I have a replacement new water pump, with about 3K miles on it. I have it torqued to the proper specs, the new belts were adjusted to new and then readjusted to "used" specs with a Krikit as per the manual, and I use the right mix of MB/Zerex G-05. I have a tiny - I mean, tiny - leak coming from the lower weep hole of the pump. In a month of this, I've seen no drop in my expansion tank; but I can tell the pump is leaking a little because of the residue left on my (polished) parts like the water pump, alternator, power steering pump, etc. This seems to happen if I drive the car, let it sit for a few hours, and drive it again. I've never actually seen any liquid but I have felt the weep hole damp after driving.

Again, I'd be surprised if the total amount of the leakage over the course of a month (driven lets say every other day) has amounted to a thimbleful, and I probably would not have noticed it on unpolished parts.

Does anyone think this is serious? Enough to replace it? Gee, I hope not...

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

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

Obviously, it shouldn't be leaking at all. Whether or not it's bad enough for you to change it again is up to you.

You might wan't to make sure your cooling system isn't being over pressurized due to a bad expansion tank cap or worse yet, a leaky head gasket.

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2000 c280 Sport (looks like an upgrade, feels like a downgrade)
1991 190e 2.3 (sold)

Neither of these will cause an "over pressurization", but just the opposite as pressure is lost when a cap is faulty or HG is leaking. In these 2 situations, pressure loss can cause over-heating.

Could that damage a water pump? Excess heat can do all sorts of things, but in this situation it would appear the problem is a leaky pump which happens to be brand new. My $$$ are on the pump being bad. It happens.

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Mike Murrell
1991 300-SEL - Model 126
M103 - SOHC
"Fräulein"

I disagree. When our head gasket leaked, perspiring coolant hoses and failures were the result. Although part of that is deterioration from oil contamination, oil in the coolant and NOT vice versa is a good sign that combustion pressure has leaked into the coolant passages where the pressure will then be excessive. As these are fast pressure bursts, I would not expect the reservoir cap to protect in all cases.

Check for oil in the coolant.

Steve

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'91 MB 190E 2.3
'08 RAV4 Ltd 3.5
'83 Lazy Daze m'home 5.7

I disagree... the oil leaked into your coolant due to the pressure of the lubrication system, that pressure being created by the oil pump. The headgasket failed where there is just a thin seperation of gasket material between a pressurized oil passageway and a coolant passageway in the head. The oil system is pressurized higher than the coolant system. Exhaust leaking past the headgasket into the coolant system on these motors is pretty rare. The gasket is metal re-inforced around the cylinders.

As to the original problem statement: Bad water pump, excessive clearance on the pump shaft seal. It may be acceptable for now, but eventually it could lead to bearing failure on the waterpump (which BTW is lubricated by the coolant).

If temperatures are OK, and leakage is minimal / non - measurable, then just keep your eye on it and plan on replacing it when you can. If you get more concerned with it, take the tension off of the belt and try to wiggle the pulley. If there is any wiggle, then replace the waterpump ASAP. If the leak rate increases, or temperatures increase, then replace ASAP.

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On the plains of hesitation bleach the bones of countless millions who at the dawn of victory, sat down to wait, and waiting -- died

I tried the wiggle test, only the tiniest barely feelable wiggle. I'll keep an eye on it. The money is bad, but not as bad as the effort in replacing it or the time/effort in polishing it. I put on only about 5Kmi/year. I read a post where a guy with similar driving patterns watched a very slow leak in this area for about 10 years until he decided he couldn't take it anymore, so I'm hoping for the best.

Given this summer, wonder how I'll tell when temperatures are creeping up

If I'm in motion, the car sits at about 84; standing still after coming off an expressway, it can go to 95 until I start moving again, if the temperature is over 80 outside. From what I hear, this is downright cool for this car

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

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

It should be fine then. With my water pump, I could hear it making knocking noises at idle speed, it was leaking out the weep hole a lot, and with the belt off, the pully had a lot of wiggle.

Note that it was still pumping just fine, though the pump impeller was probably wearing into the pump case at that point. (I never did an autopsy on the pump like I normally would have...I guess I just figured broken is broken...)

Try washing the white residue at the weep hole away and see what happens. I have heard of some shaft seals that need a bit of run in time before they start sealing well. On other cars I've owned, they were sensitive to the anti-freeze / water ratio. Too much antifreeze resulted in poor sealing and poor heat transfer, not enough anti-freeze resulted in poor lubrication to the seals and eventual leaking...

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On the plains of hesitation bleach the bones of countless millions who at the dawn of victory, sat down to wait, and waiting -- died

i would return the pump. at three months it should not be leaking. bad pump. i wouldn't drive with it that way.

i would worry about being stranded.

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

My new replacement started leaking after about three months too, but it also started squeaking. A small leak I could handle but the noise I couldn't. The pump was under warranty but my labor wasn't



Rule of thumb: If you don't know how old the thermostat is, change it.

Another rule of thumb: If you don't know how old the radiator cap is, change it.

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5 speed '91 190E 2.6 320,000 mi. (new car, fast, smooth as silk six, couldn't find any more Peugeots)
5 speed '85 Peugeot 505 2.5l Turbo Diesel 266,000 mi. (old car, fast for a diesel, had 2 others)
5 speed '01 Jetta V6 (new wifes car, pretty quick)
5 speed '85 Peugeot 505 2.2l Turbo Gas 197,000 mi. (wifes car, faster, sadly gone just short of 200k )
5 speed '83 Yamaha 750 Maxim 14,000 mi. (fastest)
0 speed 4' x 8' 1800 lb Harbor Freight utility trailer (only as fast as what's pulling it)