analogcd

Service manual states that method to refill SLS system is to run engine for approx. 1 minute at medium speed. While filling up, load vehicle rear in trunk with approx. 150 kg (330 pounds) or hold down so that level controller can be set to "filling". Filling position is when the level controller valve arm is in the upper position (above horizontal). Manual states system can also be filled with connecting rod disconnected on lever of level controller in position "F" (filling). For this purpose, run engine at medium speed for approx. 30 seconds. Then mount connecting rod again. Summarizing this, it simply means the SLS level controller valve must be in the filling position (lever moved up) to allow circulation of hydraulic oil, to purge air from system. Engine running at "medium speed" (roughly 1,500 - 2,000 RPM) increases flow through the valve enabling the bleeding process to move air bubbles to oil reservoir. After servicing the SLS hydraulic system, If the vehicle is driven without any significant load...

You need to identify year and model of vehicle. Otherwise no viable answers can be offered. It is also common courtesy to state amount of miles vehicle has accumulated or “unknown” if that is the case.

This question is far too vague to be answered succinctly. “2 non-functioning cylinders” could be caused by any of the following: faulty ignition wires, distributor cap, spark plugs, cylinder head gasket, cylinder head, valves, valve adjustments, rocker arms, camshaft, piston rings, cylinder bores, fuel injectors and many other possibilities. For any reasonable diagnosis, you must provide specific details. It is not even stated if these cylinders are always non-functioning or only intermittently affected. Common courtesy is to tell how many miles vehicle has accumulated or state the amount is “unknown”. Can it be fixed? Sure, have the faulty engine rebuilt or install another one in the car.

The “Economy” meter is actually a vacuum gauge plumbed into the intake manifold. Inspect vacuum lines under hood to verify all are connected. Next would be the line at rear of instrument cluster, it has rubber tubing connected to hard plastic line. Rubber fittings deteriorate, thus creating leaks. For diagnosis, it would be worthwhile to test automatic door looks (if vehicle is equipped with this feature). Failure of locking system indicates vacuum leak, which may be related to gauge not reading. A hand operated vacuum pump is very beneficial for testing, isolation and diagnostics. Normal operation is: idling provides sufficient suction, causing significant needle deflection. As throttle is opened farther, vacuum drops off reducing reading.

Most likely the cause is the bushing in the speedometer. This is the fitting one sees when speedometer cable is removed, looking into threaded mount at rear of cluster. Suggested resolve is: remove cluster, apply four to five drops of SAE 20 oil (sewing machine oil, “3-in-1 Electric Motor Oil” or equivalent) to the rotating element. This is speedometer part with square recess into which speedometer cable mates.

The vacuum to shut-off valve is not present, so there is likely a leak somewhere. Refer to vacuum diagram under the hood on radiator support (here's link to one in case yours is missing: https://mercedessource.com/problems/vacu...-correct-1980-1985-diesel-vacuum-system-hose-and-line-routing). The emissions controls valves on top of valve cover are first fittings to inspect, since this is near the linkage which you serviced. Next, carefully check each fitting near the firewall where lines enter passenger compartment. Any single fitting being loose will cause reduced vacuum thereby preventing engine shutdown. An easy way to verify leak is confirm that automatic door locking is also not working. Vacuum to door locks also controls engine shut-off valve. Lastly, look at the rear of fuel injection pump, where brown line connects. This is the fitting to shut-off valve and must be properly connected for key-controlled engine shutdown to work correctly. Do not assume a fitting is tight by looking at it, pull the...

Factory procedure assumes engine has been removed with transmission, but it is not required. Remove transmission after taking out necessary preliminaries (starter, driveshaft, exhaust, slave cylinder line, shift linkage, rear engine mounting bracket, etc.). To reach the top two bolts on clutch housing use a three foot (one meter) extension with a wobbly socket. Without this combination, reaching the bolts is very difficult. Transmission removal is straightforward, most common tools (ratchets, 3/8" and 1/2" sockets, metric hex wrenches, combination wrenches, etc.) will suffice. When replacing clutch, be sure to use new clutch release bearing (a k a throwout bearing) as well as new pilot bearing (that which is contained in end of crankshaft). Also inspect front and rear flex discs on driveshaft while you're under the car. For someone who has never changed a W123 clutch, expect process to take six to eight hours. I have seen the job completed in less than two hours by a factory trained Benz guru.

It is very common for W123 seats to have limited rearward travel when a coin has become lodged in track. Pennies, dimes and nickels are just some of the things I've removed from jammed and malfunctioning seat tracks. Get a good flashlight, dental mirror and flexible grabber retrieving tool. Inspect from front and rear ends of seat. You may be surprised what is causing the interference. If nothing else, a good visual assessment will confirm locking tabs are moving sufficiently and properly disengaging when lever is actuated.

I would venture a guess that you have a sticking fuel injector and cause is loosened carbon and sludge deposits. The change in fuel coincides with deposits being dislodged. Clicking noise would be caused by injector mechanism not moving smoothly (spring sticking, disc hanging up, etc.). Since the injector is not operating correctly, the cylinder is misfiring, cause rough running and loss of power. Switching back to previous fuel type may help, but at least one injector needs attention. You should be able to locate clicking injector using a mechanic's stethoscope or by placing a long screwdriver onto injector body, then putting your ear against the screwdriver handle. Factory manual procedure is to isolate misfiring cylinder by slightly loosening fuel delivery line at injector body, with engine running. A good injector will cause engine to stumble and run roughly when line is loosened. After loosening and confirming injector condition, tighten the fitting snugly, then move on to next injector. Test each one...

Pull the brown vacuum line from rear of injection pump. This connects to the vacuum shut-off element. If vacuum lines were connected incorrectly, constant vacuum will cause the pump to shut off fuel delivery within a few seconds after engine has started (the amount of time required to build up enough vacuum). If removing line allows engine to run, check the vacuum lines for proper connection and also test the vacuum shut-off switch (device is controlled by ignition key position). Sometimes the shut-off switch can fail open allowing constant vacuum to be applied, thus causing engine to stop running after a few seconds.

A couple additional points are worth adding. Special equipment fuses are labeled A, B, C and D. These are held in pairs at the ends of fuse box. Some versions do not have either or both pairs (some Euro variants and US 230 and 240D have crank windows, manual sunroofs and may not use auxiliary fan). On earlier model years, spare fuses were stored in foam rubber inserts (above and below threaded inserts). These deteriorate with age and can be equated with rubber tubing or simple cardboard sleeve. Keep two pairs of white and red spare fuses in these locations, blue spares can be kept in toolbox or glove compartment, (they fail less often). When servicing fuse box, always check the 10 mm mounting nut to be sure it is snug.

Idling voltage test should be done under full-load condition: turn on headlamps and set blower motor to high speed, (blower switch fully clockwise for Climate Control I - three knob system; Defrost setting for Climate Control II and III). Testing must validate voltage and current values, the latter is greater with lighting and motor loads. Comparing unloaded and fully loaded voltages can illuminate weak alternator / regulator output.

It is advised to also fill cylinder head through heater hose - disconnect at firewall end - before starting. Air pockets in cylinder head can increase likelihood of overheating after coolant exchange. Getting coolant into head is critical to assure proper cooling and avoiding air-locked system. When jacking up is not feasible, park car on a hill or front wheels on curb to elevate vehicle. Be very careful when topping coolant during refill as air pockets can cause violent releases of steam and fluid (visualize erupting volcano).

Tips: Be sure to replace the clamps with new worm-drive type having combination hex-slot screw heads. These are far superior to original type. Also be sure to orient the clamps so screw heads point toward front of car and next to the cylinder head. The latter is necessary for proper clearance as air conditioning bracket sits adjacent to thermostat housing on some versions. Take time to carefully situate the hose clamps as they are almost impossible to access once compressor bracket is in place. Also take time to clean metal surfaces to which the hose connects - lightly sand or scour with metal brush to remove deposits - assuring proper seal is important before assembly.

Removal of ashtray is also necessary to access the lamp which illuminates the cavity. After taking ashtray out, remove two Philips (+) screws, then separate metal cover from plastic housing. Next to the lighter housing is light socket. It holds a 12 volt, 2 watt, T2 bayonet base, #1272 lamp. Push, then twist lamp to remove. Clean copper terminal at side of socket as well as moving contact on side of ashtray housing. This lamp is same type as used for automatic shift indicator. This is one of the most overlooked lamps in a W123 chassis. Tip: while metal cover is removed, clean and scrub ashtray, it is much easier to access this way.

This model is also known as the Apple Studio Display 15" LCD.

Removing graphics (video) card is not necessary. Also, removing the clips which retain heat-sink can be accomplished by using a flat-blade (-) screwdriver to carefully pry them from the finned aluminum assembly. Other than these two suggestions, guide is succinct and accurate.