The car has become very sluggish recently and I read on dieselgiant about cleaning banjo bolt on ALDA. It looks as if the ALDA is underneath the (intake cover) on top of engine? Does that need to be removed? Thanks for your time and advise.

There is no banjo bolt on your car in the boost signal path. From the ALDA, follow the line to the overboost protection switchover valve then to the intake manifold. Make sure air flows freely through this path. The intake manifold and ALDA barbed fittings are the same. They take a 12mm wrench or sockets with very minimal torque. I don't know what the spec is but it's probably in the single digit inch pounds.

Sixto
87 300D

Thanks Sixto,

I'm fairly new to tinkering with the mercedes and cars in general but it's enjoyable when things work out! I believe I see the ALDA underneath the (intake cover? not sure what it is actually) on top of the engine? Do you know, if I'm facing the engine, which way will the overboost switchover valve and intake manifold be and what do they look like? How do I check to make sure air is flowing freely - remove lines and clean? Thanks again.

I don't know my way around a W201 Diesel so I don't know where the switchover valve is. The ALDA sits atop the injection pump under the intake plenum. You can't miss the flat square device with a plastic hose fitting. Just above on the intake plenum will be another plastic line fitting and a gold colored pressure sensor with a singe wire connected to it. The pressure sensor sends a ground signal to the switchover valve when manifold pressure gets to 1.0-1.1 bar. The switchover valve is energized and cuts the boost signal to the ALDA to reduce fuel supplied to the injectors. The line from the ALDA and the line from the intake plenum should meet at the switchover valve which is probably on the driver side inner fender liner.

The intake manifold gets lined with tar from years of EGR gas mixing with crankcase blowby. This tar works it way down the line but the switchover valve is a pretty good trap. It's rare to see tar all the way to the ALDA. Detach the lines at the manifold and ALDA and blow. Should be free and clear. If not, I replace the plastic line since the original is brittle at this age and squirt brake parts cleaner through the switchover valve until it's clear. I suppose you can blow into the manifold fitting but I just remove and clean it.

Sixto
87 300D

Thanks again Sixto,

The ALDA looks hard to access - do I need to remove intake plenum? What does the intake manifold look like or where might it be?

Clear the airflow path from the intake, through the line, through the switchover valve, and on to the ALDA before worrying about the ALDA.

I know that Sixto knows, just a typo, but your engine is a 602 not a 601.

__________________

Gone to the dark side

- Jeff

The intake plenum is the common log of the intake manifold so it's not a separate item.

You don't have to remove the ALDA to clean the fitting. You should be able to see where and how the boost signal line attaches to the ALDA without removing the intake manifold.

Jeff, did I call it a 601? I'll correct it but I can't find it.

Sixto
87 300D

Scratch that Sixto. I've been away, skimming the posts quickly, read W201 as 601 I guess.

I've got to get more sleep. Owning Mercedes with spark-plugs is time consuming.

__________________

Gone to the dark side

- Jeff

Thanks guys for the help - I'll give things a try and knowing my skills or lack of -- I'll be back?!