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I'll go ahead and open this can of worms...

2K views 23 replies 8 participants last post by  hamada128 
#1 ·
So I'm also looking at the e320, but in 97 it was a straight six. Better/worse/different than the m112 v6 that followed?
 
#4 · (Edited)
It's largely preference. I love love love the M104 engine... I love it so much that I have my own custom plate that says "M104"... Anyway.

Preferences, really. M112 is more efficient than M104 in gas consumption, but M104 is more pleasurable and on paper, ever so slightly stronger. At full throttle, M104 sounds beautiful, whereas M112 sounds like a neutered chicken pretending to be a v8. Ymmv. The i6 is a lot smoother than v6.

Really, both are equal in day to day usage.
 
#5 ·
The previous post was typed on my phone, wanted to say more. Now I'm on my laptop....

Downsides?

M104 will need a headgasket done at some point or another. The original headgasket was badly designed, so it would either leak oil or coolant. Once done, it's "usually" a permanent fix, assuming you use MB headgasket. If you DIY, can do everything under $600. If you don't, then make sure the HG has been done before you buy.

Just like M112, it also has some common source of oil leak, and it is also equally easy/cheap to fix.

Spark plug is every 30k instead of 100k on M112, but spark plugs are cheaper (something like $2 each vs $5-6 each for M112) and there's fewer, so it all balances out.


M112 downside:

M112 has the rear main seal leak, which needs the transmission out to be fixed. It also has a bunch of common oil leak spots, including valve cover gasket. All easy to do if DIY.

Depending on the year of the car/engine, might need harmonic balancer done.

Idler pulley needs periodically replaced, but is otherwise solid.

Can't go wrong with either one if you can DIY.
 
#7 ·
Spark plugs replacement are way much faster/easier on the M104 but it is not that hard on the M112, just more time consuming due to 12 plugs vs 6.
I prefer the M112 as it is more fuel efficient and feels more torquey although as Deplore mentioned on paper the M104 should be stronger.
Also I like the more room in front of M112 since it does not have a fan, the M104 does not have that much room even on the W140 chassis.
 
#20 ·
I think you should also look into other things apart from the engine :). All these cars suffer from electrical problems, and some more than the other. Get a car with at least two working and in good condition keys. Key / ESL / EIS failures are high cost items. Transmission wise, get a 2000+ car, because of some improvements, and avoid high repair costs. IMO, the A/C issues like the duovalve are less costly to fix in E320.

From diagnosis point of view, again 2000+ cars provide better OBD2 support for the scanners.
 
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