DIY Water Pump Replacement - V-8
 

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,

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

:confused: :confused: :confused:

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.

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.

A little help please?
 

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

Harmonic Balancer
 

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.

Thanks
 

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.

Thanks Allen141
 

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 can definitely, positively assure anyone that it is IMPOSSIBLE to get off a water pump on a 560SL without removing the balancer. The notches will entice you (perhaps what they were designed for...). Even if you DO (as I did) manage to get the bottom bolt threads out of the water pump, you will never be able to actually remove it far enough to remove the pump.

This thread is mentions "sedan" 560's; could anyone verify for me that an '86 560SL has a harmonic balancer that comes off as mentioned above (without removing the center bolt). I've liquid wrenched the heck out of the inside hub of the balancer and am going to allow it to sit overnight. How much rapping (with a hard plastic mallet) should it take to come off? A lot? Any advice on how to pull / knock it off (hopefully, without using the radiator as a backstop). Thanks in advance.

PS: a strap wrench saved me on this. Wife is out of town, and I wanted to do major work. Used a strap wrench to hold the pulley, didn't have to hold two wrenches (one on the center bolt, one on the pulley bolt) at the same time. I tried this and it was impossible for me to do alone.

To answer my own question: It is capable of coming off. I suppose that my CD didn't really cover 86+ very well. It does, however, take a lot of Liquid Wrench (and time, overnight) and some persistent knocking at 12:00, 6,3,and 9:00 positions to persuade it to loosen. And it didn't go through my radiator!!!

You can make things easier for next time by substituting the problem bolt with a piece of threaded rod screwed into the engine block then use a nut to hold the water pump on. Keep the rod as short as possible. Pump removal will not require you to remove the harmonic balancer the next time around.

water pump replacement on 420 sel
 

I've got the spare pump in the mail. It took me about 4 hours to take the old one off. I found a lot of residue, like white pouder, perhaps aluminum rust on the old pump. Should I be concern?. I followed the directions given by Mike and they were very useful. The only thing I did not take out was the air filter. It acts like a big table to place nuts, tools, lunch etc.

82 380sl
 

Help. Is there a way to wiggle the harmonic balancer away from the water pump WITHOUT having to remove the crankshaft pulley via the 6 bolts inside the pulley? I think the balancer sits on a crankshaft hub. Is the balancer friction fit onto the hub? If I tap tap here and there, I only need enough space to clear the last remaining bolt on the water pump. TIA.

82 380sl
 

If I had to remove the 6 small bolts inside the crankshaft pulley so that I can remove the balancer thereafter, how do I remove the pulley if there is a large washer underneath the 27mm bolt? Will the pulley come off?

When I had my engine apart, I had the center bolt out, as well as the surrounding ones. It had the washers stacked there, but I don't remember off the top of my head if they would have held everything together without the surrounding bolts, or if they would have allowed the pulley and harmonic ballancer to come off.

If you do pull the center bolt, make sure you have the ability to reinstall it.
It required torquing to ~230 ft/lbs. With my engine on a stand, and locked on the rear, I was still hard pressed to reach the rated torque, with a 3' long 1/2" drive torque wrench!

If you can wait until after this weekend, I'll let you know how mine goes back together, though. I'm about to tear into the water pump myself. (Seemingly the only part I didn't change! )

Looking at the EPC exploded view, it seems to me that the previous mechanic placed the big washer incorrectly. The big washer should have been placed BEHIND the balancer. Instead, he placed it in front of the balancer.

Removing the 6 13mm bolts will be challenging. I have little or no clearance to insert my 13mm socket......:mad:

Even if I removed the 6 13mm bolts, I will not be able to remove the pulley/balancer because that big washer is preventing me from removing it unless I also remove the 27mm bolt. That's the last thing I want to do.:eek:

The big washer is not holding the pulley to the balancer. It is smaller then the hole in the pulley. It only looks like it is holding the pulley onto the balancer. As mentioned above make sure you mark the pulley to the balancer. The six bolt pattern is not symetrical. Do not remove the 27mm bolt. Good luck.

On my 560SL engine, I was able to remove all the bolts holding the water pump, but had to pull the harmonic balancer out about a half inch to actually get the water pump off. I don't know if this is specific to the SL setup. I loosened the center bolt and was able to move the harmonic balancer quite easily on the crankshaft. Guess I was just lucky.

380sl
 

Thanks to all those who replied.

I removed the 6 13mm bolts and the pulley fell right off..... I didn't even have to apply pressure to the pulley to remove it.

At first, I was concern about the large washer underneath the 27mm bolt. It turns out that the big washer in the photo above had no significant meaning.

The entire project to remove the water pump on my 380SL took about 5 hours. 1/2 of the time was reading the forum and staring at the engine.

I now consider myself a "PRO" at replacing water pump. LOL Can you believe my mechanic wants to charge me 6 hours book time to replace the water pump? That's about $540 that I just saved. Whoohoo!!

After reading all the information supplied by everybody before attempting this job, I decided it was much easier to just remove the one center Bolt, 27mm, the complete assembly came off beautifully without any trouble at all, I really don,t know why they say to remove the six pulley Bolts, as you still need to remove the 27mm Bolt !!

I hope this helps somebody

Regards Michael

The reason we don't want to remove the center 27mm bolt is that it requires approximately 240 ft-lb of torque to install correctly, whereas the 6 smaller bolts require much less, and are nowhere near as difficult to keep from spinning the engine when doing so.

I found that when I was working on my engine and replacing the front main seal, that there was enough dirt stuck around the nose of the crank inside the pulley, that it kept it from coming off easily. After cleaning out that area, things worked much easier, and it went back together with no issues.

That being said, when you actually do have to remove the main bolt, there is a tool designed to lock the flex plate starter gear, through the bottom of the bell housing.

I took the easy way out when my 380 water pump leaked. I removed the pulley the backed the bottom bolt out enough to get at it with a hack saw. I cut it off close to the water pump's ear and took the pump off.

I like the idea of using a piece of all thread and a nut for reassembly but I didn't think of that. I notched the bottom ear of the water pump and slid it down on a new bolt.

That was seven or eight years ago. No leaks yet.

In reply to what hey-allen said about the torque setting of the 27 mm Bolt, I overcame the problem with a small piece of hard wood 10"x 1.5"x 3/4", by turning the harmonic balance clockwise, and fitting the end of the piece of wood into one of the cut out sections on the down side of the harmonic balancer, and the other end against the cross member, it allows you to torque the bolt to 200 to 240 ft-lbs much easier than removing the starter motor, but I will admit, you do need a good Torque Wrench !!
I think anybody attempting to do there own mechanical work at home, should have a good Torque Wrench, this is very critical if you a going to try and do the job right !!

I don,t claim to be a mechanic, I'm actually a Chef, but I have been working on my own cars all my life, and I actually found it much easier doing it this way !!

My Car is a 1986 420SL, the size of the piece of wood might vary a little bit in length, for a 420SEL but it,s basically the same engine !!

Regards Michael