i can appreciate this engine. i've been a fan of it for a long time. i've disassembled hundreds of w123's, finally i decided i would pull the trigger when the opportunity for a nice one, on the cheap, presented itself. i wouldn't of bought the car if I didn't like the chassis and the engine. you can't go wrong with a simple engine that's proven to go forever, rather than an m117 which is complicated and expensive to have people work on

nah, just thinking out loud, on the oil cooler. you can increase the size of the oil cooler, and just put it under the bumper with a cleverly installed bracket. then you've got the space to the left or right of the radiator for an air intake which can bring in more air than the stock intake. and i do agree the stock intake is cold air.

regarding the air filter, if it's a well-known, well-documented fact that the K&N is worse than the paper filter for this car, i'll go along with that. i don't claim to be an expert, but i do know that it helps for my m103 engine

this is already my initial goal. i've installed the 1991-1994 steering wheel with the airbag (non-functional, just there as a horn, really), the CLK wheels are in the works, and so are some sport shocks if I can get someone to make them for me--otehrwise bilstein hd's. some cut-down w126 springs are also in the works. we all know how everyone hates lowering a w123, so let's not go there again.

just thinking ahead to the future

it's not that i'm not happy, it's just that i'm never satisfied--always want to yank some more out of the car somehow, if it's possible.

i don't think my transmission is adjusted properly. sometimes as it shifts into second, it slips, and the rpm's go up for a second, until it finally kicks into gear. in that one second, i lose throttle response. so there is definitely either a cable that needs to be adjusted, or a new vacuum modulator in the works for me, but the slip isn't bad enough to justify throwing money at it just yet.

i will search for this stall converter--have no clue what it is though

realistically, the w123 is slow by modern standards. it may be a weight issue, and, i don't want to start a discussion about this in this thread, but i doubt there are 3.0l diesel engines brand new from the factory by any brand out there today, that produce only 130hp or less, and the chassis weighs over 4K pounds, give or take. this is a recipe for 'relative slowness', but we can all still appreciate the car for what it is

What are you hoping to achieve by altering the intake? Have you ever owned a turbocharged vehicle before? Playing with the intake will gain you nothing. Even porting and polishing the intake manifold will do very very little, so little in fact, that it is pointless. A turbo charged diesel engine works very very differently from your normally aspirated gasoline m103.

It is a well documented fact that a K&N is bad for ANY and ALL turbo diesel engines. Period.

This is not an m103, and your m103 tuning does not apply. If you only walk away with ONE piece of knowledge from this entire thread, it should be to put that K&N into the trash and install a paper filter instead.

Edit: I second kingdoc1's recommendation on maintenance. Questions for you:

1. When is the last time this car had a valve adjustment?
2. What kind and weight of engine oil are you using? Last changed when?
3. When is the last time the fuel filters were changes?
4. When is the last time the transmission was serviced?
5. When was the brake fluid last flushed and changed?
6. Are the injectors original? Have they been rebuilt?
7. When is the last time a Diesel Purge was performed?

ok, dude. i'll walk away with that and hopefully more. i fullly realize this isn't a gasser and not all mods are transferrable. but i also think you should consider changing your approach.

for the record i did state above that this is my first diesel car, so i'm new to all this tuning, even though i'm not new to this engine or chassis, having dismantled many a w123 before (almost completely)

Trying to instill a sense of urgency because it seemed like you weren't willing to accept the advice give to you by multiple folks who do know this engine very well. But since you are, I'm more than happy to help.

If your familiar with the w123 chassis that will help you in performing the required maintenance. See the list of questions I just edited into my post above. The valve adjustment and fuel filters in particular can have a very noticeable impact on performance.

Blasphemy. VNT does wonders for the low end. Stock turbo can do more than 15 but it just turns into a heatpump.

ah, i see. yeah, i did a new clear fuel pre-filter going into the back of the injection pump--i guess the next thing to do is the filter on the gas tank. valve adjustment might be out of my ability range, and i prolly don't have the tools to do it, either. i might be able to follow a step-by-step if it's been well-documented with pics though

Aside from the clear pre-filter and tank filter, you have the primary fuel filter. It is a metal spin-on canister type. I change mine every 12k miles or once per year.

Valve adjustment is not hard, and it's very inexpensive if you DIY, but requires very precision adjustments and attention to detail. It must be performed every 12k miles or once per year.

Also, if you have 150k miles or more, I'll bet your injectors are worn out and in need of a rebuild. This can have a very noticeable affect on performance as well. This is not a DIY, you'll want to take them to a diesel injection shop.

I wouldn't even be thinking about performance modifications until you've addressed all the items 1-7 on the list above. Who knows, getting it properly maintained may very well give you the performance boost you're looking for.

Agreed, so hopefully you've decided to not complicate matters for a negligible gain. Removing items such as seats, doors, sun roof, spare tire and well negate the attributes of a car. (tongue in cheek)
Folks are trying to let you know there is very little available to "hop up" this engine. I would think porting and polishing would help, but again, how much for such a time consuming task? Yet, by all means, knock yourself out.

I'll put my vote in for an SBC conversion. A Vortec 5.7 in one of these cars would probably return the same mileage as the diesel and be a lot more fun to drive. The conversion is pretty straight forward.

There is a guy on here (forget his name, out in Texas) that had a 70's 280 that was converted to a SBC. Nice car. Good mileage and the engine parts are cheap and widely available.

I think the swap is a great idea. Too many purists around here. The diesel is OK... The V8 swap is just sounds like fun!

Why is everybody bad mouthing the K&N air filter? I see them run all the time on Cummins,Duramax and Powerstrokes pick-ups many with over 300,000 miles on original motor. Are you saying they are bad just on Mercedes Benz or are these people ruining their 40,000 dollar trucks because they don't know any better? Just wondering what there is to support this?

Yes, they don't know any better or have fallen for marketing hype. Oiled gauze filters rely on electrostatic charge to draw dust out of the air, but it passes a lot of dirt. If you want longevity, use a paper filter.

Sounds like somebody didn't read the whole thread before hitting the reply button. :wallbash: From page 1:

So to answer your question, yes, those people are fools who saw a TV commercial and they don't know any better. They are letting dirt into their $40,000 truck engines and they are not gaining any power at all, not even 1 hp.