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1973 280 with m110 engine - fan clutch replacement

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Looking at the engine bay it seems i could just partially drain (turkey baster) the radiator, disconnect the top rubber hose and pull the shroud along with fan connected to the fan clutch (after removing the 4 bolts). Am i correct? In other words can i replace the fan clutch without removing the radiator?
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'72 250C, '74 280C, '85 500SEL, '81 300CD.
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The answer is yes, you can replace the fan clutch without pulling the radiator. PITA working the shroud clear and you'll learn to curse Mother Benz while removing the four bolts holding the fan clutch. You'll also find out why I refer to radiator fins as "lettuce shredders".

There is a drain on bottom of the radiator (19MM hex head usually) which you can use instead of the turkey baster. Don't forget to "burp" the system when you refill the coolant.

I prefer to pull the radiator but it can be done.
 

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1973 w114 280, m110 engine
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510 Posts
Discussion Starter · #3 ·
As always, thanks Mike!
How would i "burp" the system?

The answer is yes, you can replace the fan clutch without pulling the radiator. PITA working the shroud clear and you'll learn to curse Mother Benz while removing the four bolts holding the fan clutch. You'll also find out why I refer to radiator fins as "lettuce shredders".

There is a drain on bottom of the radiator (19MM hex head usually) which you can use instead of the turkey baster. Don't forget to "burp" the system when you refill the coolant.

I prefer to pull the radiator but it can be done.
 

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'72 250C, '74 280C, '85 500SEL, '81 300CD.
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1,171 Posts
There are a couple of different ways.

One way is to park the car with the nose elevated, radiator cap off, top off coolant, wait 24 hours and fill as needed. Works but not always the first time.

The way I prefer is to fill the radiator, leave cap off, start car, allow to run for five or ten minutes with heater controls in "heat" position, loosen the center hose of the heater manifold (the valve mounted on the firewall), allow the air to exit the system until fluid begins to flow, replace clamp and top off the coolant. It is messier but much faster.
 

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1973 w114 280, m110 engine
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510 Posts
Discussion Starter · #5 ·
For those who are looking to replace their fan clutch on their m110 engines:
1. drain some coolant from the top of radiator (just enough so that when you disconnect the radiator hose it will not leak out).
2. unscrew the two screws holding the plastic shroud to the top of radiator (at the bottom it's held by 2 springs that the shroud just slides out of pulling upward).
3. unscrew the 4 bolts holding the clutch to water pump cover. Keep one screw partially screwed in (!) so that the water pump cover doesn't come out and you can line up the new clutch later on. For me it was easiest to unscrew top two bolts from the top and bottom two from under the car. You WILL need a thin 10mm wrench - either way it's a bitch to do even for a guy with skinny arms like me.
4. Partially pull out the plastic shroud with the fan. Clear the vac pump and the radiator water neck with the shroud.
5. With careful wiggle you should pull out the clutch with fan attached (i didn't have to pull out the plastic fan shroud because it was broken in half and thus flexed enough to let the fan clutch out by itself).

Couldn't find the torque specs so i screwed in the bolts attaching clutch to fan at 10 fl lb, and the bolts attaching the clutch to water pump housing until it started turning the housing.
 
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