Mercedes-Benz M112 engine - preventative maintenance

[idealcopy]

Hello all:

Being the very fortunate owner of a good 2005 R230 SL - seals don't leak! roof works! sbc unit hasn't failed! - is a rare thing from the nadir 98-07 Chrysler period, and I'd like to keep it that way.

Just wondering if any of you have experience of the above V6 lump; it was manufactured late 90s to mid 00s to a wide range of capacities - 2.4 to 3.7 - and cropped up in a wide variety of C & E classes.

Any know problems to get at ahead of implosion ho ho?

Many thanks for any advice you can offer

_________________________________
John Moser

[alabbasi]

Hi, I'm not that familiar with the M112, but I am familiar with the v8 variant which is basically the same motor with an extra two cylinders. Common issues include problems with the harmonic balancer which can cause a rough idle.
Stay on top of oil and filter changes and use the fleece filter as there engines are prone to sludge (7k intervals). Plugs can be a pain in the rear as there are two per cylinders.

Other then that, it's a great motor. Also just picked up an 05 R230. Looking forward to learning about a new model but somewhat terrified of the SBC, ABC and Hydraulic stuff.

[idealcopy]

Thanks very much for that; well noted re balancer, plugs and filter.

And congratulation on the R230 purchase. You're dead on re sludge issue; on one of the US forums one bloke broke down either the 112 or 113 for repair and couldn't believe the amount of blow-by carbon that had collected on the rings.

Hope you have a lot of fun with it; a V8 - is great (groan)! No it just is; have the V8 in the R129 and it really is like going from chocolate to vanilla, stepping into the V6 R230 after that.

Fyi, we've done really well getting hold of first-facelift 05-onwards models. Build quality was so appalling in the early 02-04 productions years that they went into overdrive sorting out the seals, roof, panelling, electronics and sbc/abc problems.

Though the second facelift 2006 period was even better build quality, those issues with the M272/M273 balancer shaft engine are still disturbing, and a number of garages I know tell me they still have 06-09 vehicles coming in with leaking seals that are proving impossible to repair.

One outfit told me one vehicle they know has been into MB three times for leaking seals repair, to no avail. In desperation MB took to wrapping the central locking/battery unit on the right side of the boot in bubblewrap to keep the water out. No it's true - bubblewrap on an 80 grand car when new...

So fingers crossed; for the record my one has experienced no issues whatsoever to date - no leaks, no sbc problems (the 350 doesn't have abc), no roof failure, but sadly this seems the excpetion rather than rule. Praying to god it remains that way....

[alabbasi]

Thanks, this will be my third M113 motor (also own an 02 E55 W210 and 99 SL500). I'm sure that this car will be an interesting ownership experience. I considered going to an Sl550 (380hp is plenty for me) but was put off by the 722.9 transmission. I've had cars with 722.6 tranny's for 10+ years and they have been robust with only issue being the conductor plate. The 722.9's conductor plate is integrated into the valve body which requires factory coding to work with the car. We found this out the hard way when we put a new (used) transmission in an 05 S500 with a bad valve body.

As far as build quality, it seems OK so far, just lots of little electrical problems (truck open warning etc). I'll need to get the latest SDS software pretty soon. My current factory scanner will only support up to the late 90's.

[idealcopy]

You're 100% dead-on there re 722.6; that box is, in the vernacular, 'tough as old boots'.

Had a 2003 S203 C270 that used it; I keep in touch with the current owner and it's still purring along on 170k now.

Remember being a complete ignoramus when first driving that S203 and not understanding why the box wouldn't shift when cold; must have subjected it to all manner of misery before finally taking it to the garage. They were genuinely concerned it had been damaged due to low fluid + leaking multi-plug affecting the electronics - but no, after a flush, new filter and fluid it ran great forever more. A wonderfully tough unit.

That box was just one great piece of durable design; going by Wikipedia it's still widely fitted to all manner of current vehicles. The only aspect that lets it down is indeed the conductor plate and that infernally weak multi-plug, but at 25 quid and 10 minutes to fit you can get used to it.

Another minor R230 irritant is the 'bonnet open' warning when it isn't open; the only resolution seems to be to drop it from a considerable height!

So you have a 99 R129 500? Most interesting - does losing that one valve on the M113 make such a big difference over the M119? Always wondered about that!

And how is that car for you generally? It's always great to hear from another R129 owner about their experiences.

[TerryG]

I know nothing about mercs but I have "fixed" bonnet open warnings on the company ford C-MAXs by pulling the plug off the switch and putting a couple of spade connectors with a short length of wire between in to the socket. The switch is part of the bonnet lock which seems to get filled with all sorts of crud fairly quickly.

[idealcopy]

So that's the source of it Terry!

Given how so many of these kind of parts are sourced from one supplier nowadays it's probably the same on the Benzes. Ta.

[alabbasi]

So you have a 99 R129 500? Most interesting - does losing that one valve on the M113 make such a big difference over the M119? Always wondered about that!

And how is that car for you generally? It's always great to hear from another R129 owner about their experiences.

Yeah, that sealed for life BS is not a very smart move on MB's part. I bought the 99 SL500 on a spur of the moment deal. It's an auction car and comes with a bit of baggage but the motor runs fine. It's not going to be a car that I will keep as I also have a 98 SL500 (m119) which only has 58k miles. It was purchased at the insurance auction because it had a light hit in the front, but is otherwise a beautiful car. My only other experience with the M119 vs the M113 is with an 97 E420, owned for 10 years. The last two years being alongside the E55.

Both the M119 and M113 are great motors. The M119 however is a much sweeter engine. It's silky smooth and likes to rev. The E55 definitely has more power and the SL55 is obscene, but I really enjoyed driving the E420. Reliability wise, both are good, but the M113, E55 has had very few issues during my ownership. My E420 would routinely trip the check engine light on an emissions related problem that would resolve itself after a hundred miles.

The R129 seems to be burdened with some pretty crappy plastic, especially around the interior mirror. Not sure if this is apparent to people living in the UK, but in the extreme heat of Texas, it's very obvious.

[idealcopy]

Yes, interesting you mention the build quality on the R129; wonder how late versions like ours compare to a very early 90s copy qualitywise.

There are definitely moments in that interior where in hindsight you can see the cost-cutting emerging - though nothing can come near to the cheapness of that R230 plastic filler flap or door mirror - they are hideous!

So that's really good to know; no sizeable difference in driveability between the three and four valve V8 versions. Thanks for that comparison.

[alabbasi]

Not in my opinion, although some would have you think on the forums that when MB and Chrysler merged, MB elected to throw out all of their quality control measures and hire all their labor from Mississippi. The reality is quite different of course and for the most part, the later cars are much more reliable. Especially after 1996 when coil packs and EFI were well in place. I'd rather shoot myself in the head then have to work on another CIS-E car.

If people think that MB build quality is bad, they need to check out a 10-15 year old BMW which seem to fall to pieces. I wonder if that had anything to do with Rover?