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sevenmacs · 11-03-2018, 08:44 PM

My Cat C7 doesn't have a overflow or surge tank not sure what to call it. When it gets hot it just blows out tube onto ground. This happens occasionally in small amount, runs down my mud flap. Not sure if this is the way it should be or wether it should have coolant come out. This occurs under operating temp. Around 200.

VanDiemen23 · 11-03-2018, 11:40 PM

pretty easy to make one. does it simply have an oversized radiator tank instead?

Rkesselus · 11-04-2018, 08:39 AM

not understanding. You say it blows out the tube. What blows out the tube? You later say should it be coolant? Maybe a little different description would help. I have never seen a CAT in a motor home without a surge tank. If something is blowing by the cooling system I would start with the radiator pressure cap.

VanDiemen23 · 11-05-2018, 10:24 PM

You can effect a surge tank three differetn ways:
1) build excess capacity in the radiator tank and put a sight glass there so that the proper cold level is indicated and there's room for expansion.
2) design the radiator to be completely full, put the cap on the surge tank and leave room in the tank for expansion.
3) design the radiator to be completely full, put the cap on the radiator, and run an overflow tube into a recovery tank at standard atmospheric pressure. As long as the radiator has pressure above the cap pressure, as the system cools it will suck the coolant out of the recovery tank and back into the radiator

#2 is what most vehicles use now. #3 is what they used up until the 90s. The problem with #3 is that the hot fluid will eventually evaporate off. With method #1 and #2 you don't lose fluid.

The trick to #2 and #3 is estimating the volume of overflow for a system of your basic capacity so you get the tank size right.

It sounds like the OP has #3 without a tank, so his system vents all the excess coolant and runs low until it warms up.

CountryB · 11-06-2018, 06:32 AM

Quote:

Originally Posted by sevenmacs

My Cat C7 doesn't have a overflow or surge tank

It seems unlikely that the coach did not have a surge or recovery tank when it was built. Chassis/automotive builders have been using those since the late 70's. Is it possible that previous owner removed it for some reason?

I tried to verify this by looking at the Fleetwood Excursion Owners Manual, but it does not cover the chassis.

Do you have the Spartan Chassis Owner's manual?
What model chassis is it?

CountryB · 11-06-2018, 08:19 AM

Spartan does not make it easy to get their Chassis manual. I did find some info here John Deere

You have the Spartan Mountain Master chassis - according to the info I found, there is (was) a surge tank on this chassis. Maybe you are not recognizing it as it is round and not what a typical "car" tank looks like.

sevenmacs · 11-07-2018, 10:34 PM

Never had tank, hose runs down to vent onto ground. Appears to have been built this way. Was planning on adding a tank to capture overflow coolant.

tropical36 · 11-11-2018, 11:24 AM

Quote:

Originally Posted by sevenmacs

My Cat C7 doesn't have a overflow or surge tank not sure what to call it. When it gets hot it just blows out tube onto ground. This happens occasionally in small amount, runs down my mud flap. Not sure if this is the way it should be or wether it should have coolant come out. This occurs under operating temp. Around 200.

My C9 has no overflow tank either and the steel tank that might be mistaken for one, is pressurized with the cap. Overflow hose goes down in the rear towards the ground and I've since hung a plastic bottle on it.
For awhile there, I was adding a little coolant now and then and wondering why, so did this for a just in case the cap might be lifting now and then.
Since then, I haven't added any, so just maybe and even though, I've never witnessed such. Haven't seen any in the bottle either, but then it could be going back into the pressure tank, like you might expect.

CountryB · 11-11-2018, 05:34 PM

Those tanks with the pressure cap are "surge tanks". They allow for the coolant to expand out of the radiator and go into this tank, then draw the coolant back into radiator as it cools.

I think some are thinking of the old car style reservoir where there it was located "after" the radiator pressure cap. In our case the surge tank is "between" the radiator and pressure cap.

Here a pic of my C13. The plastic tank (you can see the pressure cap on it) is the surge tank.

tropical36 · 11-18-2018, 03:56 PM

Quote:

Originally Posted by CountryB

Those tanks with the pressure cap are "surge tanks". They allow for the coolant to expand out of the radiator and go into this tank, then draw the coolant back into radiator as it cools.

I think some are thinking of the old car style reservoir where there it was located "after" the radiator pressure cap. In our case the surge tank is "between" the radiator and pressure cap.

Here a pic of my C13. The plastic tank (you can see the pressure cap on it) is the surge tank.

I can't imagine it being plastic and not being problematic.
Mine is in the same general area and is made of steel.
The rubber hose is right under the pressure cap and goes down towards the ground and where I have a little bottle hung on it.
Yeah, not a lot different than the old days of cars with pressure caps sometimes lifting and losing the coolant. Back then, there was little pressure and we'd sometimes loosen the cap for letting the heat escape, during overheating. Not sure what we were accomplishing, but it was quite common to do so.

VanDiemen23 · 11-18-2018, 08:11 PM

tropical36 · 11-19-2018, 08:39 AM

Quote:

Originally Posted by VanDiemen23

You can effect a surge tank three differetn ways:
1) build excess capacity in the radiator tank and put a sight glass there so that the proper cold level is indicated and there's room for expansion.
2) design the radiator to be completely full, put the cap on the surge tank and leave room in the tank for expansion.
3) design the radiator to be completely full, put the cap on the radiator, and run an overflow tube into a recovery tank at standard atmospheric pressure. As long as the radiator has pressure above the cap pressure, as the system cools it will suck the coolant out of the recovery tank and back into the radiator

#2 is what most vehicles use now. #3 is what they used up until the 90s. The problem with #3 is that the hot fluid will eventually evaporate off. With method #1 and #2 you don't lose fluid.

The trick to #2 and #3 is estimating the volume of overflow for a system of your basic capacity so you get the tank size right.

It sounds like the OP has #3 without a tank, so his system vents all the excess coolant and runs low until it warms up.

Good explanation of systems and I do have a #1, which seems to be the way to go. Yep, the posts can be frustrating sometimes, causing a

, but do hang in there and bear with us....

tankcj · 11-19-2018, 10:02 AM

Correct me if I'm wrong here but I think the coolant tank that I have and as shown in CountryB's photo is actually and extension of the radiator. That's why it has a pressure cap on it. This would be typical on a side radiator configuration since you do not have easy access to the actual radiator cap, So if the OP has a rear radiator (I think the Revolutions are) then he can access the radiator cap and no coolant tank is required. Even with mine, if the pressure exceeds the cap it will overflow on to the ground if the level is too high in the tank. I do not have the typical 'surge' or 'overflow' tank that new cars have. They allow the coolant to overflow into a non pressurized tank when the pressure in the radiator exceeds the cap and then as the coolant cools, it is siphoned back into the coolant system. However, with the coolant tank like I have (and CountryB) it does also allow for expansion.