I sold my '91 740 non turbo(Regina) a few weeks ago and it ran fine for the new owner. Then one night coming home the CHECK ENGINE LIGHT(knock sensor code) came on and it shut down. He was able to restart and limp home and in the dark checked the oil dipstick, thought it was low and threw in another quart, which it didn't need. Since then, with a new knock sensor, it would start but dip so low at idle it would shut down. And above idle would belch out a cloud of smoke like a snow blower. We drained a quart, did all the tests I could think of, especially with the idle control valve, and couldn't find anything wrong. While I was messing around he said he saw something sliding up and down in the light colored, small vacuum hose that feeds the Pressure Sensor. I thought he was nuts but took it off, shot some solvent down it and sure enough some oil came out. Hooked it up and the car ran perfect. I had checked vacuum and voltage output on that sensor before I sold it so I didn't think it was a problem. But the bottom line is, it will override all other sensors if it can't draw or hold vacuum. Who'd a thunk it? Luckily, we discovered it by accident and if we hadn't it would have been a long, expensive trip to a shop. As it was, we spent 3 hours and everything checked out yet still had symptoms. Regina systems are pretty simple but those 2 simple sensors(temp and vacuum) are the guts to the whole system. And oil can block a vacuum line and have the same effect as a vacuum leak.

 

My advice is to walk away otherwise the new owner will be calling you a lot. You owe nothing when you do a AS IS sale. You may disagree as you want to help the new owner but once he calls and you respond he will continue to do so. As I recall this car had problems when you had it so they will continue to happen. Just advice to take or not.

 

Noted. I do believe in car karma(car-ma) and wouldn't want that to happen to me. I'm not a dealer but I do try and cover any repairs to cars I've sold for 30 days, if I advertise as "running well", which I did. Seems fair to me. If I say "as is" then that's a different story.