water pump changeout- need pics and tips - PeachParts Mercedes-Benz Forum

showme · #1 04-27-2010, 12:33 AM

The water pump has started dripping at the weep hole, so it's time for fun. I've read my Hayne's manual, and searched the DIY resources, but I was hoping somebody could either direct me to a good step-by-step thread or just give me a heads up on what to expect as far as any unforeseen problems. What size bolt heads are holding the fan on? I understand I'll need to grind a wrench to do the job. Also, any tricks to loosening the AC and power steering belts? I've changed the alternator on this car, and it seems like I've had to move these parts around, but it was probably on my Suburban, so I'm looking for helpful hints. It'll be a week before I get the pump. It's dripping at a rate of about every 4 seconds (small drops). I just flushed it and refilled it with "real, live" Mercedes antifreeze a few weeks ago. It's tearing me up watching that expensive stuff drip out, so I'm going out tomorrow and empty it in a bucket so I can not watch another half gallon of $25/gallon fluid go to waste.

Anyway, if anybody can help me out here, I would really appreciate it. Thanks, Lee

rhodes2010 · #2 04-27-2010, 02:21 AM

I've done water pumps many times.
I guess there should be a write up by now.
You might want to look at diesel giant (I think dieselgiant.com).

But here is what I do: (and I think this is an easy , easy, project).

Get a 10mm open end wrench.
10mm socket with 3 inch extension.
Flat head screwdriver.
Clean drain pan for radiator fluid.

1. Drain radiator using flat head screwdriver .
Under radiator one of the sides is a drain hole.
It is plastic and looks like a plus sign.

2. Loosen radiator shroud. Pull off clips at top of shroud.
I use flat screwdriver to pry up.

3. Start loosening and then remove fan bolts.
I press down on belt to tighten the pully enough to loosen
the 10mm bolt that goes through fan flange into water pump flange.
The tricky part here it rotating the fan to get at all 4 bolts.
I am able to use an un-loosened bolt to spin pump to get at that last bolt.

4. When I get all 4 bolts out (no special wrench or grinding needed).
Remove fan and shroud and pulley.

5. Now the pump. This is the easiest part.
With 10mm socket gently break loose all the bolts holding the small round pump on.
Maybe 6 to 8. Once they are all out you can rubber mallett tap the pump
to loosen and pull off. Or wood block and hamer. Tap lightly.

6. Clean the mounting surface completely.

7. Take a brush (wire is best) and brush the threads of all the pump bolts.
If any look weak, worn, corroded - replace them.

8. You can slip new pump into place now. I am pretty sure there is a gasket.
I have never used any kind of sealant.

9 reinstall pump bolts, gently tighten to snug. If there is a torque spec maybe
someone here knows it. I am just gentle but firm.

10. I reinstall the pulley and one fan bolt by just a few threads.
This leaves enough room to slip one fan slot in and onto the water pump center shaft.
I reinstall shroud and fan.

11. I start by hand the other three fan bolts and then bring all to tight.
Pressing down on fan belt to hold puley snug.

You will notice I do not loosen alternator to loosen belts.
But if you had to do that because it is too tight.
Simply use a 17mm wrench to loosen the two nuts holding alternator
and then use 13mm tightening nut and loosen a bit.

This is an easy job, I say easy because it does not require special tools.
Just patience and dexterity.

I can change one in a couple hours.

The biggest problem can be rounding off the fan to water pump bolts.
You cannot use line wrenches or sockets. So a well fitting 10mm open end is essential.

What do you other folks do ?

Diesel911 · #3 04-27-2010, 02:29 AM

I like to put a piece of Card Board against the Radiator Core so I do not dent up the fins or cores if I oops something.
Don't lean on the Hose that goes to the Coolant Recover Tank as the Plastic Nipple where it connects to the Radiator is prone to breaking off.

69shovlhed · #4 04-27-2010, 09:44 AM

this is excellent info. use a quality american or german made 10mm wrench on the pulley bolts, not some chinese or indian ill fitting garbage wrench. a cheap wrench will round off the bolts and ruin your day. in fact, if you plan on doing any work on cars, don't buy any imported crap tools. make sure it says made in USA or germany on the tool. SPEND MORE ON TOOLS = SPEND LESS ON RUINED PARTS AND BAND AIDS!

toomany MBZ · #5 04-27-2010, 10:30 AM

The second page is a bit of a help.
To get the fan off, you do need to be careful. there isn't a lot of room. I have ground down the end of a box end to facilitate this.

showme · #6 04-27-2010, 12:07 PM

Thanks for the excellent write up, rhodes2010! It must have taken a long while to write that out, and I really appreciate it. Big Help. And Diesel911, thanks for the cardboard tip. That will probably be the one thing that I would surely do, and be sorry for it. Thanks. shovlhead69, I agree with the tool comment. I've spent too many hours fixing screw ups caused by sub par tools (when I was young). A good warning for anybody out there who hasn't had the headache those cause. And toomanymbz, I appreciate the link. Just as I was thinking (again) of fighting my way into the drain plug, I realized it can wait after looking at page one. I've flushed this car's system yearly, and drain the r4adiator, but after trying to get to the engine plug, stopped at the radiator. I know I should pull that plug, but what a hassle! Anyway, I'm getting ready to change the oil and pan gasket, so I may end up getting to it when I do that. This is the first time I've used Mercedes antifreeze, so of course it would start leaking now instead of when I used regular, old Prestone.

One other question... When reading something last night, I read that you should check the breather tube to the head for corrosion, lime etc. First, does anybody know the best way to see if there is a problem in there, short of running a wire through it? Also, when re-installing the bolt(s) on that tube, A) Is there a certain torque for them?, and B) do you use a thread sealant, or would that mess things up? This type of connection (the bolt in a tube with moving air\water mechanics) still confuses me a bit. I would appreciate any comments on this. And as always, thanks for all the comments, and the time you took to give them. Even an easy job makes me anxious the first time. I like to be prepared for what's coming up before I even go out there. My old Boy Scout instincts kicking in, I guess.

tbomachines · #7 04-27-2010, 01:48 PM

Bits of advice:

1st...you can use a good pair of vice grips if you cannot grind down a 10mm wrench. Let it soak overnight or at least a couple hours in penetrating lubricant before taking on the fan bolts. I didn't find them to be much of a hassle when changing out the WP on my SD.

2nd - get new bolts for the water pump and thermostat housing!! They snap so easily, your question of proper torquing makes me cringe as I had asked that before snapping 2 bolts off in the WP housing. The heating and cooling weakens them over the years and they become extremely brittle and weak. Also, when you're down there its a good idea to replace the 3" tube going from the WP to thermostat housing, especially if you're going to check the thermostat. It is one of those things that you just don't want to break and replacing it is cheap insurance. Unfortunately on this site they only sell it in 3 foot lengths but you're likely to find a forum member to snip off a few inches from their tube and send it cheap (I'd offer but my existing tube is not with me atm).

hey_allen · #8 04-27-2010, 03:17 PM

I'll offer some hose, for the cost of shipping it to you. I bought a foot and a half for my SEC project, and have been slowly working my way down it's length.

The last one I sent ended up at $5.01 or so, via USPS flat rate.

showme · #9 04-27-2010, 07:56 PM

Thanks, fellas, for the tips and offers. hey allen, i'll take that offer. You don't have to send any more than is necessary, but I really appreciate the offer. My pump and belt already shipped, so it saves me a bundle, and I thank you. I'll send a PM and get your number, or email so we can get this thing accomplished. Many thanks. Lee