I belive my 1988 560SL, water pump is just starting to leak ever so slightly. Since I've never seen these things cure themselves, I have been doing some shopping arround and I have found three aftermarkets, Laso, Graf and Meyle ranging in price from $100 to $200. Then theres good old genuine MB weighing in at $400.

Does anyone have any good long term experiance with the aftermarkets.

Thank You
John Roncallo

I had a bad experience with a Laso, but it was likely entirely my fault. I overtightened the belts. I realized my mistake (probably drove only 500 mi that way) and loosened them but the pump started leaking after only 5000 miles. On my second one (from an Italian company, very old stock) it's been fine for 5K miles.

It's time consuming to do this job because of all of the other stuff you need to remove/replace to do the pump.

On replacing it, of course, you have to drain the radiator and block.

The first thing you have to do is loosen the fan shroud. Note the exact position of the height of the shroud under the top clamps.

you have to take off the P/S pump (or at least move it out of the way and tie it up), the shroud, the fan/clutch bolts (the pulley is NOT attached to the pump permanently like it is on a 380's pump), and at least loosen the air conditioning belt and the alternator belt, and the air pump belt. I used a strap wrench to hold the fan pulley and crank (see below) in place.

I removed the alternator (not difficult, but obviously disconnect the battery first).

You may read differently but I think that on a 560, it is IMPOSSIBLE to remove the pump without removing the crank pulley/balancer. It LOOKS like you can get to the bottom bolt without removing the pulley (there is a notch), but I think that this works only on earlier cars - believe me, I tried my best. The pulley is held on by six screws and one is deliberately in a different position to key the balancer position to the crankshaft. I strongly recommend putting marks on everything so you do not have to hunt for the right position, which is a big PITA.

Use a strap wrench to hold the pulley and do not allow it to turn counter-clockwise (because of the timing chain, NEVER allow the engine to turn backwards).

The harmonic balancer is trapped begind the pulley. It is NOT bolted to the crank except by the six bolts. After those are removed, you put some liquid wrench on the crank/balancer interface, wait a few hours, then pry and tap with a plastic mallet and a pry bar until it "walks" off. It will come off eventually, but probably not without some swearing on your part.

When separating the upper water inlet housing from the water pump be careful not to break the connectors or wires - they are old!

When you buy a pump you get a kit of the gaskets you need. Because everything you are working with is aluminum, you MUST use a torque wrench on everything. I came very close to stripping a top water inlet bolt on my first pump.

Note that you MUST have _all_ belts in place (but not necessarily attached to anything) before attaching the water pump pulley to the fan. Once on there is VERY little room to work with and you can't slip a belt between them.

After I screwed up the belt tension, I bought a KRIKIT belt tension measuring tool; the tension on a NEW belt and a used belt is different. I've also noticed that tension on a hot engine is HIGHER than it is on a cold engine (no doubt, due to the expansion of aluminum). Therefore, I set my belts up "loose" on the low end of recommended tension in order to keep bearing stress to a minimum when the engine is hot.

BEWARE: There is VERY little clearance between the oil filler tube and the water pump pulley. If the brackets, etc are not in place properly this can, and will, rub! Also, don't forget to PUT THE FAN SHROUD IN PLACE BEFORE REPLACING THE FAN/CLUTCH!! (I did this).

I've never had a problem "burping" my system when I've filled up the radiator/block via the overflow tank to the point where a little comes out of the upper radiator neck, and then attaching the upper hose to the water pump/thermostat outlet and filling from there until everything is full. Do NOT overtighten the clamps while reinstalling hoses on the radiator (plastic tanks/necks). "Tight enough" will do.

When you do this job, it is an "opportunity" to also replace:
-upper and lower hoses (the lower on a 560 is expensive if you don't shop around)
-all the belts (see new vs used tension, above) - they are cheap if you shop
-the thermostat
-the short hose between the manifold and the water pump inlet housing
-flush/change the radiator fluid

It was also a good opportunity to clean and detail everything that is difficult to otherwise get to. Even the hose clamps polish up nicely.

I refered to the MB manual in several places numerous times during this job. The first time I did it, it may have taken 12 hours; the second time, it took maybe 8, close to the pro mechanic book time of 6 hours. Those times do not include all of the cleaning/detailing.

__________________
86 560SL
With homebrew first gear start!
85 380SL
Daily Driver Project

http://juliepalooza.8m.com/sl/mercedes.htm

There was a time when the only pump to get was a rebuilt one at the dealer. Many of the aftermarket ones at the time did not have the proper clearance between the impellers and the housing and caused the car to run too hot. Used to be that rebuilts were less than fifty bucks. Times may have changed.

Len

The book allowes 6 hours. I thought I was going to have this out and in, in 2. I dont think I have ever done a 560 pump but I did do some 450's.

Thanks
John Roncallo

So far Graf is out an Laso is holding on by a thread. I also found another company I belive the name was Air Tech.

John Roncallo

No way... there's just a lot of stuff to disassemble/reassemble. You might even have to remove the distributor.

__________________
86 560SL
With homebrew first gear start!
85 380SL
Daily Driver Project

http://juliepalooza.8m.com/sl/mercedes.htm

My limited experience with Airtex stems from installing AC-Delco water pumps on American cars. (Airtex makes AC's and Carquest's new water pumps) They lasted a long time. They worked well. They were expensive, when compared to their rebuilt rivals. They are still, as far as I know GM Factory Installed on all new GM cars and trucks. That says a little something, right there. That having been said, I have never heard of one being put on a MB. So, I just don't know how that would work out.
God Bless,
Dave.

__________________
Currently Driving:
1986 Mercedes Benz 560SEL
1994 Lincoln Town Car
1994 Cadillac Deville
1985 Lincoln Town Car- Retired

The Official Car of a Realtor- Lincoln Town Car
The Official Car of the Successful Independent Insurance Agent- Mercedes Benz S Class

This water pump is anything but easy, hardest waterpump I've ever done. Have to pull the dist and the harm balancer and it takes a lot of torq on and off. Have fun and good luck.

The hardest water pump I ever did was a Maserati Bora. The second hardest water pump I ever did was a Maserati Khamsin. Normally I would say, this should be a pice of cake compared to these. Except that was 29 years ago.

In any event I seam to suddenly be having transmission problems, stays in second at all times. This may make the water pump very easy. Remove engine and trans from car, rebuild trans, reseal engine and replace lower guide rails and oil pump chain, replace water pump(very easy). detail engine campartment and engine and reinstall. It's a good thing I have a second car.

John Roncallo