is there antyhing to do to a 83 300CD ? - PeachParts Mercedes-Benz Forum

-=kdubbu=- · #1 05-26-2002, 01:20 AM

im not looking to make it into a monster (i already have one

). BUT, making it more responsive would be a plus, BIGTIME. im not looking to twin turbo it or anything crazy. just looking for cheap bolt ones that will show me some improvents.

anything ?

thanks all..

mbdoc · #2 05-26-2002, 09:22 AM

On most Diesel engines the basics are a good starting point.
OF course compression is the key to power. Valve adjustment is a critical point. & a Clean new air filter.
Handling is very important as well & these cars can be made to corner better than most cars.

#3 05-26-2002, 10:34 PM

Totally agree with the Doc

Always knock out the basics before "upgrading" an engine. Make sure compression is good and the air and fuel filters are clean. Get the valve adjustment as perfect as possible, don't rush.

Next measure your peak boost pressure (if it is a 300CD turbo) and adjust it as needed. Many times the spring in the wastegate actuator gets detempered over time from all the heat cycling. This causes the spring to weaken and can result in premature opening of the wastegate, which results in less boost. There are devices out there called MBCs (Manual Boost Controllers)--they are a ball and spring style valve, much like an air pressure regulator for air tools... they allow a certain amount of pressure to bleed off and thus delay the opening of the wastegate, allowing one to increase boost pressure.

Boost pressure from the intake manifold acts upon a device on the injection pump called the ALDA. More manifold pressure means more injected fuel--which is where the extra power and torque comes from. The associated hoses and vacuum switchover valve can become severely clogged with junk, and this fuel enrichment mechanism is no longer able to function. Simply cleaning or replacing those hoses/valves can restore a lot of lost performance.

Also, make sure the EGR system is doing what it is supposed to. Make sure it is closed all the way and sealed when zero vacuum is applied to the valve. Also verify that EGR disengages at heavy load and wide-open-throttle.

Just doing these things may give your 300CD a whole new feel. Give it a try...

Once all the basics are knocked out... many people find it easy and safe to increase boost pressure to about 1 Bar (14.5 psi), and tweak the adjustment on the ALDA to allow a bit more fuel enrichment. With everything else in good working order, this can give quite a bump in performance.

-Joe

#4 05-26-2002, 10:36 PM

Oops...

Also, try checking and resetting the injection pump timing. Timing chain stretch plus some other factors can cause the timing to wonder over time. I don't recommend tinkering too much, try to keep it at factory spec (maybe 0.5-1.0 degree advance MAX)

-Joe

-=kdubbu=- · #5 05-27-2002, 02:32 AM

thanks guys- i never wanted to imply that i wanted to make this thing into a moster, i just wanted to make it a little more reponsive. today I replaced the air filter and looked at the egr, everything looked ok except the SUPER dirty air filter. i replaced thta with a cheapo fram and the car is MUCH better already. im going to go thru is and replace all the "disposable" parts sujch as all vacuum lines, filters, etc...

#6 05-28-2002, 10:39 AM

consider changing your rear axle ratio. If you do a lot of long distance driving, you may not want the extra noise, but if the car is primarily a local daily driver, and came equiped with a 3.07 to 1 final drive, like most of the M-B turbodiesels of the era, you might consider substituting a 3.47 to 1 from a non-turbo W123 diesel; that's like adding 15 percent in horsepower, as far as acceleration is concerned.

Holson Adi · #7 05-29-2002, 12:07 AM

It seems that after feeding my engine with lots and lots of redline + lots and lots of driving (1000+ miles since I bought it.. hey... it's a lot for me..

) my 300CD idles smoother and smokes less.

As for power, I find the car to be pretty powerful especially w/ the A/C turned off. With the A/C on it's quite a turtle actually....
A cop just laughed at me when he saw me gun the diesel in front of him.... oh well... I put it in L and a huge cloud of black smoke just puffed out of the pipe when it shifted from first to second gear. After that huge puff the car was so smooth and smoked much less. I guess I threw a whole lot of gunk away.

He was probably thinking... poor guy... two gears and still going 35mph.

Anyway,

I am actually thinking of upgrading the brakes. i don't know if that's of your interest. The brakes on the 300CD are great. However, I was thinkin' that maybe I could fit The early W126 500SEL's brakes. I'm going to talk to my mechanic. See what he thinks.

For some reason I really do not wish for more performance out of my 300CD. If I ever come across a mint 280CE I might sell my car for it.

Especially if the 280CE is a Euro. 185hp is enough to move it to at least 100mph easily.

BTW, I'd love to have a combo like yours!
A 300CD pushin out 100 and a bit hp and a Z06 with 400hp! hehehe..
What about a picture of them both side by side?

Later,

-=kdubbu=- · #8 05-29-2002, 12:28 AM

here is a pic of the Z06

the benz pics are too big to attach

omegabenz · #9 06-05-2002, 03:21 AM

hey -=kdubbu=-,

you should look up the thread about M3 vs zo6 vs slk and post on it because you have one.

Handling and breaking are very important.

I just got 5 AMG wheels for my car-W123 coupe. I now need to save up for some tires. My friend fit 18s under his wagon. I used to have 16" lorensers with 225/50/R16 tires on 16x9 rims, I could take 25 recomended speed turns at the speed limit 45 no problem.

500 SEL brakes will fit holson, but you have to only run 15" rims at least. The 14s wont fit anymore, FYI.

Let me know what you end up doing to your diesel. I am going to try everything suggested too because my engine has 465,000 miles on it.

Austin