Greetings,

I've got a 1990 w124 300D, 2.5L turbo diesel. It seems to have the maximum amount of vacuum devices of any of the w124s. I mean let's look at the vacuum diagrams of the 1990 602 engine, with and without an automatic transmission and a 1990 603 (see photos).

I need to upload more photos so I'll jump to the next cell on this thread to make it easier to keep everything clear.

TGD

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Now on the left (passenger side) of the engine there are electrically controlled vacuum switches. See the first picture for an example.

The 1990 w124 automatic has three of these devices while the w124 manual and the 603 engine have only one (see vacuum diagrams above).

I've seen a posting of GSXR where he shows that he has removed much of this equipment but try as I might I cannot see what sequence of steps to follow.

Also I've seen a great deal of discussion about disabling the EGR but given the EDS and the air mass flow sensor I do not know how the EGR can be removed.

Continuing with the questions there is this lovely blue flying saucer on the right (driver-side) of the engine compartment. See photo 2. It also appears on the 603 engine (see above) but not the w124 manual.

I believe I have read that it may be remove but I'm uncertain.

Thanks for the help. You guys are great.

TGD

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There is no mass airflow sensor on the 124 diesel.

Are you converting to a stickshift? Otherwise some of this is necessary.

__________________

Gone to the dark side

- Jeff

I do not know the answer but I do have a couple of questions.

I have read that the air flow sensor is located in the air filter assembly. Please refer to the first picture below which is from a different w124 diesel than mine (I do not recall what year). They claim they black square protrusion in the front-right of the air filter is air flow sensor.

My car (2nd picture) has the same object and an electrical connection going to it.

Therefore I think (but I am not certain) that my car does have an air flow sensor.

I am not converting to a manual, just trying to improve the car. I do not know (but I'm trying to learn) why what I am asking would influence the transmission. It still receives its information from the Bowden linkage, the vacuum control valve on the injection pump and the "kick-down" switch.

Thanks for all the help.

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Take that K&N filter out of there.. way too much dirty is allowed into the engine.

__________________
08 R320 CDI current

Past
95 E420
87 300D Turbo 5spd
90 300TE
83 300SD
85 300TD
92 400E
85 190D

It's gone. I've just not removed the label. It was there when I bought the car.

Thanks for the advice. Always welcome.

Alla Dat Crapola on the Left side of the engine in the Pictogram can be Recycled any way youse see fit.
(Except #179 Vacuum storage mounted in the right front fender)
(AND S5/1 mounted in front of the battery)

You want to retain the Blue Flying Saucer (#123) ,it and Y30 provide the
Overboost Protection Circuit.
[Allows the ALDA to cut Fueling in an OverBoost,thereby saving engine]

The MAF (or MAP) is inside the Square air cleaner housing ,it can be now be Ignored after the "Wastegate Improvement Upgrade"

The Factory Air Filter
(Orange Foam Gasket,Cream Paper-ish Element, with steel reinforced topside)
need not be replaced
[unless you've been doing something really naughty,like driving in Chernobyl]
only GENTLY Blown out in a reverse flow manner:

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__________________
'84 300SD sold
124.128

Got it. You do not have a Mass Airflow Sensor, that is for later / smarter systems, you have merely an AFM, which measures flow only. It is used for emissions, not for any engine fueling adjustments.

The pressure-wastegate change will allow you to delete all of the items on the turbo side, can run a new pipe from the filter box to the turbo as mentioned above.

The blue flying saucer is not necessary for the ALDA / overboost protection functions, although a leaky one will cause problems there, I have mine bypassed. It is for shifting functions, and some of us here have bypassed it with good shift quality remaining so apparently it too is disposible.

__________________

Gone to the dark side

- Jeff

Thanks!!!

It looks like I'll be performing GSXR's modification soon.

Everyone has been helpful.

Take care.

In addition to my reply to the other thread (click here, see page 2) regarding the EGR / boost / etc:

The "blue flying saucer" is present to modify transmission shift firmness. However, I can't tell any difference with it removed from the system completely. Perhaps it did something when the transmission was new, but 20 years later there isn't much change. You can route the output of the VCV on the side of the IP directly to the transmission vac modulator, and remove everything related to the BFS. HOWEVER... before you do this, I would plumb this in "test mode" and drive with it for a couple of months before actually removing everything. You may need to adjust the VCV per factory procedure (click here), and also may need to tweak the vac modulator adjustment slightly (do this after a transmission fluid+filter service if it hasn't been done in the past 25kmi). It's interesting to note that the 1992-93 300D 2.5T eliminated the BFS and routes the tranny signal exactly as I decribed above (VCV output directly to transmission modulator - one vacuum tube, nothing else). I did this on two of my 1987 300D's with good results.

__________________
Dave
Boise, ID
Check out my website photos, documents, and movies!

I've removed the BFS from my 350SDL as well, I believe it was faulty. I could never get things adjusted to my liking beforehand. I may fiddle with it later but I doubt I'll bother with it. W140 300SDs do not have one.

-Jason

__________________
1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

Greetings,

You guys are great. Lots of info and advice. Thanks.

TGD

I am reading this thread with great interest as I am trying to get the courage to do the EGR delete on my 2.5. Wish there was a kit with the parts I needed.

__________________
1993 W124 300D 2.5L Turbo, OM602.962
2000 Chevrolet Cavalier, 2.4L DOHC
2002 Ford Explorer, 4.0L SOHC
2005 Toyota Prius, 1.5L

http://www.fuelly.com/sig-us/40601.png

If I was ever able to find an exact replacement wastegate, I might have created a kit. I wasn't happy with cutting & threading a wastegate that has a too-small hose fitting, but it does work. The only items you really need is the wastegate, hose, and drill/tap for the hose fitting at the turbo. The hard part is installing everything!

Can you just use a 603.96x or .970 turbo on the 602?

__________________

Gone to the dark side

- Jeff