Go to the "Tech Docs" section at www.300sel.com and download some of the PDFs there. It should help educate you further on the cars.

Look carefully at the rubber flex discs. 6.3s are notorious for going through these, particularly if raced or driven hard.

Look for oil leaks -- 6.3s are notorious for oil leaks too. Especially check the lines leading to and from the compressor, and the oil cooler up front.

Coolant leaks -- same thing -- check the hoses, radiator and water pump. Water pumps are notorious for leaking.

Gas leaks -- check all fuel lines, and especially the cold start valves on the ends of the intake tubes (next to the firewall). These valves often leak. Check the fuel pump and the area around the fuel pump, including the connections of hoses to pump.

Exhaust system rust -- I'd just consider replacing exhaust with a Timevalve stainless system -- this is what most people do and it's 5x more durable than the factory system, though about 5-10% louder than factory. Trust me, the added durability is worth it.

Chassis rust -- poke around under the car with a screwdriver EVERYWHERE. This is the most important thing you can do. Especially check around and under the wheel wells, frame rails, door bottoms, rear fenders underneath, etc.

Exhaust leaks -- make sure there are no exhaust leaks. Sometimes the crosspipe between the downpipes rusts out, it's vulnerable.

Back up slowly (like out of a garage). If you hear and feel a loud vibration coming from the rear axle, it's the rear brake hold support bearings (little rounded plastic caps that sit on the axle tubes that are commonly overlooked when it comes lube time, as the lube nipples are hard to get at). These are cheap parts, but a bit of a pain to replace. All 6.3s require replacement of these at some point.

Good luck
Gerry

RR3, what a bevy of great questions, but first, comments on other comments.
First of all, Gerry VZ is a good freind. He has owned his 6.3 for years and is one of the USA most knowledgable private, non-pro, enthusiasts. Take his advice. Mr. Emmerich, is also very knowledgable, listen carefully, read all posts with serious attention. Some posters are spouting hearsay. M100 trannies are not whimps, they have been lacking in upkeep. Oil changes have been missed. Rips in leather untended. Broken heater levers ignored. Weather stripping neglected. Sunroofs, ditto. Turn signals, "hey, no big deal, I can use my arm, yea right. The rear window is slow. Oh well, it's probably the motor or a torgued regulater. Both are costly, oh well, it works, right? You have just described a 6.3 that has fallen victim to a real Mercedes Benz fan. This 6.3 is a # 2. Yea right, this owner is not a Benz fan, he is a fan of driving a Benz into the ground. It is damn close to being a parts car.
Shocked? Well, you better know it now. I have a M100 econ theory that I should put into an essay and printed in the Lode Star. Most 6.3s are rolling parts cars. Your looking at one. Is that bad? No, if it doesn't have rust, you are starting where I did in 1990.
What did I do? I had it towed in on a flatbed and didn't drive it for 18 months while all the above, the motor, tranny and rear diff were rebuilt. What was the result? I now might just be the 6.3's biggest fan. I race a concourse condition 6.3. Everything is there and works properly. We jacked the horsepower and played with tires. It can take almost any auto at the track excepting the weird American Iron jobs without interiors and with turbos, supers, and or, NOS. And of course, a certain E500, which I choose not to mention very often, although by chance, we never raced this year.
Are you willing to spend a fortune? Ask yourself that. Spend cash, not invest it. Throw 50,000 $ into this and what is it worth, maybe 25,000 $ Throw 100,000 to 150,000 into perfecting it and that final number might be argued that it is 50,000 $ but I have never seen it in 15 years.
OK, the myths. Trannies are weak, bull. They are tough. Rear diffs are weak, well, only in one trick, a full power left turn seems to blow them. Don't do that move, you will be OK. How can you destroy one? Jack your horsepower to 440, add a super soft race tire, add to that a super secret mixture in the fuel tank, and run 1/4 races in 50 degrees f. Then you might break a diff but in a few hundred races I broke only one. Last year I tried to prove this point. We raced every week, except two, in 2003. America's and Japan's finest junk heaps would never take such a pounding. Our 6.3 did it. Not one broken part, not a single item. Ask Gerry, about the following. Every week some race rig or even three were throwing parts. The 6.3 met the test and was driven there and back home, not hauled on a trailer.
Motors and the stock system. You or someone said the stock ignition is "troublesome". Yea right. Your mechanic couldn't do the tune. He probably can't. So here Gerry has another point, yea sure, the pointless are easy, BUT. I'm not convinced they are better.
Someone mentioned miles. This means nothing as to what condition it's in. HOW WAS IT MAINTAINED. That is all you need to know. This one has not been maintained, in fact, go to my opening salvo, it is nearly a parts car. I know this. I have rust free parts cars. A low miled but not maintained 6.3 can be a fright. I have such a 6.3. We call it the Broken Arrow.
That odd feeling at low speed. This I've never had, thus no comment.
How do you start in first gear? At idle put it in 2. Give it fuel slowly, your in first. If your in 3 and hammer it, your now in 2. Easy.
Someone mention a 6.9 tranny swap into a 6.3. Yea right. The guy who told the guy that one is clever. They don't match up. Tell me, did that owner who opted for another tranny pay some engineering firm 10,000 $ to make the needed adapter? No, but who knows, maybe. Yea, right. Why doesn't that tranny have a first gear? No functioning kick down switch. The wires simply might not be hooked up correctly.
Trannys, they are tough as well. Only by altering other parts of the driveline can you toast a tranny. For most guys, with stock tires, destoying a tranny is very difficult.
RR3, there you have it. Are you brave. Join the exclusive group.

Deanyel, there is almost no way I can compare a 6.3 to a 4.5. I had several and just sold my last. They look great but they are not 6.3s. Yes, they are easier to maintain.
AJN, you are what a call insightful. RR3, pay attention to what and how he commented. The true value of the 6.3 is the combo of the following. Leather, wood of choice, brightwork, the overall design, visability of the of the slightly tinted glass, and of course, the RAW POWER. I lean more to the power side, but without the others, I wouldn't be a 6.3 fan.
Dan Smith, Oregon

Comments were in response to question on whether he should consider a 280SEL 4.5. It was my car that had 6.9 transmission. The previous owner had made the swap at a cost of about $7,000 including a new transmission from the factory. The only modification required was in the length of the driveshaft - apparently not a big deal. He made the swap because he had blown several 6.3 transmissions, undoubtedly driving hard. The 6.3 transmission may be tough but his conclusion was the people who know how to rebuild them properly are almost non-existant, and that the 6.9 transmission had been beefed up to handle more torque, and that he wanted a new transmission.

Well, this is all true. There are only two firms (one on each coast) in the continental US that are qualified to rebuild 6.3 transmissions, and even then, there are no guarantees that the job will be correct and the tranny won't slip, even freshly rebuilt.

In reality, the best thing to do is to get a NOS unit from Mercedes-Benz -- the last time I checked they were $13,000, but they've had 2-3 price hikes and about a 15% drop in the dollar since then.

Of course, the transmissions beat the price of a new 6.3 Bosch fuel injection pump. These cost over $45,000.

No, I'm not kidding.

The 6.3 and 6.9 transmissions are totally different beasts though. The 6.9 is a torque-converter (smoother) unit but of only 3 gears. The 6.3 is a fluid-coupling (rougher but less power loss) but with 4 gears. The 6.9 is optimized for smoothness and top speed. The 6.3 is geared a bit more for speed.

The 6.9 is probably a bit tougher overall, and certainly far easier to get serviced or rebuilt.

Dan Smith owns the largest fleet of daily-driven 6.3s of anyone on the planet. Trust what he says -- his experience with 6.3s goes 3x mine in length, and approximately 10x mine in the number of M-100 cars owned. that's 30x the experience overall.

What he says should be gospel to any owner or prospective owner.

Cheers,
Gerry

Thanks for your post Dan, to the point although a little dramatic.
I know that I am not purchasing this type of car to just buy and drive.
I am willing to put 10-15$ into the car after purchasing it (if I indeed do) and keeping up with the maintenance. Am I wrong to assume that this wont be enough?

Tomorrow I will be going through the car at MB with an MB mechanic and a friend of mine who is also an MB mechanic and someone who works on these cars as well.

Gerry, how do you know if the fuel pump needs to be changed. $45,000 is ridiculous. Is this an extreme case, is there an alternative or are you basically SOL when that happens?

I can't imagine people spending 150$ plus on this car - seriously.
What on average are people who own and operate a 300sel 6.3 paying or have paid to run this car?

Gerry you mentioned 5000$ per year to upkeep. What would that entail.
Again, I am not afraid of spending for upkeep on this car, but I can;t see everyone spending 45,000 for a fuel pump - sanely.

RR3, I read Gerry's post about the tranny and fuel pump as follows; it was a joke. The tranny, new, costs only a mere 45,000 $, while the fuel pump, do not confuse this with the mechanical fuel injection system, costs new around 500 to 700 $. Sorry I can't recall that exact number but I always buy new fuel pumps. Did so even this summer and I missed the call, it wasn't the problem.
What Gerry is saying is that some NOS 6.3 parts are quite costly, insanely so. I have not and will not buy a new tranny, I have pros rebuild them. An interesting point here, 1/2 are shot when they arrive. Only have a firm rebuild it if they will back it up for a year.
What is the average cost of admission? How tall is a tree? The answer, there is no straight answer. Some 6.3s were maintained and driven at regular intervals. Some, realy nice looking beasts, were parked in garages for years. They are pure junk, parts sources, or a future rebuild candidate. Better said, some garage queens can be money traps. Quote me, this is a very misunderstood fact concerning complicated machines. My best 6.3s are driven all the time.
Now an estimate on yearly costs once you "sort" this 6.3 out. My best 6.3, the one I race, is the cheapest to opperate. In a two year period I replaced Every Part on the 6.3. Subsequently, only a few items of minor importace have failed but two major race related items were replaced. Overall non race cost, 1000 $ for the yearly fluid change, 500 for a major tune, and 500 for all the rest. Blow a tranny, thats roughly 3500 $ with a day out, a day in and the rebuild.
Now, is this a fair comparison? Heck no, it's like a new Benz. So lets compare it to my longest held 6.3, a 1970, we call it the Blue Goose. The Goose is also a total rebuild , with one huge exeption, the motor is stock and never rebuilt. In the last 6 years, its been driven daily, besides fluids and an ocassional tune, it has had no failures. Ah, but that was since 1998, what about before that year? It was first rebuilt in 1990 thru 1991. Again, not the motor. It was quite costly in the first 7 years. At least 5000 $ per year. We ran it for at least 150,000 miles thru 1997. It was rebuilt again in 1998 and driven daily. Why has it been almost cost free since 1998? Quite frankly, I know what breaks them. Or, what not to do to force the part to fail.
Once you purchase your first 6.3, you learn that you now have a somewhat large Benz that can handle like a sport car. You have a tendency to, lets say, act like a high school kid. Some of those stunts can cause certain parts to "fail".
Answer that, how much does is cost to run question? Heck no. I admit that. There is no way to know where yours has been or how long it was EVER parked. Three months is a killer for possibly a dozen 6.3 systems. It will leak from every gasket at six months. The Mechanical fuel injection pump can be toast if parked a year. Most come with shot air ride systems. I've seen them with four frozen brakes.
On being somewhat dramatic. I've seen so many guys buy them, spend 30,000 to 40,000 on nickle dime stuff and still have little to show for it. After a few years, they sell them in the 5,000 range. This should not be happening. If you do it right up front, you might just become a 6.3 fan. I'm looking for new fans. The best way is to lay the facts on a guy. Owning a 6.3 is a commitment. Owning and driving a 6.3 , you will never forget it.
Dan Smith, Oregon

Dan thanks for your reply.
Have you ever used Star Motors for their rebuilt parts?
Are they good to use if I need to replace rear axles, tranny's or even engine rebuild?
I notice they have complete engine rebuild for 10-13$K, wondering if that includes this expensive injection system as well. I guess I am learning as I go.
I looked at the car an hour agao from underneath. The rear wheel bearings look like they are leaking. Theri is no rust on the car, we used a hammer on the wheel wells and and the underside of the rocker panels.
The only rust that i saw was on the side of the gas tank - the side that faced the front of the car.
We checked the movements on the kingpins they all looked great.
The motor mounts and tranny mounts look ok but I think the tranny may need rebuilding - still noticed the bounciness in reverse at parking speeds.

The brake lines looked rusty towards the back where the gas tank was.
The airbags hold, their is only one valve leaking slightly but the bags themselves look dried somewhat so I would replace those.

My biggest concern in 1. Rust, which the car has none, except where i mentioned. 2. this mechanical injection pump. How do I know if it should be replaced. I noticed the lines going to the injerctor pump are rubber and cracked a little. The fule pump which i understand is in the back by the fuel tank looks like the later model with the orange and brown caps. At 300sel.com, they mention that it should be changed to the earlier model's which pumps more fuel.
The flex disk was replaced a few months ago so it is in good shape.
There is also some surface bubbling rust on the differential casing - it is made of cast though and very thick so that should be ok I assume.

Any other thoughts?

Let's not confuse the FUEL PUMP with the FUEL INJECTION PUMP for the 6.3.

The fuel pump sits back by the rear axle and is available for around $700-800, new. There are two designs/generations, and the first design (which is better in some ways than the second, and was on the early cars) is no longer available at any price except rebuilds, which are getting harder and harder to find. Most people just get a new second-gen unit and be done with it. The second design is readily available and can also be obtained rebuilt from a few places like Star Motors.

The fuel injection pump is a large mechanical 8-plunger pump that sits in the "Vee" of the engine. It is also available from Mercedes and this was what I referenced being $45,000+ new from MB. These can be rebuilt for around $1,000-3,000 (depending on what is done and what parts are replaced) but there are only two places in the US that can (i.e. have the parts, equipment and expertise to) rebuild them -- Jerry Fairchild Industries of Redding, CA and Pacific Fuel Injection of South San Francisco, CA.

As Dan has said repeatedly, 6.3s that sit (as most of them have) are deadly for the fuel injection pumps. These pumps have their own camshaft and oil sump, and are also lubricated in part by the gasoline in them. When the gas dies and the oil sits, the pumps seep and die as well. Not to mention that at 100K miles, the fuel cams and plungers inside start to wear significantly and the pumps get out of synch, and must be rebuilt by an expert. ALL 6.3s with 100-125K miles require a fuel injection pump rebuild, and very few of them have had this done. And, some parts such as some of the fuel cam profile parts, are no longer available and must either be reused or recreated from scratch (by an expert). Reused fuel injection pump parts are never as good as new parts.

The transmissions are available from MB for just over $13,000 last time I checked. This is for a factory rebuilt transmission -- with a mere 1-year warranty. Even with a factory rebuilt transmission, only 50% of them are good out of the box. The other 50% require another rebuild, or replacement, to get one that actually does work as designed. I am not aware that "new" unused transmissions have been available as Dan says for $45K, but if he says so, I bloody well believe him. I have never seen a NEW 6.3 transmission listed in the factory parts catalog at any price -- to my knowledge this has been a NLA (no longer available) part.

Dan is probably one of Star Motors' best customers - he has used them for many many thousands of dollars worth of parts. For many parts they are the ONLY SOURCE in the USA if not world.

ALl rubber on the car (particularly all critical hoses like fuel and oil lines) should be replaced IMMEDIATELY so as to avoid a fire hazard.

Did you look inside the trunk for rust? Particularly on the sides behind the rear wheels?

Cheers,
Gerry

Hi Gerry,

thanks for your post.
yes I looked in the trunk there is no rust.
As for the transmission, Star motors has re-built transmissions for 2800$. Are they at least as good to go with vs the orignal MB unit since the MB units seem to be rebuilds as well.

The steering box bolts (3 of them) all are very tight and there are noc cracks in the frame.

One other thing I forgot to mention is that sometimes on tight turns I hear a click sound from the rear sounds like it is a rear differential. Is this normal? On my GT3 which has a very active LSD it is normal to hear that type of knock/click. Wondering if the diff. should be repalced too if this is not normal on the 300SEL.



If I go ahead and purchase the car, I guess I might as well replace all the rubber mounts the same time i redo the transmission, and maybe even replace the rear axel if needed. Does it matter if I rebuild the tranny in the car or just replace it with a rebuild from Star Motors? Would it affect the car's value in the long run and by how much?

You shouldn't have to rebuild your tranny unless it is severely leaking externally, or severely leaking down. This means leaking down overnight. Mine takes about 7-10 days to leak down. You'll know what I am talking about when you experience it.

Transmissions don't affect value. You could have your own tranny rebuilt but the car would likely be out of commission for longer while it is being refurbished, vs. pulling yours and sending it to the rebuilder as a core exchange for an off-the-shelf unit. Though I don't think that there are too many "on the shelf" units waiting to send out. Typically they will just rebuild what you send them, and you can expect your car to be inop until you get it back.

Remember that the price may have changed -- you need to call Star Motors to get pricing and details. This may well be an old price list. And don't forget to factor in labor + shipping costs. So I think with all of that it's well closer to $3,500-4,000 for a rebuild.

The mounts would be a prudent thing to replace out of pocket -- both engine and transmission. Engine mounts are around $200 apiece and the transmission is under $100 I believe. Subframe mounts for a kit are around $200 for a pair give or take -- these aren't exact prices, though I can look in the latest price list when I get home to provide them to you.

Dan Smith is the expert on differentials and transmissions as he has rebuilt and replaced many of them, including having units of both types custom-made to his specifications. I am still on my original transmission as my car is a 56,000 mile car. I live with the leakdown at this point, as it isn't a major deal for me, and my car isn't a daily driver. (I use a 560SEC and a 500E for those purposes )

Cheers,
Gerry

Gerry, my last post confused some. No, trannies(NEW), are not 40 plus thousand. I believe they are around 17,000. Without mentioning names, a M100 member purchased one. It had that friggin leakdown, new out of a crate. No, don't buy a new tranny, rebuild them. NEIL DUBEY's firm is the only one I would ever buy anything from, no bull. That's Star Motors in Endicott, New York.
Trannies go south for other reasons also. I've torqued a clutch disk into the shape of a pie plate. It still ran great, but I could tell a slight, slight difference so we had it restored. That, Gerry, was on the Bullet. Other probs are the main valve body and governors, neither can be rebuilt, great eh. Lastly and more common, the fluid coupler can leak. That is very bad. Recall the new one I bought on Ebay. In fact it was used and shot, total junk. Yep, that what it was. Oh well!!!
The cracked rubber lines to the FUEL INJECTORS, not important at all, just cosmetics. Brad on the Eastcoast knows how to make them look new, I don't. Rust on the pumpkin, no prob. Rust on the fuel tank, no big deal as well, you are going to rebuild it NOW, NOT LATER. Hope you pay attention to that sentance. King pins condition, no big deal, cheap to rebuild the whole front end, about 5,000 $.
I think, I now know what you mean by that bounce in reverse. Gerry, help me out here, but this is very common. It's cause, grease monkeys missing the key zerks. It's too late to apply grease but cheap to repair, about 1000 $. BUT, it's not important. I had one do this for a year before I even mentioned it to my mechanic. He explained the whole thing. Most went over my head, but its a part very close to the rear diff associated with the sliding axle. There is a fellow in Florida that makes a stainless or chromed system that won't rust a fail. Gerry, this guy gave a tech session on it in Portland. Any help?
On the mechanical fuel injection system. Key indicater is vapor lock but not all vapor lock means this system has failed. Confusing, welcome to the 6.3 world.
Dan Smith, Oregon

Gerry - Do I understand that you have a 56k mile 6.3, priced at $18,000 - and it's not selling? That's ridiculous. Have you tried Ebay? Europeans seem to be in a slightly crazed buying mode with the exchange rate what it is. There's got to be somebody looking for that car at that price.

Dan,

Mercedes DOES NOT OFFER new, unused transmissions for the 6.3. (In your previous post, you said that they do offer them "for a mere $45,000") Rather, they offer rebuilt units, and ONLY rebuilt units. Yes they are detailed to look like a new unit. But they are USED. There is no production line to create new 6.3 transmissions.

Star Motors' units are rebuilt (subcontracted to) by European Exchange transmissions in Hackensack, New Jersey.

The part number for a rebuilt 6.3 transmission from Mercedes is 109 270 09 01 (up to chassis #2838) and 109 270 14 01 (from chassis #2839 to chassis #6526). The latest official MB price lists, lists both transmissions for the price of $9,170. This price has come down at least $4,000 from the last time I checked it a year or so ago. But it could easily go back up again -- MB changes their prices monthly these days....

Last time I knew, valve bodies were around $1,200 but they could have gone up or down in price, who knows...

Yes, I mentioned the brake hold bearings in an earlier post being a problem with many if not most 6.3s. As you say it's because most people don't bother to grease the fittings where they are located on the axle tubes in the area of these bearings. So much for "expert" 6.3 mechanics, right? Last time I knew, there were either 13 or 18 grease nipples on a 6.3, I can't remember which number is correct. I think it's 13. probably one-half of them are really hard to get at and require a knowledgeable mechanic familiar with a 6.3 to even know that they are there. It's why Larry at MBI is such a valuable mechanic -- he knows where these little things are.

I like to tell people that MBI Motors in Portland Oregon is the only Mercedes independent shop in the USA that has a full-time M-100 mechanic on staff besides Star Motors, but that's not a fair comparison because Star Motors is an M-100 specialist.

Cheers,
Gerry

I haven't busted my a$$ to market the car. I don't really need the money, and I have a nice storage garage for it. I just drive it enough to prevent the "garages kill" syndrome that happens to all 6.3s that are not driven (it is a disease that was first diagnosed by Dan Smith himself).

I have posted it to a couple of web sites but not recently.

Remember that 98% of all 6.3 buyers see a 6.3 for $7-10,000 and get stars in their eyes. They think they are getting a hot rod for super cheap. They as Dan said you talk to them a year or two later, and they're $20K into the car with another $50K to go to get their running parts car into drivable shape, and they're looking to ditch the headache in their garage that their wife is nagging them about, for $5,000 just to get it gone.

Seriously this is the saga of 75% of 6.3 owners. I've seen it with dozens of people in the past 5-7 years.

These same "bargain hunters" are afraid to spend the $15-20K up front to just buy a great well taken care of 6.3 and then just put the $1-5K into it annually to keep it up.

People are cheap. That's the bottom line. You get a lot of people out there who want to get into a Mercedes (or a fancy Mercedes) cheaply because they get delusions of grandeur or bitten by a bug of having a vintage hot rod. You can't reason with these people. They see "6.3" and "$10,000" together and think they've struck gold.

In reality, it's a recipe for financial ruin, or divorce, for those who aren't financially prepared for it.

So bottom line, if someone wants to pay my price, the car is theirs tomorrow. The right person, will know what he/she is getting when they see/drive my car. Everyone else, 95% of prospective 6.3 drivers, merely see a 6.3 that is double their price range. They don't stop to think about the fact that it is among the best cars that they could buy, and that in reality the $18K I ask is a bargain.

So I sit on the car, and am happy to do so. It still gives me plenty of joy -- just not as much these days as the far more reliable, better bang-for-the-buck and less expensive to operate 500E/E500. If you know of anyone who would be interested, please have them email me at gerryvz@comcast.net. I get plenty of looky-loos, but they always turn out to be cheapskates once I name my price. Fine with me.

Cheers,
Gerry

Gerry hasn't told the whole story. Lets say the track tells the tale. Gerry's 6.3 is as far as I can recall, the quickest USA stock 6.3 through the 1/4 mile. AND, he never even ran my trick race tires. If so, I believe he could have trimmed a bit off that time. Thus, it has a very nice engine.
Also on the miles, yes, it appears to be real. I was the first 6.3 fan to fly to California and veiw a former pilot's, then deceased, 6.3. It was stored for years and years. A local Portland attorney bought it, trucked it to the famous Larry Miller of MBI who restored the parts prior to fireing it up. After a few years, Gerry purchased it. It is a silver blue with red interior.
What does it need, nothing mechanically, nothing. The fact that it is mechanically sound, that is a very rare occurance. Compare that to the typical EBAY parts car. Recently there was a great looking 6.3 on EBAY, but you need to see it in person. Anymore questions, feel free to ask. This is the only model that interests me.