Hi everyone, I've taken ownership of a 83 W126 (280SEL) a couple of months ago, and I'd no records of repairs done by the previous owners. While I'd love to have an engine overhaul done (the engine is a tad noisy, and fuel consumption on the high side), the cost is holding me back. I'm looking at USD$3000 (parts n labour) for a complete job at the workshop. So I'm saving up for it, and the reason why I'm looking at an overhaul is because I intend to keep the car for another 10 years. I need advice on this: are there any temporary measures (that do not cost too much) such as replacement of minor parts or adjustment of certain things that would improve the engine's condition, until the time when I bring the car for an overhaul? (likely 18 months later) As an illustration, I have had the intake/exhaust valves adjusted, and the idle control valve plus ignition control module replaced, and these have helped to clean up the idle a bit. Basics such as plugs, wires, cap n rotors etc. are all replaced. My query now is targeted at the engine body itself. I hope I do make myself clear. Please advise me, thanks! Mervyn 1983 W126 (280SEL)

I did not see any reason in your post to think your engine needs rebuilding.

You state that its "noisey". The noise should be addressed. Do you feel it is engine bearings? The M110 has fairly noisy valve mechanism. If its excessive you might want to fix the cause; a bad cam or rocker arm.

You state that it uses too much fuel. That is very unlikely to be a mechanical issue. Do you know that your compression is poor? The running should be addressed by a competent tech before you decide to keep it 10 years. My wife drove a 1981 280SEL for 14 years and it got about 21 mpg on the highway at 80.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Hi Steve,

It's me again, and thanks to you, I've got my climate control questions addressed.

Yes, I too have heard that the M110 engine tends to be rather noisy. The "noise" in question, I believe, comes from the "tappets", and sounds like a "tapping" noise. Definitely not the timing chain. Apart from generating noises, what other symtoms do faulty cams/rocker arms exhibit? If the rocker arm job is not too major an undertaking, then I may consider replacing them.

So perhaps I should have a compression test done, am I right Steve? Ok, shall do that, and from there I'll determine the fuel consumption issue.

In summary, can I suppose that the above measures should be adequate for the moment?

Thanks again Steve!

Mervyn
1983 W126 (280SEL)

Oh, one more question:

Hope I dont sound silly, but can anyone tell me what is the purpose of the rocker arms?

Thanks!

Mervyn
1983 W126 (280SEL)

What is the purpose of the rocker arms? If your car needs an overhaul,and you do not have the money at the time the best thing to do is park it until you have the money.Also Buy some books on the car and learn strange things like what do rocker arms do.Good Luck Michael.

The cam doesn't push directly on the top of the valve. The rocker arm is a lever that is supported on one end by the ballstud (adjustable pivot point on your motor, the top of an hydraulic lifter on V8s after 76). The other end sits on top of the valve. When the cam lobe comes around it pushes on the wear surface of the rocker arm about 60% along the distance from the ball stud to the valve.

The compression check will give you a baseline for future reference. I would suggest dealing with the performance issues first and see where they take you. If I were testing your compression I could gauge the amount of carbon in your engine. That is only because I have a lot of experience with my gauge and that engine. On my gauge I would suspect carbon build-up on a motor with over 170psi compression.

Decarboning an engine is another chore that improves with experience. I really hate to describe my technique to anyone who hasn't done it before. The last time I did a S500 I was pretty scared that I had bent a rod when the misfire continued after I finally burned all the smoke out on a test drive. Thankfully I had only been a victim of misfire identification and cycling the ignition reset it.

Decarbonning requires harsh chemicals and/or mechanical shock. My first experience with it came at my first dealer job (as a Chevrolet technician while I was going to college). Being next to I-75, we used to get all these cars towed in from the interstate gas stations with rod bearing noise diagnosis. The old guys would take a motor (absolutely DO NOT do this) and run it to 3 grand and in the same moment start dumping a quart of water through the intake while flooring the throttle. The engine would stay at 3000 due to the combined effects of the throttle trying to raise the speed and the water drowning it out ( a very sensitive balance with engine damage being just a short distance from carbon removal). I never was able to get the nerve to do this with success. This is one of those things that you can't just do more of a smaller amount. In other words, what one must do is smash the carbon with the water; one can tap on it all day and nothing will happen. The force level required is very close to that which will ruin the motor.

Luckily there are various tools and chemicals that bring this activity to those not so daring. The tool Motovac or any of its generic buddies can do a good job by spraying a chemical through the cars injection system with the added benefit of cleaning the injector rail and injector. I have gathered the experience to do a harsher cheaper mechanism using the product X66 (AC Delco) and the directions on the can. This is a very strong chemical, be VERY careful!!

Even with experience though I was sweating that S500.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Steve,

What a wonderful piece of information!

It certainly has enlightened me quite a bit, and as always, the learning curve is steepest at the beginning. But thanks to fellow members in this forum, it certainly makes it easier.

I'll take note of your advice, thanks again Steve!

Cheers!

Mervyn
1983 W126 (280SEL)

way back when! I knew a mecanic that would buy beautifull low milage well kept Cadilacs from elderly couples for very small sums because the cars ran so poorly as the engines were full of carbon. Most of these cars were driven mainly in the city and at low speeds all their days.This sly old fellow would then do the above water trick he used a windex spray bottle and sprayed the water at his practiced rate down the carb as his assitant keep the revs up just so ,you could hear those big powerfull engines coming back to life........
william Rogers.....