Radiator Problem Leaks, then doesn't, then leaks

[rvfishman]

I have a 06 National Tropical 350 diesel pusher.  Had suspicion might have a problem cause had to put 1/2 gal. to fill to reservoir minimum level before embarking on trip (using CAT recommended coolant).  But didn't have to fill at all during summer trip (was gone 2 1/2 mo. in Canada).  Returned from  summer trip.  After was parked in storage 1 week, was a wet spot and wet drops from the radiator/water pump.  Not sure where moisture was coming from.  Added coolant to min. level again.  About a week later saw same dripping.  Researched where to take for repair/diagnosis when returned to RV engine diagnosis said required more coolant.  Added 3/4 gal. coolant.  Took to truck repair place.  They did not have much time so after a cursory look they could not see any obvious leaks they suggested replacing the radiator cap.  A $5 purchase.  Took motor home back to storage.  I replaced cap.  Checked on RV a couple of days later.  Moisture dripping again at a fast rate.  Added another 1/4 gal. took to repair place again.  They put air pressure on the radiator to check for leaks.  There were no leaks, no drips.  Brought back to storage.  Waited a couple of days, checked for leaks.  No leaks.  Has anyone had a similar experience?  We have only owned this RV one year.  We have read where other mfgs. (Monaco) have had numerous problems with their aluminum radiator.

 

[Lou Schneider]

My guess is a failing water pump where the shaft seal only leaks when it's stopped in one particular position.  Loosen the fan belt and see if wiggling the water pump pulley shows any looseness or if the wiggling makes it leak.

 

[Northern Rambler]

I had a similar problem last year around June with my unit . It was losing antifreeze off and on . I finally found that it had a small leak where the coolant heater hose fitting was going into the motor block I tried to tighten it down more but the bolts were tight . We were just starting out on a month long trip and to be able to remove the fitting I would have had to remove the distributor plus a number of other parts . We were 1 day into our journey so I made a quick trip to Kmart and picked up a bottle of Bars-All put it in the rad . 8000 miles later no leaks .  easy fix and worth a try .

Bill

 

[Cant Wait]

Had same thing several different times while driving truck. It was what we called a cold water leak, it only leaks when the engine was cold and setting. It was usually a matter of loosining the hose clamp where it was leaking, and then retightning it to stop the leak. Remember that just because you see the water at a certain place doesn't mean that that is where the leak is, water travel from the stranges places on a motor sometimes. Try loosinging and retightening the hose clamps in the water pump area first.

 

[rvfishman]

Thanks.  These are all good suggestions.  We will give them a try.

 

[Mavarick]

Another thing to watch is the radiators plastic tanks. You usually have a small plastic fitting on the side, left side if I recall, that can loosen a bit and leak when cold. When it gets hot from driving it will seal back up. The hose attached to this plastic fitting is usually tied up with a wire tie. The weight of the hose hanging or pulling down on the  fitting will loosen it up. Tighten the fitting only finger tight, then tie the hose back up if it has come loose. These fittings strip out very easy so don't overtighten.