i recently acquired one with 233k.Is it due for overhaul?
Does it need timing chain change/valve adjustment?

Why do you feel it needs an overhaul?
1. Is it lacking power?
2. Is it buning or leaking oil?
3. Is the engine starting easily down to 25 degrees F?
4. Do you hear a rattle when after the car fires?
If you answered no to all these questions rest assured you benz is a stong runner!
You can check the slack on the timing belt to see if it needs changed. With your mileage i would strongly recommend it. Mine has 188K and has the orginal. Its not that expensive of a job less than $350 i am told.
Just my $0.02.

Do you have any history on the car, such as records, receipts, etc? If not, I would suggest adjusting the valves soon, or having them adjusted by your trusted tech. He can also check the timing chain stretch at that time. I would also change the motor oil and filter, and all other fluids (including brake fluid) and filters straight away, and start a new history. These engines are capable of very high mileage if well taken care of.

Mine has almost 250K, no rebuild. Had the timing chain replaced every 100K..runs great

Adjust the valve now and every 15000 mile. Check the timing chain every 15000 mile too. Unlike the gas engine, a well kept diesel engine may never need a new timing chain until engine overhaul. Steve posted a way to measure the life of a diesel engines (dated 2/4/01, under the topic of "Diesel Blowby").

David

fz500sel has (I think by now) well over 280k miles on his '85 300D, and he still drives the pi$$ out of it.
Isn't that right Frankie? :D

still runs like a top
 

Larry Patrick, er...Delor

Yup :D

Just turned over 280,000 and it still runs great (knock on wood). Although, I DID just start having trouble with the antenna not going all the way up. But that's another story...

(for those of you just joinin' in, these are not MY original miles. I purchased the car from the original owner at 267,000 miles)

Why overhaul now?
 

I turned over 295,000 in my '86 300SDL just yesterday and it still runs just fine!

Good luck.

Don't assume that a rebuild is needed just because it has a "few" thousand miles on it. I test drove an 84 300sd about 4 months ago that had more that 300k (the odometer had stopped at 316k). It was owned by a realtor who rarely had any maintanence performed (6k to 8k between oil changes:(:(). Depsite his total lack of care for the vehicle, it ran surprisingly well ... never rebuilt ... original timing chain.

WOW, no maintain der beast
 

My 1987 300E spark ignition with 177,900 miles and going strong.
I've always over done the oil changes etc.
But these compression ignition beasts can't be broken!
I bought mine new, but except for the tinkerring I can do to mine(mods for performance), if I could turn the calender back, mine might be going clackedy clack instead of huummm.
Happy Trails Beep Beep from Houston!!!
Donald, El Cheapo