Goatman

Any things a new buyer should be aware of when looking at the above model?

175K, auto trans, everything supposedly works.


Thanks!

Untertürkheim

Check AC operation. Also, make sure the coolant is MB and that the car has a very good documented history.

Any particular reason you want a 300SE?

Goatman

It happens to be for sale.

Why?

Untertürkheim

Just wondering if there was a particular interest in this model or whether it was more of an opportunistic move. Either way, check to see how the car wa cared for, that is the key. Also, take note of the oil used in the car.

Goatman

I'm just looking for something with good size and reliability...


Do they all take Premium unleaded? The compression ratio doesn't seem high enough to require it on that engine...

Untertürkheim

Yes, Premium only. Honestly though, if this is a concern, this is the wrong car. Everything on these cars is expensive, and the $2 per tank extra on fuel is by far the cheapest part of ownership.

Goatman

Just don't see the need when the compression ratio is relatively low...

Untertürkheim

9,2:1 is not really low, and keep in mind that these engines run lean and hot with aggressive timing.

Goatman

Most of the newer cars run 10-11 compression on reg. gas now-a-days..

Ah well....

Untertürkheim

There are diesel options of course, and I believe the US 380 models could run on regular.

Goatman

Been looking at the diesels. Have an offer one on currently. Seem to be very expensive given the price of fuel.


If I could get one that ran on regular gas, I could get another 124 miles per dollar spent on fuel/gas.. Even with 28mpg vs 24mpg...

Untertürkheim

I think you should check your math, I have never been able to drive 124miles/$

Using regular in a car that requires premium is a false economy, it ends up costing more.

Mercedes are expensive to operate, not the kind of car if you are looking for low operating costs.

Goatman

My math is 100% correct. I was using the standard of 20 gallon capacity for both vehicles. You get MORE value with the gas powered model per dollar spent than with the diesel with prices being what they are.



The mileage figure I provided is correct, just misinterpreted.


Say both cars have a 20 gallon tank, just for standardizing both cars:


Diesel gets 28mpg (84' 300D) which means the range on a 20 gallon tank is 560 miles.

Gas gets 24mpg (91 300SE) so the range is 480 miles.


As of yesterday, per the internet, the cheapest diesel in the area was 3.55 per gallon. At 20 gallons, a fill up costs $71.00.

As of yesterday, per the internet, the cheapest gas was 2.49 per gallon (regular gas, which I used in my original calculation). At 20 gallons, a fill up costs $50.00. With premium, the same fill up costs 56.60. More than your stated 2 dollars per tank.

The difference between 71.00 (diesel) and 56.60 (premium) is $14.40. Take that $14.40 that you already spent filling the diesel to go 560 miles and put it into the tank with premium. That gets you an additional 5.1 gallons, which allows you to drive an additional 122.4 miles. Add the 122.4 miles to the original tank's 480 mile range and you get 602.4 miles vs the diesels 560 miles.


Now, the acutal number cost of the two fuels is NOT important, the SPREAD is. Same thing with the tank capacities.

As my original statement said, you get MORE VALUE per dollar spent with the gas motor given the price of diesel for the last 8 years.


And that doesn't get into the higher initial cost of the diesel powered vehicles either...

Untertürkheim

Just a couple of points:

I owned a 300SE, and I never saw 24 MPG, or even close. I was able to hit 20 when driving on the highway only. Even though the 3,0 I6 is very efficient, the gearing is so low on the 300SE(L) models that 80MPH was nearly 4000 rpm.

Also, your diesel price is hugely inflated, so I can see how it would change the outcome of your analysis. Also, your fuel stations must practice strange pricing, 90% of stations have mid grade and regular at 10 cent increments per gallon over regular, while your prices are a bit higher (at 10 cent increments, it would be $54, a $4 premium over regular, which lies nearly halfway between both of our statements).

Even assuming your analysis of fuel costs may be correct, you fail to take into account the operating costs of gasoline vs diesel models, this extends beyond the savings related to spark plugs to the more complicated systems present in the M103 vs a the OM617 or 603.

The fact is, an S class will the the least efficient MB due to its size and weight, and if you want an efficient MB that runs on regular you are left with only one model, the 190E 2.3 (the 2.6 also requires premium). Keep in mind though that engines tuned to run on premium are generally more efficient so that there is no cost savings to buy an engine tuned for regular, all things being equal.

Goatman

My fuel prices were taken directly from the gas staion. No over inflation at all. All my numbers are 100% accurate.

Seems to me diesels are cheaper unitll something breaks, then its all over. Given the age and mileage of the vehicles I'm looking at, the gas will be cheaper to maintain. After all, the only differences would be the engine internals, the external components would have the same durability/failure rate.


If I'm stuck with the ****ty 190's, I'd rather walk...

Untertürkheim

Did not mean to say you inflated the prices, I was referring to the gas station.

Goatman

LOL. No doubt they're inflating the prices...

wbain

I run regular in mine with no problems.

At that mileage, look for front end wear, check the ball joint boots for cracking, the flex discs, oil consumption. If the oil mileage is a quart every 800 to 1000 miles, you will need to replace the valve guides and have the valves and seats surfaced.

Rust can be an issue as well. A good PPI will help.

It's a big car with a small engine that's geared high. Figure 3000 rpm for 60 mph but the engine is strong so RPM is not an issue. I het around 22 with mostly all mighway miles.

Goatman

Any way to check the flex disks while the car is on the ground?

Untertürkheim

No sure way, but if there is a "clunk" in the drivetrain and/or excessive lash when shifting from R to N to D, it may be the flex discs.

Goatman

K. I may go look at the car this weekend. The more I look at these diesels, the more I'm convinced the owners think they're made of gold..

Which they certainly are not...

Untertürkheim

Be sure so ask about oil consumption and check for signs of head gasket weakness on that car. Because of the low gearing and constant high RPM I would try to find one that has been running on synthetic oil.

Goatman

I'll see what I can do. Although the mileage seems low and waiting around for a car that's had synthetic probably isn;t going to happen in my time frame... This car seems to be well cared for.

In the 7 years he had it (3rd owner), the waterpump, thermostat, all brakes, distributor cap+rotor, steering stabilizer and battery were replaced.

Untertürkheim

Other things that may go wrong: fan clutch, fuel inectors and/or seats. Check under the hood for any cracked or disconnected vaccuum lines. Make sure the coolant is a pale yellow, not green or pink, most important that he has been using MB or Zerek G05 coolant, any others will damage the cooling system.

Listen for differential whine, most people never service the diff. Also check the trans fluid, people are usually very sloppy about that using cheap fluids, not draining it all, or not changing the filter.

If you end up getting it, I would still go through and change all the fluids and filters. I would reccomend Valvoline Syn 5w-40 or M1 0w-40 for the engine, and the corresponding syn ATF and differential fluids.

Also, check the power steering fluid to see if it is dirty,

Goatman

I'm an Amsoil dealer, so I think I've got that part covered...

Will do. I'd ideally like to get the thing over to my mechanic and even do a compression test on it, but he only works during the week and I don't have any time to get the car there. I may just have to wing it.


Anyway, thanks all for the info. I have a few good places to get started.