300SE-89 High RPM
 

Thats about right for that car. they had to gear down the car quite a bit to get that m103 engine to pull that big body.

Nice find BTW, can you post some pictures?

Thank you
 

When you post reply, scroll down, and there will be a manage attachments button.

Welcome to the forum!

That is a common complaint on that engine, especially with an automatic. You have a low mileage car, but it might help to replace the motor mounts and you might get rid of some of the buzz. A 4000 rpm you are running at about 70% of redline which is a good place to be for efficiency. It is a pretty speedy engine and really does not pull well until over 3000 rpms. I have a 5 speed manual on a 300E, and at highway speeds I am looking for another gear also.

That definitely is a good and rare find. Hope you figure out the workings of this site soon and welcome to the forum.
I was always puzzled at the high rpms on my 88 300 SE also. Just wondering if that contributed to the "cam towers pulling loose" problem w/the M103.......

THANK YOU ALL FOR TAKING THE TIME TO COMMENT. GIVE ME A FEW DAYS TO LEARN HOW TO NAVIGATE THE SITE AND I'LL SHARE FEEDBACK.
BEST WISHES TO ALL.
JARR56

welcome to the best of forums. looking forward for your 300se pics.

300se /89

My 1990 300SE engine revs are 3800 at 80 MPH and 4300 at 90. However, it will, and has, run like that for hours on end. I've gotten used to it. The engine seems really at home in that range.

I thought that the cam tower problem was on the 86 and 87 early production models and then MB fixed that problem in mid 87. Haven't heard much of the problem on 1988/89 models. Hope that is correct as I have an 89 engine in my 86 for that very reason.

Welcome to the forum and as a fellow 89 300SE owner you will get used to the RPM's. My 300SE has 155K on it so yours is just broken in! One thing that is nice about the higher RPM's is that the car will pull hills on the highway better. There will not be any of that shifting/gear hunting nonsense that I get on my other overdrive equipped cars. I will get 20+ MPG cruising at 60ish. Enjoy and I look forward to seeing your car! She has spent a lot of time just sitting.

3.46:1 is the rear ratio, so with a 1:1 final gear that is the RPM you receive.

If you are missing your under body shields/sound panels, try to find them. They really help keep the buzz noise down to a minimum at higher speeds.

I have a 1988 300SE WITH THE (#5) CAM TOWER BOLTS STRIPPED OUT OF THE HEAD at about 130,000 miles. Evidently they (MB) skipped this one. Not trying to alarm anyone, just throwin' that out there. I was only going about 65 mph when it happened.......

I think all 86-89 M103's had issues with rocker,cam hardness as well as the cam tower issue.

89 300se
 

A good model but has a few weak points .High reving among others.

My 300se Euro has 140K KM's . Around 120K i first noticed a slight black coloring of the ATF. At 140k KM i removed the transmission for a leaking front seal . Turned out to be a leaking front pump seal ring ,On checking the rest of the transmission the Reverse Plates were completely worn down ,replaced them .as well as a complete reseal kit .
Quite Surprised at this unsusual wear of reverse plates with negligible wear on rest of transmission compnents,
regards

When my reverse goes out, I'm going to insist that they only replace what is worn (Reverse bands). The Forward gears are very robust on these transmissions if properly maintained.

Reverse is a set of clutches, not a band. Just so you do not get taken in the future.

You say Potato, I just call things what they aren't. Thanks setting me straight. :D

Just do not want you to 'be hand' when you lose reverse and a shop takes you. Been down that road before years ago and never again.

I have that huge 722.3 PDF if you want to check it out. Shows about everything that can be shown regarding the 722.3. PM me with your email and I will send it to you.

Yeah they are geared low... and I concur with "Franco". I dont think our '88 300SEL runs quite that fast at 70 mph. I think ours is more like 3300-3500 @ 70 mph. Are your tires smaller than what the car originally came with? Maybe they are smaller, causing the faster turning? Just a thought.

I posted my RPMs as 3800 at 80 MPH and 4300 at 90 MPH. I didn't post my RPMs at 70 MPH.

The tires I have on the car are the exact size that's recommended and that the car came from the factory with.

Sorry. My post was directed to the original poster who stated that. Sorry for the confusion.

1991 300e 3500 RPM @ 80 mph. Rides smooth!

Well, actually, the tire size won't make any difference when comparing speedo and tach. They are both taking the same altered reading from the driveshaft. The car will go faster/slower, but the tach/speedo won't know it.

Biggest engineering FUBAR Mercedes made - super low gearing, and 2nd gear start on the 300SE. All they had to do was make it start in 1st gear all the time, and put in a taller diff to give lower cruising RPM. But, we've run it at 4000 RPM fo hours at a time, for over 200k miles with no major issues, so I guess it can take it.

DG