Let's talk about engines

[senorunimog]

M114, (new version of the m108) Is also a variant of the M180, however it is in the middle, having only every pair of cylinders squeezed together. So cooling shouldnt really be an issue. I haven't had cooling issues in my sedan that couldnt be traced to a water leak, so I dont think the sedans are that prone to overheating... Unimogs with M130 conversions on the other hand....now that's a different story.

I hope you didnt shave the head too much, it makes all sorts of nasty problems with the cam timing.

[mercmad6.3]

As of late( i haven't been here for almost two years) I have a 380SEL with the alloy M116,a M180 engine and trans I was given as payment for solving a problem ,a M116 3.5 engine and trans, A 500SEC with the M117 engine,a W111 220SE with the M130 injected engine ,my W114 with the M110 and my current project,the 300SEL 6.3 ...OK so what is a M100 like to own and run?....AWESOME!!!!!
I don't care what anyone says,I have owned/still own enough V8 Mercs to know that the M-100 is still King!.
Imagine if you can the sheer thrust ( Mercedes even describes it as this..) when you touch the acelerator,not push it down mind,just ease it on and the car starts moving very rapidly.I have just spent a few days rebuilding one for a fellow M-100 club member which is high compression Euro version and apart from the pinging caused by modern fuels this car is an absolute weapon ,so much so I had to warn the owner Not to push the acelerator to the floor because he stands the risk of breaking the diffs sliding joint.
These engines really come into their own at high speed when you can travel at say 70MPH and acelerate to over 120MPH in seconds,the engine doesn't even begin to feel stressed as you overtake everything that bears a japanese name plate...
OK,well how about service...These engines have an undeserved reputation for complexity which is wholly undeserved.They are very simple to both maintain and repair,the main problem areas are dirty fuel cuasing fuel pump problems,the fuel pump itself not being maintained corectly so that the oil level is allowed to overfill ,and wear ,which is mostly confined to the governor.
The other problem is the ancient twin point distributor.This is best addressed by fitting a Pertronix ignitor and a 55,000 ohm resistor in the tacho wire to allow the the tacho to read properly.
Oil is expensive because these engines need a lot and should be changed every 5000 miles.
The tappets are easily adjusted and I can even use the tool I use on the m110.
Timing chain wear causes tuning problems and frequently used m-100's should get a new chain every 12-14 months.
You will never hear of a m-100 with a broken chain ,it never happens and as for guide rails,mine has almost 200,000 miles on it and the guides are the originals.
These engines are noisy when cold,with lots of tapping and piston slap,loose tappets are not normal but are common.
Finally ,as befits any engine that was initially designed for the best car in the world,they are almost indestructible,the engines in some parts cars I have seen generally still being in very servicible conditon with car falling to peices around them...and if you check prices in the USA ,they range from parts donors at $1000 to real gems at $100,000 plus for a 17,000 mile original.
Certainly no investment value( like a gullwing....) but a lot more fun to drive.

[pj67coll]

Originally Posted by mercmad6.3

Timing chain wear causes tuning problems and frequently used m-100's should get a new chain every 12-14 months.

I know practically nothing about m100's but surely this is a typo? I've never heard of any car ever requiring a timing chain replacement that often.

- Peter.

[mercmad6.3]

No it's not a typo,the M-100 will run perfectly well on a stretched chain but if you do ,as I said ,a lot of miles as I do,the chain must be changed every 12-14 months because it's stretches like you wouldn't beleive.The MFI runs off the same chain,so you can imagine the strain on it.(248 x 3/8 links!! a long chain)
To keep the performance up ,the best way is to change the chain frequently .
It's an easy job,far easier than a m117 as an example.It's all to do with the injection ,it is set at 60 degrees and if the chain has more than 12 degrees of stretch,it puts the MFI timng out,causing stumbling,excessive fuel consumption and generally poor performance. A lot of these engines have been run in this state because neophite owners didn't realise there was even more performance in there to be found once the pump was injecting at the correct time and the cam timing was at spec.
Don't forget,these cars ( the 6.3 especially) can do the 0-60 dash in 6-7 seconds and I have a freind in Victoria whose Stock 6.3 runs 14 second 1/4 miles on stock tyres , the the diff is the stock 2.82-1 .

[jahawk]

My 1972 250C has had a leak between #1 and #2 cylinders for a few years due to an erosion at top of block between cylinders. When I put rebuilt head on several thousand mile ago I saw the erosion, apparently caused by heat and/or cooling system corrosion but did not weld it up, as I now someday intend to do. Other than running putt-putt like a tractor at idle and having some issues at start, the engine runs good at speed. It stinks a bit from poor combustion at those cylinders and people ask if its a diesel. It's a tribute to the engine that I have been able to drive it as needed. I look forward to the time when I can enjoy the smooth straight six sound.

[KyGuy]

I think I know which of Aussies Mercmad6.3 is and trust his knowledge. I've got less than 90,000 miles on my 6.3 block. It's a true beast. Maintenance needs, but not a lot of repairs. I did the timing chain, tensioner and guides (well…had them done) a couple summers ago. Noticeably quieter and some performance improvements. I was using oil (dx’d as value seals) and switched to Lubro-Moly and have had no issues since. We’ll see.

As a general rule, these engines don't break. The MFI poses problems most rookies can handle or afford to have handled. Valve seals need replacing. Timing chains need replacing, but few major failures.

Besides, there's nothing like the feeling of being pushed back in the seat when the M-100 lights up! Miles of smiles.

Ciao for now

[STORMINORMAN]

... that Geoffrey Howard's book, Mercedes Benz S~Class, Arco Publishing, 1985, to be one of my favorites.

It has a bit about the S-Class cars from the SS, SSK through the W126 Energy Concept cars of 1982.

Interesting reading, IMHO.

Cheers!

p.s. Great Thread!

[mercmad6.3]

I just replaced a timing chain in a 6.3 that has close to 200,000 miles on it.It was so badly worn ,that although the car would run strongly it was way down on power.I did the usual quicky check by lining up the cam notches and then looking at the crank mark..it was so far out it wasn't even showing a timing mark! and Rattle!!!.
I installed a new chain,the rails were like new as are the cams and sprockets,so when I fired it up it ran as smooth as any late model M117 ( albeit a bit lumpier at idle) and is running so clean and smooth It is hard to comprehend the fact the chain is the Factory original!
But here is another engine I'm playing with at the moment...an M180 in my 1926 Chev Dirt track car....

Cheap ...i was given it exchange for storing a couple of Finnys...and easy to get parts for, including complete Ex NATO unimog engines for $2,000.

[Karsten]

I like the M180 a lot, get it running right and it is a real pleasure. So elastic, smooth and reliable.

Karsten

Originally Posted by mercmad6.3

But here is another engine I'm playing with at the moment...an M180 in my 1926 Chev Dirt track car....

Cheap ...i was given it exchange for storing a couple of Finnys...and easy to get parts for, including complete Ex NATO unimog engines for $2,000.