W140 300SD

[Casey]

Wow, you don't see these very often!  And only 65k miles!

http://cgi.ebay.com/ebaymotors/ws/170706248300

[jbrasile]

140's are such great cars!

The 140 300SD's however have the problematic OM603671 3.5 liter engine which had serious issues with cylinders going out of round, bent connecting rods etc... requiring a complete and expensive rebuilt or a new engine all together. MB did replace quite a few of these under warranty but I'd stay away from that power plant. It was installed in 126's in 1990 and 1991 and then in the 140 from 92 thru 95.

It' is a shame because I am pretty sure these cars are superb drivers just like all 140's, although maintenance can get a little pricey, especially if you need a new a/c evaporator which is almost the norm...

Tks,

Joe

[Casey]

I do think MB did a great job with the 140's...very luxurious cars, truly up to the MB name.  Unfortunately I find the chassis to be rather plain and boring.

The first MB I rode in was a W140, which is what formed my addiction to them.

[jbrasile]

The style is typical 1990's, little chrome, lot's of large plain panels and squarish lines. I think the SWB car in the right color is actually quite attractive. The 300SD in the add is just beautiful with the light colored interior.

We just did an evaporator replacement on a 93 S320 from a client.... be affraid.... be very affraid..... hehehe


Take a look.







Tks,

Joe

[1980sdga]

Wow! Do the evaporators leak or what?

[jbrasile]

Yes Jon,

Chronic problem on every MB starting around 91-92 when they switched from copper to aluminum. 124's, 129's and 201's suffer of the same ailment. Luckily our 116's evaps are copper and will basically last forever...

Tks,

Joe

[KenM]

That looks seriously ugly Joe, I've heard of the dreaded W140 evap problem but haven't spoken with anyone who has had to do the job, so how bad was it?

How many hours involved here? The cost of the replacement evap is peanuts in the whole scheme I have no doubt. I think (think) I read somewhere that MB were allowing 28 labour hours to do this job under

warranty back when the cars were newer. How does this compare with what you experienced?

Cheers,

[TJ 450]

I'd still replace that evaporator myself, the 140 would be a bit tricky though by the look of things.

W201= piece of cake. I just replaced the dash in mine on the weekend, and it took me an afternoon. The evaporator is actually in the engine bay on the 201.

All modern cars have alu evaporators as far as I'm aware, and it is indeed quite an issue. Likewise with heater cores.

Tim

[jbrasile]

Ken,

The customer was charged about 30 hours plus parts at US$50.00/hour.  The evap itself with duty and all was around US$1000.00 + he had a bad heater core and the associated tubes which were another $700.00. Total damages were about $3500.00, actually not too bad considering the size of the project. My mechanic did all the work, he has done quite a few of these... I remember dealers were billing MB close to 10k when the cars were new and under warranty.

And yes, 201's are really easy to do, why couldn't MB and all manufacturers for that matter use a similar system where you can access the evap/heater core from the engine compartment, it just makes sense...

It is true that all modern evaps are aluminum and I have seen quite a few Audi/VW go through the same process.

Tks,

Joe

[Casey]

When you replace it do you just stick in another aluminum one that has the same problem in a few years??

[1980sdga]

When you replace it do you just stick in another aluminum one that has the same problem in a few years??

That's what I was wondering. What exactly leaks? Welds, tubes? 

Kudos to the owner for springing for a proper repair and kudos to your shop for doing it at a reasonable cost!

Back to the "enthusiast" thread...

VERY, VERY FEW folks in the US would have spent the $$ on this repair. It would have been tossed like an old toaster and the new owner would have what we call "2-55" AC... Or "4-55" with a saloon 

[TJ 450]

I always thought it was pin holes in the tubes due to corrosion from the outside in, possibly due to condensation? I remember with the Volvo 850 (it also has an alu evaporator), it being suggested that you run the fan with the A/C off a while before you kill the ignition, so that it gets a chance to dry out.

Tim

[jbrasile]

In theory the new aluminum units have some kind of mod that prevents them from leaking in the future. These early evaps were manufactured right when R-134 was coming online  and I believe the gas contributed to the failure.

We would have gone with a copper aftermarket unit but availability was a problem and we were able to source an original MB part locally.

The tubes develop micro leaks, in this case at the bottom of the unit. We could see a lot of dye that was put in staining the center lower portion of the evap. The heater core tubes had disintegrated as well and the core leaked and  flooded the a/c box. We were lucky to catch all of this in time.

This particular car is a 1 owner 140 with 85k km on the odometer and it just sat for a long time before the owner decided to service it and put it back on the road. An S320 like this is worth about $12k here so I told the guy that unless he needed the money (which he doesn't...) or had a space problem, he should just keep the car and make it as nice as possible, so we have been working on it for the past few months solving all the problems little by little. This a/c evap issue caught everyone by surprise... the condenser had to be replaced as well, it too had a leak, and so did the compressor.

Tks,

Joe

[KenM]

I don't know for certain but I would think that the aluminium leaking issue must come down to crap components or manufacturing. There's nothing in an a/c system that's going to cause leaks to occur. Many of

these alloy heat exchangers have the tubes bent around as with copper ones, the trouble is that the aluminium gets very thin when this happens. With aluminium tubing and fins there is no dissimmilarity in

metals to potentially cause corrosion. If their tubing is porous to start with then having it stretched thin is going to raise the potential for leaks years later with vibration etc acting on components. The only

thing I can think of that would potentially cause the erosion of tubing from the inside is the action of vapour or bubbles in a stream, when they go a round a 'U' bend at the end of the evap the vapour

bubbles could whack against the wall of the tubing and gradually erode it. I have come across this several times in reverse with steam coils, where bubbles of condensate in the steam have worn away

the U bend until it leaks, but this is a much more agressive process than with refrigerant.   Looks like a hell of a job alright in this case.

[curbill]

$ 3,500.00 is cheap in the USA. MB wanted 4,500 3 years ago when my A/C went out on our S420. It was cheaper to buy a used 300sd than get the 420 fixed. The 420 is the nicest ride of any of the MB's that I have owned over the years, including the 6.9 and the 220se 1955 convertible. Wish I still had those though because they bring big bucks in the USA.