ALDA removal........OM603 - Page 24 - PeachParts Mercedes-Benz Forum

Jeremy5848 · #**346** 08-10-2007, 02:21 AM

The plunger rod that ALDA presses on is not stuck. It has a stiff spring and moves smoothly up and down under the firm but gentle pressure of my thumb.

The plumbing that lives under the air cleaner (it operated the EGR and the ARV) has now been removed and all the associated vacuum plumbing cleaned up. I just received the rest of my order from Phil (including the vent fitting in the side of the VCV, thanks gsxr) so I can finish replacing the vacuum connections that need replacing. That should be done over the weekend.

While working under the air cleaner, I noticed that the 603 engine in the 1987 W124 model appears to have an air flow sensor. Is there a failure mode involving this sensor that might produce the "gutless wonder" feeling I get when I drive the car? If it were jammed or something it might restrict air to the turbocharger. I assume the air flow sensor talks to the Electronic Diesel System but am not sure how much the 1987 cars had in the way of that electronic stuff.

I should be able to report tomorrow or Saturday regarding the 0-60 time. We are at about 200 feet MSL, by the way. Nice, thick air. The speedometer seems to be accurate. I have a GPS in the car at the moment anyway since there is an odometer problem (it stops working intermittently) that appears to be at the root of the lousy fuel economy. With an accurate reading from the GPS, the around-town fuel economy should be somewhere in the low to mid 20s (on B100 with 2 ounces of Redline 85+ per tankful) -- we'll know in a day or so 'cause the tank is getting down.

Jeremy

gsxr · #**347** 08-10-2007, 10:39 AM

Hi Jeremy,

1) The airflow sensor is only needed for the EGR and ARV operation. With those disabled, the airflow sensor can be removed, or jammed open, if you want (doubt it makes much difference). The only remaining function of the EDS is the idle speed control. It has no effect on anything else.

2) That's good news about the speedo.

The odometer issue is relatively common. You can either send it out for repair, or replace it with a speedo from a newer 124 (as long as the donor comes from a car with a 2.65 axle ratio). The shift point hashmarks won't be the same but that's not a big deal, and you could re-paint them correctly if desired. After two unsuccessful repairs on my '87 trip odometer, I gave up and got one from an E320 that works perfectly. You can re-set the mileage to match your old speedo, which is what I did.

3) Oh yeah... mid/low 20's around town is in the ballpark for an '87. Should be more like mid 20's, but fuel BTU's, weight of your right foot, etc can vary that a bit.

jseas · #**348** 08-10-2007, 12:06 PM

I've been reading this post from end to end. You guys know your stuff. I'm new here and have the exact same problem as Jeremey with my '87. I have only changed the air filter and fuel filter (canister not the clear one). I get 22mpg city and 25mgp hwy. I'll start with the ALDA this weekend and see if accelleration improves. I'm going to yank the EGR guts out from under the air filter and remove the air sensor also. I emailed the guy that makes the 603 EGR block off kit, but no response yet. Anyone else have them?

thanks

Johnhef · #**349** 08-10-2007, 02:17 PM

interesting about the air meter thing, I still have it on mine, but all the rest of the stuff has been removed. what condition does it actually open under? or does it just sit closed most of the time at idle or whatnot?

on the speedo thing, I've fixed a few of them, all on ones where the numbers shaft had come loose out of the bushing at the other end so the gear no longer touched the one that drives it. I used to make a bracket to keep the shaft from sliding out and attach it to the housing but now I just re-crimp the end of the shaft with vice grips like the standed 123 odometer repair. All still working to date.

gsxr · #**350** 08-10-2007, 03:34 PM

Jason, welcome aboard.

You might want to read this article about the 1987 300D/TD, if you haven't seen it yet:
http://www.w124performance.com/docs/mb/articles/124.1x3_buying_tips.txt

John, the airflow sensor is closed most of the time, and as the engine ingests air, the airflow forces the door open. A potentiometer measures how far the flap opens, and determines the air quantity being used by the engine. At least that's how I understand it. That whole assembly is non-existent on Euro models without EGR/ARV, and can be replaced with the Euro "open" pipe instead. I really don't think there's anything to be gained by removing it though, other than a 5lb weight savings if you replace it with the lightweight plastic Euro pipe.

Jeremy5848 · #**351** 08-10-2007, 10:35 PM

Here it is, folks:

1987 300D Turbo (W124)
Odometer 136,000 miles (probably more)
Biodiesel B100
Altitude ~200 feet
Trap ox recall performed about 1000 miles ago, turbo replaced too
Clean air and fuel filters
Speedo low by ~3% (57 MPH speedo = 60 MPH GPS)
Odometer low depending on how much it spends doing nothing -- this time 24%
Fuel economy using GPS as tripmeter: 20 MPG (279 miles, 14.0 gallons, B100)

With gentle footfeed, the car starts off from a dead stop feeling like it really wants to go but the promise is not kept and the acceleration eases off after the first few seconds. Full immediate footfeed gives "slug" performance. The same feeling of "nothing" occurs when the accelerator is floored with the car running at 60 MPH. Acceleration is almost non-existent; one must make an appointment long in advance to overtake another vehicle.

0-60 time (analog stopwatch, 1970s vintage)
Test 1 (gentle footfeed at first) 21.5 seconds
Test 2 (full footfeed immediately) 27.8 seconds
Test 3 (full footfeed immediately) 26.0 seconds

By comparison, the W123 car (1985 300D Turbo, California version with trap catalyst, EGR removed, ARV disabled, B100 biodiesel, 225000 miles)

Test 1 (full footfeed immediately) 19 seconds
Test 2 (full footfeed immediately) 19 seconds

The '85 accelerates well from 60 MPH, by the way. I'm sure it will do even better once I get the trap cat replaced with a 'test pipe.'

Incidentally, neither car has had its accelerator linkage checked so I'll do that next as well as look at the 87's airflow sensor to be sure it isn't stuck partway closed. I also have a few more pieces of vacuum hose to replace on the '87.

Jeremy

Brian Carlton · #**352** 08-10-2007, 11:09 PM

Quote:

Originally Posted by Jeremy5848

Here it is, folks:

1987 300D Turbo (W124)
Odometer 136,000 miles (probably more)
Biodiesel B100
Altitude ~200 feet
Trap ox recall performed about 1000 miles ago, turbo replaced too
Clean air and fuel filters
Speedo low by ~3% (57 MPH speedo = 60 MPH GPS)
Odometer low depending on how much it spends doing nothing -- this time 24%
Fuel economy using GPS as tripmeter: 20 MPG (279 miles, 14.0 gallons, B100)

With gentle footfeed, the car starts off from a dead stop feeling like it really wants to go but the promise is not kept and the acceleration eases off after the first few seconds. Full immediate footfeed gives "slug" performance. The same feeling of "nothing" occurs when the accelerator is floored with the car running at 60 MPH. Acceleration is almost non-existent; one must make an appointment long in advance to overtake another vehicle.

0-60 time (analog stopwatch, 1970s vintage)
Test 1 (gentle footfeed at first) 21.5 seconds
Test 2 (full footfeed immediately) 27.8 seconds
Test 3 (full footfeed immediately) 26.0 seconds

I notice that you have already removed the ALDA and observed the same results.

Therefore, if the IP is providing the requisite fuel, the only other possibility for such poor performance is an exhaust restriction or a non-rotating turbo. But, with 11 psi of boost, the turbo is fine.

I think you've got to drop the downpipe and take it for a drive without the exhaust connected.

deanot442 · #**353** 08-10-2007, 11:23 PM

Jeremy
After reading the last few pages I had a couple of thoughts. I have seen similar issues when the problem was a partially clogged exhaust. To diagnose this we disconnected the flex-pipe just after the turbo outlet and took a test drive. The power dramatically improved, and the search began for the clog. The other thought was regarding the B100. Is the B100 home made or commercial? It could be a filter (even though its new, also both need to be replaced). When was the last time you ran a tank of D100? You could try to change the diet again and do a test to see where your results fall. I run b100 that i get from my brother-in-law's "still" and I notice a slight power decrease but nothing like what you are describing. The only other thing I can think of is that your waste gate is open or not sealing all the way and not allowing full boost pressure to the manifold.

Jeremy5848 · #**354** 08-11-2007, 12:18 AM

Quote:

Originally Posted by Brian Carlton

I'm a bit amazed that you have 11 psi of boost with this vehicle. Are you positive of the boost reading?

With those times, you've got no fuel enrichment.............the vehicle is running as if it was naturally aspirated.

So, the next step is to remove the ALDA and take it for another set of 0-60 timed runs.....

I didn't check the boost today but it was 10-11 psi earlier this week and performance the same.

The ALDA has been sitting on the work bench all week.

I had Laura step on the accelerator pedal while I tried to watch the linkage. Manifold and preglow wiring is in the way but...

-- one link is held together with a cable tie...(picture)

-- the cable end from the accelerator pedal (ends in a spring) is held onto the metal lever with a plastic cable clamp...(picture)

That can't be right.

Since I've never had the privilege of examining another 603 engine in detail, I don't know what it is supposed to look like. The diagrams in the CD-ROM version of the FSM aren't the easiest to read. Nevertheless, the linkage does seem to move through its entire range of travel. However, it certainly can't hurt to have the correct parts in there.

We also checked the 617 engine in the '85, it appears to have the correct linkage (much easier to see) with no bad bushings.

Brian Carlton · #**355** 08-11-2007, 12:19 AM

Quote:

Originally Posted by Jeremy5848

I didn't check the boost today but it was 10-11 psi earlier this week and performance the same.

The ALDA has been sitting on the work bench all week.

Yep, I saw that after I wrote the original post.

See my revised reply, above.

Jeremy5848 · #**356** 08-11-2007, 12:27 AM

Quote:

Originally Posted by deanot442

Jeremy
After reading the last few pages I had a couple of thoughts. I have seen similar issues when the problem was a partially clogged exhaust. To diagnose this we disconnected the flex-pipe just after the turbo outlet and took a test drive. The power dramatically improved, and the search began for the clog. The other thought was regarding the B100. Is the B100 home made or commercial? It could be a filter (even though its new, also both need to be replaced). When was the last time you ran a tank of D100? You could try to change the diet again and do a test to see where your results fall. I run b100 that i get from my brother-in-law's "still" and I notice a slight power decrease but nothing like what you are describing. The only other thing I can think of is that your waste gate is open or not sealing all the way and not allowing full boost pressure to the manifold.

Good ideas. The entire exhaust system and the turbo were replaced this soring as part of the trap ox recall (PO never got around to it). The performance (as I remember) was poor before the recall and poor afterwards. The dealer's wrench noted on the repair sheet that the car was a slug, by the way, so they saw it at the time they did the work.

The B100 is commercial, made somewhere in the midwest and shipped in by rail. Our '85 uses the same stuff and, as it gets out of town occasionally, also uses D100 and in-between mixtures. Since I don't see a significant difference in performance or economy with the W123 car and its 617 engine, I doubt that there would be a real difference in the later model and its 603. Nonetheless, I'll keep it in mind.

The primary filter appears to be clean but again, I certainly could change both of them. However, that would suggest that the performance was OK and got bad as the filter clogged. That is not the case, it has never been good, I just didn't know it until I had the chance to drive another 603.

gsxr · #**357** 08-11-2007, 12:35 AM

If you disconnect the exhaust and it's still a slug, it's likely to be low fuel delivery. Sure would be nice to check IP timing and cam timing, btw. I'm assuming that the linkage is reaching the full-load stop pin, visible on the back side of the IP. EGR valve isn't stuck open, right? If all of the above checks out, the pump may need to be sent out for calibration...

gsxr · #**358** 08-11-2007, 12:36 AM

Oooops. I forgot something obvious:

Fuel tank strainer!!! Checked? Clean? No obstructed flow?

sixto · #**359** 08-11-2007, 12:39 AM

Speaking of which, does the diff have to come off to check the tank strainer? It's staring me in the face with the diff out but there's a 3/4 tank of gas on the other side of it :/ Oh, and is the strainer on the driver side or passenger side fitting?

Sixto
87 300D

Jeremy5848 · #**360** 08-11-2007, 01:12 AM

Wouldn't the engine stumble if there was a fuel delivery problem anywhere between the tank and the IP? I haven't pulled the screen yet, btw.

I think the linkage is reaching the stop pin but can't be sure -- hard to see and I don't really know what I'm looking at.

EGR is in a box somewhere. All of the EGR and ARV vacuum plumbing has been removed. Engine has one of Brian's EGR block-off kits, temporarily installed for testing purposes only.

I agree that IP timing or delivery off idle is looking more probable as other things are eliminated. My indy pointed out that the head has been removed at some time (still a #14, unfortunately) and it's clear that someone has been messing with the linkage and the IP lines -- half of the IP line vibration clamps are missing and I have them on order to replace before the lines begin to break from vibration.

If the cam timing or chain stretch is really bad, I would think the engine would be hard to start. Based on Brian's descriptions, ours is easy, for a 603 -- 15 second glow and it starts after about one twist, almost always idles smoothly with no footfeed. Starts from cold after 5 seconds of cranking with no glow at all.

Maybe I'll take out a second mortgage and run the car in to my indy for a thorough check of the IP.