W116, BENZ AID - COMMON QUESTIONS AND ANSWERS

OM636 circa '85 top end service

Hi guys, I don't plan to take this forum off on a marine tangent but I have just bought a small 1985 motor sailer powered by a marinised Mercedes OM636 which appears to have had very little professional service, ever. Sticking to the similarity of the engine to all the older four cylinder diesel Mercs I am confident that the Fast Start Glow Plug conversion is an immediate requirement as she is a very slow, and then lumpy, starter. My question then is, what special tools (if any) are required to remove and decarbonise the precombustion chambers? Obviously I will have injectors serviced etc but what other matters should I be looking at whilst picking out the black bits? Which of the manuals you have produced will be the most help to me in getting this engine back up to spec?

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Diesel Engine Specific Aid

84 300SD power steering trouble

howdy. i have an 84 300sd. i have changed and purged the power steering fluid using instructions and filter from mercedes source. when i turn the steering wheel, the car makes a loud squeaky/grating sound. louder as the ends of the turning radius are reached. it's like the oil is not circulating and everything is dry. the reservoir is foamy on top . what's happening? matt

Chassis Model Number

W126

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Diesel Engine Specific Aid

A/C compressor, '76 240D [115 chassis]

One thing I've never tried to mess with myself is A/C. The mechanic who recently checked out my non-functional system said the compressor was ruined because a previous owner had converted it from R12 to R134. This didn't surprise me, based on what I've read on these forums, but what did was his categorical remark that replacing it with a used or rebuilt compressor wouldn't do. That struck me as unrealistic and perhaps also just mistaken. Can anyone with experience with used or rebuilt compressors confirm or deny whether these are a viable option on old Mercedes?

Chassis Model Number

W115

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Body and Interior Specific Aid

1980 W123 A/C issues

A/C doesn't work, the DEF is the only switch that works, used a jumper wire & started the compressor, works fine. There is no power at the switches on the dryer & no power at the switches on the CC console, also, the vacuum hose that goes into the 6 point distributor does not hold vacuum, what are some things I can check before taking drastic measures.

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Chassis Model Number

W123

Help - intermittent momentary engine missing 93 500sl

I could really use some help with this one. I own a 93 500sl with ~84,000 miles. Last summer and this spring I have noticed a very slight missing that occurs is noticiable at any constant engine RPM or road speed. The missing is very short lived, just feels like a little tug backwards. Most of the time it doesn't even show up on the tach - other times I believe I can catch a fleeting every so slight dip in RPMs. It can occur when the car is hot or when cold. It can occur when the weather is hot or cold. It can occur if the gas tank is full or near empty.

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A/c and Heater '83 300SD

I've seen this question on here before. But I never saw the fix. I turn on my AC or heater on low fan speed it works just fine. But if your hot or cold and turn the fan to high speed it runs fine for abuot three mins.Then it's off for about 1 min. on for 5 secs. off for 5 secs. it dose this for about 5 mins. then it will run for about 1 1/2 mins. and starts this all over again. It also dose a screeching sound under the dash on and off too with the no and off. Is there a hight limit on the fan or somthing? Thank for any help the weather is starting to heat up

Chassis Model Number

W124

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Body and Interior Specific Aid

Veggie tank faulty Sending Unit

i'm having some trouble with my sending unit in the veg tank. when the gauge reads half it is actually empty. does anyone have experience with this problem? i'm sure i could take the tank out and clean the unit, but i'd rather not. maybe i could fill the tank with diesel or biodiesel and that would clean out the gunk in the sending unit. thanks matt

Chassis Model Number

W126

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SVO Fuel Conversion Specific Aid

'87 300DT - When To Replace Primer Pump?

I have an '87 300DT sedan, 603.960 engine, 143500 miles. Reading thru my electronic copy of the W124 Service Library concerning the fuel primer pump, it lists the minimum pressures it should be able to achieve at idle and at a certain rpm. Measured at the supply line between the cartridge fuel filter and the inlet to the injection pump, doing the conversion from bar to psi, it looks to indicate that the primer pump should obtain a minimum pressure of 4 1/2 psi at idle. I have an underhood fuel pressure gauge installed (Mr Gasket 15 psi from Advance Auto) in the line specified in the FSM. Initially idling cold, it registers 6 psi. After driving 20 miles to work, idling when hot it registers 5 psi.

Chassis Model Number

W124

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