Hi all, My California 1984 Mercedes Benz w123 turned 200,000 miles today 9/16/16; and I want to share how I have gained great performance with my w123 300DT. This car has been in my family for 31 years and has been a daily driver for my father, then my mother, who drove it until she was 91 years old and now in my possession for the last 5 years. It was a dog when I got it, peddle to the floor just to get it slowly going of the line. Here is what I did to get this back to life and possibly better than new performance even with 200,000 miles on the car. I received the car from my mom with 149,000 miles on it and it was really slow! (garaged every night of it's life). All service receipts since 1984 and fluids and maintenance completed on schedule. Lots of carbon buildup however due to not having been driven more than 40 MPH for 15 years. Just a trip to the store and back home, no high speed or freeways at all for 15 years. Between the carbon buildup, sticky ring or rings, the ALDA & fuel pressure out of speck it really took time to get up to speed.

First things done: Compression test finding 406 PSI, all equal on all 5 cylinders! All 406PSI, incredible!!!

1. Oil Changed to Mobil1 15w50 Summer & Mobil1 TDT 5w40 Winter (changed every 5,000 miles)
2. Transmission fluid changed to Mobil1 ATF
3. All other fluids changed with appropriate fluids.
Adjusted the valves.
4. Several Italian tune ups.
5. 1 bottle Marvel mystery oil in gas tank (Yes it works!) but one time only.
6. 1 bottle Marvel mystery oil in the engine (Yes it works!) one time only. (I dumped the oil after 500 miles to get mystery oil out)
7. Origional Injectors rebuilt by local Authorized Bosch injector service.
A. Paid extra to have all injectors pop at exactly 135 BAR.
8. Cleaned the banjo bolt and adjusted the rack damper bolt.
9. 1 bottle of Diesel purge run directly into the fuel pump.
10. EGR delete
11. Air recirculation valve (ARV) delete
11. A. Set the fuel pressure valve bolt spring on the back of the fuel pump to exactly 25mm. (It was too short and not providing enough fuel pressure)
12. Drove car for another 3,000 miles Italian style as much as possible.
13. Oil Changed Mobil1 15w50.
14. Verified no timing chain stretch.
15. Reset the timing using the Mercedes Benz A-B light system method and then advanced the timing by just a small amount.
15. Cracked Open the ALDA and turned screw counter clockwise in small 1/8 steps for best performance without smoke off the line. The sweet spot was 1/2 turn CC for this car.
16. Solved all vacuum problems everywhere.
17. Set the transmission pressure regulator mounted on the transmission to stock for my model year. Set the transmission vacuum valve on the IP to achieve the range of 0 to 14 bleed off Pressure. I did not have to adjust the waste gate on the turbo as I have plenty of boost once I get to 1900+RPMs.
After getting rid of all the buildup carbon and possible sticky ring or rings in the engine I was amazed at the performance. Honestly it drives like a gasser off the line and through out the entire power curve.

OPTIONAL:
18. Pulled the head and ported the head to the manifold. High performance valve job including back cutting the valves. Now much more power through the entire power curve. Definitely more horsepower after the valve job and porting.

No adjustment done to the fuel injection pump at all it is stock.

The 1984 California 300D did not have a "Trap Oxidizer"

Results, unbelievable performance.
Mileage with A/C on 18- 20 town, 28 highway up to 75 MPH. A/C off 21 in town, 28 to 30MPG Highway straight and level up to 75 MPH.

It continues to be garaged at my home and is my daily driver. Everything works as it should and probably better than original. I have gone through just about every inch of this car to get everything right and It was a great and rewarding learning experience. I hope this post can be helpful to anyone wanting to get there w123 Diesel up to the best performance possible without messing with the Turbo waste gate or the stock injection pump internals.

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Well done. Only disagreement I have is the 15w50 oil. I don't think it is diesel rated.

Make sure the oil you choose is diesel rated and its good. A 40 weight oil is fine in your condition vehicle. Low miles, great even compression. Most have found that the Dino oils are equal in longevity and lubrication protection on this sooty motor. The soot level climbs rapidly ending the oil at the same lifespan as the synthetics. Unless you install a large soot bypass filter, using synthetic oil on the cast iron head Mercedes diesel is not helpful for extended oil changes.

Hastings makes an oil filter with tight primary specs, and a larger than normal bypass section for this motor that is worth a shot.


So... Pics? And I hope you are continuing the garage life for the car... Sounds like she will be cared for for many many years to come.

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

I searched for two years to find a car like that.

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1981 240D Four on the floor, Orient Red over Parchment, bought with 154,000 but it's a daily driver and up to 180,000 miles, mostly original paint and all original interior.

That's a good post purchase checklist particularly for a car with no records. I'd add adjusting and lubricating the throttle linkage.

Sounds like a California car. Does it have a trap oxidizer?

Did you run MMO in the engine for an entire oil change cycle or just before changing?

Any work on the suspension and driveline?

Sixto
83 300SD

Why you need to do so much work if all maintenance was done properly? I never did anything similar to your list to my 83 300D and mine still runs like a champ. I just fixed up all issues. One thing I did is to clean the ODO digits after 380K miles. It has almost 2 times of yours. The digits were dirty, especially the firs decimal point. Your is dirty too.

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Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry.

All service receipts since 1984 and fluids and maintenance completed on schedule. Lots of carbon buildup due to not having been driven more than 40 MPH for 15 years. Just a trip to the store and back home, no high speed or freeways at all for 15 years. Between the carbon buildup, sticky ring or rings, the ALDA & fuel pressure out of speck it really took time to get up to speed.

No trap oxidizer on 1984 California car only 1985 California.

Mobil1 15w50 Summer & Mobil1 TDT 5w40 Winter (changed every 5,000 miles)
I do not extend past 5,000 miles. Mobil1 15w50can be used for light duty diesel and was rated as such in the past. Our cars are not heavy duty diesels.

I'm sure that for a daily driver you've done EXACTLY the right things. Mine, being race-only - I went directly for the kill and got a SuperPump from Dieselmeken. I went from a 100 MPH truck to a 130 MPH truck. My engine is a tad tired (I don't think it had excellent maintenance before I got it) and I know more compression would be a good thing. My next step is a lot more turbo (working with Tim's Turbos on that as we speak) and I'll eventually freshen up my spare engine with fresh rings and bearings and valve service as time and money allow.

BTW - Lots of Internet "experts" claim that their OM617-powered vehicles run 100-110 MPH. All I can say is "Bring it to the track and let's see." That takes about 125 REAR WHEEL HP and few make that. Mutt has worse aero than a 'Benz so my 220+ HP just gets me to 130ish. When you put a vehicle thru actual timing traps you find what it can REALLY do - GPS is NOT accurate and the faster you go the farther off it is (GPS is pretty good at highway speeds, say 70-80MPH but reads overly high the faster you go). We've seen that over and over again at the track.

Dan

"How to get great stock performance" perhaps

Now just need a turbo swap and custom IP to go with your head job

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1978 300D, 373,000km 617.912, 711.113 5 speed, 7.5mm superpump, HX30W turbo...many, many years in the making....
1977 280> 300D - 500,000km+ (to be sold...)
1984 240TD>300TD 121,000 miles, *gone*
1977 250 parts car
1988 Toyota Corona 2.0D *gone*
1975 FJ45>HJ45
1981 200>240D (to be sold...)
1999 Hyundai Lantra 1.6 *gone*
1980s Lansing Bagnall FOER 5.2 Forklift (the Mk2 engine hoist)
2001 Holden Rodeo 4JB1T 2WD