I have owned my 89 300e for almost 7 years now. I have at one point or another rebuilt every system on that car. It's very likely I'm in to it $15k or more.

Parts are somewhat reasonable as long as you shop around. When I say reasonable, I mean that it's cheaper than a bmw, by a little, and 20x more expensive than a similar vintage ford.

If you plan on having the car repaired by your mechanic (or any mechanic) you should sell it as the repair bills will bury you. 300e's are only worth at most 3k so you are at the point of no return now.

Looking back on my years of ownership I can tell you this.

1. Make sure you bought a good one. No rust, low miles, or well maintained by an enthusiast.
2. Your car will always need something. It will never truly be 100%. You have to be ok with owning a car that is in constant disrepair.
3. You bought a 25 year old car that is going to have 25 year old problems. Rubber is dry, seals are shot, water will infiltrate, you get the picture.
4. And finally, my 300e has been problem free for about 8 months out of the 7 years of ownership. It is difficult and expensive to get the m103 to run PERFECT. If you think you can get your car perfect, get rid of it ASAP.

When my car was running well it was an absolute joy to drive. You have to really commit to these cars. If you like fixing cars, and like to learn about cis-e, bust your knuckles, burn yourself, and permanently have dirty fingernails, then go for it.

Otherwise, dump the car and buy something newer.

__________________
Eugene

10 E63 AMG
93 300te 4matic
07 BMW X3
14 Ford F-150 Fx2