Oasis making a strange noise

[Tnedator]

Went to RV garage to start draining the tanks to sanitize. When I ran some hot water prior to draining, the Oasis kicked on and MUCH louder than normal. I took a video, but the engine noise is much more prominent on video than there live. Sounds mechanical, like either a blower fan (do they have one) or pump. I didn't think to turn the burner off and run just on electric to see if it still made the noise, before I pulled the water drain valve and headed back to work.

Any thoughts, what would make a loud mechanical noise in the oasis system.

Probably unrelated, I also noticed a lot of corrosion, reminded me of what you would see on a battery terminal, on one of the inlet/outlet hoses on top of the main unit where the burner is (not the back unit with the pumps). I'll admit I don't get in that bay often, but this sure seems like something that I would have noticed before.

 

[MemoriesByTheMile]

Without hearing the noise I would check what you already mentioned.
In addition, because of that corrosion, be sure to check your coolant level in the main box. I found the circulating pumps will make more noise if there is air in the system. If there is air, be sure to fix the slow leak you have that caused the corrosion, ensure the suction tube is attached in your overflow tube, then fill the tank under that radiator cap with the right boiler fluid. I flip the switch forcing the circulation pumps to run while I had the radiator cap off, (of course don’t open this while hot, let it cool). Over a few minutes the pumps evacuated air from the various zone hoses and had to keep adding fluid before putting the radiator cap back on.
The air compressor pump can also go bad, making extra noise.

 

[Tnedator]

Air compressor pump related to oasis?
I checked the overflow tank in engine compartment and it had about 1" of fluid in it. If I recall, that used to be about 1\3 or half full when cold.

Was leaving town to have neck fusion in January and to not risk coach freezing, I left AC on and turned boiler on, in case main garage heat went out. However, I know it always kicks on when fluid gets cool enough, so it's probably been running with small leak for a while.

Can I remove panels with unit still powered to see if there is any damage in main boiler area and possibly better isolate sound?

I'll be at NIRVC in a couple weeks, but have enough other work, that I'm not sure they will be able to fit this in so would like to trouble shoot and see what I can do first.

 

[MemoriesByTheMile]

There is a small air compressor pump in the oasis main box. Part of annual service is to check the air filter on this.
I have run the oasis with the front cover off so I could check for rattles and also do this after annual nozzle cleaning and o-ring replacement to be sure the fire box is burning well - before putting all the screws back in.
Is the sound coming from the boiler box or the distribution box?

 

[Neal]

If you can repeat the situation and hear the noise and if you can crawl in and get near the distribution unit with the pumps and see if it's coming from a pump or the main heating unit. The corrosion is a problem and I recommend that is fixed ASAP. Hopefully it's just a bad clamp on the hose but it could be a defective fitting. I think there was a recall on later model years that may use a different fitting but not sure if yours is affected.

 

[Tnedator]

Noise only occurs with the diesel burner running. It's also not the combustion fan, because I turned the power off and it runs the combustion fan for a little while when power goes off and when power comes on. I can hear the fan but it's quiet. So it's something that only runs with the diesel burner, but isn't the combustion. So, either a dedicated fuel pump if it has one or possibly the compressor mentioned above if it is only used with diesel burner.

 

[Neal]

If you can take a video, upload it to YouTube you can share it here or send to ITR for them to listen to. Call them first as they haven't been the greatest in answering emails for me in the past and they'll give you an email to send to and will respond promptly.

 

[Tnedator]

 

[Neal]

I can't really tell anything abnormal but look underneath the coach and see if there is an issue with the exhaust.

 

[Tnedator]

That's why I didn't initially post video. The mic picks up so much more rumble of oasis, that the abnormal sound which is very apparent in person, wasn't picked up in video.

Good thinking on exhaust. While it sounds mechanical (like a pump or like), I suppose it could be from vibration if something came loose in exhaust.

 

[Tnedator]

Talked to ITR.

First, as I was thinking, he agreed, leak and noise are going to be unrelated. He said the leak is pretty common, as Newmar uses multiple brass fittings, rather than a single 1/2" NPT to barb. They are sending me new 1/2" npt to barb fittings. Sounds very straight forward, as long as I properly pinch off the supply and return.

Second, on the noise. Said it's very hard to know, but he would suspect compressor or combustion fan. Since I told him the combustion fan ran, with no abnormal sound, on power down and power up, he said that eliminates that. His suspicion is compressor. However, he said it could be the unit itself making noise (starting to fail), but could also be noise from how it's mounted, if something is coming loose. He said the best way to test the compressor, would be to take it off and test on 12v source, since it would also isolate from other noises. He also said he would be hesitant to replace, unless the noise is really bothering me, as it could continue to put out pressure for a very long time, and is a $425 or so part.

I'm going to make sure there isn't a any issue with the exhaust, as Neil suggested, and also check and see if I feel any looseness with the mounting. Since this seems to be isolated to the diesel burner and unrelated to the leak, my biggest fear, which is completely losing the Oasis with a couple big trips coming up, seems unlikely.

 

[DavidL]

I assume yours is similar to my Hydrohot...the burner fan runs in "skateboard bearings". If you are going through the trouble of removing the burner (pretty easy), then you might as well replace the bearings.
So, order them, have them on hand.

While it's apart, get some carburetor cleaner and decarbon everything. Who knows, the noise might be carbon broke loose and is hitting the fan et al.

Replace the diesel filter and consider replacing the nozzle if it's been in service a while.

Don't overtighten the J Hooks that hold the burner to the housing as they can crack the burner aluminum fairly easy.

 

[Neemer]

First, as I was thinking, he agreed, leak and noise are going to be unrelated. He said the leak is pretty common, as Newmar uses multiple brass fittings, rather than a single 1/2" NPT to barb. They are sending me new 1/2" npt to barb fittings. Sounds very straight forward, as long as I properly pinch off the supply and return.

@Tnedator , your picture prompted me to go out and look at mine. I have the beginnings of the same corrosion issue. Looks like I’ll give ITR a call as well. Thank you for your post!

 

[Tnedator]

@Tnedator , your picture prompted me to go out and look at mine. I have the beginnings of the same corrosion issue. Looks like I’ll give ITR a call as well. Thank you for your post!

The tech I spoke to said it's very common with the way newmar does it. Even though I have no leak or corrosion on the supply side, he recommended changing both, because he said it's more than likely going to start leaking at some point. What they sell for like five bucks is a single fitting 1/2" NPT to 3/4" barbed, if I remember the sizes right. Newmar has several fitting screwed together, and it's prone to leak.

He also said rarely do they leak a significant amount and even sometimes self-seal as a calcifies from the heat. So he said not a rush but he definitely recommend it changing.

He said a very easy repair, as long as I ensure that the hoses are clamped off, because he said you can lose a lot of fluid very quickly if you don't clamp both the supply and the return.

 

[Neemer]

@Tnedator , when you receive the new fittings, would you mind posting a pic of them?