⟐ Answer accepted October 26, 2021 at 16:52 MST

⟐ Commented July 13, 2018 at 14:27 MST

⟐ Commented February 21, 2021 at 9:05 MST

⟐ Commented August 27, 2019 at 14:57 MST

My own problem is that window stop rolling down , when is 3/4 open and 1/4 left to be totally .

Can you please share some data base on your experience at this matter ?

Thanks you very much .

Mauricio Q.

⟐ Answer accepted September 05, 2017 at 17:41 MST

I just bought a restored Euro spec 1983 Mercedes 300D W123 that was running beautifully until last week, when I filled it up with Propel Diesel HPR, a renewable diesel that is supposed to be compatible with all diesel engines (and is marked as Diesel #2 that meets ASTM D975 specifications: http://www.dieselhpr.com/ ). Then I drove for four hours to Las Vegas from Los Angeles without any issues. It ran well for that evening after driving to a restaurant, parking, then starting again and back the hotel, where I had to park it outside on a cold and rainy night overnight with about a quarter tank left.

The next morning, I had a crazy cold start and the engine was shaking and wobbling a lot, along with the car as a result, even while I was driving slowly and definitely at idle. It eventually evened out, or so I thought. I figured it might be the Diesel HPR, so I filled it up later that day with regular Diesel #2 but the issues didn't go away the four days I was there.

I drove back to LA four days later, experiencing no issues on the highway, where it sounded and ran well. I ran the tank down until the fuel indicator went on, and then, in an effort to rule out Diesel HPR as the culprit (since it's supposed to be better for the environment), I filled it up with Diesel HPR again, thinking maybe it was just the cold in Las Vegas that caused the issues.

This week in LA, the temperature hasn't been as cold at night, even though I park it in a garage, and the issue seems to be worse. The wobbling isn't so bad once I get going, but it's there at the start and sometimes when I stop for a light. Meanwhile, the clicking sound is pretty constant, and sounds as though it's coming from the bottom of the car, though it sometimes quiets down at higher speeds and randomly at some lights. Since it was literally conking out during the cold start once I started reversing or driving slowly, I am now cold starting with the ignition lever turned up, and that hasn't really made much of a difference (just makes the clicking sound faster). Also, white smoke comes out of the exhaust during this initial starting period, and a few minutes after getting on the road, though it seems to disappear later. I've been waiting for the glow plug lights to go off, as indicated in the manual. (Weirdly, the glow plug light went on again a couple of times after the car started during the rough cold start/idle.)

At any rate, at this point, I'm not even sure if it's the Diesel HPR or something else (the cold, driving to LV) that created the issue, but am wondering if anyone has any ideas as to what the issue could be. Or does anyone have any experience with Diesel HPR and older diesel engines? I'm hoping this is an easy fix, since I just bought the car.

I'm going to take it in to get looked at, but am wondering if this is serious and urgent or if I should try it one more time with regular diesel to see if that clears up the issue. I definitely don't want to make the car worse if driving it more to troubleshoot does that.

In a perfect world, I'd like to be able to use Diesel HPR as it is better for the environment, so I'm wondering if it is even the culprit here. Thanks in advance for any advice or insight.

Tom

⟐ Answered July 26, 2025 at 17:51 MST

how do I fix this problem.

⟐ Commented July 20, 2022 at 10:20 MST

thank you.

⟐ Commented June 18, 2025 at 18:15 MST

⟐ Commented March 22, 2025 at 6:39 MST

⟐ Answer accepted May 22, 2017 at 18:01 MST

⟐ Answer accepted October 26, 2021 at 16:47 MST

Here is the hubcap

⟐ Answer accepted October 26, 2021 at 16:47 MST

⟐ Answer accepted October 24, 2021 at 6:25 MST

I also bypassed the ALDA overboost protection circuit and plumbed the line from the ALDA directly to the back of the manifold banjo bolt (cleaned with carb cleaner to remove oil and soot). The car feels more responsive once I did that, but doesn't feel as good when accelerating like my 84 300D did. I'm wondering if the ALDA isn't operating properly, as it feels like it isn't providing enough fuel once it gets into boost. Would deleting the ALDA fix my problem? I've also read that there's a fuel pressure bleeder valve on the back of the IP next to the engine block that has a spring that compresses with time. I've also read that the lift pump could be wearing out. All things to consider doing myself, but being fresh out of college, money is somewhat on short supply.

The car has a "claimed" 255,000 miles (odo works) and has had the rear end gearing swapped to 2.88s instead of 3.07s. Maybe the lower gearing has slowed the car down, but I still feel like that engine isn't making power under boost like it should. My 84 300D would climb up the 7 mile 7% grade where I live doing 60 mph with 3/4 throttle, but this car can barely maintain 50 mph with my foot planted and WOT.

Hopefully I can figure this out, I love these cars and want to get this one performing a little better.

Just to respond for other's reference, I ended up deleting the ALDA from my car by removing the first injector hard line with a 17mm wrench and removing the two allen head bolts holding the VCV valve to the top of the injection pump. I used an adjustable wrench to hold the 27mm nut holding the ALDA to the injection pump, and using a pair of channel locks, I grabbed and rotated the whole ALDA assembly. The ALDA was on tight, but eventually budged with some Aero Kroil. The ALDA also has a 24mm nut directly below it that supposedly can be turned with a thinner wrench, but it was too tight to turn using the two wrench method. I also removed the banjo bolt from the rear of the intake, and plugged it with an M8 x 1.0 20mm bolt while reusing one of the washers that came on the original banjo bolt. I also removed all the ALDA crossover lines, as well as unplugged and removed the overboost solenoid from my firewall.

Doing this has significantly improved the acceleration and power of my car, but I also plan on installing a new lift pump and checking out the fuel pressure relief valve. I'll respond once I get a lift pump, as I'm chasing down an intermittent vacuum problem at the moment.

⟐ Answered May 07, 2020 at 3:22 MST

⟐ Answer accepted October 14, 2018 at 7:12 MST

Anyone know where I should look next?

⟐ Answer accepted December 06, 2017 at 7:27 MST

⟐ Answer accepted July 09, 2015 at 19:13 MST

⟐ Answer accepted October 26, 2021 at 16:46 MST

⟐ Answer accepted March 18, 2021 at 14:19 MST

does it drain rain water to the outside or does it have another function? threaded plastic weed wacker line to see if i could find the exit area and I did not see it.

⟐ Answered November 10, 2018 at 7:50 MST