Buying advice on an '84 300SD turbodiesel, please!

[deniss]

Hello, folks. I'm new to this forum, but I am considering buying an '84 Mercedes 300SD Turbodiesel. I never had any previous experiences with Mercedes, and I never owned a diesel car before, so I would love to get some advice on what to watch out for when looking at buying a car like this...

Here's what the ad said about the car:

"1984 300sd in good condition. 237k miles and runs great. Not perfect but a very good car. New tires and shocks. Still looks pretty good, not rusty. Black w/ gray interior. A/C works, all glass good. Here's the bad things about the car: Reverse lights not working and vacuum door locks not working. That's it, everything else is good."

I talked to the owner, and he seems to really love this car but has to sell it due to some personal circumstances. He changed the oil every 3,000 miles religiously, kept the car well-maintained and did many things himself. He says the car starts fine, and he didn't need to use the engine block heater even when starting the car in low-20F temperatures. He said also that the engine does not leak oil at all and doesn't burn oil and that the compression is still good.

He's asking $2,800 for the car. That seems to be on the expensive side of things, but like I said - I don't really know a whole lot about the value of these cars.

What would be a reasonable price for this car depending on condition and what things should I look for or ask about when I go to see/inspect this car myself?

Many thanks in advance!!
Denis

[RUN-EM]

Look for rust in the jack points of the car. Also look in the trunk and floors to determine if the car leaks when it rains. Check out the condition of the windshield/rear glass weatherstripping....breaks in the rubber can indicate leaks. See if any carpet is wet/mildew-ed. On the engine...unscrew the oil filler cap and see if the cap does a tea kettle lid dance with the engine running......watch for excessive smoking with the oil filler cap off/loose. Take note of all guages /lights on the car to really check their performance. Common items are tach function, dash light function, cruise control. Try and drive the car with attention to how the car shifts......harsh shifts are somewhat normal.....you do not want any flairing on shifting......that is the engine reving up while between shifts....nor any slipping while flooring the accelerator. Zero to 60 mph acceleration should be in the 16 to 19 second range with most items running properly. Full floor acceleration should indicate rpm shifts about 3,000 to 3,600 or so on the 1-2 shift, rpm on each additional shift should be 300 to 600 rpm higher (eg. 2-3 shift @ 4,000 or so and 3-4 shift @ 4,300 rpm on up). The turbo should be coming on at about 1800 to 2200 rpm....judged by the car accelerating much better with the boost on. The hood pad will probably be going south with this many miles if it has not been replaced already. There should not be any pulling to either side on severe brakeing....these cars track pretty true and do not road wander at high speeds (built for autobahn travel you know)....unless there is severe cross winds during your test drive. Severe side winds/single u-jointed rear ends do walk about a bit due to the design of the car....but not un-controllable. Try to mirror-look see the brake pads....pads are not expensive, but just another expense and talking point. Good hunting.

REgards

Run-em
1983 300SD - aka - SPARKY THE DIESEL

[RAYMOND485]

1984 300d Turbo 137k
Hae A Mercedes Inspector Give You A Report, All Work Orders , Axles,engine Mounts, Shocks, Trans Mount, Rear Axle Center Mount And Some Are Diy Order Parts,kits From **************.com
Guide Books Are With The Parts If You Do The Labor Ok, Go To Alldatadiy.com For Guide Yearly Fee Ok, Always Buy New Parts, What You Pay Is What You Put Back In For Parts, Good Ride, Fuel
Mileage Is Good 20 City, 26 Highway, New Was 30 Grand, Valves Have
To Be Adjusted At 15k Call Performanceproducts4benz.com, 1-800-243-1220 For Catalog With Pictures And Prices, This Site Also For Parts, Install A Water Fuel Filter From **************.com And They Have Other Kits With Guide Books,

[P.E.Haiges]

deniss,

Valves don't have to be adjusted at 15,000 miles. I have found that 25,000 miles between valve adjustments is sufficient on older engines. I think this is because the valves and seats work harden after miles of use and the clearances change less than in new engines.

I have even seen after 25,000 miles, when the clearances were measured, that none of the valves needed adjustment. This proves that the valve clearances should always be measured before any of the adjusting nuts are loosened, thus saving a lot of time.

A valve adjustment is a relatively easy DIY project. U will save $100+ for a 1 to 2 hour job. This is a maintenence job, not a repair and should not reflect on wether or not to buy the car.

P E H

[deniss]

Thanks for all the replies!...

1) where are the jacking points for this car?

2) what are the signs that valves need adjustment (never had to deal with that)?

3) is $2,800 an ok price for this car, or should I try and shake it down some? no idea what these cars normally go at for this age and miles...

Many thanks!

Originally Posted by deniss

Thanks for all the replies!...

1) where are the jacking points for this car?

2) what are the signs that valves need adjustment (never had to deal with that)?

3) is $2,800 an ok price for this car, or should I try and shake it down some? no idea what these cars normally go at for this age and miles...

Many thanks!

1. Jacking points are holes about 3/4-1 inch diameter under the front and back doors

2. Abnormally loud clacking? Not really sure

3. i've seen them for 600.00 and 6000.00 depends on condition and how much you and the other guy actually know about these cars.

[krs]

Look at the doors for rust at the bottom under and below the rubber door seal. It's a very common rust location that many people miss when inspecting a prospective purchase.

Rust is a nasty and progressive disease that is dificult and/or expensive to repair. It's our secret that you may be willing to coexist with invisible rusting and drive happily for years as many times rust in and of itself will not effect the driveability of a car for long after it is first noticed.

The price is OK - perhaps a little high due to milage but certainly not excessive for a good example.

When driving listen for any clunking sounds that come from under the car behind the front seats, particularly when braking to a stop. If there are such noises it's not fatal to the car but should be a point for negotiation - a garage will charge freely for it's repair.

[deniss]

More questions...

1) Are brake pads fast/easy to replace DIY?

2) Does this car have a timing chain rather than a belt and at what intervals does that need to be replaced?

Thank you for all the help!

[James L]

check a/c valve caps to see if it has origional designed freon (R12) or been converted to (R134a). if it still has the R12 and working good-great. if it has the R134a conversion(brace yourself, pray, fingers crossed, whatever). it will fail eventually, trust me, been through 3 w126 conversions...$$$ stick with R12 and mineral oil.

I paid $1400 for my 289,000, 1984 300sd, nice body condition but i knew it needed alot of diy stuff. $2800 would be a good example and only 5% of used cars fall into this area.

i would bet there is stuff that it needs that you nor the owner know about...yet; motor mounts/eng shocks, oil cooler lines, supsension stuff like upper/lower ball joints, guide rods, tie rods, idler arm, stering rack stuff, subframe bushings, axle boots.

door locks could mean a vacuum leak or pump, fun tracing this down....transmission reverse could be easy or serious hard to tell, could spend alot of trace down time. as mentioned look for rust, what area do you live in?

[deniss]

Im from central New Jersey.

The owner thinks that the reverse lights is due to a sensor that, as he explained to me, screws into the transmission from underneath. He said it's been an issue before and he never got around to fixing it.

If there's a vacuum leak, then I guess it would show during idling, right? I have a turbo car currently, and if there's a vac leak, there's either a high idle or an excessive idle dip after returning from elevated RPMs. I'll keep this in mind.

I've done balljoints and suspension work myself on my Saab 900... Is it about the same work on the 300SD, or is the suspension set-up a big pain to work on? I could handle balljoints, outer tie rod ends, and things like that, but when it comes to things like a steering rack, I'd probably have someone else do it...

[P.E.Haiges]

Deniss,

Yes, the jacking point are under the doors but only the MB crank/screw jack can be used there. I suggest that U don't use these jack points as if there is any rust there, the sheet metal might collapse. Get a hydraulic floor jack. about $20, and use that under the car. Jack points are at front is under frame in back of the front wheel. At rear is under the suspension arm just in front of the rear wheel.

Valves don't "clack". Signs of valves needing adjustment are hard starting when cold because the wear pattern is for the valves to have less clearance, not seat and start to leak compression.

Offer the seller his price and get some type of warranty, say 60 days and 3000 miles, with for any major repair needed to keep the car running paid for by the seller and return of car and money for a repair that is too expensive. Of course this would have to be in writing and preferably notarized. If there is nothing major wrong with the car, seller should not balk at this. This wouldn't cover small stuff like the door locks that don't work, just the drive train.

Brake pads are the simplest to replace. Just knock out a pin and pry out the old pad. Then spread open the caliper piston with a screwdriver and put the new pad in. Do only one pad at one time so you don't pop out the other piston.

This engine has a double row timing chain. Life should be 300,000 miles or more, depending if synthetic oil was used. The timimg chain can be checked for elongation when the valves are anjusted. More than 4* off should be replaced or an offset washer put in the cam gear. New chain is about $70. Pretty easy to replace, it is fed thru engine attached to the old chain while the engine is turned by hand. 2 people can do but its better to have 3.

P E H

[P.E.Haiges]

Deniss,

Vacuum leaks have no effect on a Diesel engine because the intake air is not throttled like it is a gasoline engine.

Things like the back up lights and door locks that U know about should be fixed before U buy the car because it won't be fixed by seller once he has your money.

Ball joints can be difficult to repair and U might need a special spring compressor. But the ball joints have a very long life, especially if U grease them with a hypodermic type needle like I do.

P E H

[thorsen]

Originally Posted by deniss

I've done balljoints and suspension work myself on my Saab 900... Is it about the same work on the 300SD, or is the suspension set-up a big pain to work on? I could handle balljoints, outer tie rod ends, and things like that, but when it comes to things like a steering rack, I'd probably have someone else do it...

I have a 1991 900 that I use as my winter car and a 1984 300SD as my Summer car.

The suspension on the Saab is IMO much easier to work on. The problem is that if you are doing work on the Benz and need to compress the spring, you have to use a special compressor that is $$$. There is a steering box on the Benz, so you won't have to worry about a leaking rack.

The Benz is a much better ride and is really at home on the highway. I am not a big fan of FWD cars, so I am somewhat predisposed to the Benz.

Either way, I hope you like to turn wrenches.

[P.E.Haiges]

Deniss,

Listen to Thorsen, he has great ideas about what use to use in winter and summer. Let the Saab rust away and preserve the MB.

His other statements are true too.

P E H

[Jeremy5848]

Deniss,

As one of the other posters noted, you should loosen or remove the oil filler cap while the engine is operating; see how much vapor comes out. If it spouts like a volcano, that's a sign of blowby from leaking valve guides or worn rings, both expensive to repair.

To quantify this test, put the oil cap back tightly. Then locate and remove the short length of hose leading from the valve cover to the air cleaner. This is an early form of smog device that cars have had since Shep was a pup. The slight vacuum pulled by the intake also helps to reduce external oil leaks.

Once you have the crankcase vent hose loose, plug it with the engine idling and start a stopwatch. After a few seconds, the engine will slow and die as pressure builds up. The engine should run for at least five seconds or more. THe quicker it dies, the worse the blowby. If it doesn't last at least five seconds, don't buy the car.

Remember to put the hose back after the test!

Jeremy in Santa Rosa, California