Polaris 3900 Sport - not backing up, not sweeping

[DoAsFan]

Hello All,

My Polaris 3900 Sport was left by the previous homeowner. No idea how old it is, but it's definitely the older style, before Polaris fixed various design issues. It was kept in the pool all the time, and ran on a timer for a couple hours everyday.

First off, it cleans. The wheels turn and the bag fills with leaves and sand. The bag has a 3" rip, but a new one is on its way. I've cleared the in-line filter.

My issues with it are:
1) It doesn't back-up. My pool has cake-like steps and the cleaner gets stuck all the time. The back-up valve cycles on/off at the expected intervals, but doesn't seem to have enough pressure to actually move the unit backwards. There's always a steady trickle from the valve and what seems to be a healthy gush during the back-up cycle. I was able to open the collar fairly easily, found no cracks on the case, and the gears turn and operate the valve as expected. A post in another thread indicated there should be ZERO flow from the back-up valve during the forward thrust cycle. Would replacing the o-rings be the right move ($5), or better to replace all the internals ($40)? Considering tossing the whole valve also ($50).

2) The sweep hose doesn't move at all. I've turned the adjustment knob all the way in both directions. The hose sprays water, but just doesn't whip around. Not even a little. There's no scrubber on the tail, but I've got one in the mail. Just realized that I should've just ordered a TailSweep Pro had I done a little more reading.

3) The black inside plastic part of the pressure relief valve seems worn. Not sure if this could be affecting the above issues, but wondering if i need to replace it.

Has anyone upgraded their 3900 with the new/improved tune-up kit? Seems like it addresses drive related issues rather than any sweep or back-up functions, but just curious.

Here's video of my back-up valve in operation.
[youtube:2mbt2y2i]95enf3JZWLQ[/youtube:2mbt2y2i]

 

[UnderWaterVanya]

The Polaris 3900 requires a booster pump - I did not notice one in your signature. Do you have a booster? Without a booster it will run s-l-o-w-l-y and not be very useful. I don't think that's your problem but it needs to be verified before we delve into more exotic reasons. Just to be clear - a variable speed pump is NOT sufficient even on HIGH to run these - they require a HIGH Pressure / Low Volume pump (ie Booster) not a LOW Pressure HIGH Volume pump (circulation pump).

EDIT:
The pressure relief valve looks OK - does it leak strongly at that connection? Mine leaks a little and works fine on a Polaris 380. Have you removed the quick connect fitting and looked to see what restrictor disc (if any) is in place behind the quick connect? These units need the right restrictor in place to get the pressure and volume correct.


This is your unit right?
http://www.polarispool.com/Pressure/Polaris-3900.aspx

I notice that it now includes "Tailsweep Pro" not sure if that's a retrofit item...

 

[DoAsFan]

Yep, I do have a functioning Polaris booster attached... which is a power hog btw, so I've removed it from the timed schedule and will only be operating when I can babysit it. It cleans pretty quickly as long as I nudge it backwards when it gets stuck.

Took 3 screws out of the 3900 and found manufacturing stamps from 2009. From what I've read, Polaris redesigned the drive train (a $170 upgrade) and added TailSweep Pro ($20~30) in 2011. They should've just given it a new model number or something to differentiate between old and new... 3900 Sport Plus Turbo :blah:

Tinkered with it some more, buy still no luck getting the tail to sway or the the valve to back-up. All 3 wheels go forward and back together, so seems the drive system is still good. No response from Polaris support yet, but its the holidays.

 

[UnderWaterVanya]

Is there a restricting disc in place? What is the flew like with no cleaner attached?

Sent via Tapatalk...

 

[DoAsFan]

Apologies for abandoning the thread for so long, and for reviving it again. The pool and I have been in hibernation.

I haven't been able to determine which (if any) restrictor disc is installed. I can remove the pressure relief valve, but can't seem to unscrew the universal wall fitting.

With the hose detached from the UWF, I have high pressure flow coming from the wall, but no matter how I adjust/turn the pressure relief valve, it feels like the same amount of pressure flowing out of the relief valve. Even completely tightened, or loosened to the point of detachment, the pressure relief valve releases the same flow. Busted?

The amount of pressure flowing out of the backup valve is significantly lower though. It has a constant, low trickle during normal operation, and maybe a 25%~33% of the flow I feel from the UWF/relief valve. I'd say it's a little less pressure than what I get from the thrust jet on the cleaner itself. See embedded video in original post.

Do I buy a new:
Pressure Relief Valve (9-100-9002)
Backup Valve (G52)
Tune-up / retrofit kit
Polaris 280, and just trash the 3900 Sport entirely

Thanks!

 

[DoAsFan]

I pulled the UWF out and see that it has a blue disc in. I can't seem to separate it from the part threaded into the wall however.

Opening up the belly of cleaner, I can see that the chain is loose. Not much tension on it. I'm considering removing a link as prescribed by others before ordering the tune/upgrade kit.

I cleaned out my cartridge filter last weekend which seems to have improved the cleaner's performance. Still needs a nudge every few minutes, and never backs up. Frequently stops at the top of a climb and just hangs there, wheels stopped.

I've been using my 3900 a lot this week as I'm shocking. Basically running about 1-2 hours a day, filling a couple of bags worth of stuff each day.

Since improving the overall water flow seemed to help, I'm now wondering if it would be worthwhile to try to service my booster pump. Attached is a photo of the booster, which I'm guessing is some iteration of the PB4 (or PB4-60?) from August 2000. I'm thinking of removing the volute and inspecting the impeller for debris and wear.

Can anyone confirm the model and/or point me to a comprehensive guide on servicing the booster? Thanks!

 

[DoAsFan]

Found a very nice guide on "DIY How to Repair Your Polaris Booster Pump":
http://www.poolsupplysales.com/blog/rep ... ster-pump/

The Polaris/Zodiac catalog shows the exploded parts diagrams for the 2 generations of the PB4-60:
http://www.polarispool.com/Replacement-Parts.aspx

Owner's Manual for the new model:
http://www.polarispool.com/~/media/Zodi ... hx?force=1
Owner's Manual for the older model:
http://www.poolcenter.com/polaris-boost ... all-OM.pdf
Instructions for various replacement kits they sell:
http://www.polarispool.com/~/media/Zodi ... hx?force=1

I'm guessing mine is the earlier model, even though I don't have a legible serial number anymore. The pump stand looks more like the older one, and the manual age seems about right.

 

[DoAsFan]

Haven't had a chance to break down the booster, but I did do a complete teardown of the sweep.

Found that the float was nearly full of water. Unfortunately the float on my older model 3900 is not the replaceable silver unit, and would require a complete upper assembly swap. I'm thinking of drilling a hole to drain it, but wondering what you folks might suggest to plug a hole after? Some sort of epoxy, bondo, duct tape solution?

The gearbox functions, but definitely sluggish. It generates a clickity-clack noise as it turns. I'm assuming this is why it needs a nudge every few minutes to get it going again. I also have a problem with it climbing most of the way up a wall and just hanging mid-air until I bump it.

I've been corresponding with Polaris support about the drive issue, in hopes they'll comp me some parts. I'm pretty much requiring a complete overhaul at this point and not just the upgrade kit.

Backup valve still drippy and doesn't generate enough pressure to pull it back.

Good news is, the tail moves great now. I'm guessing maybe it was clogged.