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      03-01-2013, 02:10 PM   #39
woodpecka's Avatar

Drives: E91
Join Date: May 2010
Location: Montreal

iTrader: (2)

Originally Posted by Artmasterx
I saw a similar thread that was specific to the N52 engine, so let's open it up to the whole crowd. I tried searching but didn't see a similar poll. N52 guys/gals, definitely respond to this poll as well.

N52 thread here:

Many of us are starting to get well into the range where they start to fail, so let's get some statistics.

Feel free to comment if you have a engine power mod, as that could have an effect on the failure rate.

If you had it replaced, feel free to reply with the cost and whether it was dealer or independent shop.

If you replaced it as a preventative measure, feel free to post that too in the thread.

Mine has ~55,000 miles and is on the original pump.

If we end up with a lot of responses, I will try to make some graphs/stats and stuff and post them here at the top. Thanks!

[[[[ Update 2/28/2013 ]]]]
Everyone, I have compiled initial statistics based on 106 responses so far.

This gives the failure probability and the +/- 95% confidence intervals for that failure rate. Obviously, we need more data points to get more confidence, especially at higher mileages.

Everyone help out by voting!

Also, there will likely be a skew towards more failures given that many people with healthy water pumps may not check out the thread.

The plot gives the failure rate as a function of mileage. In the x-axis I list the total responses for each mileage bin. For those of you interested in the calculation details:

Total response in each bin = n_i
Failure probability for each bin (p_i): p_i = #dead_i / n_i
95% Confidence Interval (CI): CI_i = +/- 1.96*[ p_i*(1-p_i) / n_i ]^0.5

Nice work! This confirm that I should change it after 110k km to prevent being stuck on the road.