Which Diesel Model Should I get. - PeachParts Mercedes-Benz Forum

wabenzee · #1 11-15-2004, 10:20 AM

Ok, I am confused. I am about to buy a 124 diesel. I am looking at 2 right now. Both have 200,000 miles. One is a 6 cyl 1987 300d W124 series with the straight six turbo. The other is a 1990 300d 124 series with a five cylinder 2.5 turbo. Which is the better engine? Are there any problems with the 6? Why did Mercedes only make it for only the 87 model year. Any advantage in buying the 2.5? Is it slower?
Please help me make up my mind. Thanks

#2 11-15-2004, 10:29 AM

Either of the two engines are nice. The 6 cylinder is nice. I drove a 1987 300 Turbo 6 cylinder for about a month. I got addicted to it for a brief period while my 1986 300 SDL was getting a transmission kit installed.

Make sure whichever car you choose, that you do a check on all systems ie.
suspension system, transmission, A/C and Heater, engine check, any leaks, fuel, oil and tranny. All important in purchasing a car and how much your going to pay.

Scott98 · #3 11-15-2004, 10:30 AM

The six cylinder engine had a problem with the heads cracking if it overheated. You can do a search and find out more than you would like to know. I think the general consensus is that the engines are just fine as long as you don't let them overheat. My parents have had two of them with no problems. Mercedes made that engine in '86 and '87. Don't know anything about the other engine. Too new for me.

Scott

nachi11744 · #4 11-15-2004, 11:20 AM

I did not own one personally, but friends do. It is a bulletproof drivetrain and gives very good performance from the 127bhp with almost 30mpg fuel consumption.
One of the all time MB diesel greats in the US market

H-townbenzoboy · #5 11-15-2004, 12:27 PM

I know you're looking at two W124s, but have you considered the bulletproof W123 or W126 chassis equipped with one of the bulletproof OM61x family engines? You won't have to worry about head cracking on these models! And, they're easy to work on. W124s are good too, but just a suggestion.
-Joe

boneheaddoctor · #6 11-15-2004, 12:31 PM

Quote:

Originally Posted by nachi11744

I did not own one personally, but friends do. It is a bulletproof drivetrain and gives very good performance from the 127bhp with almost 30mpg fuel consumption.
One of the all time MB diesel greats in the US market

Oh come on don't you see all the Ebay ads that say these all get 40mpg? heck there must be something wrong with it.........

TimFreeh · #7 11-15-2004, 02:12 PM

Don't laugh too much - a 2.5 turbo is capable of 40MPG but conditions have to be perfect to obtain that kind of mileage. I've had a 2.5 turbo for 4 years and 110K miles and I've gotten 40MPG on two tanks during my ownership period.

Typical highway mileage for my car is 37-38 MPG at 65-70 MPH with no A/C use dropping to 34-35 under with A/C on.

I don't do much city driving but in a mixed suburban environment my car never drops below 30MPG - even on winter fuel.

The 2.5 turbo has been a great car for me - the earlier 603 powered version lots more power than the 602 but it's not capable of much more than 32-33 MPG. The tradeoff is pretty clear - the 2.5 turbo is about 10-15% slower but it gets 10-15% better mileage. The 2.5 turbo does not suffer from the cracked-head syndrome.

I think if I did alot of city driving I'd go for the OM603 - the added power and torque would be very usefull in stop and go driving. If on the other hand you are going to do lots of interstate driving the 2.5 turbo (at full boost) will cruise effortlessly at 90+ MPH and tackle any hills I've encountered on the east coast. The later W124's have some interior/exterior changes that some people prefer to the earlier W124, again its a personal choice - no real advantage.

Either choice will be worlds ahead of a W123 in terms of chassis dynamics - but not in terms of repair simplicity/cost.

#8 11-15-2004, 02:35 PM

As far as models it's just by choice. I pefer the W126 model. I've driven the W123. There all good. The 124's are more up to date, but it's a matte of design that may interest you.

d.delano · #9 11-15-2004, 03:21 PM

I read somewhere that the 2.5 had a weak oil pump chain or something. But I may just be on crack.

hughet · #10 11-15-2004, 03:44 PM

I have a 84 300 sd and a 92 300d. both are very comfortable,safe and durable. The 300D 2.5 motor is an improved 5 cylinder version of the motor in the 87 300D. The May/June edition of the Star magazine details the engineering that went into those improvements. The 300D used the ill fated trap oxidizer to reduce particulate emissions, but the 90-93 2.5 had a redesigned combustion chamber and a different prechamber and diffuser to bring about more efficient combustion and 40 percent lower particulate emissions inside the cylinder. In addition, the 2.5 added electronic controls to control turbo boost etc. The result of all the re engineering they did is that the 300D 2.5 really does get 27 to 30 mpg in town and 33 to 35 MPG on the highway. I have seen 38 and 39 MPG on some trips but you can take the 27 city and 33 Hwy to the bank! That is on a car with 167k miles with no major work done on it. (I am on the 5000 mile synthetic oil change plan and 25,000 all other fluids plan) The only maintenance items have been a new chain, glow plugs, idler pulley, belt and motor mounts at 131k.
Not as much power as the 87 300D but much better economy and fewer first year glitches.
Be sure to have an extensive prepurchase inspection done on whichever car you buy!

DslBnz · #11 11-15-2004, 04:51 PM

The '87 300D, from personal experience WILL net 31 mpg or better if properly tuned and driven easy. The TO was removed(do a search) through a campaign procedure.

The TO starved the car of power and economy.

I get ALMOST 30 mpg in my W126 S-Class come summer.

The 2.5 turbo shouldn't do much worse than 34 mpg all around, IMHO. I've not driven one for an extended period of time, so I can't comment specifically.

#12 11-15-2004, 06:25 PM

Keep in mind, if the 87 model has a -14 head, if it ever does start to go, your most likely looking at almost $2k just in parts. The best my 1987 gets is 28mpg hwy with the A/C off, and 27 mpg with the A/C on. The Power of the 603 is impressive, but I expect my next one will be powered by a 606 or 602.

I know it may be a funny question concerning a diesel, but is the six any smoother then the 5 cyl? Anyone switched from a 603 to 602, and really missed the power? I am planning to tow a small trailer with my two motorcycles on it, I expect the 602 will still make plenty of power for this purpose!

bill murrow · #13 11-15-2004, 07:28 PM

Quote:

Originally Posted by H-townbenzoboy

I know you're looking at two W124s, but have you considered the bulletproof W123 or W126 chassis equipped with one of the bulletproof OM61x family engines? You won't have to worry about head cracking on these models! And, they're easy to work on. W124s are good too, but just a suggestion.
-Joe

I second that!

I bought a 123 due to the ease in which most repairs can be made. Maybe the power is a little less, but its plenty peppy and I'm willing to sacrifice a little power.

Something I saw posted here--w124=expensive repairs
w123=inexpensive parts plus DIY

I've never had a 124 but I can certainly vouch for the reliability/DIY friendly 123's.

Good luck and let us know what you decide.

Cheers,

Bill

chuck95e300d · #14 11-15-2004, 08:45 PM

You might also consider the 95 E300Ds. With high miles they are in the $7-9K range these days.

Rick Miley · #15 11-16-2004, 09:26 AM

Quote:

Originally Posted by d.delano

I read somewhere that the 2.5 had a weak oil pump chain or something. But I may just be on crack.

Close but not quite. There was a batch of bad timing chains that found their way into some 602s. They stretched very quickly and should have all been replaced by now. Especially the one he's looking at w/ 200K miles.