Coolant level problem

[garyp285]

On a recent 4k mile trip to Yellowstone towing a 10k 5th wheel my 03 did pretty good except getting to about 220 a time or two. I found the fan harness plug was not snapped in tight, and that made a difference.
The question I have is when I added some coolant to the max line, latter that day it would puke a pint or so out of maybe the reservoir or radiator, and then stay normal.
I added some again and it did the same thing a day latter. Does this mean the radiator cap is bad, or any advice would be good.
Thanks, Gary

 

[sag2]

So you set it to the Max line cold and it spit some out and was not at the Max line the next morning? If so, did you drive it a second day and see if the level holds at the same place or continues to drop? As long as there are no external leaks I would let it stabilize and see if it stays there. If your not sure if it went out the overflow, put a plastic cup under the overflow and see if it leaves any coolant in the cup.

 

[MarkEkberg]

I have had that problem time to time on cars. Sometimes they need to find their happy place. Older diesel would empty the overflow, but never use another drop? Engines have a personality for sure.


If you continue to drop coolant your eating it somewhere. Head gasket, passage into oil, or leaking out on the ground.


Even had a water pump that would only leak when hot. As soon as it shut down and drop a few degrees it stopped and of course dried the leak.

 

[garyp285]

Thanks Sag2, and Mark
Its holding steady 3" below max the last 1500 miles home, but it looks like the loss was from the radiator cap, so I'm going to replace that first.
I think it lost some pressure and the coolant got to hot on mountain passes.
Its been 70k since flushing the coolant, and it looks ok, but might do a flush again.

 

[petersonj]

Does this mean the radiator cap is bad, or any advice would be good.
Thanks, Gary

During normal engine operation coolant is transferred back and forth between the radiator and coolant reservoir almost continuously. The relief valve in the radiator cap (typically around 15 psi) allows coolant to flow from the radiator to the reservoir. This occurs anytime the coolant is expanding, such as when a cold engine is started and warms to operating temperature, or when engine load is increased for a time (pulling a grade). When the engine load is reduced or the engine is turned off, coolant will flow from the reservoir through a one-way check valve in the radiator cap back to the radiator. This complete process ensures that the radiator will be 100% full under all operating conditions, including when the engine is shut down.

The reason I mention this is because it is very important to check the coolant level in the radiator as well as the coolant level in the reservoir when the engine is cold. If only the coolant reservoir is monitored, a small coolant leak in the engine cooling system may not be noticed because when the engine is cooling down the source of the leak may allow air to enter the engine cooling system rather than drawing coolant from the coolant reservoir. As a result one may think that because the coolant reservoir level is steady (or fluctuates some), there is no problem.


So, if you check the radiator level when the engine is cold and the radiator is not 100% full, you definitely have a leak. The leak will likely be a minor repair and should be able to be found with the use of a radiator pressure tester.

- John

 

[garyp285]

Thanks John, that is some good info, I'll check it when cold, and see if I need a pressure test.

 

[WalterJ]

I cannot see my reservoir level, so instead of using the 'stick' method, I topped off the reservoir when done driving & coolant was hot. Now when cool, I can easily see the level 2-3 inches below the cap.

Now that I'm thinking of it, maybe I'll add a bright LED under the reservoir tank & see how that works for evening checks, etc.

 

[MarkEkberg]

Just last week when it was stupid hot here in New England my 96 powerstroke boiled everything out of the overflow and radiator.

When cargo straps became loose I pulled over to tighten. Walked around the truck and antifreeze is pouring out from the overflow? Got it to a rest stop and let it cool down (gauge was still in normal where it always was) and I take the cap off the over flow................ The guts of it were gone? Completely gone? Not even in the bottom of the overflow?

NO idea where they went, but a new cap from partshouse and I was on my way.

 

[S.Morris]

Make sure the rubber line that attaches to radiator below the cap (goes to overflow) is attached and does not suck air (if it does it will not transfer coolant back to radiator as engine cools)


I suspect that by filling the cold level up to the top (hot) setting there is simply not enough room for expansion and the overflow is leaking off the excess.

Lower the level in the reservoir to at least halfway (engine cold) and make pencil line at that level. If everything is working properly that same cold level will be returned to when engine is cold at same ambient temp