Success

[WGB]

1) All Mercedes Benz Diffs of the era from 116, 126 and 124 that I have ever owned have had some sort of diff noise which developed after the first few Km were over. My 6.9 is no different from the other Benzes I have owned..

2)Is this additive for the LSD or to silence the diff PB - could you run the parrt no past me again please?

3) I have never found babying a new motor to be good for it - particularly as regards oil consumption - but bullying it too much in the first few hundred Km is not great either. I prefer starting at the recommended rev limit and then when a few hundred Km are past I slowly increase  the revs and the power used until at the end of the prescribed mileage the car is doing everything it is allowed to do.

Bill

[TJ 450]

It sounds like I should just drive it normally, although that's already happening anyway. BTW, your driving yesterday was fine... Nathan was a bit rough though, given the engine temperature at the time.

However, I don't think I was driving slowly at all, just very smoothly.

Anyway, the evidence is there as to how these cars should be driven. The smoothness of even the transmission's operation now is no coincidence... it's a credit to you guys for showing me how things should be done.

BTW, the performace of your car PB, is still considered phenominal off the mark... perhaps it has something to do with your exhaust system allowing better breathing at low RPMs?

Tim

Editied for additional content again.

[koan]

The recommendations for running in an engine have changed over the years, haven't seen a "Running In, Please Pass" sign for along time

Most recent thinking appears to be drive it normally, open it up now and then, avoid prolonged running at any throttle opening and RPM, and change the oil often.

koan

[TJ 450]

That sounds pretty logical, Koan.

I've now realised what caused the missfire the other day. Yesterday when I went to start it, there was only enough juice to just turn over the engine.

I went out today in it only to find the tach bouncing and cutting out and the engine eventually died, so I was stranded on the side of the road!

So yes, there was a huge voltage drop, because the alternator was not charging the battery, or at least it was intermittent.

I already knew that the alternator was suspect because of bearing noise and it is no surprise that it failed. I'll remove it tonight and inspect the brushes and regulator.

Tim

[Big_Richard]

the 6.9 alternator i donated to you is also shagged, it would only produce more than 12v at 2000rpms or greater, so effectively at idle the battery was discharging.

the new one produces 13.8v even at 500rpms engine speed.

Don't know what the difference is, but the brushes in that thing i gave you are pretty atrocious, 3mm meat left.

sadly, while my car from standstill acceleration hits you like a baseball bat the the head, it feels like a breathless pig near the redline, but all 6.9's are like that due to the piss poor intake manifold design and the drinking straw exhaust manifolds and antiquated "engine management" system. There is no substitute for modern technology & engine designs I'm afraid. 6.9's can no longer be considered fast cars these days as they simply arent.

[TJ 450]

I just had a look at that alternator of yours, PB. The brushes are pretty bad. Fortunately mine still have plenty of meat left on them... one was stuck and they were all gummed up. The spring loaded contact for the regulator was covered in grease, so I used some CO Contact cleaner and got rid of all the muck. The bearings are OK, so it's either the air pump or the A/C compressor that has the bad bearings.

I charged the battery and ensured that the terminals were secure and took it for a test drive. It seems to have solved the problem, which is great.

Here's the regulator. Unless the actual regulator is kaput, it looks good to me.


The car has now done about 400km in my ownership and it's getting better all the time, with the exception of this mishap.

Regarding the performance, I would say it's pretty quick by any standards for the size and weight of the car... but by no means comparable to modern performance cars, with the exception of torque. You could still out accelerate the vast majority of cars on the road today, I would reckon.

I'm in the process of uploading a lazy acceleration video and it will be posted shortly. I didn't feel like lighting up the tyres tonight.

Evident in the video is the whine, which seems to be subsiding as the car is getting used.

Tim

[TJ 450]

Here's the film:

Bear in mind that I didn't open the throttle all the way. It was not even trying. Perhaps when I'm in an open area, I will demonstrate the real deal. I also plan to take it on a 6-8 hour return trip out into the Wheat Belt next month, to stretch its legs a bit. This will be after I get a few annoyances and issues sorted out... the biggest being the exhaust leak at the RH manifold joint.
http://www.youtube.com/watch?v=2uaVIH2eUZs

Tim

[koan]

The source of noise will be the air pump, my old one sounded like marbles in a bucket. I got a rebuilt unit off ebay for less than $50, still noisy but not as bad.

Pulled the old one apart, don't remember any replaceable bearings, noise is from the graphite vanes "flapping" about.

To borrow from Rolls-Royce "performance is adequate" is how I describe 6.9s. Has sufficient power to see off 90% of other cars. The thing I like is cruising in top gear, a short bust of throttle and I'm travelling 30kmh faster with out drama, no down shift, no noise and no strain (just a 1/2 litre of fuel gone).

koan

[TJ 450]

It is the air pump. I used the "screwdriver as stethescope" trick to find the noise.

To borrow from Rolls-Royce "performance is adequate" is how I describe 6.9s. Has sufficient power to see off 90% of other cars. The thing I like is cruising in top gear, a short bust of throttle and I'm travelling 30kmh faster with out drama, no down shift, no noise and no strain (just a 1/2 litre of fuel gone).

That sounds pretty good to me. My 450 still requires the occasional kickdown when on the open road. I would imagine brisk overtaking to be a relaxed affair in a 6.9.
In other words, it's the ideal car for me.

I gave the car a proper Italian tuneup this afternoon. It settles down to a 500rpm idle that is absolutely smooth... I'm most impressed.

It's now time for the 6.9 to go into hibernation at least until the weekend.

Tim

[Big_Richard]

just be careful giving your 6.9 too much of an italian tune up, you wouldnt want it confiscated for 28 days after all the effort youve gone through

just keep it sensible, like my example i set for you 

[TJ 450]

The Italian tuneup was performed along Toodyay Rd. and covered a nice range of RPMs. There was no reason to attract the attention of the "Law Enforcement Officers" and the fun was not compromised.

The Metropolitan Area is no place for an Italian tuneup, unless you hold second on the FWY... the aforementioned 28 days is then well within the realm of possibility.

Tim

[Big_Richard]

ahh yes, that's one of my favorite enjoyment driving roads and it was an excellent day for 6.9 cruising - it actually wasn't raining for a change!

[TJ 450]

I think it's one of the best roads around for scrutinising a car's handling and performance. One does need to be sensible though and remain withing the confines of the law.

I'm still in the process of evaluating my opinion of the car's handling and I will inevitably compare it to the 450 when I have reached my conclusion.

Tim

[Big_Richard]

by the way, i forgot to mention,

with my new everything approach to the front and rear steering/suspension refurbishment. that annoying floaty "feature" of my 6.9 wandering off on a direction of its own on the undulating, gently curved section of the freeway has disappeared. I have no idea what was causing it and probably never will. where you point the steering wheel is prezactly where it goes.

[Big_Richard]

OIL ADDITIVE - 30ml, Noise reduction, locking differential: 000 989 82 03

Application: 300SEL 6.3, 450 SEL 6.9



Also note that, off the shelf, LSX 90 garbage isnt suitable for these Diffs, you must use the genuine MB LSD oil.