Harman Insert Combustion Motor w/HOUSING replacement procedure--

[sandpipe]

I'm about to start replacing the combustion motor/housing assembly tonight on my dead Harman Invincible Insert. I was wondering if there are any procedural tips / tricks anyone can send my way. I'm hoping it will be straightfoward-- 4 bolts and all out but I have an ominous suspicion that there may be problems.

For example:

I was wondering if I need to use hi-temp 500deg silicone sealant, or furnace cement (or nothing) between the blower housing and the stove?
Did I need to get a special gasket for the install?

I did get new impeller blades to attach to the motor as they do not come with them!

I'll check back for any tips and for sure will be back if I run into any problems. And if all goes well (eventually), I will summarize the process for others.

Thanks in advance!

 

[SidecarFlip]

I suspect your old gasket will be less than useable so red RTV will be the seaant. I used RTV after the first removal...always. You'll never get your old impeller off the old motor shaft so the new one is mandatory plus the old one will be brittle from the heat.

 

[sandpipe]

Thanks SidecarFlip. I put the new blower in last night. Since it came with the housing the motor was attached with a brand new gasket. I thought I was going to have to replace the motor AND THE HOUSING but when I saw that changing the housing looked like a four hour job and probably a fail by me I just unscrewed the new motor from the new housing and it was an exact match (except for slightly more amperage). It all went together perfectly and the stove is working aok.

I see aftermarket places selling a new different motor that doesn't have the rear fan (in addition to the all important paddle blade impeller that you had mentioned ) and these sellers say it works on the old Invincible Inserts but I guess to get the correct replacement for this model it is necessary to get the motor/housing combo from Harman and then remove the motor and attach it to the in place old housing. There is confusion regarding this situation that I would love to have cleared up by someone in the know!

 

[Bkins]

It looks to me that all you will need is a new gasket and your good to go. The problem with the 500 silicone is it may not be able to withstand the heat at that location and its a groan to get back off the next time in. Me, I would be using a gasket. You can get gasket material and make your own from most auto stores if your pressed for time but the easiest way is to just get a new one designed for the stove and the heat.

 

[SidecarFlip]

It looks to me that all you will need is a new gasket and your good to go. The problem with the 500 silicone is it may not be able to withstand the heat at that location and its a groan to get back off the next time in. Me, I would be using a gasket. You can get gasket material and make your own from most auto stores if your pressed for time but the easiest way is to just get a new one designed for the stove and the heat.

I'm gonna disagree with your premise. I've been using Permatex red RTV in place of combustion fan gaskets (and sealing vent pipe joints for years) (probably 3 decades now) with no adverse effects and no heat degredation at all, nada, nothing. The stock gaskets NEVER come off in one, useable piece, never.

I also disagree with your premise that using red RTV makes it impossible to remove the outer housing from the inner. It's a very simple matter of slipping a putty knife between the outer housing and the inner and prying slightly, breaking the bond that the RTV has made. Once the bond is broken the housing seperates with little issue. The issue is removing the old RTV from the housing halves prior to applying new bead of RTV when reinstalling the housing. That takes some time and patience but it's perfectly doable.

You can buy a sheet of glassine gasket material and cut your own (time consuming) and your 'new' one will tear when you remove the housing again, or you can use red RTV. I prefer the red RTV myself.

From your comments, I'd say you never did the procedure and have no first hand knowledge, just postulation. I have (done it) numerous times.

 

[SidecarFlip]

Thanks SidecarFlip. I put the new blower in last night. Since it came with the housing the motor was attached with a brand new gasket. I thought I was going to have to replace the motor AND THE HOUSING but when I saw that changing the housing looked like a four hour job and probably a fail by me I just unscrewed the new motor from the new housing and it was an exact match (except for slightly more amperage). It all went together perfectly and the stove is working aok.

I see aftermarket places selling a new different motor that doesn't have the rear fan (in addition to the all important paddle blade impeller that you had mentioned ) and these sellers say it works on the old Invincible Inserts but I guess to get the correct replacement for this model it is necessary to get the motor/housing combo from Harman and then remove the motor and attach it to the in place old housing. There is confusion regarding this situation that I would love to have cleared up by someone in the know!

Some manufacdturers (and OEM's) are eliminating the rear fans because they can be a source of concentrated 'dust bunnies' in the windings if the internals are not maintained properly. Myself, I prefer the extra cooling capability and I keep my components clean and windings free of dust bunnies, so it's a non issue with me. If you are one who is lax on internal cleaning, then no external fan might be a better idea.

You can remove the external fan by removing the Tinnerman nut on the motor shaft and removing the fan....

A CA blower without a new expeller fan is useless. Your chances of removing the olkd fan from the o9ld motor shaft is almost nil. I'm not saying it cannot be done, I'm saying chances are it won't come off in a useable condition.

 

[johninwi]

don't forget the antiseize on the setscrew and the motorshaft,

 

[SidecarFlip]

In the grand scheme of things, it won't make much difference except for personal piece of mind. By the time it needs to be removed (because the motor has succumbed to the heat and dirt in the cabinet and died), the fan will be securely welded (by heat/cool cycles and the nasty exhaust stream) to the shaft anyway. Even if the setscrew come out, chances are the fan is welded to the motor shaft.

The other (less obvious) issue is, the fan has become brittle from the heating-cooling cycles and will actually shatter if you try to physically remove it. (I've experienced that first had btw). The fan blades will literally shatter if forced at all, leaving you with a hub and no blades.

 

[johninwi]

I pull the fan off a few times a year to clean, it's more likely the reason it still comes off but the antiseize can't hurt. Getting to the fan is pull out the ash bucket and remove the fan cover plate, couldn't be easier so no excuse not to. In terms of my experience, 5 years, it's working, 30 years will be a entirely different discussion. The heat cycles i'd not considered so i appreciate the warning.

 

[sandpipe]

The extra cost of a new impeller was around $13. I wouldn't want to put a 15 year old one on a brand new (shiny) motor!

Regarding the optional "cooling" fan-- what's it supposed to cool-- the area around the wires and connector block? Was it a misguided engineering implementation in the old Harmans' that has now become a superfluous and unnecessary component?

 

[tonyd]

In my case the bearings went. Two bearings from my sons collection of roller blade bearings did the trick, Yes, the fan blades are a pain, but they are doable. Re peen the fan blades and a little locktite. Been going fine since January of last season.

 

[Bkins]

Well now Sidecarflip how do you know or not know what my experiences are. Have you been in my shoes while I've done the work? You need to take a chill pill before you start attacking members here.

If you want to spend the time getting Rtv sealant off so be it. I don't. It is not hard to make your own gasket. I doubt you have tried from your comment. And yes gaskets are made to be replaced each time and for people that don't do this often a new gasket is the best way to go, in my opinion. No problems with to little or to much Rtv sealant, or using the wrong kind. Don't believe I said anything about it being impossible to remove Rtv, what I said is its a groan which is a PIA. If you don't mind doing that kind of work go ahead and do it. It's not for me and very well could cause a issue for somebody not mechanically inclined to make sure it's all off the mating surfaces the next time.

We are going to have to agree to disagree. I would appreciate you not jumping on my chit because I don't do it YOUR way. I have not made comments on some of your posts that I've found questionable because that's not who I am and THERE ARE different ways to get to the same end result.