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Hey all new here. I am thinking of buying a 2004 Mercedes Benz C240 tomorrow but id like a little Intel if anyone has some. I am kinda scared seeing its only getting about 19-20 mpg on most sites. Anyone own one that's getting better or has some tips? Do people install short/cold air intakes on Benz? I have owned a Bmw before but mainly its been Mazda and Hondas. Suggestions? The car has 110,000 miles, guy is only owner and says he has all the history and receipts. Asking 6500 obo. Older gentleman seems pretty nice.
 

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Fuel economy in a C240 is not exactly a strong point. I get 17 or 18 mpg in city driving, but that is with a fairly short 20 minute commute, and the car spends most of its time getting up to operating temperature. Highway mileage is 25 to 28. Not spectacular, but certainly not 20.
 

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The C240 is a great car - solid mechanically. Like all MBZs, it already has a cold air intake, so there' not much to be gained there. In fact, with the C240 using a 2.6l de-tuned (shorter stroked) version of the 3.2l M112 engine used in the "320" series cars, there isn't much you can do for performance. If you want better performance and better MPG, look at a C230 Kompressor, or better performance and about the same MPG, a C320.
 

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the c230 (4 cylinder supercharged) gets better mileage (33 highway). there are pros and cons to either the 4 or 6 cylinder. intakes are generally a waste of money on MB (and most cars, where they make more noise than power).
 

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I think C240 / C320 is a great car. The M112 engine is quite solid, except I hit all the typical problems including Breather cover leak, stubborn PCV hose, Valve cover leak, Oil Filter housing leak and rear crankshaft seal ring leak. All were fixed by myself except I live with the rear crankshaft seal ring leak as I learn that it's well beyond typical DIY.

BTW,anyone knows if M112 is prone to the head gasket or valve stem gasket failure?

The C240 is a great car - solid mechanically. Like all MBZs, it already has a cold air intake, so there' not much to be gained there. In fact, with the C240 using a 2.6l de-tuned (shorter stroked) version of the 3.2l M112 engine used in the "320" series cars, there isn't much you can do for performance. If you want better performance and better MPG, look at a C230 Kompressor, or better performance and about the same MPG, a C320.
 

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Those top-end leaks and hose problems are easy and cheap DIYs and typical of older cars - of all makes. The crankshaft seal is actually not as bad as you might think - the biggest challenge as a DIY job is lifting the car enough to drop the transmission. The crank seal leak is nowhere near as common as the top-end leaks. Even so, any car with north of 100K miles is going to develop some leaks.
 

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Front Crankshaft seal leak

Those top-end leaks and hose problems are easy and cheap DIYs and typical of older cars - of all makes. The crankshaft seal is actually not as bad as you might think - the biggest challenge as a DIY job is lifting the car enough to drop the transmission. The crank seal leak is nowhere near as common as the top-end leaks. Even so, any car with north of 100K miles is going to develop some leaks.
How common on the C240 to have a leak from the front shaft seal? I think that's what I have causing the serpentine belt to be smudged all the time. Initially I thought it was the AC compressor or the power steering pump leaking but that's not the case. Is there any other place where a leak may keep the belt greased?

I am dreading removing the bolt on the crankshaft. Is there a known torque on this bolt? can I just use a breaker bar to take it out? I did order the special holder tool..

Any help is appreciated.
 

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A common oil leak source on these engines is from a panel about an inch square held by two bolts above the crank pulley. Remove the panel, apply sealant, install the panel. I don’t think there’s a gasket for that panel. It’s also possible the oil filter housing is leaking. That takes a gasket. Front crank seal leaks aren’t common but aren’t unheard of.

Clean the front of the engine then go leak hunting. I spray grimy areas with engine cleaner then rinse with a bucket. Particularly around the oil filter housing and power steering pump. There aren’t sensitive electronics at the front of the engine. Mind that the cleaner is safe for magnesium or whatever these engines are made of. Caustic cleaners will start corossion that looks like white blisters.

The torque on the crank bolt is something like 250Nm. Don’t quote that number but it’s beyond the range of the typical torque wrench. If you take your breaker bar to the crank bolt, you’ll spin the engine backwards and possibly upset the timing chain tensioner. You need a way to prevent the engine from turning while removing or fitting that bolt.

There is a special tool that requires removing the starter. The tool fits in place of the starter and meshes with the ring gear to hold the crankshaft. Another tool is a castellated tube that engages the spokes in the crank pulley. The tube has a handle to hold it steady while you use a breaker bar through the middle of the tube. Other MB engines have a ring gear holder that attaches to the bottom of the engine but I haven’t seen this style holder for the M112. Could just be ignorance on my part.

You can probably blast the bolt of with an impact gun. The engine probably won’t spin backwards. You shouldn’t install the bolt with an impact gun though.

Sixto
98 E320s sedan and wagon
02 C320 wagon
 

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Thank you for the reply, That small timing cover is clean and dry and so is the filter housing area.


I plan to clean the grimy area which is mainly below the crank pulley and and also spreading toward the alternator. I got a spray cleaner from walmart that does not require rinsing which seem to work pretty good after i tried in a small section.

I have ordered this tool:

https://www.amazon.com/PMD-Products-Crankshaft-Harmonic-Compatible/dp/B0154ATGMS/ref=sr_1_1?s=industrial&ie=UTF8&qid=1546658135&sr=8-1&keywords=B0154ATGMS


I will need to get an impact wrench and a BIG torque wrench.
I was hoping someone could post the WIS directions for replacing the shaft seal.
 

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Thank you Rodney,
I just wanted to make sure of the torques on the crankshaft bolt, 200 NM is about 150 lb-ft. I saw some videos where the torque was 220 ft-lb. May be that includes the additional 1/4 turn.

Also some videos recommend coating the seal with a thin coat of sealant, but WIS says NOT to use sealant.

Oh and the WIS instructions do not specify to use a new bolt. I've read that it's a one time use only. Any thoughts on this?

Thanks again.
 

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I generally go by what WIS instructs as it was written by MBZ's engineers. Generally, the only reason a bolt is one-time-use is when it's made from softer metal, like the aluminum bolts on the 722.9 transmission pan. 200Nm is not a huge amount of torque. There are some cars that use that, or close to it, for wheel bolts.
 
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