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Ghost coolant leak

Well I'm on my way to AK from Florida and I seem to have an intermittent coolant leak. Temp remains good. I drove 300 miles...added about 20oz of water because the overflow reservoir was down...took off down the road for another 200 miles shutdown let it cool for a couple hours and looked good. Later that night went down the road to dump the tanks and back...checked it this morning and the reservoir was empty...WTH no visible leak anywhere...no smoking and nothing in oil...of course all this on my move to AK hmmm any thoughts also only thing I see is a cracked overflow reservoir cap
Darren and Chris
2000 Foretravel U270

Re: Ghost coolant leak

Reply #1 –
If there was air in the system, it may take several "top-offs" of the reservoir to remove that air pocket.

When cold, start removing the radiator cap.  Coolant should be right there/start leaking out.  If not, you have an air pocket and need to start by topping off the radiator/sealed 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: Ghost coolant leak

Reply #2 –
I had the hoses changed out two weeks ago. The level when cold is right at the cap and a little leaks out when I take it off...I first assumed that is was an air pocket the first time but this will be the 3rd time I have topped it off. I am some what of a worrisome guy when it comes to this kind of stuff as I have a long journey ahead...I just pray it ain't a head gasket or something like that.
Darren and Chris
2000 Foretravel U270

Re: Ghost coolant leak

Reply #3 –
Do you think the cracked overflow reservoir cap could be a cause?
Darren and Chris
2000 Foretravel U270

Re: Ghost coolant leak

Reply #4 –
Really not that unusual following a coolant change.  Lots of yards of hose and places for air to collect in hoses, water heater, dash heater core, etc.

Cracked reservoir cap should NOT be an issue-- it is not a pressure cap. Basically there to keep dirt out and allow you to add coolant.
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: Ghost coolant leak

Reply #5 –
Actually thinking back it was losing coolant before the hoses were replaced
Darren and Chris
2000 Foretravel U270

Re: Ghost coolant leak

Reply #6 –
Any common hidden leak spots?
Darren and Chris
2000 Foretravel U270

Re: Ghost coolant leak

Reply #7 –
Start by checking torque on all hose clamps.  Constant torque clamps are best.  And, if a pesky location, no problem adding a second hose clamp as long as it is fully supported by the metal inside the hose.

If the leak is in the basement, you would smell it.  If on the ground, you should see it.  May have to crawl under to inspect (with safety stands of course).
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: Ghost coolant leak

Reply #8 –
My coolant overflow bottle cracked and had a slow leak.  Took awhile to find it.

Rich
Rich and Peggy Bowman
2002 U270 3610 WTFS, build #5939--"Freedom"
2022 Jeep Grand Cherokee Summit 4xe
SMI AirForceOne brake system
PakCanoe 15

Re: Ghost coolant leak

Reply #9 –
Was it not wet? Or was leak that slow?
Darren and Chris
2000 Foretravel U270

Re: Ghost coolant leak

Reply #10 –
Be sure to check the small diameter hose that runs from reservoir to overflow tank.  Like Rich, my sister's coach had a cracked overflow bottle....and a failure of the neck on the reservoir tank.  Both small leaks, hard to detect, but accumulate significantly.
"Not so  long ago we were a nation of risk takers, riding five million pounds of  thrust straight into space."  Joe Gresh
Chuck Pearson
1996 U295
2018 Can Am X3 TurboRS

Re: Ghost coolant leak

Reply #11 –
I'm gonna do a pressure check on the system what pressure should I go to
Darren and Chris
2000 Foretravel U270

Re: Ghost coolant leak

Reply #12 –
Look at your radiator cap.  Assuming it is the correct one, that is the safe working pressure.

Off the top of my head, I remember them being 15 PSI caps, but please confirm.

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: Ghost coolant leak

Reply #13 –
Check along the very bottom edge of the radiator. End caps tend to seep, and the coolant from that tend to gather along the very bottom edge of the radiator on either road side or the inside edge.
Dan - Full timing since 2009
2003 U320 40' Tag 2 slide

Re: Ghost coolant leak

Reply #14 –
Not familiar with your 270 engine but on my 320 with M11 it has a metal tank on right side with pressure cap next to the plastic overflow tank.  If you have both tanks which tank are you talking about? 
If the metal tank I'd first change out the pressure cap, not sure of pressure rating but should be a standard radiator cap. 
Then I'd look at the small hose connecting the metal tank to plastic tank and make sure it's not cracked and leaking.
But I agree with Brett, could be air pockets that just need to all burp out.
We're in Watson Lake, Yukon.  Roads aren't great but no problem.  Some smoke from Alberta fires a few days ago.
Forest & Cindy Olivier
1987 log cabin
2011 Roadtrek C210P
no longer 1999 36' U320 build #5522
2013 Rzr 570 & 2018 Ranger XP1000
2006 Lexus GX470
2011 Tahoe LT 4x4
Previous 1998 45' 2 slide Newell, 1993 39' Newell

Re: Ghost coolant leak

Reply #15 –
Well at this point I guess I'll just top it off everyday. Found nothing and it's mind boggling to me...thought about just bypassing the heater hoses but not exactly sure the correct way to do that as what I believe are the heater lines on the driver side of engine there is a "Y" in each line. I assume if I wanted to bypass it I would take the single of each and hook them together.
Darren and Chris
2000 Foretravel U270

Re: Ghost coolant leak

Reply #16 –
As they would say "Down Under" no worries.

With your recent coolant change and no visible leaks under or "smell" in the basement, continue to top off for the next 5 days.  If still dropping, THEN look for the source.

Only other suggestion is to tape some paper towel under the overflow reservoir.  An easy report card for minor leak from the plastic reservoir.
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: Ghost coolant leak

Reply #17 –
Quote
Really not that unusual following a coolant change.

I changed my coolant a few months back. I had to top off the overflow tank four or five times.
jor
93 225
95 300
97 270
99 320

Re: Ghost coolant leak

Reply #18 –
If you think of all of the possible places that coolant can leak, you could spend years chasing down a small leak.

After our engine rebuild a few years ago I had to add coolant each morning for several drive days. I blamed air bubbles, as eventually it got to where I only add a small amount of coolant every few driving days. I've filled the overflow bottle to a marked spot when the coolant was cool, driven 250 miles, and found the next morning it was exactly where it was the previous day. Another 250 miles of driving and it is down a bit. Go figure.