Coolant level not stable

[R F S]

Have a C-7 in a 2005 Mandalay that I recently purchased. Noticed that the coolant level in the resevoir was low so I topped it off. After a few short trips maybe 1000 miles or so coolant is down again. No noticable leaks or abnormal looking color to oil or coolant color. What to look at next.? RFS

[CJBROWN]

I know the new ones can be fussy about coolant level and will go into limp mode if it gets low. Have you checked the level when hot? Like stop after a climb and look at the level? It could simply be expanding and overflowing out the bottle.

Otherwise you have a minor leak. You should be able to detect dried coolant over time even with a drip on one of the hose connections. I would go over all the hose connections and clamps and make sure everything is snugged up. Likely you'll find a dripping one somewhere. If it's very slight you most likely won't find it running down the motor and onto the ground.

[palehorse89]

If the coolant was just serviced it will take several heat ups and cool downs for it to stabilize and hold a contestant level, if it has not been serviced lately, you are loosing it somewhere as the level can only go down for one reason. If you can't see or find any leaks you might want to send a oil sample in for testing and make sure it is not going into your oil and if it is you might now be able to tell by looking at your dip stick. How much did you add after that 1000 miles?

http://www.jglubricantservices.com/

[phays]

Are you checking the coolant level when the engine is hot? If it is at the proper level when hot, don't add any more fluid.

Check on the Diesel RV club at Diesel RV Club, an FMCA Chapter - Index for further help.

[spike45]

Originally Posted by R F S

Have a C-7 in a 2005 Mandalay that I recently purchased. Noticed that the coolant level in the resevoir was low so I topped it off. After a few short trips maybe 1000 miles or so coolant is down again. No noticable leaks or abnormal looking color to oil or coolant color. What to look at next.? RFS

Are you filling to the very top of the tank? Diesel cooling systems on trucks do not, generally, have a coolant recovery tank. IF you fill to the top or very near when the coolant is cold, thermal expansion of 9% on average will cause the pressure cap to relieve and dump the coolant overboard......unless you have a coolant recovery system as is commomly found on LD vehicles.

[brookra1]

Have a 2004 Mandalay C-7. Bought it in the summer of 2010 w/18,000mi. on it. Had the exact same problem with mine. When I went south for the winter had to change the radiator out while down south. Noticed a small amount of fluid on the frame after setting a couple of weeks at the park. After further inspection the rad. was leaking at the bottom on the inside between the rad. and the air box. Had to replace rad. could not re-core it. I did the change out myself in the park (which was against the rules) but I was lucky nothing was said. Still cost me $1,200 to do myself. So, check the frame at that point and see if any fluid is noticeable. Was adding coolant occasionally and could not find anything before that. Hopefully your problem is just coolant level as the others have answered.
Good luck, Rick

[RVluvin]

Had the same problem on a gas engine pickup for several years, had to consistently add coolant every couple of months. Never could find any external leak, and never noticed any coolant in the oil. I finally had to assume that it had to be a head gasket leak into the cylinders and evaporated out has the engine was started.

[Steve Ownby]

Originally Posted by R F S

Have a C-7 in a 2005 Mandalay that I recently purchased. Noticed that the coolant level in the resevoir was low so I topped it off. After a few short trips maybe 1000 miles or so coolant is down again. No noticable leaks or abnormal looking color to oil or coolant color. What to look at next.? RFS

You might consider having a sample of the engine oil and transmission fluid tested to make sure the coolant is not going somewhere that indicates a more serious problem. Coolant will kill a transmission in short order.

[R F S]

How possible would it be that coolant can enter the trans. case? Would it be noticable at the dipstick such as the engine oil?

[Steve Ownby]

Originally Posted by R F S

How possible would it be that coolant can enter the trans. case? Would it be noticable at the dipstick such as the engine oil?

Most motorhome chassis builders build the transmission cooler into one of the end tanks of the engine radiator. This is a known failure point and one that's fatal to the transmission. If there is enough coolant contamination then you might see it on the dipstick or in surge tank. At this point your transmission would be beyond saving but the engine might be ok.

If Spike45 is monitoring, he is the guy who can give the best answer.

[spike45]

Originally Posted by R F S

How possible would it be that coolant can enter the trans. case? Would it be noticable at the dipstick such as the engine oil?

The trans temps will not be sufficiently high to cause the same effect as in the engine at the oil fill cap. You may be able to loosen the transmission pan drain plug (do not remove) to see if any water drains past the threads. Water will come out before oil as the coolant will be more dense than the oil thus it will be on the bottom.

[R F S]

How about increased fluid level at trans. check from gear select touchpad ?

[R F S]

Also would think that if the two were mixing I would notice at coolant resevoir ?? Trying to sell myself on a small problem instead of ginormous one.....

[Steve Ownby]

Originally Posted by R F S

How about increased fluid level at trans. check from gear select touchpad ?

This would indicate the problem, but the transmission will be beyond saving if this much coolant makes it to the transmission fluid. With this type if cross contamination, the only hope is to catch it when it's only trace amounts.