1981-85 SD Performance Questions
 

I have seen on other forums that the 1981-1985 Mercedes 5 cyl is the best for durability.
However, I see that it is also a little doggy on take off.
I heard it sometimes takes 2-3 seconds to get moving?
Who can tell me more about this and can it be zipped up with some add-on hardware (i.e. bigger turbo etc.)

I would appreciate any and all info.
thanks
jt

A bigger turbo will give you MORE lag off the line and no change through the rest of the power band.

Adjust the ALDA, clean ALDA lines, fuel finters, fuel tank strainer, valve adjustment, diesel durge, and adjust the boost to MB specs.

2-3 seconds to get moving? In 2-3 seconds I am pushing 20+mph already, a properly running 617 powered 300SD is not a "slow" car, it should hit 60mph in 12-13 seconds.

And all those things too... :D

I agree that any car that takes 2-3 seconds to get moving has issues, but you are not going to win many drag races with any 617. You're talking about 125 HP in a 3500 pound car. It isn't realistic to get much more power out of that engine at low rpm. Go drive a couple of good ones, if they're not fast enough buy something else.

You said it Bubba !:D



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You guys are fast with the answers
 

thanks a lot for the answers. I am looking to get a 300SD
if I can find the right one.

I gather the 617 engine is the 5 cyl in the 81-85 diesel models?

I care more about crusing about 70-80 than take offs. I rarely take off fast even with my 325 HP CUmmins. Just burns too much $$.

So it appears that the 617 is great.
Can you explain ALDA. I dont know exactly what that is.
I will keep all this info when I buy one.

Also, is there any major differences (i.e. features etc.) between the 1981 and the 1985 SD's.
thanks again
jt

It's a little messy, but the 617 is the 5 cylinder diesel used in the 300SD through 85. There were both turbo and non-turbo 617s, but all the SDs were turbo. This link will help tie the US models, chassis numbers, and engine numbers together. Remember that engine numbers starting with a 6 are diesels:

http://home.hiwaay.net/~gbf/mbmodels.html

A 300SD is perfect for highway cruising at 80. They will run at 80 (about 3500 rpm) all day without a problem.

The ALDA is a device that controls how much fuel is injected based on altitude. It can be tweaked to increase the low end power of the engine noticeably. The turbo doesn't "kick in" until about 2000 rpm and these engines are a little flat up to that speed.

The 5-cylinder type 617 cast iron diesel is considered one of the best Benz engines. They powered the 300D, SD, and SDL models from 1982 through 1985. Most models imported into the USA had the turbocharger. An earlier version of the engine, sans turbo, was available as early as 1975. They are not particularly quick but at least with the turbo they are not dogs and as Craig says, they will cruise at 80 MPH all day.

There are still quite a few of them around and parts are available. In fact, compared to American cars, I'm continually amazed at how easy it is to get parts, especially little trim parts and stuff that you would think would no longer be available. An advantage of making fewer model changes, obviously. Finally, there are a lot of 617 owners and former owners on this forum to provide advice.

Once again thanks folks for the great MB info. I especially like the model to engines listing. It will help a lot when I go to purchase one.
jt

The 617's are plenty fast off the line if in proper tune, they are also quite able to keep up with traffic with modest effort. Remember they have 125hp at best, don't expect AMG like 0-60 times.:D

Most of the the 617 are dogs storys come from cars that are well, shot.

I used to have a 300SD/81 for years, mine was abused by the previous owner, did not realize when I bought that car, but ended up paying for all his neglet big time.
Anyway, when MB installed turbo on their 5 cylinder diesels, the engine operation remains non turbo up to a certain rpm, above that point the turbo kicks in and you can feel it in you neck. The initial sluggish start is just the nature of non turbo diesel engine. These 5 cylinder diesels, both 300D's and 300SD's, have a very rough feel in their accelerations, not a fault, but is the way the engine/transmission behaves in normal driving.
These are the last of super reliable diesel engines that MB produced.

Vahe
240D/77 350K

Very Slow off the line SD
 

I have an 84 300SD that I just bought - guy was a maintenence fanatic - got a whole book of reciepts for all kinds of stuff preventative and otherwise. Car sat for almost a year and is VERY slow off the line - takes an honest 10 secs to hit 20 mph, when it finally gets there, accelerates fairly well. Have changed both fuel filters and blew through the ALDA line going to the intake and there seemed to be no restrictions. Any suggestions? Thanks

Have you adjusted the ALDA?
Make sure you are getting full throttle at the injection pump. Have a helper press the pedal to the floor (Engine off :rolleyes: ) and see if the linkage hits the stop screw on the IP.

Alda
 

Make sure the ALDA Banjo bolt that screws in to the back of the intake manifold is not plugged.