View Full Version : Auxiliary water pump - noisy or normal?

02-15-2017, 12:10 AM
I just replaced the auxiliary water pump in my 2006 which has the preheater with timer. The coolant system has been bled out and all is functioning well but the pump, the Vemo brand, seems incredibly noisy. Here is a recording:


Normal, or loud? The recorder in my phone pegged it at 55 dBa held near the steering wheel. The original pump was dead when I bought the van. I can't think these pumps should be so irritatingly loud! Perhaps the few $ I saved by not buying Bosch was a bad idea.

02-15-2017, 11:53 AM
The firewall mounted electric water pump should be more or less silent. Typically the only way to tell if it is running is listening for the coolant circulating or to put your hand on the pump and fell the vibrations. Even running pumps with nothing in them (for a test), they are very quiet. So, I would say that there is something amiss here, it should not be that loud.


02-15-2017, 03:09 PM
I bought the cheapest option on ebay a couple years ago when replacing mine. Its definitely louder than the Bosch one. You can hear it at idle, but not when driving down the road. It has been working fine for 2 years and about 40k miles. I didn't think anything of it until helping a friend out with his espar and noticing that his BOsch pump was nearly silent. I remember reading on the forum that the Bosch units crap out about every 60k miles or so. Hope this helps.

02-15-2017, 05:52 PM
I think any of the pumps wear out if they have brushes, because they run continuously. The brushes are quite easy to replace once you get the hang of it - you have an essentially new pump for a couple of $. My Bosch clone that I bought on ebay is pretty darn silent also. Seems like a business opportunity just refurbishing the Bosch pumps.


02-15-2017, 06:01 PM
Thanks, that's what I figured because my other Sprinter's pump runs a lot quieter. I'll return it to IMC and request a Bosch replacement. The sound is extremely annoying. I did find the post re: replacing brushed so might fix the old one as a spare.

02-15-2017, 08:46 PM
I could show you how when I am out there on vacation in August!! The thread write up is pretty good on the brush fix, there is really nothing to lose.


02-17-2017, 08:37 PM
I installed a new Bosch pump and sent the Vemo brand back. As I was putting it in the box I only then noticed the 'China' sticker. Night and day. The Bosch makes zero noise. Ah...peace and quiet. This plus the Walker Quiet-flow muffler, sanity returns!

02-18-2017, 08:18 AM
It took a bit of hunting, but Amazon had the bosch pump for around 70$ a few months ago. Like you mentioned, its very quiet. Just a gentle hum with gurgling coolant.