What is a reasonable lifespan for the M103 & M104?
 

I'm pretty certain I'm going to be in the market for a w124 in the next few months...this will be my wife's car.

As I am looking online to get a sense for what I'll be able to afford, I'm realizing that I don't have a great sense for mileage on these cars. Being that my 300D has 240k and it still going strong, I'm wondering if, even at fairly high mileage, I should expect quality performance from a gasser in the w124. I am guessing they don't have the longevity of their diesel counterparts, but that's just an assumption.

Thanks.

Its not so much a question of the longevity of the physical motor itself....its that of the fuel system/sensors/computers/gobs of gook that run it. After my intense initial parts throwing escapade, our 300E has proven to be very nice and reliable. M103's should be good for about 200-250k without major work (aside from the high likelyhood of a headgasket replacement) depending how they are driven. Ours has 136k and can still pull hard and strong to 110+mph and doesn't use much oil at all.

The M104 is probably similar, but its a more complex motor.

Bottom line: A gasser will need more ongoing care to be happy and reliable than a diesel, especially a 240. :eek: I like the variety working on both types....even though it seems I do most of my work on the gasser....

Went to the junkyard and saw a total of 6 300E's with the M103 motor.

212k, 256k, 240k, 313k, 356k and like 168k IIRC. The 168k was new to the lot and it did not have an air filter...Looked under the flap and it was horrible...Guess it was ran w/o filter and got something into the pistons.
All very reasonable numbers!!

Engine life is always dependent on servicing.

I've put pistons & rings in cars with 50K miles & seen other cars with 300K+ that were NEVER apart & still no engine issues.

Early 103's seemed to LOVE valve guides & seals. Replacement parts were better.

Some people HATE CIS cars & others hate EFI cars.

A good 1992 300E would "most likely" cost less to maintain that a 1993 300E with a M104 engine.

The 1994 & later do have a ventilation dust filter system that is better for the driver.
I also like the body up-dates on the 1994 & 95 models.
Make sure on a 1993 & later car that the engine & starter wiring harness has already been replaced!

2nd generation 104 motors (i.e. HFM 2.8L / 3.2L) with proper care don't seem to need valve jobs. They have head gasket issues but I don't think anyone really knows how long they will go - which is a good sign given that they've been out for 16+ years. Recent Star magazine had an article about one with 450k, no issues other than one head gasket. To me the argument for HFM 104 is the better diagnostic system - too much guessing on a CIS.

It's well and good to talk about the engines, but most W124 are also ready for some expensive transmission work and some expensive HVAC system work, too. Suspension work, too, if it's a wagon.

I've got two 190E 2.6's with the M103 mill.
 

The '91 has 170K and has only had tranny issues. Engine has been maintained and is solid. Burns half a quart between 3k oil changes. It does suffer from poorly performed body work, though.

The '90 has 295K miles and has had the same tranny issues as well as valve guides and seals replaced. It sucked oil at an alarming rate until the valve work was done at about 250k. Now it drinks about a quart between 3k oil changes. Decent for the mileage.

These engines burned a little oil even early in their lives at high RPM. I saw vapor out back at full throttle and I'm quessing it was oil and fuel. CIS seems to over-fuel as a safety measure. I much prefer EFI on gasoline engines.

That's good service from a relatively cheap car in my opinion. Auto trannies suck in general so I'm not surprised by one replacement and one rebuild.

I'll take my OM617 powered cars over the gassers any day. I've got a W220 S430 and even it usually sits in the garage while I drive my old, trusty '82 300D. It has character that the W201's nor the W220 could ever dream of.

I like the M104 as used in the '93-'95 124 cars. I've found it reasonably easy to diagnose and work on, not that mine has required all that much attention in 6 years of ownership. Plug changes are trivially easy. There is no cap or rotor. The water pump is a bit involved, but seems to be easier than the 103 engine. This past weekend I changed the fan belt in less time than was required for the topsider to drain the oil.

Just make sure the head gasket and wiring harness have been replaced on any candidate car. Might be worth asking after the ETA as well.

- JimY

My 1996 E320 with M104 engine is approaching 150K, the only major issue in my ownership was the broken water pump. Hope to reach 200K without big problems.

Yep, I have seen a 190E with 190k....and a 300E (4matic) with 209k....probably junked due to the 4matic though.....the car was in very very nice shape...a shame.

As MBDOC said, its all about the maintenance....better maintenance = longer life....for any engine/car.

WRT W124 cars, I've owned one OM603 wagon, three M103 sedans and 1 M104 wagon.

The last of the W124s are the best cars.....even though one of my M103s had a 5 speed. M104s do not seem to have the valve seal/guide issues of the M103s.

Jim

Basically the same design but the M104 has some head improvements. In high mile threads there are cars that hit 400k. From what I've read you expect 250k with proper maintenance before you need head gasket and or valve work. Along the way you may need transmission, water pumps, alt regulators, relays, bushings, etc. Some believe the bottom end should last indefinitely...

Thanks - this is great info. Help me out - CIS versus EFI? CIS is a mechanical fuel injector, versus an electronic (e.g. computer) controlled injector?

Thanks Jim. I like the later ones too, although I'm leaning toward an older one b/c...1) they're cheaper - I'm trying to stay under $5k, and 2) the m103 is easier to work on.

I'm just beginning to understand how to work on my vehicles, and while I'm excited to understand these gassers, I don't want to screw myself over by getting some too complicated for my simple brain!

All that said, if I can find one that's been well cared for (with documentation), I'll spring for a later one.

Roger that, pawo - as always, thanks. You're right on...