Second thoughts
 

I have a completely serviced 1982 300d in the driveway ready to go on a 7700 mile lap of the US,and after reading all these posts..am afraid to take it.Leaving in 24 hrs. Geez..got to quit reading about these engine failures on here.And it runs like a sewing machine.

The trip is still on,the reliable family truckster with a 3800 has been awesome and is probably what we will end up driving.

Ye of little faith. I drove a W123 with over 500,000km for 8 hour trips when I was living away from home, as well as driving it to work.

I know.I don't have any history with the car. And thanks to this forum ,I was able to repair all the little things. It feels very solid and reliable. I guess all those posts..burnt pistons,vac pump bearings falling in the engine ect. Made me paranoid at the last second.

Keep in mind that few if any people post on a maintenance forum unless they have a problem. Those that are simply driving and enjoying the ride don't have a reason to look for help. The view then is distorted.

The W123 with the OM617 engine is one of the auto industries success stories. They are solid and reliable. Mine has 353k miles and I would get in it tomorrow and drive anywhere. We also have a W211 Diesel but my w123 is still my preferred ride on long distance trips. Part of it may be the attention it gets but I still prefer the feeling of solid mechanical reliability.

Put a set of fuel filters and 1/8" or braided fuel return line in the trunk with tools to change and go. Add a set of hand tools if you're worried. Perhaps oil and trans fluid if you have leaks. Going 8,000 mi between wrenching is common.

I used to drive the manual w124 300d all over the west coast getting 38-42mpg until I discovered the w211 wagon. Fuel economy be damned this thing is more comfortable, quieter and it hauls a lot more of our crap. The 300d is just for short trips now. I don't think I could do hours in it anymore.

Sometimes they blow up on the highway when you're doing 80 and are days away from home. Sometimes they blow up in your driveway. Sometimes a dumb little part destroys the whole engine. Sometimes they last hundreds of thousands of miles. What's the matter kid, don't you like clowns? :rolleyes5

-Rog

Go visit other forums
 

Go visit other forums. Ford, Chevy, Lexus, you name it, they all have problems. Take the Mercedes and enjoy it.

A few things to remember with an older car:

Prepare the car by changing high failure parts before the trip start is near.

Bring a cell phone.

Keep speeds down around 55 - 60 MPH.

Check oil at every fuel stop.

Watch oil pressure frequently in case an oil line or other failure occurs.

Worst case you rent a u haul and trailer to get the car back home.

as long as flex are newer,don't worry,watch oil,and temp

I have complete confidence in our 1981 240D, it would make it. Now if I took the 1994 Olds with the 3800 I would have serious doubts.

I bought my 300cd in CA, went out with a bag full of tools, and my wife and I had. A memorable trip.

How much needs to be known about the vehicle is a little bit tbd....as someone said, some run for hundreds of thousands of miles, others have a small part fail an engine. Key is to be aware of the things that you can control and adjust them.

It’s not like any vehicle with a 3800 is relatively new...

You forgot the almighty Auto Club card with extended tow.

55-60 is likely prudent for a 240D, but not for a turbo 300d or better.

Oil lines, if original or leaky, are one of the items that should be replaced. Whether one runs at 55 or 75, the oil lines will see extended time at temperature, which is something that many of them don’t regularly see. And a loss of an oil line, while bypassable, is one of the messier and more difficult ways for a rubber part to get you stuck.

LOL what year do you live in?

Doesn’t really matter. Speed limit is the limit, slower traffic stays right.

Resistance is roughly cubic relationship, so the difference between 55 and 75 mph might be only 1.36x more speed, but 2.5x more power.

Diesels like to be heavier loaded, but it does relate to more time at temperature and more vibration instances that can fatigue or slowly loosen items.

NOT saying 55 should be the rule, unless perhaps the gearing of a 240d creates too much NVH. And the engines are designed for longer term at higher power.

But there’s something to be said for taking it easy too...

It matters quite a bit when you're impeding traffic with your 55mph rolling road block and even semi trucks have to go around you. If your entitled piece of junk can't keep up with traffic it's time get off the road before you kill somebody. This isn't 1983.

ARTICLE 2. Other Speed Laws [22400 - 22413] ( Article 2 enacted by Stats. 1959, Ch. 3. )
22400.
(a) No person shall drive upon a highway at such a slow speed as to impede or block the normal and reasonable movement of traffic unless the reduced speed is necessary for safe operation because of a grade.

This is an old car with lots of miles, no service history and a driver with minimal mechanical skills. If making time is the goal, book an airline flight.

Will it make the trip at 80 MPH? No one can say for sure but the power train is more likely to suffer a failure at higher load / RPM.

Interstate and turnpike roads sometimes post a minimum speed. What is the min posted speed that you have seen? I've seen 55 for a 70 rated road.

As for keeping up with traffic. I've been on beltway / ring roads where the speed limit was 70 and cars are flying by at 90+ as they weave in and out across 4 lanes. Should I be keeping up with traffic at 90+ as well?

If the cars going 90+ were weaving through 4 lanes to stay at 90 mph, they are speeding. If all cars are going 90+, then that is the speed of traffic.

You know it’s funny. People often cite Europeans as having more requisite driver training and skill requirement, and as their cars and roads being the gold standard for speed.

Yet, go on those roads and amongst the fast cars and all that, is rapid speed limit onset and changes, and, caravans from Eastern Europe with limits of 60/80/100 km/h. These max speeds are clearly displayed by sticker on the rear bumper. And there’s no issue.

Yet here we chest thump about speed limits being too low and chest thump (here of all places) about low speed cars being unsafe.

SJW/EJWs making their stake by going the limit or lower in the left lane is an issue. It’s unsafe. Oblivious people getting passed on the right is an issue. People blasting past the flow of traffic, claiming it is too slow, is unsafe.

Staying right and within the posted limits (I’ve generally seen 40 min) is fine so long as they are alert and stay right. If the flow of traffic is 70-72, some statistically significant portion of travelers should be going 55-65. If the posted limit is 70, and the bulk of traffic is going 90, Id argue 30% over is a bit excessive, and they are not only on the hook for massively liability, but should expect to see trucks and governed vehicles, at least doing 72-73 max. And even that is unsafe.


Funny you state 1983 but cite a law from 1959. None of these concepts are new.

And if we’re talking entitled... pot, meet kettle. After all, you’re making the case to be entitled to go whatever speed you wish amidst a legally set limit.

Taking it slow might be good within reason. Then again, I had no trouble driving my 1968 W110 200D fintail at 70-80 MPH for hours on end. It was happy to keep that speed range between Washington and Utah. And this is with an engine that had over half a million miles on it.

Now that I have a 1980 W116 300SD? Those speeds are nothing and I've even let it cruise at 100 MPH where the speed limit is 90 MPH and traffic is flowing faster.

Obviously, knowing your car is key, as is not being a cheapskate and waiting until parts fail to replace them. But, failures can still happen. It's a risk we all take. I won't hold up traffic unless everyone else is driving like a maniac and going well over the posted speed, then I move over to the right. Not because I don't want to stress my car, but I feel speed limits are there for a reason and I don't want to be driving 20+ MPH over just to appease everyone else's recklessness.

I always laugh when I see people driving their old diesel Mercedes super slow. I think, "The accelerator pedal moves down farther than you think!"

Just drop in behind a semi and draft it, works great in the 240D.

If I ran 75 miles an hour in the 240D for more than an hour I would lose my mind. 7,700 miles would be nuts! AC on the comfy cruise speed is 63MPH, I hope the 300D has taller gears.

I drove cross country in my 300D.

Car did very well . I had by that point done a lot of service on it. Though I had an issue where my brakes failed later that year.

Take a breath, have fun. Best car to drive in on long trips. If you're worried, get road side assistance so you can get towed to that Uhaul for a trailer and truck.

People saying to go slow don't drive in TN. I was passed while doing 80 in the 84SD. This is a car with an engine miss and rust but refurbished brakes and front suspension and cooling system. It will cruise all day at 80 mph and the temp gauge stays slightly above 80 C with air temps in the 90 F..

I check for fuel, oil and coolant leaks anytime the hood is up. There are none of significant size currently. I'll have it towed and get a rental car if it quits while on a trip. I only keep return line hose, belts & fuel filters. I don't consider belts necessary because They are kept relatively new but the old set get's dropped into the truck in case they are needed.

Go drive the car. A few Ben Franklins will fix any problem that comes up.

I wonder if the OP planned out how many miles per day / how many driving hours.

That was pretty much my thinking. I love my 240D, and it scoots well. I’d drive it anywhere with confidence, but it would have to be slow. It’s just geared so it’s revving really high and thus fairly loud.

My 300cd has cruised at 75+ for hours. The 350SD obviously has no issues with anything, more modern engine and all :)

I regularly take my 240 on 9 hour road trips at 75mph.
The only thing that’s ever stopped me was a small piece of plastic (clutch master cylinder pushrod) which I fixed with wire and gorilla tape.

Ive been driving my 87 300d all over the place recently. From Sav to Chas twice a week. Clogged one fuel filter. Carry spares. You never know.

Traveling Speeds
 

Interesting thread .

A Couple years ago I drove across Ameica in my 1982 240D, at that time the car had 300,000 + miles on it and #1 cylinder had maybe 200# compression due to a tulipped exhaust valve .

The tranny had never been rebuilt although I did keep it serviced and full of fresh ATF, it leaked a fair bit and I was adding "Trans-X" periodically .

It's an automatic so 60 ~ 65 MPH was the prudent speed, I used some oil and ATF but had a nice three week adventure that included some seriously steep hills in the Navajo Nation where I had to pin the throttle in first gear to keep it moving ~ it never got hot nor smoked one bit .

As mentioned, carry spare clear plastic fuel intake screens and always dose your fuel with fungus killer ! . if you keep on top of this, even getting a tank full of bad fuel won't spoil your trip nor cause any difficulties .

I tend to replace the v belts as soon as I see cracks in them and carry the spares in the trunk ~ the factory tool kit is comprehensive and I've used it to replace an alternator on the curb and adjust the other belts when I was 3,000 miles from home .

I imagine a four speed 240D would do 65 ~ 70 without over speeding the engine, every engine has it's sweet spot, find yours and stay in it, you'll do fine and have a nice comfortable and safe road trip .

Remember to check the spare for pressure and lack of visible belts ~ you never know how far you'll need to travel on the spare to lack of cracks and at least 35 PSI pressure is far more important than visible treads on an old, cracked & weather checked tire .

Make sure the jack works easily too .