line.

Do a quick search on ALDA, if you back that sucker off some you will get better off-boost performance, at least ensure that the changeover valve and vacuum/pressure lines are functional and not clogged by oil/soot like many are.

I think I'm going to buy the '92/'93 (not sure which) from my friend, will remove the head/turbo/IP/manifold/etc. for my boat project, and likely scrap the rest of the car within a week. LMK if you need something and I'll see what it's got, probably lights and switches will go on a shelf to sell, maybe trim bits and some electronics, easy to pull and sell stuff, ... need to justify buying the thing somehow.

__________________

Gone to the dark side

- Jeff

Oh, of course I don't oil a paper filter, they'd just clog up.
Often times folks post online about a K&N filter, they are the autozonenapaschuckso'reily crowd that claim a 200hp increase while getting 60mpg. You know what I mean there.
My dad just bought one for his Jeep Wrangler and I told him to take it back and get a paper filter because unless he oils the filter and actually sticks to a frequent maintenance schedule it's not going to work (it's very dusty where he lives in New Mexico.) So he stuck it in anyway...

Did you check the number on the head in your OM603? I'm sure you've read about the overheating issues with certain series. I don't have an SD but I've worked on one that overheated then had the motor replaced with an OM617 turbo. I also diagnosed a dead OM603 for a forum member but I've not had much of a chance to work on any actually working cars with that motor.

Phil Forrest

__________________
1972 220D "Trudy," named by a friend.

"The 220D sounds good... I suspect it is the only car that you need a calendar for, rather than a stopwatch, when doing acceleration tests."
Tom Abrahamsson

If it runs like a dog with little power, it may just need a new switchover valve. Make sure you have the tubes correct and leave the proper side open to the air.

These actually work. Last week I had trouble getting over 35mph in my 81 300SD. Pulled over, popped the hood, and found that one tube had come off the switchover valve. Slid it back on and, presto, the zip is back.

The W140 603s use the EDS computer to control the wastegate just like the 300D 2.5 turbos. If the computer thinks there is a fault with the EGR system it goes into limp mode.

-J

__________________
1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

Wow guys, thanks ALL for your input!

OK, enough about the air filters... hahah... I knew you don't oil paper elements, I was thinking that maybe there was a trick I had missed out on; but it turns out not. ;-)

The EDS computer? I know I have a MAF, but was thinking, I don't have any idea where the computer is! How crucial is the computer?

I don't reckon that it is in limp mode, it goes 95, no problem, but sometimes it takes the slow boat to get there; and other times it comes on pretty good and strong. Hmmm...

2 mentions of the "switchover valve", where is this and does anyone have a schematic to go from?

My EGR still has the vac line hooked up, and is pretty crusty in the opening... YUCK! Does anyone know if the Vac holds it shut, on this model, or holds it open? Anyone have schematics for the turbo and all its lines? There's an oil line on top of the turbo that is all wet/leaking, how does it go together and how do I stop it from leaking? Is it just an O ring, or is it a gasket? There is a thick line that comes up from under the turbo and connects to the intake manifold, is this something I need to check too, to see if it is blocked or anything? I don't want to get into things that will make it worse or not able to be driven...

I am loading the pics after dinner.

Doug

The EDS (Electronic diesel system) computer runs the idle speed, turbo boost, and EGR. I imagine it lives in the computer box under the hood. You can use a test light to get blink fault codes from it.

-J

__________________
1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

Nobody has mention fuel filters yet? Replace your primary and secondary as routine maintenance. Don't forget the fuel tank strainer. Next I would check your ALDA/control lines. You can take your ALDA off completely (for diagnostic purposes because you'll in turn loose boost control). If the power delivery changes then it's probably a leaking ALDA or more likely a blockage in the control line. This can be done with the intake manifold in place, but when I get a new-to-me 603 powered car I always yank the intake, replace the GP's, ream the prechambers, replace the delivery seals, block the EGR and de-gunk the IM for piece of mind.

ALDA Adjustment

IP before I change O Rings


IP


ALDA Cover?


EGR open, different view


Open end of EGR in mirror


Leaking oil line




Manifold plug and view of missing EGR pipe


I'm not sure what all this stuff is...


A look inside...

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More photos, sorry, I am a bit rusty posting to forums.

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Yes sir, I mentioned it... I replaced both the pre and main filters, both with factory filters. ;-) I have yet to venture into the tank to check the strainer... I have PTSD from the last time I ventured into the tank on my 240D!

Which one is the ALDA? The gold one or the black covered one behind it? I want to pull the intake, eventually replace the GPs, ream, I am replacing the delivery seals next weekend, block the EGR and clean whatever I can from EVERYTHING! The soot is pretty thick around the EGR.

I was told the Turbo was replaced and that leak on top of it bothers me... Is this a cork gasket, or O ring?

I see I'm already too late. But here's my 2 cents:

- EGR delete is a stupid dog trick. Does almost nothing for performance or economy, creates problems, and it's a misdemeanor in the US. Not to mention that it makes you a gross polluter. Sorry for your loss.

- K&N, and all other induction mods, waste of time as the engine always runs with excess air. more air doesn't make it go any faster. The K&N sacrifices filtration efficiency for no benefit.

- This model has a switchover valve which is used to defeat turbo boost if an EGR malfunction is detected. Not sure if the dog trick included faking this out or not. If not, that's your performance problem.

- There should be a port on the left side of your intake manifold with a hose attached. This is the alda sense line. It's function is to "read" manifold pressure so that the alda can adjust enrichment. If it's clogged, it's like having no turbo. That should always be the first thing you check with a turbo performance problem.

- Oil in the turbo air stream. I went through two turbos before I realized that the oil was entering from the valve cover breather. If this is your problem, you will find a puddle of oil in the accordion pipe leading to the turbo. The cause is likely to be a faulty breather valve, but it could also be an air leak in the crankcase, as from a worn oil filler cap. It sounds illogical, but see for yourself how it works:

Mercedes Valve Cover Breather

The same technology (it's called Type II PVC) is used by several other manufacturers, not one of which was dumb enough to make it an unserviceable part of the valve cover. So I have hope that something
can be added externally to make this work better. Or I may just break down and shell out for a brand new cover.

Not too late Frank, I thank you for your 2 cents!

That is a shopping list that I need to check through... I was away over the weekend, so I will need to tackle it next weekend.

Sometimes I do feel like the turbo kicks in, but not all the time; however it could be, I am just not used to a car with low power and high weight.

I will do more detective work.

Thank you again!