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Coolant loss

I have a question about a 2003 u295 with isl Cummins engine. When the engine is running there are air bubbles in the plastic coolant bottle. It looks like boiling, but engine temperature 180 it overfills the recovery tank. The radiator cap has been replaced with 2 different caps and still does it. One new cap tested at 15 pounds and the other 13 pounds. Both are new 15 pound caps. Looking for ideas of what could be the cause.
previous 1984 35 ft ORED 250 HP 3208 Cat       
previous 1998 40 ft U295 CAI 325 hp Cummins
previous 2003 40 Ft u320 build #6140 450 Cummins M11.                                                         
1999 Mazda Miata
Ron, Nancy, Tipper the cat, Max The dog
1997 U 270 36 ft build number 5174 8.3 Cummins

Re: Coolant loss

Reply #1 –
Do the bubbles get worse when you rev the engine up?
Keith
2003 U320 38' #6197

Re: Coolant loss

Reply #2 –
Obviously, a leak from a cylinder/head gasket would result in bubbles in the coolant.

Any "smell" or sheen to indicate combustion gasses in the cooling system?
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Coolant loss

Reply #3 –
No, have talked with a diesel mechanic and he suggested that it could also be the engine air compressor. Just wondering if there are any old truckers that ran into this over the years.
previous 1984 35 ft ORED 250 HP 3208 Cat       
previous 1998 40 ft U295 CAI 325 hp Cummins
previous 2003 40 Ft u320 build #6140 450 Cummins M11.                                                         
1999 Mazda Miata
Ron, Nancy, Tipper the cat, Max The dog
1997 U 270 36 ft build number 5174 8.3 Cummins

Re: Coolant loss

Reply #4 –
I hate to say it but usually that is an indication of a blow head gasket or engine gases getting
in to cooling system.
Peter and Frieda Morin
1999 36ft. U320 Foretravel
Build # 5436
1998 Suzuki Sidekick Sport

Re: Coolant loss

Reply #5 –
That is kind of what I am thinking.
previous 1984 35 ft ORED 250 HP 3208 Cat       
previous 1998 40 ft U295 CAI 325 hp Cummins
previous 2003 40 Ft u320 build #6140 450 Cummins M11.                                                         
1999 Mazda Miata
Ron, Nancy, Tipper the cat, Max The dog
1997 U 270 36 ft build number 5174 8.3 Cummins

Re: Coolant loss

Reply #6 –
What does the engine oil look like? How about the exhaust?
1993 U225 Build #: 4285
500 Watts Solar
Honda CRV AWD
Former 1981 Foretravel Travco
Retired, Full Time Off Grid Snowbird

Re: Coolant loss

Reply #7 –
Been trying to help on this also

coolant is clean and so is oil... no water from exhaust either... maybe stuck thermostat or radiator?
2002 U320 36' Single axle  MOST MODED IN HISTORY SO MUCH ITS ALMOST ILLIGAL
2 slides ( living room and bedroom)
undisclosed
male
female
genderless
nonbinary
transgendered

Re: Coolant loss

Reply #8 –
maybe trapped bubble in the system? needs pumped out?
2002 U320 36' Single axle  MOST MODED IN HISTORY SO MUCH ITS ALMOST ILLIGAL
2 slides ( living room and bedroom)
undisclosed
male
female
genderless
nonbinary
transgendered

Re: Coolant loss

Reply #9 –
I've seen head gaskets gone with no smell and everything clean but the bubbles was the
giveaway. The compressor idea from red tractor could have some validity as I believe they
are water cooled. Not sure how to check it. 
Peter and Frieda Morin
1999 36ft. U320 Foretravel
Build # 5436
1998 Suzuki Sidekick Sport

Re: Coolant loss

Reply #10 –
Quote from: oldguy –
I've seen head gaskets gone with no smell and everything clean but the bubbles was the
giveaway. The compressor idea from red tractor could have some validity as I believe they
are water cooled. Not sure how to check it.
Just bypass the compressor, some are easier than others though. My crane has 3/4 heater hoses in and out.
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: Coolant loss

Reply #11 –
Keith, yes the bubbles seem to get worse when the engine is revved up.
previous 1984 35 ft ORED 250 HP 3208 Cat       
previous 1998 40 ft U295 CAI 325 hp Cummins
previous 2003 40 Ft u320 build #6140 450 Cummins M11.                                                         
1999 Mazda Miata
Ron, Nancy, Tipper the cat, Max The dog
1997 U 270 36 ft build number 5174 8.3 Cummins

Re: Coolant loss

Reply #12 –
Use this kit or drive to a radiator shop and have them check for products of combustion in the coolant. https://www.napaonline.com/en/p/BK_7001006 Works on gas, diesel, propane, etc. I solved the problem in a 327 Chevy by just re-torquing the heads. My FD used a block sealer on one of the apparatus with a badly leaking head gasket. This was a successful application that worked exactly as advertised and lasted.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)
 

Re: Coolant loss

Reply #13 –
The coach was taken to a Cummins shop and found the head gasket had blown out on #1 cylinder. The head checked ok so only needed gaskets.
previous 1984 35 ft ORED 250 HP 3208 Cat       
previous 1998 40 ft U295 CAI 325 hp Cummins
previous 2003 40 Ft u320 build #6140 450 Cummins M11.                                                         
1999 Mazda Miata
Ron, Nancy, Tipper the cat, Max The dog
1997 U 270 36 ft build number 5174 8.3 Cummins