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Transmission issues

Started by 300SDude, 28 August 2011, 06:58 PM

300SDude

I have a '79 300SD that I purchased last August. I put some tranny fluid in it when I purchased it (for $500 mind you), and it seemed to shift an run OK.

We live in the mountains, and I have to come over the summit to get to our house. I will have it floored and in Drive and it tops-out about 35-40mph. I have even shifted down to "S" and it does drop back down into second gear, but the speed does not really increase......it may top-out at 40 before I should shift it back.

I just took it for a little drive to town (8 miles each way) and on the way home, it topped-out about 25mph going-up a hill. I have not checked the tranny fluid in a while. I am just going to add more, but it definitely doesn't seem right that this car slows down that much to go up hills.

The engine has I am assuming 190,000 on it (the mileage works when it wants to, including the trip odometer), and I am assuming that the transmission is about the same.

Should I spend the money to have them take it out and fix it, or should I just buy a different one?

We have put about $6000 into this car, so I am on the border on whether to fix it or just sell it.

Thanks people, I don't know what I would do without this forum!

300SDude

1980sdga

I'm not sure it sounds like a tranny issue.  Sounds like an engine power issue to me. The "kick-down" on these cars sometimes isn't real responsive like a typical US gasser.

chrismsullivan

+1 for ^^

I'm not so sure it's a problem with the transmission either. It certainly sounds like it's power related.

If we think about why a car is lacking power (particularly turbos in this instance), we can probably figure this out.

First up, it's not an overly powerful car compared to the weight it has to lug around, so it's never going to be fast on the hills.

110 bhp (82 kW; 112 PS) @ 4200
168 ft·lbf (228 N·m) @ 2400

I'd be taking a look at all of the turbo hoses and the turbo itself to ensure that everything is connected and operating as usual. If the turbo isn't spooling up enough, you'll be lacking airflow, which equates to a lack of power.

Start there and get back to us.

Cheers,
Chris

WGB

It does not sound like the transmission.

Have you checked the throttle linkage.

Some years ago my wife's ML270CDI started slowing on hills and generally being more lacklustre than expected and it was a simple throttle cable adjustment.

Bill

300SDude

WOW! Thank you all for your input!

I have never owned a Mercedes before, much less a German car.

I have loved Mercedes for as long as I can remember, and this is the first one I have owned. So this is all new to me.

I was thinking when I was driving it home today that it may be more of a turbo issue than a tranny issue. Granted, this turbo has to be about 200,000 miles old! I have driven a Chrysler 4cyl. with a turbo that were WAY more peppier than this!

I am not looking for a race car or something that will pull a house over a mountain because it is diesel.........I want to drive this car because I LOVE Mercedes, and the fact that I drive this one on veggie oil. This actual model (W116) is my favorite because it reminds me of my youth. (I was born in '70). ( I have the option to run it on veggie or diesel).

I just love this car and would love it if it would perform like it it did in it's day. I am sure this is not what it ran like, LOL.

Thanks again people!

I am thinking....if I am going to find a new turbo, I should just go through the whole engine. What....if anything, my engine will last until I die, lol.

Thanks,
300SDude

chrismsullivan

It's great to see that you're excited about the W116!

Don't get too excited about replacing your turbo just yet. It might be as siple as a vacuum line being loose or something like that, which is preventing the turbo from spooling up.

Also, Bill's suggestion about the throttle linkage is a good suggestion and well worth investigating.

Sometimes it's the smallest of things that can make the biggest difference. Start small before plunging into the big stuff.

Cheers,
Chris

ckamila

I have a similar power issue when going up steep grades (12%). I checked my pressure line from back of manifold going to the over boost at firewall and only had 6.5 - 7 psi in the cabin while driving up decent hill at 3500rpm+, where it should be 11 - 13(?). Still need to verify pressure from over boost to ALDA but don't think I will have more pressure downstream than upstream.

Also, what about compression on this engine? Valves? IP timing?

Chris
1980SD, 170K
If it's not broke i haven't fix it yet...


1980 300SD, 170K
1985 300D, 235K

ckamila

More ideas....

Fuel filters - how old, easy to change
Bad fuel or wrong fuel (gas)
Banjo bolt at rear of manifold and pressure line clogged
If it's not broke i haven't fix it yet...


1980 300SD, 170K
1985 300D, 235K

ulysees

This sounds like an air filter issue...

two things with a diesel...   1) air  2) fuel....  start there

i have 2 SD's  a '79 and an '80     Erwin and Hans

300SDude

I dropped it off at my mechanics yesterday and told them to keep it a week and drive it around and see what they think. They have been our mechanics for 10 years or so, so I completely trust their judgement.

we'll see what they have to say after a few days and I'll let everyone know how it progresses.

Again, thank you for your imput! It is greatly appreciated.

300SDude

ckamila

Please do.

Always like to hear the solution to problems faced by others.
If it's not broke i haven't fix it yet...


1980 300SD, 170K
1985 300D, 235K

300SDude

Just heard back from the mechanic this morning.

There was a line that had come-off on the turbo!

But still, he said it is starting to slip between 2nd & 3rd gear. We have a friend whose Dad has owned a transmission shop for the last 25 years, so I may just pop it in to him and see how much it will cost to fix it.

I'll let you know how the saga goes. :)

Thanks Again for your help everyone!

300SDude

Casey

#12
Quote from: 300SDude on 06 September 2011, 01:00 PM
There was a line that had come-off on the turbo!

When I bought my 300SD, the turbo vacuum line cracked within a couple days.  I bought a new one from jbrasile for a whopping total of $17 or something, and it made a huge difference.  I'd also recommend replacing your fuel injectors with Monarks (this kit is what I used and I highly recommend it: http://mercedessource.com/node/4878, but you could also just buy the injectors if you have the tools and know-how already - http://mercedessource.com/node/4753) as that helps give you a boost too as well as increased fuel economy - if you're lazy and just want rebuilt injectors with the new nozzles already installed and tested/adjusted for optimal pressure balance - I actually bought all the equipment for this, and am able to sell these for less than the mercedessource website.  You can also adjust your ALDA, rebuild your turbo (http://mercedessource.com/node/9042 - I've ordered this but haven't got it installed yet), and adjust the turbo waste gate to get more performance.  Lots of ways to get more power out of your engine!

I doubt you need transmission work in any case unless your transmission has been badly neglected - the transmission on these vehicles, unlike most other cars, is vacuum-controlled.  It's common for it to get out of adjustment or for leaks to develop, and is a totally different animal to address than typical transmission issues.  Check out http://mercedessource.com/node/7631 for some advice on things you can diagnose yourself.

Casey

I also just came across this which may be of use to you:  http://mercedessource.com/node/7937

chrismsullivan

It took 7 days for your mechanic to figure that a turbo hose was loose? I figured that out without even looking at the car.
I certainly hope he didn't charge you for this revelation.

In relation to your transmission... Is it an auto or a manual? If it's an auto, then the information provided above will serve you well.
It may just need new fluid.

Always start with the easy, cheaper stuff that you can do yourself.

Regardless of the fact that this guy has been your mechanic for ten years, it may be worthwhile investing in some tools to do some work yourself, or finding a Merc specialist.