Odd sound Harman p52i, figured it out but what to do?

[rob.mwpropane]

Hey guys, I installed my Harman p52i back in 2014. I love it, except for the intermittent sounds it makes. Last year I swapped out the combustion motor thinking it was bearings, and that did fix the issue, but this year I started it up and behold, sound is back. Because it's such a pain to pull out, I have to wait for a decent weekend to swap the motor out.

Link to install if needed;
https://www.hearth.com/talk/threads/harman-52i-install-let-me-get-this-right.125196/

Recently I cleaned it, and cleaned the fan blades on the combustion motor really well, and what do you know, sound was gone. So now I know it's the fan blade itself. This was short lived, and the sound came back withing a few days, so again last Friday I cleaned it again, this time removing and really getting it cleaned. This made things horribly worse!! I must have removed and adjusted that thing 50 times before I got it to sound right. Finally at some point it did the trick and all was good.....until last night? We were watching a movie (pellet stove sits ~ 3' from the tv) and I started to hear it every so often. My wife say's she doesn't notice it until I point it out, but in my defense I'm closer and I'm always listening for it because I know it'll only get worse.

I'm at a loss? I've put the fan blade on a flat surface and tweaked everything so all the blades line up and then it was worse than it's ever been. Used vinegar and a brush to clean it to look new, no good. The only thing I did to get it quiet was just keep adjusting the blades while installed in the stove...open, adjust blades, close, test,..... open adjust blades, close, test......

If I look at the fan blade, there' physically nothing wrong with it, and I can get it to be quiet, but at some point it starts to make noise and my experience is it just gets worse. I'm all ears to any suggestions? I can spin the motor freely with my fingers and there's no gritty feeling or slow down like when a bearing is out, so I'm 99% sure it's the fan blade. The only thing I can think of is days of heat throw it off balance, or it gets dirty, but the sound stays after I clean it and the only remedy thus far has been to "play" with the blades themselves (pushing slightly in, or pulling slightly out).

I know a new blade is like $20 online, but I wanted to run this by you guys first and to see what you think?

Hope everyone had a great Thanksgiving!

 

[Tails1]

Try oil the bearings in the motor with some 3 in one oil. See if that helps.

 

[rob.mwpropane]

Try oil the bearings in the motor with some 3 in one oil. See if that helps.

That was the same thing my local hardware (Harman dealer) store said last year, problem is they're sealed bearings (which I knew). I tried it anyway and it made no difference. I'm 99.5% sure it's not the bearings because this motor is less than 1 year, and again I can get it to be quiet as a mouse for a few days, but only after messing with the fan blade.

 

[Ssyko]

Is the fan blades moving when it gets hot and rubs on the fan shroud? Metal does move in extreme temps. look for marks inside the mounting are

 

[rob.mwpropane]

Is the fan blades moving when it gets hot and rubs on the fan shroud? Metal does move in extreme temps. look for marks inside the mounting are

No sir, the metal on metal is something I've experienced but only when trying to adjust the blades in / out.(And I turn it off immediately)

The sound I'm talking about is more along the lines of a fan blade that's out of balance, definitely more vibration than should be, but it's not constant which is what drives me so crazy. Now at some point, if I let it go, it does become a constant. We'll have to see what happens over the next couple days.

 

[Ssyko]

If the blade is out of balance it will take the bearings out of the motor after a while

 

[rob.mwpropane]

If the blade is out of balance it will take the bearings out of the motor after a while

I agree, but why does it come and go? It's not like it only stays quiet for a minute, it stays quiet for days? My experience with bearings is when they're done, they're done for good.

 

[Mt Bob]

There is a housing,the impeller sits in,that is attached to the stove back.I do not know if it is spot welded or bolted,but this might be the source of the noise,as the impeller gets dirty.You will have to do some checking next time you pull it out.Also,you should have the double impeller,riveted together,it may be loosening up when hot.For now,get a new impeller.Get some dry moly spray,coat impeller well.Don't forget always best to put some anti-seize on the allen head screw,and where impeller slides on shaft.If you cannot find dry moly,you can get dry graphite at any car parts store,just does not last as long.To oil brgs with a rubber lip seal,use diabetic needles,but,ball bearings are rarely oiled,they are greased.Anderol 465 is the best,for bushings,and works well on ball bearings,but oil does not stay in ball bearings

 

[rob.mwpropane]

There is a housing,the impeller sits in,that is attached to the stove back.I do not know if it is spot welded or bolted,but this might be the source of the noise,as the impeller gets dirty.You will have to do some checking next time you pull it out.Also,you should have the double impeller,riveted together,it may be loosening up when hot.For now,get a new impeller.Get some dry moly spray,coat impeller well.Don't forget always best to put some anti-seize on the allen head screw,and where impeller slides on shaft.If you cannot find dry moly,you can get dry graphite at any car parts store,just does not last as long.To oil brgs with a rubber lip seal,use diabetic needles,but,ball bearings are rarely oiled,they are greased.Anderol 465 is the best,for bushings,and works well on ball bearings,but oil does not stay in ball bearings

That's a good idea about the rivets. During the cleaning I didn't see any issues, but your right, with the heat they might.

The housing in the back is bolted, and from what I remember, there was no soot around it the last time. No seal either, just a very small hole for the shaft.

What would the moly spray do? Keep the impeller clean for longer?
https://www.amazon.com/dp/B0013J62P4/?tag=hearthamazon-20

I always use anti sieze, thank goodness too because I would imagine that gets seized up pretty fast.

I had a thread or saw one on here in regards to replacing bearings with better ones, can't seem to find it right now. If I went through all the trouble to grease / oil them, I think I would just replace them with better ones (maybe high heat ceramic?).

 

[Mt Bob]

Yes moly keeps soot from sticking,longer than graphite.I also use graphite in hopper,makes pellets slide down bwetter

 

[Mt Bob]

I have never put bearings in those new style motors.

 

[Ssyko]

The combustion motor on my 25pdvc had a small gap between the motor housing and the mount bracket that had squeek to it that got really bad as the stove warmed up. I tapped the fold-overs on the housing and tightened up the 2 and its back to normal. Age, hot and cold make metal do strange things. Replacing the bearings isn’t very difficult just put it together the same way it came apart.

 

[rob.mwpropane]

Thanks guys, I'll try the spray and new fan blade and see where it goes.

 

[rona]

A new fan blade should solve your problem. Prolong heat can do strange things. 20.00 is cheap fix.

 

[rob.mwpropane]

Good day. Hope everyone had a great holiday. I just wanted to check back and confirm that a new ~ $18 combustion fan blade did the trick. It did take a little adjusting for find the sweet spot, but it's super quiet now. I bought the replacement from ebay and it was much thicker / stronger than the one that came with the unit. The old one I could easily pull the fan blades, the new one would take some force to get them to bend.

Just as a note to be fair, I don't think my combustion motor that I replaced last year was ever at fault. I'll say I think that it was entirely the blade. Live and learn. To date, my stove has burned almost 13 tons of pellets since installed in 2014 and this has been my only real issue. I did have a slight rumble but changed the intake line (OAK installed) over to 3" instead of 4" and it solved that issue. I use it as my sole source of heat, and to date all original parts (except for the combustion motor which was probably fine). The only issue that I've noticed other than the fan blade noise is the "Cast Center Medallion" has warped from heat (I've always kept it below 5 for temp setting as suggested on this site). It's not warped enough to warrant a new one yet. And the glass has a slight discolor to the top left when looking at the stove. It's unnoticeable when the unit is on or off, only noticeable when I'm cleaning it.

Cheers!

P.S. - If anyone has a line where to get a Harman "Service Rail Kit" (part # 1-00-574354) for cheap I'd like to know. I do not have an elevated hearth, so I need rails that can lay on the floor. I purchased channel to build one and have a design, but just can't seem to find the time to build it. I've seen people mention getting them for ~ $140 at dealers cost which would be ok, but I'm not spending $400 for that. Maybe it's just me, but that's crazy...