So, on Saturday, the SSJ’s (Supercharged SJ) owner got nailed by road debris with no body damage. But it knocked out the A vacuum system.
First, a primer on the SSJ’s vacuum setup, because seriously it is the most complicated engine you will ever hear of that can actually be repaired by mere human beings. Because it is a 70's AMC design, there is a TON that is vacuum operated, including the differential. Here’s the stock vacuum diagram.
Then, because it is a modified BW1339, you add on this:
Not pictured: the vacuum amplifier (no, seriously) and another quarter mile of lines for everything else. Also note the numerous delay circuits and the thoroughly frustrating CTO (temperature operated) setup. This is why I tell people: do not fuck with the vacuum system, and do not just randomly disconnect the EGR, because it will only end in tears. Oh, and non-functioning HVAC. Which is just a grand idea in a winter car. Who would possibly want working vents in 5 degree weather?!
This is why the SSJ has two distinct vacuum systems. They are labeled “A” and “S” for “AMC original” and “Supercharger circuit.” The S system is fully divorced from engine supply in order to make it possible to do things like basic fucking diagnosis. Because, shocker, the AMC system doesn’t like it when your intake has 10 pounds of boost in it. But you can’t dump the EGR and EVAP while staying legal. You also can’t dump the spark and have to modify it because of the purge signal and PCV. So the supercharger has a completely isolated system that feeds the stage 1/2 MAPs, secondary PCV, bypass, and nose clutch lockout. The AMC system has been very carefully modified with some additional sensors because seriously, this thing is heavy as fuck, and you want to know if the brakes lose power BEFORE you try to stop.
So while driving along the highway, the special “EMERGENCY 4WD” light starts flashing. On solid means the BW1339's in ‘emergency’ mode (retained,) flashing means ‘controller is unsure of vacuum supply.’ Being an idiot light, it does not tell you which supply. Just that a sensor is out of bounds. So the owner pulls over, checks under the hood, finds nothing amiss. Lets it cool down, sets the S/C to full bypass, starts it back up. Light still flashing. Calls me.
Hit the TC BYPASS switch in the glovebox. “Still flashing.” Well that’s not good. Toggle it a couple times, check valve could be sticking. “Nope. Still flashing.” Yay, tcase is not getting boost OR vacuum and cannot engage ‘emergency’ mode! Which means that the range selector (which is vacuum operated and controlled) is in an unknown state. It HAS to go on a flatbed. Make SURE to put the transmission in neutral and set parking brake with the engine running BEFORE they winch it. (Neutral with engine off doesn’t disengage everything, by design.)
So this morning he has it home. They found a flatbed, deck capacity 12000lbs. OK! Woah, no, carrier deck is 4773lbs with 2500lbs on towbar. Way over. That won’t work. So thinking it’s in neutral, and setting the emergency 4WD switch, “yeah, we can axle tow it.” For 140 miles. Where it was then placed on a proper flatbed for the next 250 miles home.
DO NOT FUCKING SINGLE AXLE TOW PERMANENT 4WD SYSTEMS YOU STUPID MOTHERFUCKERS, EVEN IF THE OWNER SAYS IT’S COOL.
Because the BW1339 was partially engaged at some point and chewed up a bunch of irreplaceable internals. Because of COURSE pull the front axle and drag the back axle. With the axle engagement system able to knock between engagement states. For 140 miles.
Fucking thing is completely and utterly destroyed. Will not go into gear. Chain broke. Rear diff drained the blood of demons. I don’t even want to know. I just don’t. I literally just screamed “I TOLD YOU TO FLATBED” and got ‘I TRIED’ in response. And now the client’s winter car is ¯\_(ツ)_/¯ because this is easily $10k in differential rebuilds and parts IGNORING all the BW1339 parts that DON’T EXIST.
“Oh, I’ll just get my insurance to pay for it.” DUMBASS! You AUTHORIZED the two wheel tow your manual said DO NOT DO. That means all liability for damages? YOU. Not them. And I’m sure as shit not wrenching on it without you paying in advance because half the parts in here are unobtanium. And shit is ALL fucked. Because a thorn branch managed to rip a vacuum line off the center diff lines. And now they spit metal.
You. Stupid. Motherfucker.
And no! You can’t sue them! You TOLD them to do this. You can’t sue ME because I told you NOT to do this. You can’t sue Jeep because THEY’RE DEAD. You are now on the hook to me to try and completely rebuild two axles, a transfer case, AND a transmission. Only one of those items still having adequate parts availability.
I JUST WANT MY PORSCHE TO BE READY FOR ME TO PICK UP SO I CAN DISAPPEAR FOR A MONTH!!!!