Help Propane Furnace making horrible loud noise.

[TXfreeze]

This morning about 8am without warning the furnace in our 1997 Adventurer started making a very loud noise with a vibration, I immediately turned it off, I suspect it's the blower or one of the exhaust motors. I've done some searching and found that on the Adventurer it's most likely a Suburban furnace and it's either accessible from outside or in the coach, one post said if has two screws where the exhaust comes outside of the coach than it's accessible on the inside, but if it has 4 screws it's on the outside, of course mine has 6 screws for the exhaust plates and that confused me, but I read that it's a panel that swings up, just like the rest of the storage and generator panels, so I looked below and sure enough there are 2 screws on both sides that are no doubt holding the panel, My guess is the panel should swing right up. I took out the 2 screws and it's swing up panel, it looks like both exhausts tubes connected to the exhaust plate need to come out, I'm in the process of doing that there is strong sealant I need to get at, I will edit as I go along. Got the black goo out of the way, had to use a heat gun to soften it up. I got the panel off and I can see the squirrel cage, I'm going to test it and see what I can observe, will report back when I see what's going on. Ok I tested it with the propane on, the noise sounds like our Onan 4000 so it's not enough to disturb the quiet, but after waiting for 3 mins no heat was observed so I turned it off I'm also concerned that using it the way it is may be potentially dangerous, so that's as far as I'm taking it I put in a call to a mobile repair and hopefully I will hear back from them. I'm taking the time to explain this in case others run into this setup. So now I have to look at the motors squirrel cages and see what the deal is the only times a blower has made a similar type sound or vibration was the chasis heater blower I replace it with a after market I found at the auto store and that solved, the other time was when the blower on the AC did something similar, my guess is this issue isn't solved that simply and the motor itself need replacement? I appreciate any help or advice with this as it's going to be in the 30's tonight and our electric heater doesn't cut it. Thanks

 

[TheLooks]

Mice love to get in there and get chewed up. I have seen the out of round blower cage rip the sail switch off the housing. It is possible it loosened up on the shaft.....97 year has some age on it and the plastic blower could be just coming apart. If you can access outside it is an easy repair with parts....that is the problem with a quick repair.

 

[TXfreeze]

Mice love to get in there and get chewed up. I have seen the out of round blower cage rip the sail switch off the housing. It is possible it loosened up on the shaft.....97 year has some age on it and the plastic blower could be just coming apart. If you can access outside it is an easy repair with parts....that is the problem with a quick repair.

I hadn't thought about mice, lately I've been hearing scratching inside the bedroom but it went away. I was thinking the shaft could be loosened it looks a little wobbly, so I can access it outside, the motor seems to be held by just one screw in a bracket do I need to take the whole blower out to reset the shaft? I'm attaching a photo and I also have a video if it's not too big I will try to upload it.

 

[TheLooks]

That is the exact unit I had mouse problems with for a customer. But they also covered the return air for it and it overheated and warped the squirrel cage blower and it blew apart after it hit the sail switch. Why are there leaves in there? Considering the age, I would put a core replacement in as I did for that client. It is more then 1 screw, but not hard to remove.

 

[TheLooks]

Take pictures of your wiring carefully to plug it back in right if you replace it.

 

[TXfreeze]

That is the exact unit I had mouse problems with for a customer. But they also covered the return air for it and it overheated and warped the squirrel cage blower and it blew apart after it hit the sail switch. Why are there leaves in there? Considering the age, I would put a core replacement in as I did for that client. It is more then 1 screw, but not hard to remove.

So the sail switch could have been affected by the blower? That could explain why there is no heat. To answer your question, it looks like leaves but it's actually rusted pieces of rusted pipe from the bottom exhaust I think it must have broken when I pulled on the face plate. So the only way to get to the squirrel cage is to pull out the whole thing? Is it more likely the shaft since, there hasn't been any squeeling sounds or anything before this? Thanks

 

[TheLooks]

Your sail switch is just above and to the right of the middle, it has a "sail" that protrudes into the blower housing. By the looks of the unit and the fact that there are large flakes of rust involved, it may be beyond your ability to repair. There are more then one screw holding the outer housings over the 2 blowers. The one on the right is combustion air and the one on the left is circulation air for heat. One motor drives them both. If the blower is not spinning with the shaft, either one that is, it will not work. The circulation blower must spin fast enough to close the sail switch or it will not allow the gas valve to open.
There is on screw just right of center on the bottom that holds the guts of the heater in. The outer box is just a plenum to heat the air. Take care to know how the wires go if you remove it. It plugs in and will come out withouot cutting any wires.

 

[TXfreeze]

Your sail switch is just above and to the right of the middle, it has a "sail" that protrudes into the blower housing. By the looks of the unit and the fact that there are large flakes of rust involved, it may be beyond your ability to repair. There are more then one screw holding the outer housings over the 2 blowers. The one on the right is combustion air and the one on the left is circulation air for heat. One motor drives them both. If the blower is not spinning with the shaft, either one that is, it will not work. The circulation blower must spin fast enough to close the sail switch or it will not allow the gas valve to open.
There is on screw just right of center on the bottom that holds the guts of the heater in. The outer box is just a plenum to heat the air. Take care to know how the wires go if you remove it. It plugs in and will come out without cutting any wires.

I understand what are you saying about the large flakes of rust, but it's not like it's it's an unknown, I know it's the exhaust pipe or tube that comes out and connect to the face plate, the question is can it operate with part of that pipe broken, or is just best to replace that pipe if I can find a replacement part. So if the blower is making that racket chances are it's not spinning fast enough to close the sail switch. Well at this point we have 1 more cold night and than we have a warming we managed with the little space heater we have so, I'm going to put it on the back burner for now, no pun intended. But I have the screws out and the cover off and it seems like the most logical thing is to repair it and do a maintenance cleaning on the whole heater, as to whether I will DIY it or I hire someone to, remains to be seen due to the high cost to get someone to come out to fix it. One question, what is that black goo tar like sealant that goes on there? Is it some kind of HVAC specialty stuff?

 

[TheLooks]

I am not sure what it is, the picture is bit out of focus but it looks like it was slathered up with some tar substance after it left the factory.
I would say no for safety as that is the exhaust pipe and it MUST exhaust outside the unit. Some units will not run well with out the pipe in place.
If I had the unit, I could rebuild it to work right. It would only be parts for me. But paying someone to come and rebuild it is expensive.
I have recently decided that I will not go out to a service call that requires an hour drive and not totally rebuild the unit. When one thing goes down, something else is close behind. I do not like repeat calls for service because "I did not fix it" when I cannot charge what it is worth to drive 2 hours. Replace everything that COULD cause the symptom and fix ANY problem that will come back and bit you in the ass.
This is where an owner or handyman can throw random parts at it until it works. I cannot do that and make money. I have tried.
Good luck and ask any questions you have, youtube is your friend. Just search with the model # and there is lots of info out there, if you are handy. If you don't have one, get a multimeter.

 

[TXfreeze]

I am not sure what it is, the picture is bit out of focus but it looks like it was slathered up with some tar substance after it left the factory.
I would say no for safety as that is the exhaust pipe and it MUST exhaust outside the unit. Some units will not run well with out the pipe in place.
If I had the unit, I could rebuild it to work right. It would only be parts for me. But paying someone to come and rebuild it is expensive.
I have recently decided that I will not go out to a service call that requires an hour drive and not totally rebuild the unit. When one thing goes down, something else is close behind. I do not like repeat calls for service because "I did not fix it" when I cannot charge what it is worth to drive 2 hours. Replace everything that COULD cause the symptom and fix ANY problem that will come back and bit you in the ass.
This is where an owner or handyman can throw random parts at it until it works. I cannot do that and make money. I have tried.
Good luck and ask any questions you have, youtube is your friend. Just search with the model # and there is lots of info out there, if you are handy. If you don't have one, get a multimeter.

New development, I getting warmer now so I went to take a look at it again and examine the insider of the squirrel blower, at first I though there was one of the mud buildups in there, than I thought it was wasp nest, I reached in with a spade to try to scrape it off, but it had some wait to it, turns out it was a dead mouse, no doubt the one we had in the coach up till that fateful moment when it got in there and gummed up the works. I removed it and tested and sure enough the noise/vibration is gone, at the time the propane was on and we noticed a slight burning smell coming from inside the vent. Immediately turned off the heater and turned off the propane, not sure if that was causing the smell. No smell of propane was detected just that burning smell. Could it be some debris from the blower? Could the mouse have chewed something up? Now as for the exhaust let's call it exhaust pipe, no doubt that's connected to the furnace correct? That tube the removes though over the exhaust pipe. so in theory wouldn't it still allow exhaust to escape? I do have multimeter but given the latest development do I still need to test with it? Thanks

 

[TheLooks]

The burning smell was on the outside of the rig? Something like bugs etc are in the tube or it just has not fired in awhile. The plenum get really hot and the mouse parts or whatever may be on the hot surface and stinking. The exhaust pipes go on over each other and create a crude seal that makes the exhaust go outside. You don't want it to come back in the camper. Make sure your detectors are working. IF this is an old camper, the detector is supposed to be replaced every 5 years. It will save your life potentially.

 

[TXfreeze]

The burning smell was on the outside of the rig? Something like bugs etc are in the tube or it just has not fired in awhile. The plenum get really hot and the mouse parts or whatever may be on the hot surface and stinking. The exhaust pipes go on over each other and create a crude seal that makes the exhaust go outside. You don't want it to come back in the camper. Make sure your detectors are working. IF this is an old camper, the detector is supposed to be replaced every 5 years. It will save your life potentially

. No the burn smell was coming from inside the coach floor vent. It was last used last week for a couple of days, detectors are working..

 

[TheLooks]

IF inside then something is in contact with the plenum or heat exchanger, most likely something from the mouse encounter.

 

[TXfreeze]

IF inside then something is in contact with the plenum or heat exchanger, most likely something from the mouse encounter.

So I'm glad to say the furnace is working fine, I put the tube over the pipe fired it up and it warmed up and the smell is gone, with no smell or trace of propane inside the coach. I left it on for about 5 mins, checked the outside exhaust and heat exhaust is going through the tube outside with no issues. We only intend to use the furnace when a electric heater just won't cut it or in an emergency should the power go down because of a freeze like happened in Texas in 2021. My only concerns are what the RV repair fellow said that it should get a cleaning and my own concern, the heat eventually destroying the rusted part of the exhaust pipe. I was thinking maybe it could be repaired by a welder? That said we don't expect to be in this rig for another cold season, and here by the gulf the winters are fairly mild. What do you think?

 

[TheLooks]

Just be sure the exhaust is sound and your detectors inside are new....Great that it is working, be safe however.