kajtek,
i think i'll make that a goal to work toward. i think this will be a car i will be able to trust, but i'm not quite there yet (i mean, i had it for less than a week before noticing i had a problem, after all!). this 450 sel belonged to a medical doctor who was very meticulous in his maintenance; i have a stack of service records an inch thick! he replaced so many of those 'service-interval' parts that i hope i have clear sailing from here. the mechanic who recored the radiator said he didn't notice anything else wrong w/ the car. but i'm not quite ready to drive it up the grapevine yet!

 

Grapevine is easy. It goes up and down, so the engine has time to cool. Even my 90 HP Volkswagen is able to stay around 80 MPH there. The 12-mile constant grade on Baker desert is real killer if you really want to know.
Your car doesn't have much electronics in it, (if it does at all). When you read the fourm, you'll find most of the problems with newer cars are electronics. On my VW tdi the MAF sensor just went bad. Who would think I have MAF sensor on mechanical diesel pump? Darn it!
Good luck on your car. You are definitelly in good brand.

 

kajtek,
yeah, its better to go up and down than up and more up. that's kind of how the i-10 to palm springs is where i discovered my blocked-up radiator (maybe in miniature from what your describing). she seems to be running much cooler now.
i really love this 450 sel. there is a solid sense of stability combined w/ a feeling of quickness and maneuverability. she's hardly a musclecar by today's standards, but she accelerates smooth and strong and seems to have plenty of torque. and i think the body design is beautiful. i hope that basic maintenance will be all that is necessary for a while.
speaking of basic maintenance, a humerous story about the worst oil change ever. i always pay attention to the oil capacity AFTER i drain the old oil so i have an idea how much to put in before measuring. in this case, i should have done my research in advance! the container i used (big enough to easily hold the oil in my 429 ford) was way to small for the 9-plus quarts that drained out. i had oil all over the garage . as if that wasn't enough of a problem, i came to realize that my oil filter cannister was blocked by the skid plate (which is a nice touch for a saloon car to have!); i had to get a wrench above and below to turn the bolts, and the above ones were a problem! finally, after a good hour plus of hit and miss, i was able to get them off. i made a trip to the hardware store and picked up a cotter pin set-up so i wouldn't have to fight that monster next time. then i added my NINE QUARTS of oil, and discovered that the new drain plug (which i bought to prevent a leak) was leaking! i was able to turn it back, coat it w/ silicon, and do some torquing to get it tight. i was afraid i was going to have to drain the oil and start all over again. my planned 30 min oil change took the whole day! oh well, you live and you learn.
and, speaking of oil, i was going to ask for future reference. what oil and viscosity have you had success w/ on older mercedes? i bought castrol 20w/50 synthetic blend. i wanted to try synthetic on the old girl but was fearful of leaks and blow-by. what would you recommend?

 

20-50 might be too thick for the engine. Rottella oil (Wallmart) is having good references.
Remember, that when your car was manufactured the SF class oils didn't exist. I think 10-40 is good to start with and adjust it for the colder weather. Lot of newer cars drive on 10-30 and I think it is right, however I hesitate to put that "water" in my crankcases.
Synthetic? Why not? I put in in my boat... 6 years ago. That what synthetic is good for. Low hours and extended intervals make sense.
If you are from old school replacing oil every 3000 miles, you are wasting money on synthetic.
Want to talk about oil changes? I do it for over 2 decades. Owning 2 pans with 20 quarts capacity didn't make me spending additional $60 for a bigger one.
You want full details about draining 24 quarts of oil from my Detroit into 20-quarts pans?

 

It sure sounds like your boat takes more oil than my boat! A 10 quart capacity is more than enough, thank you.
I used 20/50 becuase i saw from the service records that the previous mechanics working on the car used it (which don't make it right, but its a place to start). I'm not running straight synthetic, but a blend (Castrol syntec). I actually considered 10/40, but was concerned that in a synthetic blend it might be too thin (and cause leaking or blow-by). I wanted to try synthetic in the car, and chose a blend as a cautious first step. And yeah, i plan on taking advantage of the longer interval that synthetic provides. I will occasionally check my level, and will change oil if i see that i'm burning it. Otherwise, the packaging says its good for 7500 miles, and i'll take them up on it. My understanding is that oil (particularly synthetic) doesn't actually break down, but rather it gets gunky from deposits, and so ought to be changed periodically. since i've always changed my own oil, its not that expensive, and it gives me a chance to crawl under the car and pretend i know something about internal combustion for a little while!
I drove to anaheim from palm springs today, and the car ran cool (even w/ the ac on all the way in).
one thing that doesn't work that i'd like to use is the cruise control. it doesn't seem to engage at all. i wouldn't want to go bankrupt fixing it, but i would like to see if i can get something other than my leadfoot to handle the accelerating for me. do you have any ideas what the most likely culprit is? i understand there's a switch that ties in w/ the brake pedal, as well as an actuator. the first thing i'll probably do is spray some contact cleaner into the switch, blow on it, and go for a drive...

 

Our flexible system on ML allows us average 13,000 miles between oil changes and originally it didn't require synthetic (what was changed later).
In 1970's and 80's German put cruise control on US models only, so those things haven't been too good.
My older MB had CC module on left inner front fender. Black cylinder about 1 1/2 dia.
When you find it, pull it out and check the contacts. If cleaning contacts there will not help, than you probably have bad main module under the dashboard. MB offer upgrade what was quoted $700.
For about $100 you can buy aftermarket CC. Or just cut the wood stick with the right length to fit between seat and the pedal. I did it years ago on VW Rabbit. But the gas pedal on it had only 2 usable positions.
Good luck.

 

kajtek,
i haven't crawled under the car and looked for the cruise control module yet (does 'inner' front fender mean under the car, not in the engine compartment?) so i can't say what's right and wrong yet. cruise control is definitely nice on a long highway drive, so i might end up pursuing your aftermarket option. if i need to look under the car, maybe this weekend i'll jack her up and take a look at her underside.
if i might pick your brain w/ another question: what gas mileage should i expect from a 77 450 sel? its a little tough for me to figure out, given that i've only driven about 350 miles, and have not been able to fill the tank and let it go all the way to the reserve. but so far - looking at the total miles and the total gallons - i'm only getting about 12 mpg. i know this isn't an economy car, but that seems pretty bad (i had a 1970 429 c.i. ford that got 15). i've looked online, and haven't found mpg statistics for mercedes cars from this era. what's your experience been?
i've gotten the sense that you have a high degree of mechanical ability (and i wouldn't be at all surprised to find out that you are or were a professional mechanic). this makes you a very good person to have around! on the oil changing side, i've heard some mechanics say that frequent oil changes are really not that necessary, and other mechanics say that it is the most important single thing an owner can do for their car. as for me, i'm just one of those peons who can generally take off one thing and bolt another one in its place, and do routine maintenance. so i tend to do the things that i can do (like change my oil regularly!) in the possibly vain hopes that preventitive maintencance can spare me from major problems that i can't fix down the road.
as per your wood stick option, i'll probably let that one go. with my luck, the stick would get stuck and i'd plow into a septic tank truck on the freeway!

 

Sorry for not being clear. I was talking about top of inner fender, what is engine compartment. CC for those years are common problem, so very likely you are going to waste your time. I am not too familiar with your model, but you can ask somebody on this forum who knows it better.
The 12 MPG ain't that bad. My 1969 Ford LTD with 390 was making 7 in good times. My 83' 300 tdt rarely made 20, but with my speeds even E320 can't past the "20" magic barrier. Bear in mind, that CA gasoline is diluted with some environmental stuff, what drops the mileage more, than 10 %. When you fill in another state (Nevada takes gas from CA) you'll notice magic MPG increase.
Your guess is right. Although I don't work as a mechanic, I have mechanical degrees. Not in automotive specialization, but lately cars are more computers, than mechanical device anyway.
You might find my opinion about professional auto mechanics occasionally.
The story, when 3 senior mechanics/supervisor at PepBoys in Tennessee took over 1 HR to MISROUTE my serpentine belt is just one sample of my luck.

 

i'll try to take a look-see at some of the cc components this weekend. i have a feeling that the cruise control worked for years and only just recently gave up. the doctor who bought and owned the car for 28 years was the kind of guy who fixed this kind of stuff.

my mileage may be as low as 12 (not good) and as high as 15 (still not too good). i just haven't put enough miles on the car, and the bulk of my driving has been a couple of trips (uphill and then downhill between palm springs and anaheim) without driving on an entire tank of gas. as long as the car is running well, i am happy.

i'm not at all surprised about your background. my brother is a physicist who works at boeing, and he has that engineer's mind that has always loved to tinker w/ cars (he has 2 antique t-birds, a 57 nomad, and a 56 ford truck in various phases of restoration). now me, i have 2 advanced theology degrees, which means that i am fully qualified to pray for cars and such. i will never stop believing in the power of prayer, of course, but i would also like to be more capable of diagnostic and basic repair.

 

For your cruise control problems go to the foloowing site
http://boostnbenz.1baddsm.com/DIY/
or better still
http://www.the12volt.com/default.asp?
and look for cruise control.
Hope this helps.
I followed the instructions and traced the fault to the sensor unit attached to the speedo cable.
The contacts were sooty and oily.
After cleaning with petrol and light coat of WD40 it works fine.
The CC is a aftermarket unit made in USA fitted to a Mitsubishi.