Slow 87 300D

[Jmana]

I sold my old 300SD yesterday and today found an 87 300d with 260k miles for $2,300 that I couldn't pass up. AC works, cruise works, nice interior, no rust. The only problem (other than it has the original head) is the fact that it has zero power in first gear. After it gets to 2nd it's fine, but it has a delay going into 3rd and doesn't shift until about 4k rpm. It actually is fairly peppy in the higher gears, but I started off on a hill and had the pedal to the medal, and I wasn't sure if it was going to go at all. I know something's wrong, but don't know what to check first. Once I take possession of it, I am going to switch out the fuel filter and air filter, hopefully that is the problem, but I kind of doubt it because of the amount of power it has in the higher gears (when my 300sd had a clogged filter it had no power in the higher gears).

[mickeyd]

ck on diy links on alda adjustment, you will be amazed, i had same problem ,car now goes like a bat out of hell

[POS]

He's right - search for "banjo" and/or alda or go to the DIY links above. Simple fix, costs nothing. That's where you need to start.

[Jmana]

I don't see a banjo on this car, does the 6 cyl have a banjo bolt? I know on the 300SD it was on the intake. The alda has apparently been adjusted many times before, so much so that half the screw head is missing. Does that mean the alda is no good? Or should I try to adjust it with a pair of vice grips?

[Jmana]

I am new to the 6 cylindar diesel, so forgive me that I haven't figured this out yet. The problem is the car has no power at all until 2,500rmp. When I first bought it, it would creep it's way to 2nd gear. I have put new air and fuel filters on, plugged the egr and the other valve by it, all of which has helped, but still you can't feel the turbo until almost 3k rpm. The other problem is the car lurches between 1st and 2nd gear, so much so that my wife doesn't like riding in it. I tried adjusting the alda, but it seems like it may be bad. The screw part is busted off, so I used pliers to turn it, but it was very hard to turn. The other thing that is suspicious, is that the vent switchover valve (I think that's what it's called) on the front facing firewall does not seem original. There is only one screw holding it on, and the other screw hole does not line up to the holes in the firewall, almost like it's not even the right one. So, all this being said, what do the experts think could be wrong here?

[Jmana]

I just realized that what I thought was the alda wasn't it. I just noticed the alda is under the intake manifold. It has the metal cap on it still. Now how in the world am I supposed to adjust it? I can't see any way other than to remove the manifold.

[Jmana]

The problem with the car was the alda. Realized I had to take it out to adjust it. Got it out, turned it backwards twice, put back in and the darned thing runs perfect! Nice power, no more lurching.

[Jmana]

Don't know why, but I have adjusted the alda screw backwards 3 full rotations, and each time I adjust it, it works great for a few days, then slowly it goes back to not having any power until 2500 rpm, which is frustrating because that's where the 1st to 2nd shift point is, and so it lurches when it upshifts. I think the alda is good, I plugged the end and applied vacuum and it held well. Does anyone know what could be going on here? The car is an 87 300D.

[gsxr]

You can't properly test the ALDA for leakage with vacuum, you need pressure. But even that won't diagnose a bad/cracked capsule inside. Sounds to me like you may have other issues, not related to the ALDA, but that's hard to determine via the internet.

1) What's the 0-60 time with the ALDA connected?

2) What's the 0-60 time with the ALDA disconnected?


A top-notch running 1987 300D, near sea level, should be 10-11 seconds in the first case and 14-15 in the second case. Stopwatch required, not "one one-thousand..." counting.

Could be plugged air filter, plugged catalyst, plugged trap oxidizer (if it hasn't yet een removed under recall), cracked turbo wastegate line, cracked or plugged line from intake to ALDA, plugged switchover valve, plugged fuel filters, and a few other things too.

[Jmana]

I finally figured out why I have no power under 2,500rpm and hard shifts. It is because by ALDA leaks like a sieve. I can blow on the nipple (sounds kind of kinky ) and air immediately comes out the bottom. So I left the ALDA off, plugged the line, and it has much more low rpm power, and shifts like butter. But I want to have an operational ALDA, so I need to know how to fix the leak, which I am assuming is what I will have to do because there aren't any ALDA's for sale on ebay. Anybody know what the proceedure is for this? I have done a search already, and found a few links to repair methods, but each one is different, and none of them tell me where to get a new seal, if that is what needs replaced.

[RAYMOND485]

1984 300d Turbo 139k
Order A Metic Seal Kit From Jcwhitney.com Or **************.com One Of The Small One Will Seal The Bottom One, Remove The Alda Under Is 24mm Nut Turn Cw And Turn The Case 3x3 In Ccw, Remove The 4 Screws May Have To Drill Two Out And Replace, Screws And The Rubber Washer The Moveable Shaft Goes Inside And Outside Seal Look At The One You Remove, Same Size Then Test Before Install Use A Hand Vacuum Pump Top Pressure Out 10 Psi And Fuel Pressure Gage The One I Have Rebuilt Works Good

[Jmana]

So in other words, I need to get a metric O ring, and that's all I need? That would be great.

[Jmana]

I would strongly suggest that anyone who doesn't have any power below 2000rpm, and hard shifting between gears to take off their ALDA, and blow into the metal nipple and see if it holds any air. Mine didn't and so I took it apart and realized the rubber shaft seal had dried up and was no longer sealing the unit. I don't think you can buy these seals, but I found a metric O ring that fits in there perfect, it's a little snug around the shaft, so I put some grease around the shaft to lube it. Put it all back together, and now the car runs like it should. The hardest part is getting those damn screws off. I used a rachet with a 1/4 socket that I could put in a phillips bit. One I couldn't get out, and ended up drilling right though it, then put a skinny bolt through with a nut to hold it together. I really don't understand how the whole unit works, even after taking it apart. It's really a bizarre thing that defies any common sense. But once it's sealed up it works like new, that I do know. There's really nothing else on these things that can wear out, other than the shaft seal. There isn't any springs or anything inside, just the 2 "flying saucer" looking things. And what's odd is they don't even seal up inside the housing, they are quite a bit smaller than the housing, so I don't understand how putting air pressure inside would move anything, but apparently it does somehow. And one other thing I noticed is the ALDA also affects how the tranny shifts. When mine was leaking, the tranny would shift real hard. When I took the ALDA off, I plugged up the line and drove it for a few days without the ALDA, and it started to flare really bad between gears. Now that it's sealed up and working properly, the transmission shifts just perfect.