Radiator Max/Min Fill Lines

[Pexring]

I don't suppose I would be so lucky and it would be as simple as a new radiator cap. Found this online. If your cap was defective, would your engine run hotter? Mine doesn't.

"If the radiator cap becomes defective and no longer works the way it should, it allows the radiator fluid to boil. You'll experience low levels of radiator fluid or notice that it evaporates very quickly. If your radiator cap is damaged, you should replace it immediately."

[dennis45]

Originally Posted by Pexring

I am quite concerned about my coolant issue. Once I figure out why I'm losing coolant I'll then change it out. A trucker told me this evening that perhaps the cap is on too tight so it's building up too much pressure and the coolant is shooting out the drain tube on the side of the radiator? He said to back off the cap a notch and see what happens. Any truth to that? Didn't know I had a drain tube.

Absolutely not. The cap is rated and designed to maintain a 16# pressure in the cooling system. The cap Must be fully seated in order to perform as designed. It is very possible the cap is bleeding off too early and allowing coolant to escape through the overflow. As stated in my previous post, remove the cap and get it tested.

[dennis45]

Originally Posted by Pexring

I don't suppose I would be so lucky and it would be as simple as a new radiator cap. Found this online. If your cap was defective, would your engine run hotter? Mine doesn't.

"If the radiator cap becomes defective and no longer works the way it should, it allows the radiator fluid to boil. You'll experience low levels of radiator fluid or notice that it evaporates very quickly. If your radiator cap is damaged, you should replace it immediately."

Do you have a plastic Overflow Tank? Typically, the overflow hose off the expansion tank (at the pressure cap) is connected to the bottom of this plastic tank to allow air to escape off the top of the expansion tank, into the liquid in this tank and to prevent air from entering back into the system during shut down and cool down period. There is two marks, Min Cold and Max Hot.

[dennis45]

[TwelveVolt]

Originally Posted by Pexring

Mine doesn't have a reservoir jug. I have this tank (pictured) and should be able to see the antifreeze in the little window (and this picture shows I need to add some). I constantly have to add a little antifreeze and that's starting to become worrisome.



Attachment 127562

Are you saying that overflow tube next to the pressure cap does not go to a reservoir jug? Normally, coolant gets pushed out to the reservoir as it warms and expands. Then it gets sucked back in as the engine cools. If there is no jug, are you just dumping the excess every time the engine warms up?

[ecurb74]

Pexring,

When I was having problems with my coolant level sensor I also had to top off every so often. I kept wondering where it was disappearing to. One day I happened to see just a tiny bit bubbling out from the radiator cap on the coolant tank. I never saw it collecting on the ground or residue on the coach. I change out the cap and everything is fine now. Radiator caps are just a few bucks at NAPA . Just be sure of what poundage yours is. Good luck!






Bruce & Teresa
2000 Foretravel U320 4010
Cummins ISM 450hp
Allison HD4060R 6 Spd W/Retarder

[Pexring]

I have that reservoir tank with the minimum and maximum lines, but since I bought the coach last summer, I have never seen an ounce of coolant in it. Actually, I don't see any lines leading to the reservoir or anyway to connect the line (unless it's in back). Which raises the question of where does that hose off the neck of the expansion tank go too? I know the hose goes up over the light and then who knows where? Definitely checking that out first thing tomorrow. Damn - now I ain't gonna sleep tonight wondering about that . . . motorhome is parked at my shop 1/2 way across town.

Sorry for hijacking the thread, but I appreciate you guys sticking with me on this subject . . .

[Pexring]

Sure enough but that hose goes to the far side of the reservoir. But this morning I am in extra freak out mode because the antifreeze I added to the expansion tank yesterday is totally gone. Nope never started the engine once. With it cold I pull the transmission oil check and it reads high. Is it possible for the antifreeze to get into the transmission without the motor running?

[Steve Ownby]

Originally Posted by Pexring

Sure enough but that hose goes to the far side of the reservoir. But this morning I am in extra freak out mode because the antifreeze I added to the expansion tank yesterday is totally gone. Nope never started the engine once. With it cold I pull the transmission oil check and it reads high. Is it possible for the antifreeze to get into the transmission without the motor running?

The only place that could happen is if your transmission fluid cooler is internal to the engine radiator. Many are built this way. If the cooler has failed inside the radiator then it's possible for coolant to flow into the transmission when there is no pressure on those fluid lines. When running the transmission fluid pressure is greater than the coolant pressure & fluid would flow into the coolant. If this has gone on long, both coolant and transmission fluid would show contamination.

I'm guessing that it's a long shot that your coolant is going into the transmission. However, that is catastrophic for the transmission. The glycol component in the coolant attacks the internals & makes a rebuild necessary. If it were my coach, I would pull a transmission fluid sample ASAP & send to JG Lube Services for analysis. Tom Johnson owns JG and he has a thread over on the Allison forum. He a retired Allison engineer and he wrote the Allison spec for their approved fluids. He will give you personal attention if you post to his thread. You should do an oil analysis at the same time.

If you think there is a remote chance the coolant is getting into the transmission, do not start the coach until the analysis is complete.

http://www.jglubricantservices.com/

[dennis45]

Originally Posted by Pexring

Sure enough but that hose goes to the far side of the reservoir. But this morning I am in extra freak out mode because the antifreeze I added to the expansion tank yesterday is totally gone. Nope never started the engine once. With it cold I pull the transmission oil check and it reads high. Is it possible for the antifreeze to get into the transmission without the motor running?

Before you get to excited, the oil level on the transmission dipstick will show high with the engine stopped.

As Steve suggested, contact JG labs, buy yourself an oil sample kit, and draw a sample off the transmission and engine dipsticks. Then you know for sure. But until you get the results back, do not start the engine. Assume you have never seen any antifreeze on the ground.

Also, when the overflow hose is connected to the bottom of the plastic tank, you just add antifreeze to the plastic tank. No need to remove the pressure cap on the expansion tank.

P/S, give Tom a call at JG Labs and talk to him about your situation. He is Very helpful.

[Pexring]

I ordered a new radiator cap from Napa this morning. Be here tomorrow. Just as luck would have it my friend who owns the biggest transmission shop in the area stopped to say 'hi'. I said I got something for you to look at. He pulled the dip stick on my transmission and said the fluid on the stick looked perfect. He asked if the motor smoked. I said 'no'. We started the engine and confirmed it never smoked. And the fluid in my glass of the pressure tank came right back up to where I left it. But no fluid ever goes to the reservoir. Maybe my new cap will fix that? Anyway, even tho he's a transmission guy, his opinion is that the antifreeze is not getting into the motor nor the transmission by his visual inspection. So later today I am going to try and burp the system and once I get my cap I'll add some antifreeze directly to the reservoir. But he did notice one other concern on the engine which isn't related to the cooling system so I'll start another thread.

[dennis45]

Let us know how it goes. Keep in mind that once you top up the reservoir, you need to go for a drive to get the engine up to operating temp to open the thermostat and get full circulation.
It sounds like your system may have air in it and you will need to keep an eye on the level until the air is dispelled through the reservoir.
Still strongly suggest an oil sample. I do one every year to to make sure there are no contamination issues. $50 and peace of mind.

[TwelveVolt]

Also, have a close look at the plastic tank. Mine had cracks when I bought the coach. The tank and hose are simple and relatively inexpensive to replace. I ordered from the coach manufacturer, figuring the min/max lines would be in the right place and same mounting holes versus a generic from NAPA.

A quick way to check would be to put paper towels under the tank and pour some water in. If not leaking, that water should turn red after the next drive.

[Pexring]

To burp, now I'm looking for the vent fitting on the engine thermostat housing (according to my Spartan manual). Where do I look for it in this picture?