17 second 0-60 on 300D 2.5T - PeachParts Mercedes-Benz Forum

2.5Turbo · #1 04-06-2006, 06:48 PM

I've been reading around and noticed that the published spec on the 300D 2.5T (124.128 602.962) is 12.3 seconds. The problem is, mine's getting a little over 17 seconds on multiple trials, pedal to the floor from a stop, tranny in 3. My grandparents handed it down like this, so I never noticed until I read something about it

.

Yes, it was on a flat road, and the engine was at normal operating temperature of around 80c. I was the only one in the car and there wasn't any extra junk (well, nothing of considerable weight) rolling around in the trunk. The fuel is fresh (I get it at a station where a big rig or two can be seen at any given time, so there's big turnover) Tested around sea level on a dry day if that means anything. The only known issue on the fuel system is a very slow leak on the IP. It looks to be coming from around the stop lever area. It's a black oily substance, not sure if it is old diesel fuel that has leaked out and picked up dirt and grime, or if it is crankcase oil. I've never really wanted to stick my finger in it and check...maybe I should

. As far as I know, the ALDA hasn't been touched, nor has the IP timing or injectors. One of the cylinders clatters a little more than the others when cold, and it subsides a little when hot, but it's still noticable. My grandparents went nowhere but the dealer for service, and I've been going to a reputable independant mechanic south of Tacoma.

The question is, what could be giving me this 5 second difference in 0-60 speed? And more specifically, what sould I tell the mechanic to fix?

Hit Man X · #2 04-06-2006, 07:33 PM

Plugged overboost solenoid? Mine was bad on the SDL, it was sloooooow.

Dirty fitting on intake manifold perhaps.

2.5Turbo · #3 04-06-2006, 10:29 PM

Should I take out the boost pressure sensor and check it out? Could that be clogged up with the crud the EGR makes?

The car's not running roughly, nor is it smoking excessively...it's just slow

JimmyL · #4 04-06-2006, 11:00 PM

I drove a 190 with the 2.5 turbo and it was well under 15 seconds with only 1st and 3rd gear! I think you have been given good places to start.

libbybapa · #5 04-06-2006, 11:11 PM

I simply ran a section of hose on my 82 300SD to bypass the electrical solenoid. The thing went from very slow to very fast under boost. What is the purpose of the electrical thingy. It seems like an unnecessary redundancy to me.

Andrew

2.5Turbo · #6 04-07-2006, 12:11 AM

Well I took out the pressure sensor in the intake manifold and it had a bunch of oily crud in it, so I cleaned it out. Didn't notice any difference when I drove it around. I also took an ohm meter to it before I took it off, and I didn't get any continuity between the pin and the engine block. Any other suggestions before I take it in for its oil change and tell them to check it out?

Hit Man X · #7 04-07-2006, 05:52 AM

Just bypass that valve like the other member did and see if that helps... worked wonders for mine.

farmboyhull · #8 04-07-2006, 05:17 PM

2.5 turbo

if and when you bypass it, will you write up a bit of a map? i have the exact same problem on the exact same car.

thanks

david

2.5Turbo · #9 04-09-2006, 04:13 AM

I just got back from a 600 mile trip from Tacoma to The Dalles, OR area and back. Highway MPG at about 34. I did a lot of driving around that area while down there. This evening, after stopping for dinner in Vancouver, I got in the car, got out of the parking lot, and it was like somebody dropped a new engine in! That baby is a rocket compared to what it was. Did a 0-60 on it, and got about 13 seconds with one other person and all our gear in the car. It's a whole new car when the turbo works like it should

. During the drive home on I-5, I was able to go from 60-80 in no time, unlike before. The performance is pretty much the same up to about 2100 RPM...and after that is where the fun begins

Any ideas on why it just all of a sudden started working fine after about 450 miles of driving with the cleaned sensor? We'll see if it still works tomorrow

9192benz · #10 04-09-2006, 10:43 AM

Where is the overboost selenoid located?

Zeitgeist · #11 04-09-2006, 10:52 AM

Quote:

Originally Posted by 2.5Turbo

Any ideas on why it just all of a sudden started working fine after about 450 miles of driving with the cleaned sensor? We'll see if it still works tomorrow

Your boost pressure line from the manifold to the ALDA probably had been occluded with oil sludge, but it just worked loose, allowing the ALDA to finally function correctly. This is a fairly common phenomena with pre-OM606 MB turbodiesels. Every oil change I pull the line and blow out the accumulated goop.