IMHO, enough is when you get sick of it. If you are at that point right now, either park the car or pass it on. If I were in the same shoes you were, I would honestly consider an used Honda or Toyota as the school beater. Last year we put a JDM VTEC drivetrain in a friend's 91 Civic; it now does 160 crank HP and high 30s MPG on the highway. A pre-2000 Civic goes for under $3K in pristine condition here. Drive it for a few years and it will pay for itself. And, any mechanic can fix it. That is what they were designed for. Or an older (SC1/SC2?) Saturn or Neon; they can do about the same gas mileage and are reasonably cheap to maintain.

When it is not fun anymore, it is time to move on.

That said, I am speechless about how much the car has cost you already. I do not think I have $5K in my 75 300D, and that includes paying a shop to put one engine, then, after the vacuum pump killed it, putting the turbodiesel drivetrain I bought off the yard (some modifications required). Also, tires, A/C, suspension, and so on. Now I need to get the head checked/rebuilt by someone who understands the engine and then, while it is doing that, modify the turbo oil return fitting at the upper oil pan to stop pissing me off. Probably need a new hood too. And then putting a W126 electronic speedo in the car but making it look like it belongs there. I guess it is because my W115 300D is a much more spartan/pedestrian car than the 300SD, but I just cannot find ways to spend that much in it.

FYI, If I am not mistaken your AC compressor is a Delco R4. When they leak, you can replace the offending seal without taking compressor out. Also, they can be had for under $100 at any discount autozone, just ask for, say, the compressor off a 82 Caprice Classic. I also firmly believe the priming pump is award-winning ghey. Got tired of it and put a boat squeeze ball before the pump in my car with enough hose I can use it without having to stick my hand in there. Now I can prime the car in 3-5 pumps.

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Your TACH may have a loose connection...I was wondering why your mechanic would be dead one minute then flopping around the next... PanzerSD

i am inspired. i will replace my windsheild... with an intercooler. swedishK