Good afternoon guys,

A year ago, I was lured into buying a 2015 C300 with 135 000km on the clock with a C63 body kit. She's a stunner with the bumps on the bonnet, grey leather, 19" AMG rims, pan roof and the quad pipes... only the fender indents were missing but still holds the V8 biturbo badging. After a few months I found she was a crashed car that was done-up and put back on the market. Pretty sure the milage is correct because the interior is in good condition. (VIN: 55SWF4JB8FU082858)

Had the car for about a month before she started misfiring; was so bad I got her towed to the workshop, replaced all 4 sparkplugs and did a full major service. (1st workshop visit)

Then the common fuel smell; sent her in for a replacement clip and the fuel smell stopped. (2nd workshop visit)

Immediately after the fuel clip was installed, I noticed an oil leak and took the car back; an o-ring was replaced and that was sorted. (3rd workshop visit)

After the oil leak repair, I started sending her to a different workshop because I was sure the oil leak was created at the workshop when they did the fuel line repair and carelessly fitted everything back, however, as it could not be proved, I decided to take my business elsewhere.

Car was fine for another few months then the misfire started again, took it to the new workshop, they claimed it was an electrical issue that they resolved and the car was fine; while it was there I did a gearbox service and oil service again. (4th workshop visit)

There was always this rumble at cold start from the time I got the car, I'd wait for her to warm up and when the rev dropped to 700, I would start my journey. I was told the rumble was the AC from the workshop, but I always have a feeling there's a slight miss. The rev counter doesn't fluctuate at all and the engine mounts are fine.

Fast forward to a week back; fired her up and the CEL came on. Took her to the workshop and picked up the P030085 and P030285 codes. They did a basic check, all appeared in order, did a reset and sent me on my way. Drove back after the reset and the car ran like new! better than she ever did. (5th workshop visit)

The very next day, on acceleration, I had a jolt and the car was still fine after that single jolt so I started to take it easy when driving around. This morning, the jolt came back at different gears between shifts and she went into like in a limp mode, very short shifting and if I accelerated hard, she'd jolt again. so I limped her back home and got her towed back to the workshop. (6th workshop visit)

My main query is: what are the signed of a broken piston? I have read so many horror stories about broken pistons with this specific engine.

The car is out of warranty and I will have to cover the cost of the repair, I love this car and want to maintain her. Any advice? I am currently about to tell the workshop to replace all HT Leads, all ignition coils and all sparkplugs

P.S; I know it will be easy to scrap and get a new car but I really like it and want to keep it... and I only fill "super" fuel (98oct)... but 6 visits to the workshop in 11 months is excessive, I need a proper fix, I don't mind having to shell out a few grand to sort her out once and for all.

 

Do you mean a broken connecting rod when you say broken piston? Have your mechanic run compression tests on all cylinders and this will tell you if there's a problem with a connecting rod or with any of the valves.

 

Thanks for the response; I wanted to know what are the symptoms that can prevail when you are on the way to the cracked piston issue. I understand that it could be the conrod that leads to the piston being cracked, however, what are the main symptoms?

Quick update, the workshop came back to be stating it's the crank sensor that needs replacing. Getting that done now and fingers crossed all will be well with her.

 

Update... changed the crankshaft sensor at my preferred workshop; total cost of USD180 including the tow from my house (about 40km away from the workshop).

While there is no rumble anymore and cannot notice a misfire; there is still the jolt under medium-to-hard acceleration at gears 3, 4 and 5.

So as long as I nurse her and don't hit the accelerator harder than 25%, there's no issue.

The daily school run is the primary use of the car. literally 4km there and 4km back twice a day. This weekend had to take my wife out and prayed that the car didn't misbehave; drove about 60km return, got up to 120km/h no problem but under slow acceleration in case the car did the jolt.

My wife is adamant to sell and get something else... I just want the car repaired.

Any ideas what could be causing the jolt?

 

If you can get someone with XENTRY to perform a standstill adaptation to the transmission, it might help.

 

that's the problem... trying to find someone in Abu Dhabi that has Xentry.

While on the Xentry topic, I'm considering buying either the MBito, Bluedriver or iCarsoft MB V3... is the iCarsoft worth the extra cash?

 

If you don't need variant coding, just get the V2.

 

Actually, could you get access to the Launch CReader Elite Benz V2.0? That might be cheaper plus offer more features: https://mbworld.org/forums/e-class-w...onal-more.html

There are two, the thread mainly talks about the V1.0, V2.0 is also discussed.