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Discussion Starter #1
Vehicle in question is a 1998 900SE

So, I've spent the last 24 hours or so reading through the archives, have followed many tests and tips, and I think I've identified the problem. First I'll give a little background.

-water pump replaced last year in june

-no engine overheating
-no oil in expansion tank, nor coolant in oil

-slow loss of coolant level in expansion tank, maybe 1-2L per 5 hours of driving. i've been topping off the loss with filtered water.
-slow visible drip/seepage at idle from what appears to be a bolt connecting water pump assembly to engine....drip speeds up when rpms increase.

** a note on the location of drip - after removing the grille, and passenger (US) side headlight, i can light up the area on the front of the engine, and the leak is coming from below the top of the water pump, and above the a/c condenser unit. i say below the top because it is not visible from above.

SO

is it likely that i've blown another water pump in a relatively short period of time?
could it be a seal in the water pump? i've seen a $1.99 seal part for the water pump on one of the websites.

any advice will be appreciated

cheers

-Matt
 

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Potential seal leaks

It is almost impossible to wear out a water pump in a year unless the part was defective, and that is very unlikely. I believe Asia who used to post here replaced a pump after less than a year. Can you identify the spot where the drip is? Then perhaps someone else who had the same leak can comment.

Housing Seal: The waterpump has a split housing with a fiber seal (2) and several bolts holding it together. The seal might not have been put in right, the bolts not tightened quite right, etc.

Pipe Adapter: There are also two o-ring seals (4 and 5) at a pipe adapter at the engine block. Those often start to leak well before the water pump goes bad (mine did that around 60k). Coolant could flow along the housing from behind where the pipe adapter is located, and show up at the bottom of the pump.

Small Pipe Seal: In addition there is a smaller o-ring (3) at a hard pipe which also connects to the waterpump housing.

Hose Clamps: Check the clamps at the short u-shaped hose (17) at the pump while you are at it, too.


 

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Discussion Starter #3
the first visible (so far) sign of a leak appears to be coming from the #16 bolt in the reference diagram you provided (thanks!). I can see that doesn't really make sense, looking at the rest of the assembly, but thats as close as i've gotten so far.

I will be up early to continue the investigation, (in between sneaking a peak at the tour)

Thanks for the help!!

-M
 

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The coolant may run down to the bolt because it is a low spot and drip from there. A pump usually makes noise when it starts to fail, or leaks from the shaft, has excess play in the shaft and pulley, or some combination.

I have been told by a couple mechanics that Saab water pumps and heater cores are often replaced needlessly when the leaks are coming from one of the o-ring seals. It is best to find the leak before taking the pump out, instead of hoping it will go away because all the seals get replaced at the same time. The small u-shaped hose and clamps should be replaced at the same time as the waterpump.

If not already done, the upper and lower radiator hose are the next most likely to fail (my upper radiator hose was bulging out and replaced around 85k miles).

Around 60-100k miles various o-rings start to leak. Coolant, power steering fluid, and AC lines all have problems it seems. I have had all three. Not sure if Saab is especially susceptible, but I heard about a couple other makes with similar problems.
 

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Discussion Starter #5
sooo..verdict in

water pump #2 in 14 months. (~20k miles)

only extenuating circumstances were a past due idler pully (also replaced)
working, but on its deathbed.

still seems a little funny, have yet to closely examine pump
 

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Sorry to hear that... .do you know if the pump was leaking along the split in the housing, or from the shaft? What brand pump was it, Saab, Hepu, something else?
 

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PMI said:
Sorry to hear that... .do you know if the pump was leaking along the split in the housing, or from the shaft? What brand pump was it, Saab, Hepu, something else?
Very good questions, PMI
I too would love to know.
One replacement water pump on the old '80 Mercedes had a very short life, so I am thinking that this is aftermarket QC not being that good..
But we now have nearly 400K miles on the three cars with original pumps.
I use anti-rust additive, this helps..
 
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