Currently the leak isn't that bad - it just drops into a little dish - and I haven't had to top up the water loop in a few days. The problem is - it is losing water - and quite quickly. If you wanted the water to return to the loop you would not be able to have a true closed loop - but it would be easy to position the pump such the the water re-entered an open loop.


But I generally want low maintenance - or at least the ability to run a system for a while with low maintenance - I don't always have time to "play" with my rig. Daily/Weekly fill ups are not my idea of low maintenance.

But for some I'm sure this problem would be next to ignorable.

*small update*

My johnson pump was also leaking when it arrived.
The ceramic shaft (not really ceramic, more like an hard plastic) was broken.

Made one of inoxidable steel and its ok now.

Ceramic shaft???

Mine's all stainless steel, right through the impeller.

Are you talking about the impeller housing?

Huummnn....

*checks dictionary*

i meant the "washer" that holds the shaft.

:shrug:

The problem with these particular Johnsons is that they are direct-drive, not magnetic drive (which would be far preferable). Always go for magnetic drive pumps.

By the way the MTBF of 2500 hours refers to the brushes in the motor, if I'm not mistaken. You can get Johnson and Jabsco pumps with magnetic drive, and brushless motors, which will last over 10.000 hours easily, but price, as always, is proportional... (don't ask how much I paid for a johnson CM30P7-1...).

grrr#$@ to many threads....
 

Well, I know I should read all the threads in a forum......

So I started with the one about the nice jonson pump....,
I ordered 2, as they looked gread.

Then reading this other thread.........
In Europe the pumps costs about 120 euro's, at surplus not even 30...... IS there a catch? reading this thread, jep, there is. The pumps work good for about 6 weeks..........?:cry:

As I'm biulding a low mainenance system, I can't have this problem...

So, back to the surplus, called them from the Netherlands, and after 4 minutes my order was canceled.
Great shop, good service, crappy products?

fhorst
it is not just reading 'all' the threads
unfortunatly you must also evaluate the posters
some are 'boosters' (like Ben), some are 'critics' (like myself)
over time boosters will gain experience and evolve into critics - if they can learn

always look for the potential flaws, even so many will be missed

oh come on bill dont be so negative if you get 2 pump and dont run them 24/7, always check that you dont have a leak, you are safe and my bed is that those might last quite a while.

i suspect that the people who's pumps leaked ether themselves or someone at the suirplus store ran the pumps dry and ruined the seal.

I did NOT run the pump dry.
It leaked but i fixed it.
However, it BURNED also.

And NO, there is not magneticaly driven johnson pumps.

There are. I have one on my desk here. It's manual/specs list specifically states it is magnetic drive, and also that it has a permanent magnet (=brushless) motor:

http://pic4.picturetrail.com/VOL59/7...0/36931631.jpg

A bit fuzzy (low resolution shot) but there you are.

How can such low diameter engine be magnetycally driven?
Well, i guess thats why they cost 200+...

Hummm, I suspect some confusion here. I true mag drive pump has the impellor magnetically spun. Not necassarily the motor.

From the specs nexxo gives it looks as if the impellor is what they are refering to, not the motor itself.

No, they actually also refer to the motor seperately. Look guys, I do know how to read a spec sheet, and the spec sheet does read "Ball bearing permanent magnet motor". That's the brushless kind.

Bosch, by the way, makes practically the same pump, with exactly the same spec. Including the permanent magnet motor. MTBF: 10.000 hours.

the bosh pump is also used in the hydrocool.... It's noisy!!!! (Quite a lot) Should be silent, but it's not.

I called Surplus and asked them. (prior to canceling my order)
They did have more then usual RMA's with this pump.

Anyway, I'm happy with my 2 L20's :)

I wasn't questoning you, I just thought he didn;t understand the difference between shaft driven and mag driven pumps.

Also here is a link to the specs of your pump:
http://www.johnsonmarinepumps.com/sp...ges/cm10p7.htm

and

http://www.johnsonmarinepumps.com/sp...ges/cm30p7.htm

hmmm those guys are in seatle, wa i will give them a call tomorrow to see how much those are! seems to me its ether that or the new swiftech pump

called them up sounded like really nice guys here is the deal:

CM30P7-1 costs $159.20

CM10P7-1 costs $152.00

shipping is around $5-6 the guys said but i would ask for UPS or something with insurance.


i would also get the CM30P7-1 cause of higher flow rates and its a stronger pump.

hmmm cost ALOT but its REALLY good for its size

@ jaydee116: sorry if I sounded a bit touchy. It's just I've been through this story a few times...

@ dima y: They are built like tanks and worth the money. In Hot Rod car tuning these babies are considered the pump of choice to augment your Turbo cooling... :D

nexxo am i going to need a diode and capacitors if i want to run this pump of my main PSU, just like for the $30 johnson pump?

Since it is brushless, no.

Both my friend and I got one of these Johnson pumps this summer and both of us now have a nice small pile of dried coolant goop under it (yeah, we should check the system more often). Anyway, I cleaned it off and I'm not seeing any active dripping, and this has probably been dripping for a good month and I only had to add 10's of milliliters so it's likely a *very* slow leak, but I'm wondering what I can do about it.

dima y et all (except Ben who has been hyping the Johnsons since the get-go)
do you have any feel at all for where the curve becomes asymptotic ?

re the cost vs. (presumed) performance
- are you able to express it ?

I would put the asymptote at ummmm.... $100

i think thats about the most i would pay for the pump, it would have to have flawless preformance

for example when MCP600 gets revised i would gladly pick it up.