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Pexring · 04-25-2016, 07:05 PM

I've owned my coach for almost a year, but it seems like every month or so I have to top-off the antifreeze. On my Cummins 330 I add 2-3 cups of antifreeze until I see it come up in the bubble (see picture). Is this normal? Where does it go? I have no drips or leaks. My oil level never changes and stays the same color. Just curious. . . .

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**CountryFit** · 04-25-2016, 09:51 PM

mine did that until i used pressure tester and found out the seepage along the gasket at the side of the radiator under the pressure. tightened the bolts all round it stopped.

to make sure no coolant goes into the cylinders, recommend doing an oil analysis at your next oil change. there are a lot of threads on the oil analysis topic.

Mr_D · 04-25-2016, 09:59 PM

Probably a leak that isn't enough to show as it evaporates before it drips.

lancslad · 04-25-2016, 10:14 PM

Not a Class A DP but I had a similar problem with my Dodge Dakota. Found it was the radiator joint between the aluminum and the plastic header. It only leaked when the thermostat opened and transferred hot coolant to the cold radiator. When it all heated up, the leak sealed. It took me three days to find it. New rad is the cure.

AFChap · 04-26-2016, 07:24 AM

My 350 ISC has done the same thing since new. Radiator has been rebuilt in recent years. I have tightened house clamps in the past where I found a little sign of leakage. Had oil analysis recently. Has a bit over 100k miles now. I add coolant a couple of times a year to the overflow/recovery bottle so my level is actually a half gallon or so higher than yours. I rarely mess with the pressurized surge tank in the picture.

Jagnweiner · 04-26-2016, 01:29 PM

Check to make sure your heater core isn't leaking at the other end of the coach. (Mine does)

Old Scout · 04-26-2016, 01:40 PM

Realize there are different protocols between brands/manufacturers as to how to check coolant level--I often read about owners adding recovery tanks to expansion tanks to solve "overflow" issues. However, it seems to me the purpose of the expansion tank and sight glass is to verify level at engine ops temp [ie, hot]. Coolant needs a place to expand to when hot and contract from as the engine cools. If you cant find a leak--one possibility is you are overfilling the expansion tank when cold and it is being pushed out the radiator cap when the engine is hot....or maybe not....

deandec · 04-26-2016, 03:23 PM

I had that problem for about 6 months following a "professional" coolant change and flush.

I also spent about $300 having a shop diagnose the problem with no luck.

The solution was to "burp" the air out of the coolant system.

Instructions were in my engine manual and on the front of the coolant surge tank.

No problems in the 10 years since I did the big "burp"

.

Old Scout · 04-26-2016, 05:11 PM

Could we get the "Cliff-note" version of what is involved to "burp" the coolant system--assume it involves bring the engine to ops temp with the radiator cap off to dislodge any air that is trapped--then refill with coolant. At least that was how it worked with my 87 Vette......

ladagobago · 04-26-2016, 05:12 PM

I had this problem and my theory is that the leak is hidden between the inter-cooler and radiator. the leak must be so small that when the rad is hot the fluid evaporates rapidly.

So I got a pressure tester from advance auto. the will let you borrow it as long as you put the price of the item on our credit card or pay cash. return it and get a credit or cash back.

I discovered that I had a leak in a place of undetermined origin. As a resolve I put in a half bottle of fiberseal (CRC) and have not had a problem since.

I also had a drip leak on a gate valve and no longer leaks.

Old Scout · 04-26-2016, 05:23 PM

Better make sure Cat or Cummins are ok with "fiberseal....."

**CountryFit** · 04-26-2016, 07:27 PM

Quote:

Originally Posted by Old Scout

Better make sure Cat or Cummins are ok with "fiberseal....."

agreed. we don't know how it will affect other parts inside the engine where coolant passes.

deandec · 04-27-2016, 09:55 AM

Quote:

Originally Posted by Old Scout

Could we get the "Cliff-note" version of what is involved to "burp" the coolant system--assume it involves bring the engine to ops temp with the radiator cap off to dislodge any air that is trapped--then refill with coolant. At least that was how it worked with my 87 Vette......

Open the bleed screw on the upper coolant pipe. Run the engine until steady coolant stream leaves the bleed vent.

YMMV by type of engine.

Careful, the coolant may be hot!