OKAY!!!!

Good afternoon MBworld...I hope everyone is having a great day!

WELL....After having an aggresive discusion with our AMG MB master tech, BMW master tech and one Aeronautical engineer. The question was: "Which pump flows more volume of water quicker?"

Video:

BOSCH: http://www.youtube.com/watch?v=FMmWPM8htQ0

CM30: http://www.youtube.com/watch?v=60tzWqriWM0


I decided to go purchase a coolant hose, and start the process to our test.

OEM BOSCH VS. JOHNSON CM30.....


We performed TWO tests; 30 second and 10 second intervals. Which one could move the most volume of water per test.


We started off with 2 buckets of water!


The first test was with the CM30





The second test was with the BOSCH





NOW, THE CONCLUSION:




Both pumps flowed the same amount of water per test. Not only were the results mind-boggling to our Techs, but I was suprised as well.

My END result:

I am not saying the CM30 pump is a bad buy, I understand the CM30 has other advantages but from our test results, they flow THE SAME!

I just thought I would share this "experiment" with everyone!

The CM30 is great buy but my results prove that they FLOW at the same rate!

I am told the internals are more efficient so that being said it is still a great upgrade if your current BOSCH pump fails!

That's all folks.....Have a great day!

Wow! Thanks for conducting this empirical test.

wow thank you. archieve this thread

Good info, did you use the same diameter hose for both pumps?

YES SIR! I used the same hose for both pumps!

I also did it with: 1 gallon of water, 30 secs and 10 secs....Just to make sure!

Thanks for the taking the time to perform this test...

I just don't trust the Bosch pump.. I have replaced 3 of them in my 2 cars.

So far my CM30 has lasted for over 2 years without a problem.

Now, if we can find an upgrade to both pumps without changing diameter in hoses like the (CM90) it would be ideal.

How about warranty?

Which one has the longer warranty? That might be another deciding factor. Thanks for the test.

One will pump better under a load (head) than the other.
One pump has a much lower electrical draw too.
So if you have a HE sitting around and an amp meter you can determine the best one.

i think many ppl go with CM30 for reliability rather than more flowrate...
glad mine's 80....

So my question is what does the cm30 have that prevents sc shut down, if the flow rate is the same we should experience sc shut down with the cm30 also.

Simple: The Johnson doesn't break. That's what shuts the s/c off, the intake temps get too high when the Bosch pump starts crapping out and gets weak, and as a result you get sporadic/intermittent s/c engagement. The johnson pump is a $h!tload more reliable than the Bosch pumps, and that's the real benefit of switching them out.

I have to admit I'm surprised by the results of the test, I would have thought the Johnson pump would flow better. But even so, I think this is still a valuable upgrade purely from a reliability standpoint. Most people around here have been through several Bosch pumps, but I can't remember hearing about a single Johnson pump crapping out yet.

+1 CM30 FTW!!

Are the 2 pumps new??
I opened from some days the same subject on the C32 forum under " OEM ic pump vs Cm30", guys take a look, it's interesting.

+1

Tom

i thought there were a few claims that the cm30 did flow a tiny bit more than the bosch. regardless, flow rate has never been the reason i switched to the cm30...if it was i would have gone with the cm90.

thanks for the info!

well it has also been stated that there was nothing wrong with the revised pump mb had...yet people were swapping it out for the cm30 when they were fine

Thanks for the tests

This reminds me of the bilge pump debate often had over boat bilge pumps.

They're definitely not all created equal ... the minute the going gets tough ... some stop going ... and with boats that can be real bad.

I have 2 - 2000gph pumps and one 1500gph pumps in my boat. The originals were "Attwoods" that I replaced with RULES. Horizontal rates were the same ... noticeable difference when pushing a head.

i'm a bit suprised as well, my OEM was dead when i switched to the CM30.

thanks for sharing !!

So, since the flow rate is the same, in the past, people kept saying that if you feel "less" power (not a complete s/c shutoff), then upgrade pumps. So, this is not true anymore? In other words, the bosch pump is either ON or OFF, not in between??

the 03 and i htink maybe up to 05 cars had a different ver of the bosch pump, MB later on updated it with a revised ver in 06

thats the one you want and it has warrently and runs fine, have not heard of any one with it complaining

So, I was under the impression that everyone wanted the CM30 pump for "extra" flow reasons.

The internals are better and it last longer than the OEM pump? Sounds good to me!!!

Good to know!

What else would you guys like me to test out?

Mad props for taking the time to do the test. One flaw is that any pump changes flow rate as pressure increases. If you look at published flow rates for fuel pumps they show a chart giving pressure and flow. The pump first has to work to create the pressure to over come the FPR or in this case the intercooler circut before flow begins.

I suspect that the difference will be minimal but it is an unknown variable.

i think both pump curves are available. although in a low restriction test, both pumps may perform the same, as restriction increases (such as through a cooling circuit), i'm curious which one performs better. anybody have both curves? (i remember the stock pump is more efficient)

actually, in another thread
https://mbworld.org/forums/c32-amg-c...p-vs-cm30.html

this shows the OEM pump as being more efficient, although it's unsure what the test method and setup is of the bosch.

however, the OP test with an assumed very low restriction is consistant with the two sets of data - the OEM and CM30 pump characteristics are similar at low restrictions, but the OEM will probably be better at higher restriction (vehicle circuit)

I've got an 06 E55 now using the new upgraded Bosch pump. I also have a cm30 sitting in the garage that was on the car for six months. I can feel no difference between the two in performance or reliability.

The dealer "suggested" that I remove the cm30 when they found it on the car while doing an oil change under veiled threats of warranty problems and offered to install the upgraded Bosche under warranty. I said OK and haven't had a problem since.

IMO the cm30 is no better or worse than the Bosch. If you're not having problems, I wouldn 't change it.

my CL has been running like a whole new beast with new coolant and CM30 pump after my Bosch failed completely... or is it just in my head?