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Topic: Watch those coolant recovery tanks (Read 604 times) previous topic - next topic

Watch those coolant recovery tanks

They tell a story if you watch them. 

Example:  My AquaHot failed in both the 115 volt and diesel modes which I thought was strange.  There appeared to be no common link between them so we assumed it to be a coincidence.  WRONG!!!!  but we didn't know it yet.

The service tech first checked the 115 and found that the high temp limit switch had opened.  (They do not reset and have to be replaced once they trip.)  Replacing the limit switch and testing the 115 with an ammeter confirmed that it was fixed.

Onto the diesel side.  It was quickly determined that it's high temp limit switch had also tripped.  So apparently one of the two thermostats (115 volt or diesel) must have failed ON causing an over temp that tripped both high temp limit switches.  So I decided to have them both replaced rather than futz around.  That fixed the diesel side.

While the tech was here I decided to have the whole system serviced as it had been a while including replacing the fuel filter, nozzle, etc.  We then ran the system up to temp and all appeared well.

WRONG!!!!  but we didn't know it yet.

A day or two later the tech called and suggested I should check the coolant level.  I did this first by running the system and watching the coolant recovery tank.  NO change in level, BAD NEWS.  After it cooled overnight I removed the cap and there was none within finger reach.  Visually I also noticed that the coolant recovery hose had become separated.  Thus not only did I NOT have an operational coolant recovery system but effectively it did not have a cap after 13 psi was achieved in the system.

It took a little over three gallons of antifreeze mixture to fill the system and I also replace the cap for good measure.  Now I get about a 2.5" level change in the coolant recovery tank from hot to cold.  I should have caught this myself early on.

LESSON: Applies to the AquaHot and ALSO the main engine and the gen-set.  Verify that the level of the coolant in the recovery tank goes up when the system is hot (it's hottest sometime after operation, I wait maybe five minutes).  Then check again when the system is cold.  For the main engine I check the tank when we make a rest stop during the day for the hot.  For the cold I check it with the morning pre-drive tests.  A good delta between hot and cold is a pretty good test of the entire system including the cap.

I'm pretty good doing this test with the main engine but, obviously, failed to do so with the AquaHot.
Audrey & Harvey Nelson
2000 U-320, 40' towing 2014 Jeep Grand Cherokee
nelsonah@ieee.org

Re: Watch those coolant recovery tanks

Reply #1 –
Quote from: Harvey Nelson –
They tell a story if you watch them. 

LESSON: Applies to the AquaHot and ALSO the main engine and the gen-set.  Verify that the level of the coolant in the recovery tank goes up when the system is hot (it's hottest sometime after operation, I wait maybe five minutes).  Then check again when the system is cold.  For the main engine I check the tank when we make a rest stop during the day for the hot.  For the cold I check it with the morning pre-drive tests.  A good delta between hot and cold is a pretty good test of the entire system including the cap.

Excellent advice. Thanks!
David and Carolyn Osborn
1995 U320C SE 40' Build 4726 Feb 1995
FMCA 147762
Motorcade 17186

Re: Watch those coolant recovery tanks

Reply #2 –
Quote from: D.J. Osborn –
Excellent advice. Thanks!
X2.  A gradual drop in the cold level in recovery tank (big engine or generator engine) will often be your first indication of a coolant leak.  If you check the cold level on a regular basis, always under the same conditions, then you will immediately recognize a deviation from norm.  If liquid is disappearing from the system, it has to be going somewhere...
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Watch those coolant recovery tanks

Reply #3 –
Does anyone know how fast water evaporates form the A-H system?  Since we full-time, our system is never cold.  When I see it low I always top it up with coolant, but I've never found a leak anywhere.  Should I be topping it up with water instead?
Regards,
Brett

'99 42' Foretravel Xtreme
'14 Brown Motorsports Stacker
'05 Chevy SSR
'02 BMW R1150R

Re: Watch those coolant recovery tanks

Reply #4 –
Hi Brett,

You should aim for a 50/50 mix of coolant and distilled water when you add.  It is available as 50/50 or full strength. When if varies considerably from that mixture you conductance of heat is lessened.

Jim
Jim Frerichs
2002 U320 42'

Re: Watch those coolant recovery tanks

Reply #5 –
That's what I've been doing, but I don't think the concentrated coolant evaporates.  That means that as I keep adding coolant mixture, the A-H contents become more concentrated.
Regards,
Brett

'99 42' Foretravel Xtreme
'14 Brown Motorsports Stacker
'05 Chevy SSR
'02 BMW R1150R

Re: Watch those coolant recovery tanks

Reply #6 –
Brett,

I think there is a tester for antifreeze concentrations - called a refractometer. I'm not sure what the evaporation rate is for antifreeze/water  solution.

Jim
Jim Frerichs
2002 U320 42'