Just cut the belt! Then, happiness!

The solution is to rebuild or replace the pump and routinely replace the check valves.

The fcar fittings must be removed and installed on the mercedes.

Image Unavailable, Please Login

Image Unavailable, Please Login

 

Cheap
Image Unavailable, Please Login

 

Crazy cheap!

 

If you disconnect the belt/system, I highly recommend replacing the check valves with brass caps. Home Depot has a set of brass caps that screw directly onto the threaded air injection tubes. Liberally apply anti-seize so you could take them off if you ever wanted to.

I find removing the air check valves is easier if you cut them off with an air grinder at the threads, then make a quick groove down one of the 8 flat sides. Once you've got a deep groove, twist a flat blade screwdriver in there and they pop loose, instead of risking breaking off the old and fragile air tubes by twisting with a wrench. My first set were seized on and it took less than 20 minutes to replace both.


Sent from my iPad using FerrariChat

 

+1. The thread size is 3/4" NPT IIRC.

No, He's talking about the check valves, Items, B, in this jpeg:

Image Unavailable, Please Login

The way the system works is:

When cold (water thermoswitch M closed), power is supplied to the Air Pump EM Clutch, H, which drives the air pump, and power is supplied to the electrovalve, D, actuating it, which applies vacuum to the Cut-off Valves, A, and opens them. Positive pressure air from the air pump is then blown thru the Cut-off Valves and the Check Valves and into the exhaust port.

When warm (water thermoswitch M open), power is removed from the Air Pump EM Clutch (disengaging the air pump) and removed from the electrovalve, un-actuating it, which removes vacuum from the Cut-off Valves and closes them -- so no exhaust gas is back-driven thru the Check Valves.

The problem with just disabling the air pump (either by cutting the belt or unplugging the EM clutch) is that, when cold running, the Cut-off Valves will be open so the exhaust gas will try to backflow thru the Check Valves and the (open) Cut-off Valves. The Check Valves often get "leaky" with age (especially when they don't have cool air from the air pump to cool them) so the plastic Cut-off Valves (and hoses) can get melted/damaged.

Bottom line is that if you cut the drive belt (or unplug the EM clutch) you also need to either: 1) unplug the electrovalve, D (so the Cut-off Valves always stay closed and prevent backflow of exhaust gas during cold-running), or 2) replace the Check Valves, B, with pipe caps as Cassidy indicated.

PS The round thing in the figure, near electrovalve D, is the differential pressure switch -- don't unplug that! Electrovalve D is a small cube thingy with three hose ports -- it has a red wire and a purple-black wire.

 

Lol, sure thing! He got back to you faster than I could. My system was hacked up by someone in the 80's to make a Euro car into a Federalized system. I've since cut it all out and welded back over, you'd never know where in the pipe my air valves were. Before I did that though, the caps were perfect.

Good luck, hope it comes out great for you. My air pump lives happily in a tote under my workbench.

 

With an active air pump, the only time I had backfiring on cold deceleration was when I had a rust hole in one of the check valve bodies -- perhaps you should check the conditions of your check valves and the pipes they mount onto.

 

Once again Steve, you amaze me with your knowlede and willingness to share it.

Polite, extended golf clap...

 

Keep your car original.

The air nozzle off the Testarossa must be mounted on the mercedes version.

No excuse - they are now on sale:


Image Unavailable, Please Login