phteknik

Hello Diesel folks,

I recently aquired a W202 220 CDI.. mileage 110.000 that has not driven for 6 years..

Since i got the car i did the following to get it running again..

Diesel Hardlines, all Filters, Motor mounts, 4x new Injectors, valve cover gasket, Cleaned Inlet Manifold, Cleaned EGR valve, added 2 stroke oil to the diesel,
Using Meguin 5W30 Oil MB SPEC 229.31..

My main problem(s) ATM, idle is quite loud for a CDI compared to other om611 ive noticed... the loud operation continues undtil the turbo kicks in around 2000 rpm, low end torque is quite poor and i suspect some faults somewhere in the diesel injection, could be as simple as a bad air flow meter?

I need opinions and advice on how to improve the performance or mod the engine for even higher output and more smooth running

Plutoe

Forget the mods------Offer the car for sale, as is, in an Iranian swap sheet!!

marc hanna

The noise could be a lot of things. Early injection timing, oil vapour getting past the rings, etc. How is the fuel economy? Any black smoke?

phteknik

Fuel economy seems good, black smoke appears when i cruise and then accelerate hard,

marc hanna

I would maybe start with a compression test and get an oil analysis done. A properly running CDI shouldn't put out any black smoke unless it's been specifically tuned to run rich(er) on acceleration. Black smoke is caused by unburnt fuel which can be the result a few different things, all of which are just speculation here. Worn rings can draw oil vapour in during the intake stroke and cause premature ignition during the compression stroke, which in turn could make the engine noisier. Again, just speculation. Late or early injection and poor fuel atomization can result in a poor burn, causing black smoke. Also, low cetane number of the fuel can cause an incomplete burn.

Noise can be caused by bad bearings, cracks/holes in the intake and exhaust, etc, etc.

Also, if you're getting a lot of oil through the crank case vent, that can cause pre-ignition also.

I don't presume to know your technical knowledge level, but I would recommend taking it to a diesel mechanic and getting a once over. It will be worth the couple hundred dollars it might cost.

I don't think at this point, it is as dire as Plutoe makes it out to be, because it still has really low mileage.

My main concern is that it was sitting for 6 years, and might have extensive internal corrosion. This is why I seem somewhat focused on the rings.

Again, a lot of speculation here.

Carsy

I understand that you mean no black smoke when you cruise & the black smoke appears only when accelerating hard.

This is normal.

My 2007 CDI drops a lot of smoke with hard acceleration ,has done from new. It also deposits carbon on the rear guard over time. Both normal for pre Diesel Particulate Filter vehicles.

My 1994 diesel Peugeot used to black out the road on heavy acceleration.

I agree with Marc Hanna, take it to an expert for a quick look . You may then be able to do the work, if any ,under his supervision/guidance. It may be something simple .

I am keen to know the outcome.

Micah / AF1 Rac

Does that engine use VNT turbocharger? Had a similar issue on my ford 6.0 when VNT guide vanes were seizing up due to EGR/PCV Carbon buildup in hot side of turbo housing. Ford had issued a TSB on cleaning and de-coking the VNT assembly, since out of warranty I did myself according to TSB instructions, all has been good for last 100,000 miles of mixed use on that turbocharger.

Carsy

Micha,

I believe it is a variable geometry turbo .It is a OM646 4 cylinder.

I found the following details on the web.:-
5 GTB1752V Garrett 752990-0006 Mercedes-Benz C class OM646 / OM646DE22LA

OM646 DE 22 LA EVO 646.811 2148cc 125kW at 3800rpm 400Nm at 2000rpm W204 C 220 CDI 2007-09

The car has blown black smoke since new when under heavy acceleration ie when the turbo is caught out with low boost & a heavy foot. Therefore I do not think there is a problem. Thanks for the heads up.

john.

Micah / AF1 Rac

Mmmm....you might want to put a little reading into VNT behavior when vanes are not properly actuating. My W211/OM648 smoked on the occasional hard launch when dead stock from blowing off built up carbon...zero visible now with open pipes exducer to bumper. Same with my truck. At least on the OM648 with VNT charger boost comes on early enough that ecu slows turbine a bit sub 2k rpm just to keep from generating too much low down boost. Your situation with poor power and a lot of smoke below 2k sounds very much like VNT vane issue.

Ausmbtech

Check the vacuum supply to the turbo actuator valve and also to the EGR actuator valve. If you're not getting at least 80kpa/25inch vacuum then you need to look for a leak. Will there is a vac leak the turbo will be sluggish to build boost and the engine will be a bit louder due to low EGR flow. If the supply is good let us know and I'll give you the next step to check.

phteknik

Thanks for the replies, apreaciate it..

I am from Denmark and the forums availiable over here has no or very low knowledge..

Im planning to do the vacum test in my workshop ASAP and post codes from the diag..

phteknik

I did the vacum test, and vacum supply at turbo actuator is much lower than at the EGR actuator, so a leak somewhere is know a fact, also the actuator for throttle flaps inside the intake has very low vacum supply

I did my best to follow the hoses but was unable to locate the leak?

Where do i begin? i found a vacum line at the brake booster, this goes directly to The EGR Actuator..

Does the turbo and manifold throttle control have its own supply

phteknik

Found the vacum leak on of the lines was leaking, now i get strong vacuum everywhere...

Engine runs better, but still sluggish to spin up turbo, what about a turbo clean?

Micah / AF1 Rac

I cleaned the VNT turbo on my Ford 6.0 which is technically quite similar to the Benz/Garrett turbochargers. If yours is vacuum actuated just test actuator and see if rod moves smoothly. On my Ford the problem was obvious, the dealer did a de-coking procedure once while under warranty, I just followed the Ford TSB for doing it myself the second time around. If your motor has been running typical EGR active state then it may very well be the VNT/VGT guide vanes are sticking, not allowing low rpm spool up properly. Yet another in a very long list of reasons I think EGR is a terrible thing to do to a perfectly good motor. This is a pretty common issue on many stock late model diesels due to soot buildup.

Replaced electrical fuel pump in my W211 today, never had a stretch of road open enough to hit peak boost/fuel pressure on way home but did see 21,000 psi aggressively climbing hill (27% grade) a mile from my house, that's pretty close to my set limit of 23,650psi and when fuel pump was dying anything over 17,000psi was triggering low pressure MIL. Hopefully my diagnosis was good?

Ausmbtech

Do you have any excessive smoke on full acceleration that clears once you get full power?

Any obvious air leak noises once you have full boost?

phteknik

Yes i got the smoke problem, worse when i accelerate hard from low rpm..

at high rpm there is no excessive smoke though...

Still got the problem with sluggish turbo and much worse when the engine is cold ,is that normal?

I will try a turbo clean, but the cleaning product have to enter the turbo from the exhaust side, any good ideas or do the turbo need to come of completely?