300D - Preemptive part replacements?
 

When I finally find a 300D in the right condition and for the right price I'd like to proactively replace rubber and plastic components, filters as well as any other components likely to fail so as to start with a clean slate.

On my list thus far:

Window and door seals and runs

Sunroof seals and pads

Brake rotors and pads

Tyres

Shift bushings

Flex disks

Exhaust suspension 'doughnuts'

Air filter and elbow seals

Glow plugs

Oil filter

Voltage regulator

Could anybody help me compile a list of all the hoses, seals and other bits and bobs that would be prudent to preemptively replace in the engine compartment and elsewhere?

Thanks,
Orangehaggis

Very expensive list. Except for filters and consumables, inspection is your friend. Don't replace anything that doesn't need to.

Throwing money and parts at a car is wasteful. Find out what needs replacement and replace what needs it. Wear and tear is a function of maintenance, environment, and climate. If you wind up with a car that was well maintained, you'll have a minimum of stuff to fix.

One thing worth replacing entirely is all of the rubber vacuum fittings under the hood. By this point, they're all in need of replacement and they're cheap to do.

Get the car, do a good inspection and figure out what needs replacing and repair, then build your list. Not the other way around.

As the old saying goes: "If it ain't broke, don't fix it."

agree with the above,

I had a long list, but at this point its best to drive it and see where the issues are.

inspect ball joints, flex discs and brakes for safety reasons.

also take a look at the oil cooler lines, and the fuel lines.

Thanks for the advice! My budget should allow for a good bit of part money but I defer to the experience of the membership here.

I plan to look at a 300D in a week or so and have a mechanic give it a good look over.

My intention is to use the car daily so I wanted to reduce the risk of being stranded somewhere...

Orangehaggis

No way to be proactive overall until you get the car. The true overall milage plus any past service records knowledge can help. On most of my 123 purchases I got very little information. . On a high milage example the list to increase general reliability in service can be quite extensive.

Window seals etc should not be replaced if they are still fine.

So much depends on if the car was maintained in general over the last period of time. Or just neglected in general.

Today it probably pays off more than ever to attempt to locate a really good example initially. A pre purchase examination by a competent mechanic familiar with these models can be very important.


He may be the best bet to tell you if the condition of the car is somewhat consistant with the current odometer reading. Many need really extensive work. Odometers well shy of the true overall milage are very common on these cars.

You would be really surprised how much money and time to do it all even yourself can add up. Paid for service to attend to all the needs is impractical usually. These are thirty to forty year old cars remember. So unless past owners have been diligent there usually will be a list of needs.

Currently unless good fortune played a part. I might have to spend a fair amount of money in just finding a good 123 example. It would not be found in the area we live in.Really good ones are not falling out of the trees either.

Add to the list things like if the oil cooler hoses have never been changed or seem to be the originals. Change them as they can cost you the engine. Inspect and clean out the fuel system if the need is indicated. Inspect and repack the front wheel bearings. Inspect the brakes and repair where indicated and change out the rubber brake hoses in the system. Flush the brake system as well. A real general tuneup and check of the timing chain for wear. Plus the valve adjustments. Simply because all too many people believe if a diesel runs it does not require it.

It also helps to know which generation 300D you're talking about. Is this a W123 300D? A W124 300D with the 3.0L engine? W124 300D with the later 2.5L engine? Different generations have different things to watch out for and different suspension designs and drivetrains. Knowing which one you're looking at helps to focus the conversation.

Junkyard/ebay passenger seat spring and cushion, and fit it to the driver's seat.

I like to replace all the little vacuum connectors and t's under the hood in one clean sweep, every dozen years or so. That's because vacuum leaks cause all sorts of unexpected problems. Other than that, just wait for it.

My take after having gone through this a few times. You sound like this is new to you. This is a classic Mercedes-Benz, not an American muscle car. Many of the original parts, despite being very old are still better than aftermarket replacements. It really sucks to pay for one of these jobs and find out it doesn't improve the car at all or needs to be redone.

- Window and door seals and runs:
Don't bother. Your OEMs may last a lot longer and there could be quality and fittment issues with the replacements. Don't use Uro except if you have no other option. If you must, prepare for a real PITA.

- Sunroof seals and pads:
Don't bother. The OEMs will likely last a lot longer. The rear seal is a royal PITA and extremely difficult to get it to stick properly in place. Don't buy any of these seals made in China unless you are desperate. You will also pay a fortune for some of these parts from the dealer.

- Brake rotors and pads
Check the rotors with a dial caliper to see if they are within specifications. For the pads, you have an electronic sensor. Make sure that is working and it will tell you when to change the pads.

- Tyres
Change every 7 years or when treads are worn.

- Shift bushings
No real benefit to replacing early

- Flex disks
Yes, absolutely. Replace these with OEM and strategize it with other repairs like fixing oil leaks or diff/transmission service to get more bang for your buck.

- Exhaust suspension 'doughnuts'
Yes, this is cheap and easy.

- Air filter and elbow seals
These will periodically wear out. I wouldn't bother dealing with them until they become a problem.

- Glow plugs
Yes, I have done this on all of mine. It just makes troubleshooting easier and is fairly easy to replace.

- Oil Filter
You should change this with the oil, right?

- Voltage regulator
Yours may be old, but I wouldn't assume the replacement is better. Check the brushes and replace if worn. Chinese made is bad, but ok for an emergency. Keep a voltage tester in your car and keep an eye on it.

Dkr.

Thanks!!

lemforder for your flex discs, motor mounts, upper control arms, lower control arm bushings, tie rods, and idler arm

bilstein shocks

MB for valve cover gasket, and any other gasket

Bosch for the plugs

monarch/bosio for your injector nozzles

and definitely MB for any body seals

Thanks for the great info. Glad I can get information here instead of trying to figure it out myself.

Orangehaggis

Since you haven't had first hand experience, I would refer to this list as a starting point for buying from different manufacturers. You can really get burned with some of the brands out there, so do your research before buying anything:

Edit: the forum won't let me post the URL, but I did a Google search for the following terms and it was the first result: 500 e board good bad mercedes parts

Dkr.

Capital! Thanks!