2007 Chevy tahoe subutban

It's a 07 so it would be as is from dealer. I was hoping it would have been private party purchase. Always test drive any car or van or pick up for that matter. If it knocks don't buy it. Always change fluids and filters and pack bearings on purchase of used vehicle. Oil pressure should read 0 when key is on. About 40 to 50 is generally where oil pressures are going to be in normal conditions of driving. There is no reason to rev up RPM. The motor will set itself when it is ready to go and not cold.

When I test drove this it was great no problems no lights coming on. Motor was not doing this. 40 miles to home and it all started

If I dont rev it up the oil pressure light comes on and wont stop dinging and the engine will have the knock. If its revved up it stops and runs ok

I drove it for about 15 -20 miles no issues. Replaced sensors including crank shaft. It has 143,000. Had someone look over today with what time they had looks like new oil pan like the bottom part of the motor has been gone throu ar some point.

I am curious which dealer would have done this. what city state area did this occur if I may ask. What I would have done to prevent this is get a mechanic to do a thorough inspection of the vehicle. It will cost you about $50 BUT it's a LOT cheaper than the money you may have just lost. I live in the mountains of Utah, a GREAT place for test drives and finding out if there are dead pistons or missing spark plugs. I also use the uphill to see if my fuel pump is working properly ( going downhill the fuel pump works less to maintain the same speed because of gravity/ momentum). have a nice Thursday!!

The next thing I would do is report them your local better business bureau. It's a poor business ethic.

Your Tahoe comes with either a 4.7 or a 5.3 depending on if it’s 4 wheel drive or not. They are a great running engine and rebuilt properly a lot of 5.3l you will see on the race track making upwards of 800+ hp. Those engines are also well taken care of. Most people tend to treat SUV’s and trucks like they are bullet proof. I’ve worked on a lot of engines and I’ve seen a lot of things, unfortunately what you have is a bad rear main seal. While the engine is running the pump, bearings, relief valves, along with the rotating assembly and seals will keep a constant oil pressure of between 40 and 50 psi, my 03 Suburban with a 5.3l keeps a steady 45 psi. If your oil pressure drops to nothing but increases to proper pressure while accelerating it’s because of the rotating assembly creating it. This normally happens when your driving but the relief valves even out the pressure. When you stop or idle the rotating assembly does not spin enough to creat enough pressure, it’s escaping past your bad rear main seal. It will cost you just as much, if not more to replace your crank, caps, and bearings along with the added honing, as it would to replace the engine. I can also pretty much assume that your differential and transfer case (if it’s 4wd) fluid has never been changed either and it looks like black jello. A rebuilt 4.7 with a warranty will set you back about $1200, a 5.3l about $500 more but then you have to have it installed. Sorry about your loss.