Which is best - PeachParts Mercedes-Benz Forum

#1 05-21-2008, 06:28 PM

Quote:

Originally Posted by Biglex

So what was your reasoning for removing your ALDA and EGR?

ALDA- Everything is tuned to proper specs., instant boost available from the turbo and smoother acceleration.

EGR- The EGR is an abomination to all diesels everywhere throughout time, the engine is healthier when not eating it's own feces.

pmckechnie · #2 05-21-2008, 07:45 PM

Biglex, There is a lot of good information on this site but sometimes you have to sort the good from the bad.
For instance, on the 602 engine in the 90 to 93 300D is different from the 617/603 engines. It is basically the same but the control system is quite different. First, if you disable the EGR system the car will run really slow. The computer will detect the EGR is not working and will disable the turbo. The EGR can be removed but the turbo system has to be changed to a non-computer type by changing the waste-gate actuator on the turbo. Now for the ALDA, I tried removing mine and the black smoke was a hazzard to anyone behind me and my mileage was terrible. I reinstalled it and adjusted it out about 2 turns (CCW). It runs great now, gets 32 MPG on the road and 24 driving about 3 miles a day. I also found that using 10W40 fully syn oil made a big difference in power. The turbo will spool up much quicker. It starts making boost by 1500 RPM and is at 14 lbs by 2200/2300 RPM. Also, the air pipe that goes from the turbo to the intake manifold has a tendency to plug up from the blowby gases mixing with the EGR exhaust. It is not difficult to remove it and clean it out. Also check the vacuum lines from the intake manifold through the overboost valve to the ALDA and make sure it is open. These are really great cars, run very well for the engine size and car weigtht, and will last forever if taken care of.
Enjoy
Paul

rcounts · #3 05-22-2008, 05:12 AM

Quote:

Originally Posted by pmckechnie

Biglex, There is a lot of good information on this site but sometimes you have to sort the good from the bad.
For instance, on the 602 engine in the 90 to 93 300D is different from the 617/603 engines. It is basically the same but the control system is quite different. First, if you disable the EGR system the car will run really slow. The computer will detect the EGR is not working and will disable the turbo. The EGR can be removed but the turbo system has to be changed to a non-computer type by changing the waste-gate actuator on the turbo. Now for the ALDA, I tried removing mine and the black smoke was a hazzard to anyone behind me and my mileage was terrible. I reinstalled it and adjusted it out about 2 turns (CCW). It runs great now, gets 32 MPG on the road and 24 driving about 3 miles a day. I also found that using 10W40 fully syn oil made a big difference in power. The turbo will spool up much quicker. It starts making boost by 1500 RPM and is at 14 lbs by 2200/2300 RPM. Also, the air pipe that goes from the turbo to the intake manifold has a tendency to plug up from the blowby gases mixing with the EGR exhaust. It is not difficult to remove it and clean it out. Also check the vacuum lines from the intake manifold through the overboost valve to the ALDA and make sure it is open. These are really great cars, run very well for the engine size and car weigtht, and will last forever if taken care of.
Enjoy
Paul

Good info on the EGR and the computer controlled turbos. I didn't know that was the case with a 92. Thanks for (sort of) correcting me on that. I'm here to learn and just so I don't make that mistake again, what year was the computer control introduced?

On the issue of the ALDA adjustment, what I do know for sure is that it was the first suggestion in another thread I started on another MB board. I followed the directions I was given and adjusted it a half turn at a time 'til I saw black smoke on WOT launch from sitting still and then turned it back in about a quarter turn. The result was lots more power with no black smoke from off-idle. Seems to have solved the problem.

As for the other items you suggested FI, I have to admit to not having checked the valves (no noises though) or chain stetch, but all the others have been and were done first. Linkages are all tight, and the filters were all new except the air filter - which I replaced before the ALDA adjustment. It was still sluggish until the turbo spooled up and then a BIG surge in power. A little tweaking of the ALDA and that problem seems to have been solved. Now I have smooth acceleration as I apply the pedal from off-idle - with power building very linearly until the turbo builds boost (around 2k RPMs), and then just a mild "bump" in power when it spools up and boost kicks in, followed by an even greater, but still linear, power increase as I apply more pedal.

A valve adjustment and timing check are next on my list, and I guess it only makes sense to check the timing chain too - while the valve cover is off. That will be followed by a Diesel Purge to clean the injectors up.

My only question is IF adjusting my ALDA has in effect "masked" one or more of those other problems as the true culprit for the off-idle sluggishness I was experiencing, what can I expect once these other things are done? Excessive black smoke until I adjust the ALDA back in?

pmckechnie · #4 05-22-2008, 08:08 AM

Rcounts, I wasn't trying to correct anyone. I sometimes don't say things correctly and they are taken wrong. You got, and gave a lot of good information about EGR and ALDA as related to your engine. I just didn't want Biglex to spend a lot of time doing something that would have to be undone. I just wish I had known that the 602 didn't work the way the older engines worked and I would have saved myself a lot of time. I did end up with a non-EGR engine with a non-computer controlled turbo and am very happy with it. It took me about a year of learning, thinking, trying, failure, etc but I finally got there. I was sharing some of what I learned to other 90 to 93 2.5 turbo owners. Keep up the good work, learn all you can about your car, and enjoy one of the best cars ever made.
Paul

rcounts · #5 05-22-2008, 01:01 PM

Quote:

Originally Posted by pmckechnie

Rcounts, I wasn't trying to correct anyone. I sometimes don't say things correctly and they are taken wrong.

Ditto. I guess I should have said "correcting US, or giving more correct info", or something along those lines. I wasn't offended in the least, and was completely sincere in what I said. So If I'm reading you right the computer control that detects the EGR's operation was introduced in the 90 model year? I really do want to learn, not just about my car, but as much about MB diesels in general, as I can.

Quote:

Originally Posted by pmckechnie

You got, and gave a lot of good information about EGR and ALDA as related to your engine. I just didn't want Biglex to spend a lot of time doing something that would have to be undone. I just wish I had known that the 602 didn't work the way the older engines worked and I would have saved myself a lot of time. I did end up with a non-EGR engine with a non-computer controlled turbo and am very happy with it. It took me about a year of learning, thinking, trying, failure, etc but I finally got there. I was sharing some of what I learned to other 90 to 93 2.5 turbo owners. Keep up the good work, learn all you can about your car, and enjoy one of the best cars ever made.
Paul

Very good. That is what these boards are about. Sharig hard won, hard learned info with others to try and save them some of the pain. I'm soaking up everything I can like a sponge in hopes of being able to gain enough knowledge to "give back" myself.