1987 300SDL Turbo
 

Alright I've had this car less than a year now and am working on restoring it. Any work I do I will use pictures for people to better understand. Few questions....

1. The car seems to have very little power until high speed. Replaced O-rings underneath ip and at the injectors themselves. New vacuum hose, breather hose, and modulator.

2. Sunroof is stuck and I can hear the motor running, but no movement. This really sucks because whoever had it last left if tilted when they closed it so whenever it rains I get soaked along with the interior.

Just small problems but I will keep updating as I make progress. :pleased:

you probably need to adjust the ALD unit.. do a search on it

thanks!
 

yea I just came across some info on it just now and I don't know if I have the banjo bolt or not but maybe I could try cleaning the line going to the switchover valve.

I'm getting an experienced diesel mercedes tech to install a new vacuum modulator and bracket for me tonight so I'll try to work on it first thing tommorow.

Thanks for the input! :D

Sounds like you've run into two of the problems that are the bane of the SDL owner.

For the power keep in mind that the turbo doesn't kick in until ~2200 RPM. Without it, the engine is quite anemic. I'm 99% certain you issue relates back to the vacuum lines. Here's what I would check / replace.

• Overboost protection switchover. In the SDL, this is located on the driver's side, unlike previous turbos. You see the switchover valve attached to the firewall with two clear (teclan) tubes running from it. The one running from the top needs to attach to the ALDA. The one running from the bottom needs to attach to the charge air intake manifold. There is a small nipple to which it attaches. If these lines are black, that means you're likely losing boost readings due to constriction from oil, tar, and whatever else the engine spits back into the charge air intake. I would also test the switchover valve, per Mercedes procedure. It also wouldn't hurt to make sure the electrical connection is attached.
• Transmission Vacuum Connections. Make sure everything is clamped properly, that you have the green dashpot and there are two connections to the blue vacuum amplifier. These are magically tied into the turbo and may affect the operation if not working properly. Of course, you'll know when they aren't if you get whiplash every time your car changes gear.
• Boost Pressure Sensor. This is an octagonal, brass sensor on the charge air intake, right next to the teclan tube going back to the switchover valve. If not present, well ... I suggest removing it and cleaning the accumulated crud with a greasecutting product, such as Simple Green. Needless to say, make sure the single pole eletrical connector is attached and that there is no resistance between the sensor's body and the air intake, which acts as a ground.
• Filters. A clogged air or fuel filter will rob you of much performance. I change them every other oil change (6K miles), and I'm amazed at the accumulation of crud.

Realize that a valve adjustment not only won't help you, but it's unecessary as this car has hydraulic, self-adjusting valve lifters. A loud, stacato TAC, TAC, TAC noise indicates one or more has collapsed. I haven't seen this correlated with performance, or a lack thereof, but it does help quiet it done.

As far as the sunroof, there are known issues with these that extend to the W124s and even W140s. I would highly recommend taking it to a trusted professional and have them fix it. It's actually a rather complex mechanism that is extraordinarily sensitive. The chances of a DIY mess-up are too much.

Outside of that, you should be shipshape, at least until you run into the next problem. Cracked cylinder head, leaking transmission, oil leaks galore, drive shaft failure, vacuum actuator replacement for climate control flaps, collapsed hydraulic lifters . . . Well you get the idea. At least it's much more exciting to drive than a Toyota.

I love my car, warts and all, and my wife will need to take my dead, cold and clammy hands off the steering wheel for me to give it up and buy a Camry.

Cheers

First off, I just want to thank you guys for actually replying to my message for help. Thats plenty of information for me to tackle and find out what the real issue is.

I have a boost gauge running to the intake manifold and get a reading of about 10-15 psi, after having the mercedes tech bypass some things dealing with vacuum (EGR, something else) but with no increase in acceleration, the engine just gets louder.

I held my hand on the overboost switchover and felt it click while revving the engine, is that good or what??

I've recently replaced both green dashpots with no difference. Brand new vacuum lines and air filter.

Haven't gotten around to replacing fuel filters yet, this car is very slow and has no difference in acceleration no matter how hard you stomp it.

I really appreciate the help and hopefully will find a solution.

Thanks alot!!! :D:D

New info would be helpful
 

After replacing the modulator, the car seems to actually shift now, but the mercedes tech has a friend in cali that has expert advice for mercedes diesels and says that its possible either the transmission governor is bad or the valve body is sticking.

He suggested taking the valve body apart and looking for something off.

Any suggestions on what it could be or how could I treat this issue???
Any help is greatly appreciated, thank you! :D

I had a bad sunroof on my 124, mounted next to the motor in the trunk was a "nut" on the transmission for the sunroof. Turning this "nut" would open or close the roof in an emergency. I think it is 14mm, its worth a try to stay dry.

While browsing the image gallery the other night, I came across your SDL and left a comment for you. I noticed that your car still has the trap oxidizer installed. I wanted to let you know that it would be worth your time to take this car to the dealer nearest you where they will install (at no cost to you) a new, updated exhaust system - possibly including a new turbocharger. This work has been carried-out under a factory warranty recall campaign and will likely go a LONG way to solving many driveablity issues you may be encountering currently. Seriously. Do a search here on trap oxidizers and the recall. You'll be glad you did.

Attached, is the photo from YOUR image gallery showing your engine. The arrow points to the trap. Have the dealer get that thing outta there and you'll see a great improvement in driveability.

Nasty Trap Oxidizer!
 

I second the advise by Adenauer, I had the same experience with the 603 in my Blue Bomb, the '87 300D turbo I resurrected from the dead. Turns out the PO drove the car with the Trap Oxidizer in place until the engine overheated and it cracked the cyl head. Down one #14 head :eek:
I replaced the head (w/ another good #14), the timing chain, lifters, vac pump, piston rings, just about everything I could to make it perfect but it still ran so bad it would not even get out of its own way! Seriously bad! Then I removed the cap in front of the exhaust manifold, it is there for taking back pressure measurements (I wonder why????) and the car came to life, enough to indicate the Trap was plugged up.
Get your car off to a dealer ASAP, have it towed if necessary. You'll need to call ahead and make an appointment for the Factory Open Campaign that replaces the Trap with a new Cat system. I'll wager that is all you have wrong, hopefully, but it needs that thing exorcised!
The pic on the right is my engine after the Trapectomy

Update
 

Trap ox removed and now it has enough power that I guess these things are supposed to produce.

I've been told many times by just about everybody these things aren't race cars so I'll just take it nice and slow in luxury I guess. I can hear the turbo chirp so that makes it worth while.

By the way the MB dealership said it seemed like the car was not producing enough boost for some reason? Usually get 13 PSI if stomped. The turbo is in good condition and the overboost is working, I think.

Called MB for a transmission governor... $300!!!! And added some Lucas Trans Fix stuff.

Thanks for the replys everybody! :D:pleased:

Good job on eliminating the trap.

And, thank Adenauer for the call..............keen observation.

Do us a favor and do a couple of timed 0-60 runs with it. We really need to see if the vehicle is performing properly or your expectations of it are unreasonable. It does quite well when properly tuned...............but, a gasser it is not.

Post the results of several runs in each direction and we'll know for a certaintly.

The $300 question...
 

Thanks to everybody for the help with removing the trap ox!

After having a new modulator installed along with new vacuum lines and some slight vacuum moding and adjusting this car is pretty damn descent!

Now here's the question, my mercedes tech said he's eliminated the problem down to its either a bad transmission governor or the valve body is sticking.

When I put the car in reverse it lags for a second then catches. The car also seems to have alot, almost too much power in reverse. If I rev up before putting it in reverse it races then chirps the tires. Could a bad transmission governor be mistaking how much boost for each gear???

If so I must bite the bullet and pay the $300 to the Mercedes dealership.

P.S. Is there any way an air intake like the one on my car would affect its performance???

Any help or ideas are greatly appreciated.
Thanks for the support this far as well!:D:D:D:pleased::pleased::pleased:

You've just opened a can of worms with that. IIRC, that's a K&N model that is suited for muscle cars, &c. The filter is about 1/3 the size of the stock filter, so no matter how well it works, it can only bring in 1/3 the potential of the stock.

A few years back I had Banks Power mod my (ancient) Dodge Cummins. One of the things they did was to add a reusable filter, similar to the K&N in design, that fit in place of the stock filter. They told me it was counterproductive to replace the stock intake housing, that adding the reusable filter was the best way to increase airflow, and therefore power.

Granted I know nothing about the model that was placed in your car, I would suggest removing it and putting the stock housing back in. K&N makes a drop in replacement for the stock filter. I've personally noticed little difference between the stock and the K&N in terms of performance. The biggest difference has been putting in a clean filter.

One last thing. The 86+ diesels have an air mass sensor, similar to the gassers, which is located right below the filter. It looks like that is altogether absent. It seems the combination of the lack of an air mass sensor and constriction on the air intake would lead to less power. The sensor is big $$, and those wiser than me could say whether it's worth replacing.

Casey

The air mass sensor is only used for EGR control. There is absolutely no benefit to having it or replacing it.