Author Topic: Aqua Hot fuel pump repair  (Read 9372 times)

Gerald Farris

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Aqua Hot fuel pump repair
« on: May 11, 2017, 04:39:29 PM »
As many of you know, I recently purchased a 2002 Beaver, and it is my first Beaver with an Aqua Hot system. Of course it would not fire up when I looked at the coach, so I was aware of my need for a crash course in Aqua Hot repair. My previous coach had a Hurricane system that required about $200 in maintenance parts over the 13 years that I have owned it to keep it operating. Therefore, I was aware that my operating cost was going to increase with the new coach.

I traced the inoperable condition to a broken blower clutch that was caused by bad blower bearings. I purchased an igniter gap tool, blower clutch, bearings, and a new nozzle online for about $100 from Rodger Berke's site and started to work repairing the burner. However, when I installed the repaired burner and fired it up, there was diesel dripping from where the burner connects to the burner chamber. Under further investigation, I determined that the fuel pump was leaking at the top plate. Aqua Hot does not list any parts for the pump and would only sell me a new pump for $350, so I took the cover off an found a bad O-ring that I sourced as a #84 O-ring at Ace hardware for 79 cents. Installed the O-ring and Aqua Hot system is operating flawlessly with no leaks.

One word of caution, if you try to repair a fuel pump leak at the top plate, there is a convex tension washer under that plate that has to be centered when reinstalling the plate to prevent damaging the new O-ring.

Gerald           
« Last Edit: May 11, 2017, 05:24:26 PM by Gerald Farris »
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David T. Richelderfer

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Re: Aqua Hot fuel pump repair
« Reply #1 on: May 11, 2017, 05:33:46 PM »
The lesson here is:

1. Research leads to a proper diagnosis.
2. Research leads to finding the proper parts.
3. Research leads to finding the highest quality versus best price for the parts.
4. Research leads to finding out how to effect the proper installation of the parts.
5. Research leads to a knowledgeable helper, and maybe a professional, if needed.
6. Research leads to satisfaction in your work.

If you cannot get the research done to complete every step, then take it to a professional from the beginning.
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I had a dream... then I lived it!

Edward Buker

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Re: Aqua Hot fuel pump repair
« Reply #2 on: May 11, 2017, 08:50:52 PM »
Gerald,

I knew you would conquer it in short order. Probably a love hate relationship is in store for your future....

Common problems that could come next....

1. Intermittent burner igniting. The ignition transformer has an inverter circuit built into it because it runs on 12v and needs AC to step up the voltage. If it does not fire perfectly, with the arc jumping the gap when the inverter circuit first sees voltage, it will most likely not fire after that until voltage drops and the circuit is re-energized. May fire perfectly 50 times in a row and 51 fails etc. It can be an intermittent nightmare to diagnose, but you can see this issue on a bench with a 12V battery, putting 100 start up cycles on it without a miss using your burner electrodes.

2. Next is the burner shuts down but the burner blower will not quit unless you drop all 12V power to the unit. The relay in the silver box that controls the burner blower circuit causes this. It has dropped the voltage down signaling blower shut down, but the relay contacts do not release given the springs have aged....very fussy old school design. Only fix is to replace the unit. The relays are not available, and as you know all these burner parts are pricey.

3. Less problematic is a cadmium sulfide burner ignition monitor. It is a photocell that is in a safety circuit and if the cell does not see the flame, for a predetermined time, it shuts the burner down. That has to be in position and clean to see the flame. These are glass covered and are known to crack.

4. The button thermostats, that are against the boiler front face, they control the burner and the 120V heating element. They have contacts that arc and erode over time. The 120V heating element ones handle a lot of current and are more problematic then the burner ones. I had one fail on the road. They are inexpensive and changing the ones that "make" to turn things on would be a good thing to do preventatively. The ones that are overtemp safety thermostats, do not normally see make and break cycles and will last much longer.

If you do not run into any of these issues in the short term, you should be good to go if you can keep the unit leak free....that is another whole story.

Good luck with the new coach, it is beautiful.

Later Ed

« Last Edit: May 13, 2017, 12:38:56 AM by Edward Buker »
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Keith Moffett

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Re: Aqua Hot fuel pump repair
« Reply #3 on: May 12, 2017, 09:41:56 AM »
The Aquastats (button thermostats) on our 02 had the corrosion on the spade connections.  The unit fired great but sometimes ran a bit rough, then it failed to fire.  A good cleaning and one new connector fixed the problem and cured the rough operation.
Just a heads up though.  The burn chamber is in three parts and the aerator in the middle must mate flush.  A warp or crack can cause loss of containment in the burn chamber.  Ours had a gap of several mm's.  I think the high limit contact was bad and the burn chamber suffered over time.  New burn chamber assembly and a tune up was $350 ish.

So glad for you and Glenda on the new coach.  Did you trade the Marquis?
2007 Patriot Thunder
45' C-13
2006 Explorer Ltd.
DW is Carol
Safe travels and
May God bless!

Gerald Farris

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Re: Aqua Hot fuel pump repair
« Reply #4 on: May 12, 2017, 03:27:42 PM »
David,
You are correct about the research. I did two days of research and reading about the Aqua Hot unit before I even started the diagnostic process. My research was hampered a little because I never could find a repair manual for my unit, but Rodger Berke informed me that my model had very little production and it was just like another model with the exception of the fact that my model has 2 electric elements and an extra button thermostat. With a good mechanical aptitude, a few tools, and extensive research, you can fix almost anything.

Ed and Keith,
I checked all button thermostats for corrosion, tight contacts, and resistance in my original diagnostic process. I was especially concerned about the two A/C current thermostats because they operate on a higher amperage (17 amps each at 120V) than the standard Aqua Hot 120V heating element (11 to 14 amps depending on unit), but everything there checked good this week. Who knows about next week?

Thank you for the coach compliments. I still have the Marquis that I will need to sell after I clean it up and transfer a few things like the onboard 200 psi air compressor to the new coach.

Gerald 
     
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Mike Wild

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Re: Aqua Hot fuel pump repair
« Reply #5 on: May 12, 2017, 11:54:18 PM »
All I know is that if I need my appendix out or a triple bypass, I will call Gerald to do it.

It amazes me how we lost this type of creative genius in basically a generation. My boys don't know what a screwdriver is -- I just don't know how to use it!

Mike

Bill Sprague

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Re: Aqua Hot fuel pump repair
« Reply #6 on: May 13, 2017, 03:45:13 AM »
Hydro Hot Fuel Pump R&R Starting Marty and Jay:  https://vimeo.com/67970941

Bob Stone

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Re: Aqua Hot fuel pump repair
« Reply #7 on: May 13, 2017, 06:11:10 AM »
I had the fuel pump on my Hydro Hot replaced last month when in the Yuma area. The unit was exhausting increasing levels of black smoke over the past year. Apparently the pump was operating at too high a pressure and the adjustment screw on the side of the pump made no difference.
I did watch the video on pump replacement but considering high price of the pump and potentially creating additional more costly problems I had Rob & Patty at Sun Bum RV install a new pump and do the annual tuneup. Practically smokeless now.
Bob Stone
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Bill Sprague

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Re: Aqua Hot fuel pump repair
« Reply #8 on: May 14, 2017, 12:30:56 AM »
.....I did watch the video on pump replacement but considering high price of the pump and potentially creating additional more costly problems I had Rob & Patty at Sun Bum RV install a new pump and do the annual tuneup. Practically smokeless now.
It is not a blockbuster.  That said, 190 have watched it. 
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Joel Ashley

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Re: Aqua Hot fuel pump repair
« Reply #9 on: May 14, 2017, 03:25:38 AM »
The world operates on O-rings.  Many times I've torn some expensive or out-of-date part down to find it just needed an O-ring I might already have in my bin.  It's both an amazing invention and the means to aggravate, is the cause for tragedy (the Challenger space shuttle disaster), and keeps people employed making and selling entire replacement part assemblies for little efficient reason.

Wherever I encounter fluid transfer issues, air, water, or oil, I include in my primary suspicions O-ring failure somewhere.  One does have to carefully discern the right composition replacement however, in addition to dimensions, as in some applications an O-ring may not be chemically compatible with the application intended.  They come in more than one chemical make-up, not just "rubber".

Joel
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Lee Welbanks

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Re: Aqua Hot fuel pump repair
« Reply #10 on: May 15, 2017, 12:17:29 AM »
Joel, You are so right about all the different applications of O Rings, McMaster Carr carries just about every type, shape, size of O Ring in the world. They have a handy chart that shows which is best for what you are trying to seal.
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Joel Ashley

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Re: Aqua Hot fuel pump repair
« Reply #11 on: May 15, 2017, 12:47:49 PM »
Wow, thanks for that reference, Lee.  If I can't find any right one I need among 11,200 types of O-rings and associated products, and using their good descriptions and search filters, then I'll give up the search.
https://www.mcmaster.com/#o-rings/=17mvxc1

Joel
« Last Edit: May 15, 2017, 12:53:45 PM by Joel Ashley »
Joel and Lee Rae Ashley
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Michael Hannan

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Re: Aqua Hot fuel pump repair
« Reply #12 on: September 13, 2020, 12:39:11 AM »
Hello Gerald.  Is you fix for the fuel pump leak still holding?  I have the same problem.  Actually, I have that plus another related problem.  I had a lot of white smoke coming from the Aqua Hot and narrowed it down to the fuel pump.  There was a constant drip coming from the high pressure fuel line at the fuel pump connection.  I was able to tighten that and it stopped.  That's when I noticed that fuel was still leaking from where the fuel pump attaches to the plate.  I searched and found this thread after, like you, finding that Aqua Hot didn't offer a seal for sale.  Apparently there aren't any #84 o-rings in Canada (could be a metric thing) so I ordered a few from the US. There's a YouTube video on replacing the fuel pump done by a mechanic that shows disassembling the entire blower assembly so I have a good reference to use.  You mentioned a tension washer under the plate.  Are you talking about the top plate of the fuel pump or the plate that it attaches to? I haven't removed the fuel pump yet as I don't want to lose any parts while waiting for the o-ring.  I was envisioning that the o-ring as at the bottom of the fuel pump and could be replaced without disassembling the fuel pump.  Am I wrong on that?

Thanks
MJ

As many of you know, I recently purchased a 2002 Beaver, and it is my first Beaver with an Aqua Hot system. Of course it would not fire up when I looked at the coach, so I was aware of my need for a crash course in Aqua Hot repair. My previous coach had a Hurricane system that required about $200 in maintenance parts over the 13 years that I have owned it to keep it operating. Therefore, I was aware that my operating cost was going to increase with the new coach.

I traced the inoperable condition to a broken blower clutch that was caused by bad blower bearings. I purchased an igniter gap tool, blower clutch, bearings, and a new nozzle online for about $100 from Rodger Berke's site and started to work repairing the burner. However, when I installed the repaired burner and fired it up, there was diesel dripping from where the burner connects to the burner chamber. Under further investigation, I determined that the fuel pump was leaking at the top plate. Aqua Hot does not list any parts for the pump and would only sell me a new pump for $350, so I took the cover off an found a bad O-ring that I sourced as a #84 O-ring at Ace hardware for 79 cents. Installed the O-ring and Aqua Hot system is operating flawlessly with no leaks.

One word of caution, if you try to repair a fuel pump leak at the top plate, there is a convex tension washer under that plate that has to be centered when reinstalling the plate to prevent damaging the new O-ring.

Gerald         

Gerald Farris

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Re: Aqua Hot fuel pump repair
« Reply #13 on: September 13, 2020, 01:43:55 AM »
MJ,
The O ring repair worked, but a short time later the shaft seal on the fuel pump started leaking, and I could not find a source for a replacement seal, so I had to replace the pump. I found a new Webasto replacement pump (straight from China) on Ebay for $125, and it is still running fine three years later.

The tension washer is under the rear plate on the fuel pump. You will see it when you remove the plate.

Good Luck
Gerald

Michael Hannan

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Re: Aqua Hot fuel pump repair
« Reply #14 on: September 13, 2020, 02:03:45 AM »
Thanks Gerald.  I appreciate the china source info for a new pump too.

MJ