Restoring my newly bought 2005 Mercedes-Benz S350 project car

The car was in a neglected state. It was driven less than 500 km in the last 2 years. I decided to buy it as my project car & try to bring it back to shape.

BHPian 123.rishabh recently shared this with other enthusiasts.

As auto enthusiasts, we keep scrolling used car platforms & keep window shopping for rare & classic cars. I also have been doing the same for many years but could never make up my mind for getting some project car due to the impracticality factors plus NGT.

One fine day, I saw a single owner modern classic German car on sale. It was the most neglected & commonly found luxury RIP Mercedes-Benz model in India, the W220 S Class.

The W220 is one of the most controversial S classes. Revealed at the 1998 Paris Motor Show and sold from 1998 to 2005, it was a technology marvel at the time but was also plagued with lots of electronic issues making it unreliable.

In 1996, Daimler targeted raising Daimler-Benz's operating margin by increasing efficiency and cutting costs via efforts like internal competitiveness drives and Japan's just-in-time manufacturing. In 1998, the merger with Chrysler to form DaimlerChrysler AG was announced. This was done to enhance the long term competitiveness of both companies.

According to experts & what I have read on the forums, the new chairman of the Board of Management, took Mercedes' focus off engineering as he believed Mercedes cars cost too much to produce and sell because of "overengineering" & they ended up spoiling the basic engineering.

The W220 ended up with "better performance with lower fuel consumption, more interior room, increased safety, lighter weight, and a range of equipment that was as comprehensive as possible. As it was the flagship vehicle so it had to have pioneer new technologies that would set it apart from rival contenders.

It was the first car in the world with keyless start, radar-based cruise control (DISTRONIC), Cockpit Management and Data System (COMAND), with GPS navigation, updated Linguatronic voice-controlled phone/audio functions, and TeleAid.

The facelift model was launched in 2002 & it had solved a lot of electrical issues which were present in the older car.

Now coming back to the present, the car for sale looked decent in the pictures so I went ahead and talked to the dealer who had posted the ad. He said the car is with the owner & is a single owner 2005 S350 3.7 Petrol with a full-service record from MB till 2018 & is in decent shape.

Firstly I went to the Mercedes Benz service centre & checked the service history of the car which seemed to be in order. Post that I fixed a date & went to see the car in person.

I found a clean W222 S Class parked outside the house which made me sure that the car is in the right hands and would be as it looked in the pictures.

On seeing the car which was parked inside the garage, it looked decently maintained for its age, but definitely had issues which I could notice in a short inspection like:

• Air suspension was not levelled properly
• Starting the car took a lot of time
• Central locking was not working
• Soft close not working
• Rear seat electronics (Vent, Heat, Adjust) not working
• Single key in a broken condition (Was working fine)
• AC not working
• Both front fenders & boot lid were painted
• Driver side seat had a tear in the seat cushion central part
• Sunroof hesitating while operating

On asking the driver I came to know that the car was driven less than 500 kms in the last 2 years & even before that the driving was not more than 2000 km per year at least for the last 6-8 years.

Took a short drive of the car & understood that the car needed a lot of TLC for bringing it back to shape. Requested the owner to let me take her to MB for a checkup on which he refused.

Opened the hood & while opening broke the brittle old star monogram on the bonnet (Felt it was not fixed properly & some fixing had been done before), engine bay looked decent & finally I left for home after telling the owner that let me evaluate the expenses & I'll come back to you.

Some good things about the car:

• No rust in the bodywork & no accidental history
• Leather needed conditioning & thorough cleaning but apart from the driver seat rest of it was in impeccable condition
• Suspension up & down function was working fine
• Car was breathing out clean water from both the tailpipes
• Genuinely done only 75000 km
• Engine bay looked fairly clean

Went home & thoroughly went through all the service history & made my mind that I'll pick this project car & try to bring it back to factory spec.

Took delivery of the car & drove it straight to GT Tunerz for a comprehensive scan.

Found the following errors in the vehicle after scanning:

• PSE Pump Failure - Multiple Errors
• SRS Failure - Passenger occupant detection sensor fault
• MAF Sensor - Multiple Errors (Possibly responsible for the dead pickup)
• Cylinder 6 misfire

On further DIY inspection, other issues which we identified:

• Sunroof Not opening & closing properly
• Airmatic suspension not levelling properly
• Headlamps out of focus
• Rear Boot close retractor not working
• Faded headlamps, dirty taillamps inside
• Shaky glovebox unit
• Full service requirement with all fluids & filters
• Dull chrome all around
• Rear electric seat functions dead
• IC central display visible after 5-6 kms of running
• Coolant had some traces of oil - Possible oil cooler failure

After this took the car home & planned the way forward for the work to be done.

Here are a few pics of my 3 Germans together.

As a weekend project, have planned to do things one by one. BHPian Jatin Patel helped me a lot by sharing his knowledge & letting me know how to work on this car & where to begin.

Project 1

Identify & Fix PSE Pump

PSE - Pneumatic System Equipment is responsible for the following functions which were not working.

• Central locking
• Boot opening & Boot close handle auto retraction function
• Lumbar support
• Door Soft Close

Found that the pump is located inside the boot in a black box which is further placed in a thick foam casing to avoid shocks. Took the help of my FNG mechanic & removed all boot trims & found this box with a number of pipes coming out of the same.

Carefully disconnected all the pipe fittings & the electrical connector from the box & took it out of the car. On opening the same, found a motor & an electrical circuit board which had a lot of black powdered stuff around it.

On further inspection & opening of the motor, we found the Graphite impeller had shattered & turned to powder form (A common problem in these cars).

Reviewed my service records & found that the whole pump unit had been replaced once, so tested the motor & it was working fine. Started the hunt for an impeller that could fix things up & found one supplier in the UK from where I plan to order the same in future.

For the time being, arranged a working used pump & took out its decent condition impeller & installed it in my pump housing post cleaning up everything.

So for the time being central locking, boot handle retraction, lumbar support, & rear seat headrest retraction functions are fixed & working. The soft close still needs a fix.

Project 2

Sunroof Repair

On opening the sunroof, it was opening an inch & stopping again & again. I thought that since the car was parked for the last 2 years, the sunroof would need lubrication & hence that will be helpful in the smooth opening & closing of the same.

Opened the sunroof all the way by pressing the button again & again & gave the rails a good clean with a damp cloth. Made sure that the drain holes were not blocked. The sunroof had dust in the channels but was in a decent shape overall.

Before

After

Ordered a Silicone Lubricant Spray from VW which was suitable for lubricating the sunroof channel. After cleaning, sprayed the silicone spray in the sunroof channel.

After doing all this in the sunroof, there was no improvement & the hesitation still persisted. Called Jatin & he told me that the sunroof needs a re-learning procedure as the car was standing for a long time. He sent me a video of the same and I followed the procedure to make the sunroof relearn its operation & the sunroof started to work perfectly.

Also used the silicone spray on the Ashtray rails & Rear Boot Retractable handle & they work smoothly now.

Meanwhile saw a W222 at a local FNG which had come for a paint job in the open.

Project 3

A/C Issue Diagnosis & Fixing

Since the AC was not switching on & the compressor was also not turning on, we suspected that there was no gas in the system. Put the car on the Robinair AC refill machine & checked for leaks.

The machine immediately detected a leak & we started searching for it.

Started from the engine bay side & we were lucky enough to find the leak in one of the main pipes located in the engine bay near the LHS shocker mount.

Was able to arrange a new OE pipe & fixed the same. Leak testing was done again & no leak was found. New gas & compressor oil was refilled using the machine & the AC started to work perfectly.

Project 4

Interior Cleanup & Leather Restoration

Since the car had not run for a long time, the leather had turned hard and there were dirt deposits & some kind of fungal growth as well.

Used a water-soluble all-purpose Leather & fabric cleaner concentrate to clean the seats and carpet, followed by Nanoskin leather cream conditioner in order to restore the original shine & supple feel of the leather.

Will need to do some more leather conditioning to get the softness back.

Project 5

All Fluids, Filters Change & Belts Inspection

Since there was no record of the car being serviced in the last 2 years, so it was really important to do all this properly.

Planned to skip the Transmission oil & filter for now since it was done in 2016 at 66000 kms (9000 kms back). Ordered other OE equivalent parts from MANN Filter & the following were changed:

• Oil Filter & Engine Oil
• Dual Cabin Filters
• Dual Air Filters
• Brake Fluid Flush & Bleed
• Coolant Flush
• Serpentine Belt Inspection
• Steering oil & lines Inspection
• Suspension checkup

The air filters were in decent condition, but as per the records, I could not see any AC filter change in the last 2 services. It came out in a pathetic choked condition.

The Serpentine belt was changed in 2016 & looked brand new upon inspection. Engine Shield was a heavy metal part with ventilation ducts for engine cooling. It had scratches & scuffs leading to superficial rust formation. Gave it a good sanding & got it resprayed in Black both inside out.

The Steering Pump & Oil had been replaced in the past so we just checked the level & checked the lines for any leaks or seeps & did not change the same.

Moving to the coolant reservoir, we noticed slight oil traces in the coolant which is suspected as a future failure of the oil cooler. Flushed the coolant with distilled water multiple times & have ordered a new oil cooler post which we will be filling in new coolant.

Brake pads were cleaned and reinstalled & a full brake fluid bleed and replacement were performed.

A suspension checkup was done and everything was found to be in decent shape.

Project 6

MAF Sensor & IAT Sensor Issue

The car has a lethargic pickup and also the FE is pathetic, on scanning, we got an error which was related to the MAF sensor, hence I have given the car to GT Tunerz and they are working on the diagnosis of the issue.

Will continue the thread further once the car is back from there.

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