Grundfos MQ3-35 leaking

[JKTrevecca]

I was hiding some Christmas presents in my crawl-space and noticed my pump is leaking substantially. I bought my home 2 years ago with the pump already installed. In the last 24 hours I've learned a lot about something I never thought of before now. Oh the things I take for granted. I removed the pump and bypassed it last night. The shower this morning left much to be desired.

I have 30-32 psi static pressure without the pump. I can fill a 5 gallon bucket in 1:13 from the lowest faucet in my house which in in my garage in a utility basin. It takes exactly 1:00 to fill the same bucket with the hot and cold valves both wide open. My inlet supply line is 3/4 inch but I live on a hill and my water meter/tap is on the lowest corner of my property quite a good distance from the house. I live on a 1.3 acre lot and the water meter/tap is about as far away from the house as it could be given the shape of my lot.

The pump shaft seal or seals on the Grundfos is the source of the leak. I'm inclined to pay $70.00 for the seal kit and rebuild it but in reading about this pump, I'm finding out it isn't expected to last more than 2-3 years and has a poor reputation. One person I spoke to today suggested I buy an Amtrol Pump/Tank combo system to replace the Grundfos with. He has no skin in the game so has no reason to suggest the Amtrol for his own gain.

Thoughts? Any votes for rebuilding it or is there a clear consensus that it's a paper weight and rebuilding the seals would be futile? If I should replace it, what do you suggest as it's replacement? My understanding is that combining a pump with a tank will result in much longer pump life.

I'm all ears and appreciate any advice you're willing to share.

-- Jason

 

[Terry]

Hi Jason,
That's a pricey little unit.
http://www.supplyhouse.com/Grundfos-96860172-MQ3-35-Pressure-Boosting-Pump-115V

The parts are a little cheaper here
http://www.supplyhouse.com/sh/control/search/~SEARCH_STRING=mq3-35 parts

 

[Sponsor]

 

[Valveman]

I wouldn't keep throwing good money after bad. The seal is leaking because the pump got hot. The pump got hot because the electronic controller is malfunctioning. Those MQ pumps have a little pressure tank inside them about the size of a coffee cup. This tank is not large enough to be of any good, and when the controller doesn't shut the pump off as it should, it gets hot and the seal is the first thing to go.

A pressure tank is a good thing, but you don't need a very large one like Amtrol will try to sell you. Amtrol makes tanks, not pumps. So of course they are going to sell you a pump system that requires the largest tank.

Get a good jet pump like a Goulds J07S and it will last for many years. Then if you use a Cycle Stop Valve like comes with the PK1A control kit to control the pump, you won't need a very large tank. The PK1A kit comes with a 4.5 gallon size tank and will deliver strong constant pressure to the house and make the pump last for decades.

Pump companies make pump controllers that shorten the life of the pump so they get to sell you another. Tank companies make pump controllers to increase the size of tank needed as that is how they make their money. Pump and tank companies do not recommend a CSV type system as they make pumps last longer and allow the use of very small tanks.

 

[JKTrevecca]

Thank you Valve Man and Terry!

 

[semipro]

My experience is limited to my own MQ3-35 only.
I would take a shot with the seal repair. The unit seems designed to be very serviceable. A booster pump has a rough life and repairs should be expected. $70 is not a lot when you consider the cost of alternatives and their repairs, The seal install seems pretty straight-forward.
There aren't many comparable alternatives out there so learning how to repair your MQ and what its shortcomings are may be useful.
The shortcomings I've identified: a main plastic housing so you need to be careful with screws, not cross-threading them or over-tightening; a rather expensive control board; and limited diagnostic information availability.
BTW, there are some good tear down and reassembly videos on Youtube.
A suggestion, if you go back with the MQ, plumb it in so that it can be bypassed with the turn of a few valves.

Edit: repair manual here:https://www.google.com/url?sa=t&rct..._PYqrH4fT7b6-GuZnLVhjA&bvm=bv.139782543,d.cGw

 

[Valveman]

This is a picture inside a Dumpster behind a typical pump supply house. I do see a couple of old cast iron pumps in there, but I will bet they are 30+ years old. The rest of the Dumpster is full of MQ's?

 

[semipro]

This is a picture inside a Dumpster behind a typical pump supply house. I do see a couple of old cast iron pumps in there, but I will bet they are 30+ years old. The rest of the Dumpster is full of MQ's?

Point taken.
I'm not trying to be argumentative and I qualified my experience with these as extremely limited; just providing my observations.
That said:
- the other pumps in the photo there appear to be the Goulds unit recommended above?
- the fact that pump "supply" houses don't fix these doesn't surprise me. There's little money to be made there. Replace rather than repair is way too common these days. I saw this when I worked as an auto mechanic. (I was the guy that rebuilt alternators, carbs and such rather than replace them).
- also, anecdotal "common knowledge" like "you need a safety line" or "you have to install redundant check valves" are just that. I'd prefer to see real objective evidence of failures rates versus the numbers sold. The fact that that bin is full of MQs may reflect only that many of them are sold and not that their failure rates are high. On the other hand...
- finally, I just installed an $80 flow sensor in my MQ to fix a short cycling issue. We bought the pump in early 2012 and that's the first repair it has required. I hope the MQ continues to work but if it doesn't I'll post about it (as I chew on some crow).

 

[semipro]

I was hiding some Christmas presents in my crawl-space and noticed my pump is leaking substantially. I bought my home 2 years ago with the pump already installed. In the last 24 hours I've learned a lot about something I never thought of before now. Oh the things I take for granted. I removed the pump and bypassed it last night. The shower this morning left much to be desired.

I have 30-32 psi static pressure without the pump. I can fill a 5 gallon bucket in 1:13 from the lowest faucet in my house which in in my garage in a utility basin. It takes exactly 1:00 to fill the same bucket with the hot and cold valves both wide open. My inlet supply line is 3/4 inch but I live on a hill and my water meter/tap is on the lowest corner of my property quite a good distance from the house. I live on a 1.3 acre lot and the water meter/tap is about as far away from the house as it could be given the shape of my lot.

The pump shaft seal or seals on the Grundfos is the source of the leak. I'm inclined to pay $70.00 for the seal kit and rebuild it but in reading about this pump, I'm finding out it isn't expected to last more than 2-3 years and has a poor reputation. One person I spoke to today suggested I buy an Amtrol Pump/Tank combo system to replace the Grundfos with. He has no skin in the game so has no reason to suggest the Amtrol for his own gain.

Thoughts? Any votes for rebuilding it or is there a clear consensus that it's a paper weight and rebuilding the seals would be futile? If I should replace it, what do you suggest as it's replacement? My understanding is that combining a pump with a tank will result in much longer pump life.

I'm all ears and appreciate any advice you're willing to share.

-- Jason

Any chance it got cold enough in your crawl space to result in freeze damage to the pump?

 

[Texas Wellman]

It's kind of amazing to me that this is jet pump country and I have never seen a grundfos jet pump or centrifugal. Must be a regional thing.