testing overboost switch on firewall 5cy turbo - PeachParts Mercedes-Benz Forum

coachgeo · #1 06-06-2003, 07:14 PM

ok.. It took me almost two hours to extract this damn little switch off the fire wall of CRUNCHED MB but I finally got it.

In case you have not followed any of my other post ..... this is not a normal MB. Thus the Plan is to put this switch into my Unimog that has a transplanted 617 952 in it but it does not have the over booste switch. It has the solenoid on the intake manifold just the wire from it goes nowhere.

soooo anyway.... how do I test the vacume or is it pressure. switch thingy I got off this wreck. The very top has a small piece of something that had a plastic cap.. or maybe it was a hose... I dont think so, anyway. that is not there. . .

here... let me take pics of it.

ok..... so as you can see there is not cap or hose on the top. The line that is on it on the bottom came from the banjo fitting on the head, so I assume the line that is NOT on it goes to the Alda.

Wires: I know one wire goes to the Overbooste solonoid on the intake, and the other to ???? ground or ingnition switched power source (or it may not matter if it's switched?)?

Colors of wires: One wire is red w/black stripe w/green dots and the other is Green w/brownish orange? stripes. Which goes where?

thanks in advance

psfred · #2 06-06-2003, 08:47 PM

Red with black goes to "ignition" somewhere, the brown with green goes to the switch on the intake.

For the pressure lines, one side will blow out the cap when the solenoid is energized, that side goes to the ALDA. The other goes to the intake.

You can test it by blowing through -- unenergized, pressure should go in one hose and out the other, no leakage out the top. Engergized one side will seal and the other will vent out the top, or both will vent out, depending on unit.

Peter

coachgeo · #3 06-06-2003, 08:59 PM

thanks psfred!!!!

How hard should I blow?...she says on her kne..... JUST KIDDING...

Anyway......... how hard should I have to blow?

Thought I was going to pop a lung. Well not that hard.. it was like as hard as that first bit to get a balloon to start blowing up but consistent at that pressure; where as when blowing up a balloon it gets easier after the stuff finally starts stretching.

Hows that for a description

I did remove the line so I was just blowing into the short black hose. The clear one on it that was from the bango on the car's head had a good bit of carbon build up in it but there was no difference in amount of lung power to blow thru the switch with it on or off.

rwthomas1 · #4 06-06-2003, 09:07 PM

Okay, dumb question... I have seen the pics of the Mog dash and there are more gauges than a 747. Is there a boost gauge in that array? If so, why bother with the switch? Keep an eye on the boost when pulling hard and don't let it exceed @14psi and you'll be fine. Why overcomplicate things with another electrical switch on a vehicle that spends some time wallowing in mud. RT

coachgeo · #5 06-06-2003, 09:18 PM

I was just replacing it per reccomendation and besides that its an easy thing to do. I did not know what "overbooste" was till you just said 14lb. My gauge; yes I have one, is in Bars; so would that be over 2 bars is a sign to shut her down?

If the blow test I just did; w/hard blow, indicates the switch is good I will install it. One less gauge to watch when Im climbing Mt. Everest in my camper Mog

:p

coachgeo · #6 06-06-2003, 09:24 PM

oops.. just checked my handy dandy net conversion calculator....

see.... if I hadn't done that I woulda blown somethin up waiting for 2 bar on the booste gauge before shutting down.

converter says 14psi is just under 1 bar (93. something somethin somethin)

Capt Kirk · #7 06-07-2003, 01:15 AM

1 bar is equal to 1 atm or 14.5 psi

roughly

If you let that thing run up to 2 bar then you should be worried if your wastegate is stuck or not

coachgeo · #8 06-07-2003, 07:45 AM

it wont go bast 0.5 bar at the moment assuming the gauge is correct.

but..... back to the question.... should it be this hard to blow thru the thing.

ohhhh and how do I activate it to test to see if it works correctly then aka--- bypasses the pressure and makes it come out the top? Put 12v to what wire and ground the other then blow thru?

Capt Kirk · #9 06-08-2003, 02:27 AM

to me that thing is a little magic box, something goes in and something goes out. I don't really know what happens to it and I'm almost afraid to find out, the magic smoke might escape

RAYMOND485 · #10 05-26-2005, 06:27 PM

Use A Fuel Gage 0-10 Psi 0-30 In Vacuum Connect To Top Output Of
Vacuum Hand Pump For Pressure 0-10 Psi ************************ Part Of Gage Is Vacuum Use Pressure For Test Connect The Pessure Gage To Output Of Relay Or Switch Other Side Input Of 10 Psi Of The Vacuum & Pressure Gage
Pump To 10 Psi Input To One Side Of Switch The Side And Read 10 Psi
On The Gage And Pull The Wire Off On Maniford Over Pressure Switch The Wire In Your Hand Use A Jumper Wire To Ground Engine Top Turn On Ign Switch No More Pressure To Gage

Also Check Your Alda For Pressure Leak 0-10 Psi My Alda Was Leaking And Removed Alda Remove 2 Screws Drill Other Two And
Found The Small O Ring Seal Inside Leaking. Jc Whitney. Com Had The Rubber 0 Ring Kit Metic And They Have The Copper 0 Ring Kit Metic For Alda Pressure Test Ok Top Of Alda Is Adjustment 10 Mm
Lock Nut And Turn Small Sloted Screw 1/8 In At Time