For those of you contemplating replacing the water pump on your 500/560 SEL/SEC, I have just completed the task, and it was pretty straightforward. Shops charge 4.5 to 5 hours for the job. For me, it took a couple of hours longer (learning curve) so I thought I would briefly list the steps here for those who are interested:

1) Remove air cleaner assembly (for working space)

2) Remove radiator and fan shroud (both just clip into place) after removing water and transmission hoses. Cover tranny hoses with zip-lock bags to keep out dirt.

3) Remove fan (4 bolts).

4) Remove all 5 drive belts.

5) Mark approximate location of distributor rotor button, then remove distributor (6MM allen wrench)

6) Mark the relative position of both the crank pulley and harmonic balancer in relation to block. (Once removed, they will only fit the bolt holes one way).

7) Remove the 6 13MM bolts holding on the crank pulley. This will require the use of a mirror, as they are deep within the front of the pulley, and surround the main crank bolt). Tap on the sides of the pulley and remove from crank.

8) Using pry bars at the top and bottom of the harmonic balancer in a rocking motion, work the harmonic balancer off of the crank. (Requires 2 people unless you are adept at playing "Twister")

9) Gently move the dip-stick slightly to the left (allows access to one of the water pump bolts)

10) Loosen the hose clamp on the short hose from the thermostat housing to the intake manifold, remove the thermostat housing bolts and remove this housing and the thermostat.

11) Remove all 8 bolts to extract the water pump.

12) Clean off old gasket material from surface of block.

Installation is the reverse process. Ignition timing will need to be re-set, as distributor was removed and replaced. Pre-marking of rotor location get's it close enough to crank and drive.

I renewed the thermostat, the bolts for the pump and fan, and all drive belts. My hoses looked to be in excellent condition, so I reinstalled them.

As an aside, I have always had a fear of wrenching off bolts when doing this kind of work, so I used penetrating oil liberally and with lots of patience to prevent such a calamity.

Good info. Thanks! I copied the text into my 560SEL DIY folder

It's just a matter of time...

HI Allen

Nice post. All DIY could use this as a great how-to, good detail. I will just add that I don't remove the radiator or the distributor but then I got a great big box full of funning looking tools to get around that stuff and yes I am good at Twister :-)

fasthair

Not knocking your procedure, but pulling the harmonic balancer seems a bit excessive. There should be a cut out somewhere on the circumference of the balancer which allows for access to the lower pump bolts. You just have to rotate the engine by hand to line the cutout up.

__________________
Mike Tangas
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72

'02 CLK320 Cabriolet - wifey's mid-life crisis

2012 VW Jetta Sportwagon TDI...at least its a diesel

Non illegitemae carborundum.

Mike,

With respectful disagreement regarding the slots in the harmonic balancer, although they appear to have been created for access to the bottom water pump bolt, please refer to the following URL.

Having read this thread from the MBCoupes newsgroup, I didn't even attempt to proceed without removing the pulley and balancer. And anyway, their removal and re-installation is a fairly quick and simple process.

http://db.mercedes.cx/sec/200206/27/0003.html

OK, I'm confused now. After reading Satish's post regarding removal of the vibration damper, I had to check the manual. Sure enough it calls for removal of same BUT the picture accompanying the verbage shows the damper in place with the notch aligned at the lower bolt. Mixed signals.

Guess I'll have to wait for a water pump to go south to find out for sure if it can be done easily without removing the damper. Perhaps it requires a wobbler to get the proper angle of attack.

__________________
Mike Tangas
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72

'02 CLK320 Cabriolet - wifey's mid-life crisis

2012 VW Jetta Sportwagon TDI...at least its a diesel

Non illegitemae carborundum.

It may be possible. It surely appears that the two radiused slots (180 degrees apart) on the balancer are there for pump bolt access.

As I said, I didn't even try that. It turned out that removal of the pulley & balancer were fairly easy. In addition, I didn't want to turn the crank, as I had marked the relative attitude of the distributor rotor button.

With regard to radiator and fan shroud removal, I did so after checking prices of a replacement radiator, should a wrench launch itself in the wrong direction ;-), and to create additional working space.

I'm about 1/2 way through this project and have question.

To take off the harmonic and pulley, do you only need to take off the perimter 13 mm bolts or that big 27mm in the middle as well? From your description is sounds like not.

thanks.

J. Boggs

Do not remove the main (center) crankshaft bolt, only the 13mm bolts. Work the balancer off the shaft by alternately pulling the upper/lower or the right/left sides. It will come, but not easily. Be sure to mark the relative location of the balancer vis-a-vis the bolt holes on the crankshaft. It will only go back on one way, as the bolt holes are not exactly symmetrical.

You were right, not that bad a job if you know what you are doing. I wrestled with the balancer for quite awhile this afternoon and was just about convinced that the big bolt had to come off-depsite postings to the contrary. About to give up, I finally stuck a crowbar behind the balancer and felt a little give. That was enough to convince me that it would come off. I pushed and pulled and all of a sudden it broke loose, that that last bolt was revealed.

I'll be buttoning it back up tomorrow.

I assume that the re-assembly will be a lot easier. Did you pressure test yours or just assume it was water tight? I don't have a metric torgue wrench, how tight did you do the bolts?

Thanks.

J. Boggs

Mike was right the first time with a thin walled deep socket you can position the slots in the balancer to get bottom bolt,at least on a euro 420 engine ,as did it last summer .........
William Rogers..........

Reassembly goes twice as fast.....learning curve. I did not pressure-test the system. After 6,000 miles, no leaks.

I can't remember the figure, but I used torque specs for a 13mm bolt.

As mentioned above, it may be possible to do the job without removing the balancer, but it's not too difficult to remove, and surely makes the pump removal / replacement easier.

Don't forget to use a timing light to reset the ignition timing (appropriate for my '84 at least). Some later cars have more automated spark-timing systems.

Got it done, took about 12-13 hours to do, several of which I could have saved if I had just yanked a little harder on the harmonic. Of course now that I know how to loosen and retighten all the belts, that wouldn't be so slow.

As you said, keeping the harmonic and the pulley lined up is key. There is such a slight difference, that I can see it would drive you crazy trying to get it back together unless you knew the trick.

And no, on the 560sel and sl there is not enough cutout or clearance to get the last bolt out. Simply cannot be done. Sure wish it could have been.

Thanks, your detailed steps made it a lot easier than trying to decipher the manual. My CD ROM Manual has a couple of mispellings that if I had not had yours to follow would have sent me in the wrong direction.

J. Boggs

You get one "Atta-boy"

:-)

I replaced the bottom water pump bolt with a threaded stud and used a nut to hold the water pump on. That way next time I had to replace the water pump, I was assured I didnt have to mess with the harmonic balancer and pulley etc.

__________________
I got too many cars!! Insurance eats me alive. Dave

78 Corvette Stingray - 3k
82 242 Turbo Volvo - Manual - 270k
86 300e 5 speed manual - 210k
87 420sel - 240k
89 560sl - 78k
91 420sel - 205k
91 560sel - 85k
94 GMC Suburban - 90k
97 Harley Davidson Heritage Softail - 25k
00 GMC Silverado 1 ton 30k