Hello everyone! For fellow USA Testarossa owners who don't have to worry about emissions any more (over 30 years old where I live), here's something I recommend... First off, when my TR would start up, it would be so cranky: clattering, clapping, sounding blah. When it warmed up, it sounded better. I thought it was just because maybe my oil was too thin and took a little while to lubricate the clattering pieces, etc. I was reading somewhere else in this forum about how, when the aux air pump is going bad, you'll hear a bunch of clattering while cold (when warmed up, the air pump switches off) I noticed the clattering would greatly decrease if I covered the air intake on the little black air filter on the driver's side, above the oil reservoir. This feeds air to the air pump. That air pump exists to push extra oxygen in to the exhaust to help burn any unburned fuel in the exhaust. Anyway, I made an executive decision, climbed under the car and cut the belt that drives the air pump... And WHOA! The engine sounds so much nicer on startup, and even in general! Smoother idle, even when warm (but that could be the power of suggestion) And I even think I have more power now, too! So, in closing, if you hear clattering on cold startup and it goes mostly away if you cover the little black air filter on the driver's side, and if you don't need to be tested for emissions anymore, cut that belt and you'll be sooo glad you did!
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
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
You're talking on the pre-cats, right? My cats and precats were hollow when I got the car and I put brass plugs in those a few years ago.
+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.
Thanks for your extremely valuable input as always, Steve! Something else I noticed was, before, my car would backfire upon deceleration when cold. With the pump disconnected, no backfire when cold! What are your thoughts on that? Sent from my Moto Z2 Play using Tapatalk
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
