ALDA, The 603 and Terminology (pics) - Page 2 - PeachParts Mercedes-Benz Forum

Jim Wickham · #16 04-02-2007, 07:49 PM

I was driving it up my quarter mile driveway with my foot on the floor and got the boost needle to move, once ( I think) and that may have been 1.5 lbs... although this is the boost guage out of my modded Dodge so its a 0-60 but 10 is a far cry from 1 on it. I made at least 10 passes at the drive with little to no result.

No black smoke.... EVER no matter how hard I have it stomped. I did not however push a pipe cleaner in that barb on the intake... if that is the only problem I'm going to kick myself and maybe the mercedes. DOH

justinperkins · #17 04-02-2007, 08:37 PM

Quote:

Originally Posted by Jim Wickham

Real quick? I'd get out run by a vespa in this turd!!!

I'm going to try the ALDA removal as soon as I get a chance. I'm hoping that fixes it... next course of action is to cut out the stupid cat.

Hey, my P200 was a quick little Vespa. You must have one of those new fangled four-strokes...s l o w.

psfred · #18 04-02-2007, 08:59 PM

The engine will probably not run with the ALDA removed. It has a pre-load to set correct fuel delivery (the screw on top, which you should NOT move, and a shim underneath). It extends under pressure, it does NOT retract, so removing it will greatly reduce fuel delivery at all times.

Pressure from the intake manifold pushes the diaphram down into the IP to increase the fuel delivered. If you have very poor off-line performance and normal "surge" when the boost comes up around 2000 rpm, you need a thicker shim.

No boost means the turbo is dead or the wastegate is stuck open -- easy enough to check. Pull the air hose off (with the engine STOPPED) and spin the turbo. If it is rough, drags part way around, vibrates, etc it's shot and will not produce boost no matter what you do -- if there is a bunch or oil dripping off it, for sure it's toast.

The wastegate is operated by a link from the pressure canister on the front of the turbo (KKK, the Garret may be different, but still has a link). This link should move under pressure -- they have been known to come adrift, and if not connected the wastegate will fall open and stay there. No boost.

Peter

d.delano · #19 04-02-2007, 09:10 PM

Quote:

Originally Posted by Jim Wickham

No black smoke.... EVER no matter how hard I have it stomped. DOH

Jim that's a classic symptom of no fuel enrichment possibly caused by non-functioning ALDA and/or blocked switchover valve/dead boost pressure sensor. Wastegate springs wear out also, and waste too much boost as a result, but still boost some and unless you are throwing oil smoke out the tailpipe it is likely that the turbo is still strong and bearings are OK. Take the boot off the turbo and spin it, if it spins freely you're good. I'd take the ALDA off and plug the plastic hose, and take it for a spin. This could tell you a lot, takes 5 minutes, and won't hurt the car. Also cheap.
The '87 300D OM603 turbo six is a car I'd like to have because it is FAST and gets better than 30 mpg, also has the w124 handling bonuses. It's the one the Finnish diesel rodders routinely modify into drag cars. Not supposed to be slow at all.

justinperkins · #20 04-02-2007, 09:19 PM

Quote:

Originally Posted by psfred

The engine will probably not run with the ALDA removed. It has a pre-load to set correct fuel delivery (the screw on top, which you should NOT move, and a shim underneath). It extends under pressure, it does NOT retract, so removing it will greatly reduce fuel delivery at all times.

What about all the people that have talked about how great their 603 is running without an ALDA?

d.delano · #21 04-02-2007, 09:20 PM

Quote:

Originally Posted by psfred

The engine will probably not run with the ALDA removed. It has a pre-load to set correct fuel delivery (the screw on top, which you should NOT move, and a shim underneath). It extends under pressure, it does NOT retract, so removing it will greatly reduce fuel delivery at all times.

Pressure from the intake manifold pushes the diaphram down into the IP to increase the fuel delivered. If you have very poor off-line performance and normal "surge" when the boost comes up around 2000 rpm, you need a thicker shim.

Peter

Peter, may want to check with Brian Carlton about this. He has posted recommending ALDA removal for fastest performance, wherein your foot is the ultimate controller of the fuel rack.
Some other 603 owners have reported same results. See this thread:

ALDA removal........OM603

Good luck with your troubleshooting everyone. I'm so happy now that I have finally surmounted my power issues, when everybody told me 'it's a diesel, it's supposed to be like that'. Trouble with these cars seems to be that you're never quite sure how much go they are truly supposed to have.

Jim Wickham · #22 04-02-2007, 09:53 PM

where is the boost pressure sensor?

d.delano · #23 04-02-2007, 10:22 PM

Quote:

Originally Posted by Jim Wickham

where is the boost pressure sensor?

on the back of the intake manifold

http://catalog.worldpac.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1XL1DZCYA21X1BUZFE&year=1987&make=MB&model=300-DT-002&category=B&part=Boost+Pressure+Sensor

psfred · #24 04-02-2007, 11:48 PM

How do you keep the oil in the IP? Drive a bung in?

You get full fuel with full boost -- otherwise you get smoke, not power. It may retract under pressure, I don't mess about with them. The need for adjustment for correct fuel delivery isn't due to wear in the ALDA, its inside the pump, ergo one should correct it with the shim.

Anyway, the pressure sensor is in the middle of the manifold on the 603, right hext to the pressure tap for the boost signal line. It's on the rear of the manifold on the 617.

One other note -- if you have really crappy performance, make sure the stop lever is all the way up and that the fuel filters are new and clean. Either a partially down lever or dirty filters will prevent significant fuel delivery, and also will prevent the turbo from generating any boost.

Peter

Brian Carlton · #25 04-03-2007, 05:26 PM

Quote:

Originally Posted by psfred

The engine will probably not run with the ALDA removed. It has a pre-load to set correct fuel delivery (the screw on top, which you should NOT move, and a shim underneath). It extends under pressure, it does NOT retract, so removing it will greatly reduce fuel delivery at all times.

Pressure from the intake manifold pushes the diaphram down into the IP to increase the fuel delivered. If you have very poor off-line performance and normal "surge" when the boost comes up around 2000 rpm, you need a thicker shim.

No boost means the turbo is dead or the wastegate is stuck open -- easy enough to check. Pull the air hose off (with the engine STOPPED) and spin the turbo. If it is rough, drags part way around, vibrates, etc it's shot and will not produce boost no matter what you do -- if there is a bunch or oil dripping off it, for sure it's toast.

The wastegate is operated by a link from the pressure canister on the front of the turbo (KKK, the Garret may be different, but still has a link). This link should move under pressure -- they have been known to come adrift, and if not connected the wastegate will fall open and stay there. No boost.

Peter

Peter, it helps to think of the ALDA as a fuel restricting device. If the device was not present, you can get all the fuel that the IP will allow per it's full load setting by just mashing your right foot.

Remember, the rack controls all. If you can fully open the rack, you get full fuel. Whether the engine can use full fuel is a completely different question.

Without the ALDA, you can control the fuel to the engine with your right foot. Mash the pedal below boost conditions and the engine will smoke a bit. Press down 1/2 way and you'll deliver the right amout of fuel until the engine boost comes up.

With the ALDA, the device limits the fuel because the driver typically won't be judicious with the pedal. Mash the pedal and the ALDA won't permit the rack to open fully until it starts to see boost. Then, it gradually permits more and more opening of the rack until it sees maximum boost..........about 13 psi..........when it allows the rack to fully open.

You can certainly tweak the ALDA to provide more fuel at lower power levels by turning the screw counterclockwise.

I simply eliminated the ALDA completely on the 603's because it's not very easy to get smoke from them unless you are quite abusive with the rack at low rpm's.

tobybul · #26 04-06-2007, 05:21 PM

along with the banjos and the boost line, I would try that first

stephenson · #27 04-07-2007, 11:21 PM

Did you bypass the switchover valve?

I cleaned mine to death and never got it to work ... I bypassed it and the car changed incredibly - and instantly. It appeared to perform as everyone expressed it should re 0-60 ... amazing difference. I hooked valve back into circuit then back to the poor performance.

I never have replaced the switch - assuming the waste gate works, I shouldn't be able to blow it up, right? :-)

Same fuel mileage BTW, like driving a car with another 50% horsepower!

tobybul · #28 04-08-2007, 09:45 PM

Quote:

Originally Posted by stephenson

Did you bypass the switchover valve?

I cleaned mine to death and never got it to work ... I bypassed it and the car changed incredibly - and instantly. It appeared to perform as everyone expressed it should re 0-60 ... amazing difference. I hooked valve back into circuit then back to the poor performance.

I never have replaced the switch - assuming the waste gate works, I shouldn't be able to blow it up, right? :-)

Same fuel mileage BTW, like driving a car with another 50% horsepower!

Most likely, the valve must be plugged up. Only reason why it was not performing. Bypassing does the same thing as making sure the valve is not plugged up except you wont have overboost protection...

stephenson · #29 04-09-2007, 12:35 AM

Yep - if the wastegate is operating, is there really a serious risk of overboost? Plus, most of us have a "feel" for our car's performance so we would be aware of massive increase in boost, right?

Brian Carlton · #30 04-09-2007, 12:38 AM

Quote:

Originally Posted by stephenson

Yep - if the wastegate is operating, is there really a serious risk of overboost? Plus, most of us have a "feel" for our car's performance so we would be aware of massive increase in boost, right?

Probably not.

The large increase in boost is not accompanied by any increase in power. Therefore, unless you're very astute and you can hear the turbo spool higher than normal.........the radio must be off..........you won't know the difference.