Author Topic: Suburban furnace fan lubrication  (Read 2862 times)

Offline lvmci

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Re: Suburban furnace fan lubrication
« Reply #30 on: November 08, 2017, 03:40:09 PM »
Thanks Richard, tom, lvmci...
MCI 102C3 8V92, Allison HT740
Formally MCI5A 8V71 Allison MT643

Offline richard5933

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Re: Suburban furnace fan lubrication
« Reply #31 on: November 10, 2017, 03:16:43 PM »
Update on this issue...

Project is now complete other than reinstalling the furnace in the coach. I'll do that as soon as it warms up a bit or gets sunny enough to warm the inside of the coach. Ironic, eh? Fixed the furnace but now it's too cold to work outside.

The motor came in and was an exact fit for the original. The only problem was that the new motor had three mounting tabs spot welded onto the motor case. The original mounted with a wrap-around clamp. A little time with the Dremel took care of that.

I discovered that the crossover tube was never replaced during the recall decades ago. Since the furnace was never used the rubber crossover tube was still in good shape. However, I went ahead and replaced it. The recall parts are no longer available, so I replaced it with a high-temp silicone tube which is sold as an intake tube for guys that hot rod cars. It's four-ply reinforced and was sized nearly exactly to the original. It holds in snugly and I think is going to do the job just fine. I've got a brand-new carbon monoxide monitor to mount to be sure.

Here are a few photos of the work:
Richard
1974 GMC P8M4108a-125 (Current Bus)
1964 GM PD4106-2412 (Former Bus)
Located in beautiful Wisconsin
KD9GRB

Offline lostagain

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Re: Suburban furnace fan lubrication
« Reply #32 on: November 10, 2017, 04:37:02 PM »
Good job! These furnaces are pretty simple really when you take them apart and look into them. I know, the worst part is getting to them...

JC
JC
Blackie AB
1977 MC5C, 6V92/HT740

Online chessie4905

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Re: Suburban furnace fan lubrication
« Reply #33 on: November 11, 2017, 04:55:33 AM »
Now If you have a BBQ tank, you can bench run unit to verify everything still works ok. Although I guess you ran it when you heard the noisey fan.
GMC h8h 649#028 (4905)
Pennsylvania-central

Offline richard5933

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Re: Suburban furnace fan lubrication
« Reply #34 on: November 11, 2017, 05:50:46 AM »
I was able to bench test the fan, and it works very well. No portable tank so I cannot bench test the firing. The unit fired up fine before I removed it, so I'm not anticipating any problems. My only real concern is getting a good seal as I reconnect the flared fitting for the LP line. I'll double check everything with soapy water before firing up the unit, and then check again before closing the access panel.
Richard
1974 GMC P8M4108a-125 (Current Bus)
1964 GM PD4106-2412 (Former Bus)
Located in beautiful Wisconsin
KD9GRB

Offline richard5933

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Re: Suburban furnace fan lubrication
« Reply #35 on: November 13, 2017, 02:46:09 PM »
Final followup...

Sun was shining enough today to make it bearable to work outside. I got the furnace back into the coach today. Surprisingly things went pretty well, and other than a bit of frustration trying to get all the ducts and intake/exhaust lined up there were no problems. LP connections did not produce any bubbles on the leak test. The fan kicked on both with 12v and 120v, and it stayed on after the burn until things cooled down. The burner had a nearly pure blue flame, and the pilot looked good. Thermostat seems to do its job. Best part was that the CO monitor read "0" the entire time I was conducting tests. Got the panel in the wardrobe above the furnace put back in, and was even able to staple down a nice piece of carpet to replace the one that was sacrificed in order to get the panel removed.

Best part?? The furnace warms the coach nicely and runs quietly.

Total cost for the repair was $100 for the motor and another $25 for the replacement crossover tube.

Unless I'm missing something, I think that I'll classify this as a successful project.
Richard
1974 GMC P8M4108a-125 (Current Bus)
1964 GM PD4106-2412 (Former Bus)
Located in beautiful Wisconsin
KD9GRB

Online chessie4905

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Re: Suburban furnace fan lubrication
« Reply #36 on: November 13, 2017, 03:03:10 PM »
One down, 100 to go. You don't have a Uline icemaker, do you?
GMC h8h 649#028 (4905)
Pennsylvania-central