Bosch SKT5002GB/02 Compact: Recurrent pump problems

[MattF]

Hi all,

I’m almost at the point of trying to talk to someone at Bosch about this, but I’ve just found these forums, and thought I might do better asking people who see these sorts of things day in, day out, so here goes. Sorry it’s rather long, but there’s quite some history!

Bought a SKT5002 in Aug. 2000, and it did what was asked of it perfectly well for 18 months, when the circ. pump motor started screeching badly before giving up completely. Had a look and found front motor bearing rusted solid due to seal failure. Bought replacement pump unit (including all seals) from BSH Spares, and fitted.

Everything was fine again until May last year, when it happened again – at least my repair lasted longer than the original! This time, I wasn’t prepared to shell out another 90 quid for the whole pump unit, so I just bought new rotating seal, impeller and o-ring, and replaced the by-now-greaseless motor bearing. There was very little rust this time, and my refurbished motor ran sweetly… until last week!

Now, I’m intending to do exactly the same as last time provided things aren’t too badly corroded, but just before I order the bits, has anyone seen this kind of recurring seal failure before, and have any idea what can cause it? Any ideas on how I can improve the quality of the seal? I have an electronics background rather than fluids/mechanics so not too well up on rotating seals. The water here (Leicester) is pretty hard, but I always keep the machine topped up with salt and there are no signs of any scale deposits inside. Detergent used is (currently) Finish liquid but have used many others, usually powders. I put a stop to people pouring leftover tea/coffee/wine into the machine the first time it failed, in case there were some corrosive effects there.

I’d be really grateful for any expert advice on this!

Thanks,
Matt

[Penguin45]

Re: Bosch SKT5002GB/02 Compact: Recurrent pump problems

I would suggest that you buy 065548, the springloaded carbon face seal and 065550, the impellor with the ceramic counterface on it. When fitting the springloaded seal, a wipe of sealant where it pushes into the backplate will prevent minor dribbles. The impellor should be screwed fully home, when spun over by hand you should feel resistance – this is caused by the seal faces being pushed firmly together, thus (theotetically) making the watertight seal.

HTH,
Regards,
Penguin45.

[MattF]

Re: Bosch SKT5002GB/02 Compact: Recurrent pump problems

Thanks, especially for your rapid reply!

Those are the parts I was going to order, though I haven’t put any sort of sealant in before – do you mean the rear surface of the carbon seal? What type of sealant would be best for this?

Impellor: I did notice last time (when I finally realised that the darned thing was simply reverse-thread-screwed to the shaft!) that it didn’t take much effort to remove, so I’ll give that some extra tightening.

Matt

[Penguin45]

Re: Bosch SKT5002GB/02 Compact: Recurrent pump problems

Ah, the left hand thread – truly a sin before God. Do not apply any form of sealant to the running surfaces, indeed ensure that they are spotlessly clean before assembly. The flange where the seal seats into the chamber cover can use the very lightest smear of silicone or similar just to double seal the joint.

For resistance, the pump should not actually be stiff to turn; just a light drag as you turn it.

Regards,
Penguin45.

[Author]

Posts