Hi all, Help me identify the source of the leak, please.

There is some brownish liquid dripping down the lower radiator hose where it connects to the water pump. The stuff is water soluble and smells sort of fishy or rusty. Since there is not much room to peep and I know its not leaking from the hose connection. Is it possible that the water pump cracked? I am still puzzled with the brown color, seems like rusty water/coolant. the coolant inside the expansion tank is clear so I don't think the rust is from inside. Any thoughts? The ML in question is a 98 with 66k miles on it, water pump is original.

Attached pictures: first one as seen when look up from the bottom of truck to water pump pulley.

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Was there any residue that looked white and kind or powdery? That could be from coolant. Has the coolant every been changed?

Would you by chance have a larger picture that shows more of the area adjacent to the area of the leak?

The coolant was changed less than 2 years ago. No white residue yet since it started 2 days ago and I wiped clean the floor and the engine hose area. I am very positive it is coolant since the fluid feels somewhat slimy and water soluble. The brown color is most likely rust (perhaps from the water pump pulley, not sure though). I try to slip my finger behind the water pump pulley and there is a puddle there. I am thinking the leak is through the shaft that connects the pulley to the pump. I was going to replace the pump next year, but it looks like I may have to do it next week. I will try to post a bigger picture tonight.
steve

The water pump has a weep hole under there somewhere. I wonder if it could be leaking for there. The weep hole looks like a hose or something like that goes over it, so I don't think you will just see the little hole. It does seem odd that their would be much in the way of rust, since most everything is aluminum, or so I thought.

Ron,
I just stopped by the dealer parts counter, the parts guy told me that when the water pump is starting to go bad, the coolant will ooz out of the weep hole. Then it will just drop dead any time. It's funny that the water pump was making some loud chirping noise every now and then in the last 2 months while the engine is running. Perhaps that's the tell tale sign of failing. I still don't know what the brown stuff is or where it might come from. Will post more info when I get to replace it.

On a separate note, would the tires wear out unevenly (more the outer edge) if the shocks/spring is weak? My rear tires are wearing out quicker on the outside then inside (an alignment was done 5000miles ago).

Make sure it's not the belt tensioner making that noise. My tensioner failed leaving me stranded, although mine never made any noise before it failed.

I don't know the answer for sure on your tire wear problem, although I would not think the shocks are the problem, especially with your low mileage. Could it be the brand or tires you're using, seems like an aligment issue. Maybe someone else who had this problem and offer advice. I know the 98's had different transfer cases but I wouldn't think that's the problem either.

I replaced the belt tensioner already (last year), so I can safely rule that out. The tires are Michelin Cross Terrain, good stuff, had them for 30k miles already. They have been wearing out very evenly until last year I asked the dealer to perform a 4 wheel alignment (damn it, my mistake!!!!). Now 5k miles later, I see the rear tires wearing out faster on the outside. Looks to me that the camber was set too positive. Dealer claimed innocense, gave me a bunch of blahh.

Possibly camber or toe, is there any feathering of the tread?

I'd try tightening the upper clamp on the lower hose first. Could also be the hose. No idea why the coolant would look dirty like this, unless the stuff in the tank looks the same. You could also have a pressure test done with a cold engine.
Gilly

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no feathering, Gilly, just the outer edge wears out faster than the rest of the tire. I will try to get a different shop to take a look at it.

The hose clamp was very tight, I couldn't turn it any more without squeezing/breaking the rubber. I took a small mirror and took a peep at the connection while the coolant still dripping, nope, not came from the hose. Well, I will get to the bottom of this when the new parts show up.
steve

I have the same problem with the rear tires, wearing out quicker on the outside than the inside . At 52K I've got to show the tech at the dealer before the new tires were installed so they are aware of the problem before they do the alignment with the new tires. I thought then the problem was resolved.

Well, now at 89K miles I have the exact same problem when I am ready to get new tires again. I have been using all along the General Grabbers.

If there is some light, it will be appreciated. I am getting new tires in the next 2 to 4 weeks.

Thanks,

Rene
'99 ML320

I rechecked the expansion tank and something didn't look right, the tank looks darker and darker every day or it seems. So I took a big siphon and stirred up the tank a bit and sucked out a portion of the cooling and it is turbid, containing some fine particle looks like metal but not sure.

I checked with a car buff at work and he said that the bearing may be shot due to a bad/aging seal. I looked at the new water pump I have at hand and his reasoning sounds logical. This may explain why the leak is brown in color, might have been the rusty bearings.

Unfortunately, I cannot replace it yet since I am still waiting for a counter holder and the skinny wrench to remove the fan clutch. Anyone know where I can borrow those tools?
Question for Gilly, would those stuff hurt the engine? How do I completely flush them out?

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No ideas on where to borrow tools in your area. On the hex part of the fan you can possibly make do with a common wrench. Counterholder will be tougher to fake, may take a bit of enginuity (sp) but sure it can be done somehow.
The coolant looks pretty rancid, I still am not convinced the pump is bad. NOT saying it isn't, but I'm not really so sure. Will a magnet pick up these particles out of the cup of coolant?
About the only thing in the cooling system I can think of that would be affected would be the pump (although you are thinking that's where they came from) and the aux coolant pump, strapped to the inside to the battery box with the smaller hoses leading to it. ML has no heater valve.
For flushing, there are lots of commercially available flushing solvents you can use, myself for something like this I'd just use mostly water and a big squirt or two of dish soap, rinse it all out and start fresh, use the MB coolant.
Gilly

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When I thought I might have to do a water pump I checked out the special tools too. For the clutch holder it's part #113589004000 and for the open end wrench bit it's part #113589000100, very expensive most likely since you can use a special torque wrenc with it. You can probably use the right size wrench so long as it's thin enough.

I found the holder at link below. The add reference the proper part number so it should work.


http://www.zdmaktoolhaus.com/wbstore/main.asp?action=PROD&PROD=MK-1714C&CTMP=1

Ron, I ordered the parts I need from ZDMAK this Mon, was hoping the parts will show up so that I can do the pump over the weekend. Still no show yet. Anyone know if the black particulate will do any harm to the engine?

No, I don't think it would hurt anything except possibly the water pump itself (assuming it's not at fault already), the aux pump, or if it were bad enough to start blocking the radiator tubes.

Gilly

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