Water pump confusuion - Page 4

80stech · #31 06-21-2022, 10:14 AM

The surface mount caps are a big red flag as well, the slightest bit of moisture will ruin those because they are made in cut layers with the edges exposed. Yes there is a lot of sealer goop over them but that could leak some moisture over time or if not perfect. Surface mount caps have improved a LOT since 2008 so that shouldn't be nearly as big a problem anymore.

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80stech · #32 06-26-2022, 10:45 PM

Next time I install one of these I will attach the thermostat on the bench with the 2 screws, install the u-shape hose between the stat and pump, tighten the clamps with everything lined up and then pull the 2 screws for the stat and then install both with the stat only attached by the hose so it can flop around. The reverse should work for taking it out of the car pulling the 2 stat screws but leaving u-shape hose and stat attached.

80stech · #33 10-14-2025, 12:24 PM

So the flipp'n water pump failed again after about 50k km and lots of idling time. Zulu called it when he said the pump might not have been original so the previous owner probably replaced it around 50k km and it failed again at 92k! I now have the 4 zone pump and they are totally interchangeable. The OE part is now made by Continental and is "supposedly" somewhat improved. The 4 zone and non pumps are totally different though in every way other than the mounts and connector and I'm thinking the 4 zone one might be a brushed motor because it has a bit of that sound when it's running slow.

andrewwynn · #34 10-14-2025, 02:44 PM

I monitor my pump RPM Because the car really doesn't tell you when it fails or is failing.

Ouch on 50km!

After replacing my motor i swapped my water pump over because it's much newer and i do notice the pump sound more than i did before even though it's the same pump.

I would be very surprised if it's brushed but now I'm curious

–awr–

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80stech · #35 10-20-2025, 11:24 PM

The pump did get more noisy before it failed. After doing a really good pressure test I now found that the tailpiece that goes from the outlet to the block and has the small branch going to the rad or oil cooler is leaking at the branch. The branch is poorly electro-welded (not sure if that's the right term) in, and is leaking slightly (I might have been a bit hard on it pulling the hose when I changed the radiator) so I ordered a new one (over$200, but comes with the short piece of hose for the water pump) hoping that they might have improved the way it's made but it looks no better so I'm reinforcing the new one with JB weld before I change it.

andrewwynn · #36 10-21-2025, 09:44 AM

I was going to suggest JB. Good call.

I'm about to start putting n55 into wife's car i think I'll copy cat you.

I monitor the coolant pump and fan realtime with bimmerlink. When the pump starts to fail it'll drop to zero rpm and the fan will go full speed in pulses.

I first noticed when driving slow i could hear the fan trying to pull the car forward like a plane propeller!

I opened up bimmerlink and sure enough. Coolant pump drops to zero so the fan kicks in. Just for five seconds then the coolant pump goes to max and the fan shuts off. This repeated every 20 seconds or so but then the pump would stay on for days before it happened again.

Eventually it stayed off longer even minutes where I had to pull over and restart the car to get the pump to come back on. Fortunately only had to do that twice as the pump was in the mail by then.

–awr–

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