alda/overboost on a retrofitted 5 cyl. 240D

[origamitect]

Hi,
83 240D body with 84 300SD engine stuffed in. Manual tranny behind it all. 240D did not have overboost protection. I have what I think is the overboost thing from the engine donor car. I need advice on the best way to get this back in the system. Does anyone have a diagram laying out how the overboost gets connected? (both vacuum and electrical?) I have looked over the FSM diagrams, but I am unfamiliar enough with the system to not be sure of what I'm looking at. Also, since the manual tranny 240D doesn't have a tach, what is the best way to adjust the ALDA? Or is my only option to steal the tach from the donor car and trade out my clock for the tach/clock unit? I'm trying to tweak my fuel consumption which is averaging about 23 mpg for about 50/50 hwy/city. Best I have gotten is 27mpg for about 260 miles of flat but windy driving. Also, slightly off topic, does anyone know what brand was "original equipment' for the wheel bearings? Thanks in advance for your help.

[Hit Man X]

Consider swapping that 240D rear axle to a 2.88:1, you'll pick up quite a bit of fuel economy.

[origamitect]

It does have a 2.88 diff. I forgot that in the long list of things that have been done to the car...

Originally Posted by origamitect

It does have a 2.88 diff. I forgot that in the long list of things that have been done to the car...

Hows that match up to the manual? Do you have to drag the clutch much more than with the stock 3.69?

[origamitect]

starting from first. The rest doesn't seem much different. It doesn't help that we had to fabricate a throttle connection since the SD linkage setup from the accelerator pedal was a bit different from the 240D (and the 240D rod out of the firewall went missing at some point during the swap .

but! back to the subject at hand.... can anyone point me in the right direction for hooking up the overboost protection and adjusting my ALDA w/o a tach?

[SD Blue]

The overboost protection is pretty straight forward. Install a line from the port on the back of the intake manifold to the overboost detection switch and from there to the alda. Both the intake and alda ends use banjo bolts.

Adjusting the alda with a tach? I have not seen or heard of this procedure. The only thing I did was adjust it to where there was good acceleration with minimal smoke. If you have heard of something different, speak up, inquiring minds would like to know.

[origamitect]

Electrical connections to the overboost protection? or is it all vacuum? Just to make sure I have the right thing - could someone post a picture of the overboost thing?

I'll dig around on the list to find the procedure, but basically the technique is to, in low gear, and with your foot on the brake, rev the engine to 4000 rpm and watch for smoke. Basically the same as what you are saying, only with your foot on the brake and keeping it at a constant rpm. Keep adjusting until very little smoke appears. I was hoping someone would say "you don't need no stinking tach!" Thanks!

[Old300D]

I'm not running the overboost function at all. The chances of wastegate failure are minimal, and the consequences of that failure are also minimal. On a gasser, it could be catastrophic, but more air on a diesel will simply max out the fuel. No big deal.

[Diesel Giant]

It easy.

http://dieselgiant.com/mercedesaldaboostsystemservi.htm

If you have a decent boost gauge and glance at it every now and then, you should be fine.

However, these turbos (Garrett and KKK) can put out 25psi+ of boost at WOT and 5000rpm. The risk is there.

[Hit Man X]

I'm still on the fence to install that KKK turbocharger or not.

[origamitect]

Awesome write-up/pictorial DG! that's exactly what I needed. I guess I'll be paying the neighbor kid to watch my exhaust pipe while I gun it down the street this weekend...
One last thing - I mentioned it early in the post, does anyone know the "original equipment" brand of wheel bearings? Or more importantly, does anyone have experience with SKW wheel bearings? Thanks again!