MArch 809 Problem - Losing Prime

Like the title says, I've got a March 809 that keeps losing it's prime. I can't possibly see how it is a plumbing issue on the rig and the pump worked fine for a while. I bought it from a buddy who used it for about two years and I've been using it about two years. It is the circing pump for my HERMS so it gets pretty heavy use.

I am about 99% sure it is simply a matter of a part wearing out but... I'm not sure which part.

I was guessing if I tossed it out there, someone would almost instantly say something like, "Oh yeah, the XXXXXX always wears out, just grag one and you should be fine".

... so... anyone got any experience with this?

Thanks.

More than likely your grain bed becomes compacted and this can cause the pump to cavitate and lose it's prime. The cure is to stop the circulation and stir the grain bed thoroughly, then resume circulation. Repeat as necessary. This may not be the cause of your problem, but it's the first thing I would look at. I seriously doubt that there is anything wrong with the pump.

There is something wrong with the pump. It loses prime when there's no grain in the rig at all. It'll pump just plain water for about 30 seconds and you can hear it lose the prime.

It started happening here or there about two months ago and has gotten progressively worse since... until now... where it'll only pump for about 2 seconds before losing the prime.

There are no clogs anywhere, I've cleared everything a couple of times.

I have a brand new pump and it does the same thing.

Subscribed.

I gotta take the thing apart and check it out. I was really hoping someone would just say, "Oh yeah... it's XXXXX"

the pump worked perfectly for well over year. The plumbing is extremely direct, not clogged... and again... worked perfectly for over a year. My other March 809 (got two on my rig) works perfectly.

This one started acting up and like I was saying above, has slowly gotten worse and worse to the point where it just doesn't pump at all.

... and again... this is with zero grain in the rig. That pump is plumbed to do two things... 1) circ the grain bed and 2) sparge from the HLT (obviously no grain bed) and it acts the exact same way with both sources.

Mine isn't as bad as yours it sounds like.

When was the last time you took it apart for maintenance? Cleaning and such?

"Oh yeah... it's XXXXX"

I would contact Walter from march pumps, he's on here and even gave out his number in another thread.

https://www.homebrewtalk.com/f11/march-pumps-ac-5b-md-review-214796/#post2579288


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Any chance you have an air leak in your plumbing causing the pump to pull air w/the liquid?

The March 809 loose prime if they get a sniff of air. If it runs for 30 seconds than stops.....you probably have a small leak that's allowing air to get into the pump. I use an autovent on mine and I still have to stop and start the pump once or twice to get it to pump constantly. Do a search, a lot of threads on here about this.

Cool.. Thanks for the comments guys. I'll poke around and see what I can find.

IrregularPulse said:

When was the last time you took it apart for maintenance? Cleaning and such?

Click to expand...

Ehhhhh. Nowwwwww. When you say, "maintenance".....

Never. My rig is CIP. Never had any infections so just assumed i was good.

I'll take it apart and check it out.

I could be wrong as its hard to tell without seeing the pump first hand, but the most common problem i find with the beer guys is having "crud" stuck on the impeller shaft and freezing or slowing the impeller down to the point it doesnt perform as it should or frozen all together. I can only guess its the sugars in the brew that are crystalizing and binding up the pump. I assume everyone here cleans these out after use in sort of fashion....not sure if you guys are just pumping plain water through or what. But heres a tip for anyone that may be having issues:
Take a 17/64" drill bit and pass it right through the center of the impeller where the shaft normally goes. This will open up the bore of the impeller and allow more liquid in between the shaft and the impeller to help in lubrication and in cleaning later. You wont loose any performance..... Air leaks are a different problem all together!

-Walter

Thanks Walter, i'll take it apart and see if i can see anything.

This pump easily gets the heaviest use out of the two I have and it is moving a lot of wort so, some crystalized sugar or just plain crud could be the problem.

I DO clean it after every use by pumping boiling water, then some oxyclean and then more boiling water through that circuit of my rig but I guess that doesn't mean there can't be some crud in there.

The fact that it seems to have gotten progressively worse over time sounds reasonable with the "crud theory" as well.

I had posted my original question because a few of my club cronies were at the house this past weekend and when it was acting up, a few simply said, "yeah, after a while you need to replace a part or two on those pumps"... hence my original question...

but they're boneheads.... so... you're probably right.

Thanks for the help. I'll have time this weekend to pull it out and take a look. i'll drop a note here afterwards on the results.

thanks again.

I had the same problem...losing prime. But I've resolved it and tried the new solution for the 1st time today and it worked GREAT ! It cost me some money, but here's what I did:

1. I set the orientation of the pump head so that the input is at 6 o"clock and the output is at 12 o"clock


2. I bought one SS 1/2 " Tee, three 1/2 " x 2 " SS nipples, and two SS 1/2 inch valves..( plus I already had a 1/2" barb )

3. I put the Tee on the pump output.....then 2 nipples coming off each side of the Tee....then a valve on each nipple to connect to the Tee, the barb on my "purge" side with a hose going to a bucket....and the other nipple on my output side.

4. With all the pump valves closed...I open my Kettle valve... then start my pump....I open the "purge" valve until I see liquid being pumped though it....then close the "purge" valve and open my output valve that either goes to my HLT, or my mash tun, or to my heat exchanger.

It's the first time I've ever been able to brew with this pump without losing prime...and it was awesome. It did what I had been expecting it to do since the day I bought it.

From 1976 to present, all I can say is gravity works best, and I have 2 of those freekin "pumps".........

The thrust washer wears out on mine from time to time, especially the pump that handles the boiling wort. Its a small white teflon washer that sits between the impeller and the body casting. In my experience, if its worn out and completely gone it can make the pump do some strange things. Pull the head off the pump and take it apart is the only way to know for sure.

Walter - do you know a part number say from McMaster/Grainger or the like to get replacement thrust washers? Maybe its just me, but I wear through a washer about every 4 brews, so I'd prefer to buy them in bulk rather than one at a time at a dealer.

McMaster/Grainger do their own part numbers so i wouldnt be able to tell you that....our part number for the washer is 0809-0043-1000

or you can go find yourself some teflon washers that have a .032 thickness, 13/32" O.D. and have a .250-.260 I.D. hole for the shaft.

River city brew, you ever find the correct washers on McMaster?