1989 Mercedes 300E Water Pump Leak

Does anyone have any idea why my new Geba water pump leaks at the o-ring? I followed Guenter's post on water pump replacement located on the Benz forum
to the "t". I have taken the water pump out four times in the last 2 weeks and I can't seem to stop this leak. Each time I have changed the o ring, bolts and washers (4 each), and tried different ways of torquing the bolts. Am I tigethening the serpentine belt too tight? I replaced the tensioner, damper, and adjustment and made sure I set the tightness right to the notch on the scale. I am really tigthening the bolts down on the pump to the point where I'm afraid the bolts will snap if I go any further. Could it be a defective pump? Every time I take the water pump off, I immediately check to see of the o ring held it's position and in each case it has. I replaced the bolts because the ones that were on there were all bent, except for the allen bolt. Is there some sort of mechanic's trick that I'm missing? On the last attempt, I even put a little "super black" form-a-gasket in the o ring slot to see if would help and it didn't.
I'm ready to fly the white flag and bring the problem to a mechanic. Pleas help.
Thanks,
Gene
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Gene, sorry to read about your problems..... the only thing I did different from you by the looks of it, is that I got a remanufactured waterpump from MB.... don't know re Geba, but I guess it should be OK. As you surmised, the biggest obstacle is making sure the o-ring stays put. Yours obviously had, soooooo, I'm wondering about that Geba pump....
best wishes, guenter

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Guenter,
Thanks for your inputs on the water pump. I just finished taking the pump back off. O ring was perfectly in place as usual. I did get an o ring when I bought the pump but I didn't put it back in during subsequent re-installs (4 installs and 5 removals) becuase I considered it used.
It almost looks like this Geba water pump is leaking from the weep hole (at least from what I can see) and running down the block making it loook like an o ring leak.
I'm ready to buy a remanufactured water pump now. Where did you get yours? I have a Mercedes dealer about four hours away, should I buy there? I've been searching the next and they all put up the same brands Laso, Geba, and one other that I don't remember.
I printed and followed your post on water pump removal to the letter (the tape on the universal 1/4 drive was huge by the way!). I've got removal of the pump down to about 50 minutes, now that everything is cleaned up nice. The surface on the block is as smooth as a baby's bottom and shiney! I put new bolts, washers, and o ring everytime. I'm going on fifth attempt this week. I swear it's like Groundhog Day for me. I'm becoming obsessed with this pump!!! My back is killing me though and I'm not sure how much I can take. The nearest Volkswagon mechanic (no Mercedes around here in Helena, Montana) is a month out for appointments.
I think maybe I'm tightening the bolts too much as every time I take the washers out, they are severely crimped. It's hard guessing the torque with all the universal joints, extensions, and hard fits on those back bolts (as you know). However, when I take the bolts out, they come right out without a fuss. I threaded the bolts in the holes without the pump just to see how it feels to snug them up. It seems that I can always go deeper without the bolt ever bottoming out. I stop when I'm about 1/2 inch (about right when pump is installed) sticking out.
I really interested in where you bought your pump. I won't do anything until you reply.
Thanks for your very thorough post on the water pump changeout. I would have never attempted this job without it! I've got a manual coming this week, but I'm not sure how much help it will be on this job...I feel like an ACE mechanic on this job now!!
Thanks,
Gene
Guenter Scholz wrote:

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Hi Gene,
I called my local MB parts guy and asked him whose pumps they are selling said he couldn't tell (or didn't want to bother). I'll look at mine tonight and see what I can see.... I'd guess that you simply got unlucky with your] pump. Probably one of the other knwledgeable posters like Karl would know of the top of their head.
cheers

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Guenter,
I just ordered a MB pump from t he dealer. It will be here tomorrow afternoon. I thought $230 with shipping, thermostat housing, and o rings was real fair. According to the part's guy this is a genuine MB part. When I asked him what could be causing my leaks he mentioned the following: place teflon paste on all four bolts in case the bolts are breaching a water compartment. He also mentioned that the exploded view of the pump no longer shows the allen bolt in the upper front. They are all the same bolts now. Was there a change or recall that we are not aware of? Should I change this to a standard bolt while I'm there?
I personnally don't think the bolts are the issue, do you? I think I have a bad pump. I can't believe that any mechanic, Mercedes or otherwise, would be as obsessed in being so careful with cleaning, positioning of the o ring, etc. Afterall, I'm not doing brain surgery here where I would need a sterile room/equipment and absolutely precise procedures...am I?
Thanks
Gene
Guenter Scholz wrote:

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Gene, re

the teflon, surely, is just so you can get the bolts out easily at a later time.... I don't believe that teflon grease can do the same job as teflon tape... ie seal threads agains water leakage. The chance of breaching a water compartment by the bolt threads is probably 0.00000000001% :-) I thought about changing to standard bolts, but then reconsidered because the new bolts might not be strong (tensile) enough... so I just left it considering you are unlikely to do this again on this car.

Absolutlely you must have had a bad pump... did you get to spinn the shaft ... it should feel quite 'stiff' ie not spin freely.

I wouldn't have thought so, mechanics are anything but anal.... Case in point are valve stem seals I had replaced a couple of years ago. Mechanic inserted the valve cover seal with a twist in it.... oil all over the place I mean OIL ALL OVER EVERYTHING .... Isn't that one of the main reasons some of us do our own work - just so it's done right?
cheers and good luck with the pump
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Update on Water Pump Problem 1989 300E):
I put the MB water pump in yesterday and so far no leaks! What a difference the MB pump makes over the Geba. No noise (smooth) and it really fit on to the block perfectly. I only used 4 small dabs of grease to hold the o ring in place. I also bought that specially sized 2" hose that goes from the thermo housing to the block as well (new MB). During the previous changes I just cut a 2" piece from my old, lower radiator hose which seemed to work (no leaks). But, the actual one from Mercedes has two different diameters and is a much better fit.
I would recommend that anyone doing this job go with genuine MB parts and follow Guenter's step-by-step procedures on the MB forum. While the knockoffs might work for some, it didn't work for me on this job and in fact caused lots of extra headaches!
Thanks for all of your help,
Gene
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Hello, i have a 1994mercedes s320, i need help with removing the leaky water pump. Directions, pictures articles would be appriciated. I need to get this car on the road yesterday as this is the only vehicle i have. please help
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I don't think your vehicle is set-up the same as mine. I wish I could help you, but the best advice I could give you is to post a separate thread detailing your problem. There are some serious experts on this site that will get you straight on your problem. They have helped me on numerous occassions.
Gene
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It is the same engine... very slightly different... so help him out Gene...
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1989 300E should be a EA30 [after the WDB in the vin] and has a 103.983 engine.
A 1994 S320 is a 140 body, either GA32 or GA33 [after the WDB in the vin] and has a 104.994 engine.
Umm...... not the same engine!

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Right... 2 valves and 4 valves per cylinders... 1994 E320 is same pump as 1994 S320. I took a look at the picture on the 89 300E water pump and the newer one... they are almost the same... just a different fitting but otherwise almost identical.
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He may have a water cooled oil cooler on the oil filter housing. It is fed by a water tube from the water pump. Changing the water pump disturbs that tube. If he does not replace the o-ring on the other end of the tube when he replaces the pump, I guaranty it will leak when he starts the engine. To replace it, he will either need to remove the water pump again or remove the oil filter housing. See #11 here: http://www.detali.ru/cat/oem_mb2.asp?TP=1&F 0033&M4994&GAr2%2E368371%2C502508%2C605&GMq7%2E454&VIN=%2A&CT=M&catR0&SID&SGR5&SGN Footnote 025 covers engine 104.994 depending on the engine number.
Go to the 2nd picture here: http://www.detali.ru/cat/oem_mb2.asp?TP=1&F 0033&M4994&GAr2%2E368371%2C502508%2C605&GMq7%2E454&VIN=%2A&CT=M&catR0&SID &SGR5&SGN
103 engines do not use this set-up.

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