Radiator coolant tank

Diane98 · 08-14-2015, 01:00 AM

Has anyone put an overflow tank on the radiator coolant tank.

We have a 2005 Itasca Horizon, with a 400 Cummins, that seems to lose antifreeze/water from the coolant tank, we replaced the coolant cap as we were told that is where it was leaking water and that seemed to stop for a bit. Now, the coach has been sitting since the end of November due to husbands back surgery, but started every 2 weeks and went to check today to get ready to go on a short trip and tank took almost a gallon of antifreeze/water mix. He wants to put an overflow on the coolant tank so the tank can recover the fluid instead of it going wherever it is going. Has anyone ever done this?

question - recovery kit he purchased came with everything he needed, but it says to put the rubber gasket inside the coolant cap to make it a closed system. Is this something we need to do?

stink · 08-14-2015, 01:48 AM

Yup. You need to install gaskit to seal cap so while cooling system cools opon shutdown the coolant will contract drawing coolant back into cooling system from recovery bottle.

grtharris · 08-14-2015, 08:40 AM

Diane98 I was just thinking. If the coolant is getting high enough to overflow the large coolant tank there might be something else going on. It should not get above the max hot coolant line when the engine is warm.

AFChap · 08-14-2015, 09:23 AM

If the metal surge tank is filled only to coolant being visible in the sight glass, it will not normally be expelled when the engine is hot. However, if the metal surge tank is completely filled or close to it, some coolant will be "surged out" as it gets hot and expands. My coach came with a plastic overflow tank in addition to the metal surge tank. I keep the metal tank full, the the level goes up and down in the plastic overflow bottle as the coolant heats and cools.

cbeierl · 08-14-2015, 10:15 AM

My understanding is that that plastic coolant reservoir is part of the pressurized coolant system, not just an overflow tank. Many folks with your age coach have had to replace that reservoir due to aging of the plastic and subsequent cracking/leaking. Searching on this forum (and maybe on rvforum.net as well) should provide a number of threads describing how folks have replaced that reservoir with either the same one or an alternative one.

FIRE UP · 08-14-2015, 01:35 PM

Quote:

Originally Posted by Diane98

Has anyone put an overflow tank on the radiator coolant tank.

We have a 2005 Itasca Horizon, with a 400 Cummins, that seems to lose antifreeze/water from the coolant tank, we replaced the coolant cap as we were told that is where it was leaking water and that seemed to stop for a bit. Now, the coach has been sitting since the end of November due to husbands back surgery, but started every 2 weeks and went to check today to get ready to go on a short trip and tank took almost a gallon of antifreeze/water mix. He wants to put an overflow on the coolant tank so the tank can recover the fluid instead of it going wherever it is going. Has anyone ever done this?

question - recovery kit he purchased came with everything he needed, but it says to put the rubber gasket inside the coolant cap to make it a closed system. Is this something we need to do?

Lee,
First off, I'm assuming that you have a rear radiator coach, correct, even though you have the Cummins? If so, do you have the conventional "Plastic" pressure/over flow tank that many of us do? If so, does it look like this? (in the upper right corner of the picture)

If so, those are prone to sun/heat damage and, will eventually leak/crack to a point they loose coolant. But, usually owners/drivers are up pretty good on their maintenance and catch them before they get to that stage. Those systems, has have been stated, are a closed system and that tank is all that's needed for both overflow and, consistant fluid level. You really should not need to ADD an additional tank. Your choice.
Scott

AFChap · 08-14-2015, 01:36 PM

Quote:

Originally Posted by cbeierl

My understanding is that that plastic coolant reservoir is part of the pressurized coolant system, not just an overflow tank. Many folks with your age coach have had to replace that reservoir due to aging of the plastic and subsequent cracking/leaking.

The plastic coolant reservoir on my coach ...Cummins ISC on Spartan chassis ...is NOT pressurized. The pressure cap is on the metal surge tank. The surge tank pushes coolant into the plastic reservoir as it heats up, and sucks it back as it cools. (I have indeed had to replace the plastic reservoir due to cracking.) The surge tank has a sight glass on it at minimum coolant level. As long as there is coolant visible in the sight glass on the surge tank when cold, adding coolant is not necessary. Some rigs have only the pressurized surge tank w/o a plastic overflow/recovery reservoir. In that case, completely filling the pressurized surge tank beyond sight glass level will cause coolant loss as it expands beyond the capacity of the system. Anytime there is ANY coolant in the surge tank, the radiator is completely full+.

Toward the bottom of the surge tank is a sensor for the low coolant alarm. It is a very piercing shriek on my coach. When my radiator developed a pin hole leak in the top cap in remote British Columbia, it lost coolant primarily during the cooling process overnight. In the mornings I would start it up and add coolant until the alarm shut off. That took close to 2 gallon of coolant every morning. It was still probably a gallon or more below the sight glass level and way below "full", but as it warmed up and expanded it would reach sight glass level and run within normal temps all day, even on long grades (and even though I had the pressure release lever open on the pressure cap to minimize coolant loss). I was tailgunner on a caravan, and nursed it 4-5 days about 2,000 miles back to Tacoma where Cummins NW repaired it.

Long story, but the point is if the OP has only a pressurized surge tank with no unpressurized recovery reservoir (which sounds like the case) they should NOT fill the surge tank completely full. There should be a fill level indicator of some kind (sight glass, etc), and the tank should not be filled above that level.

AFChap · 08-14-2015, 01:42 PM

Quote:

Originally Posted by FIRE UP

Scott ... what is the white square-ish tank on the right below the coolant tank? That setup is totally unlike mine. The long skinny coolant tank at the top is what is equivalent to the metal surge tank on mine. It is obviously plastic, and obviously pressurized. And the fluid level is easy to see.

A picture certainly is worth a thousand or so words!!

cbeierl · 08-14-2015, 01:51 PM

A 2005 Horizon with the 400HP Cummins is going to have a side radiator.

That white squarish tank in Scott's picture is the power steering reservoir (Dexron III or equiv.).

cbeierl · 08-14-2015, 01:58 PM

Here's a video of the surge tank replacement on a side-radiator Freightliner chassis:

Surge Tank Replacement

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Ray,IN · 08-15-2015, 10:08 PM

FWIW, I replaced my overflow tank with a generic one from Carquest. It's smaller, so it's nearly empty when cold and fills nearly to the top when hot, but it works fine. The generic cost $14.95, whereas the OEM costs $75+ shipping.
An overflow tank may be added to any vehicle where there is room to do so.