Radiator Empty Overflow Bottle Full--How

[Partyat33]

Truck has been running about 10 degrees hot lately. Figured it was just the summer heat. Checked the radiator and could not see ANY fluid !!!



Yet the overflow bottle is almost full. Is this normal.



Should I add 'fluid'.





Thanks



Dennis

 

[CRuD]

I say fill the Rad with a 50/50 mix of antifreeze and water. The way the system works is off of vacum. Please bear with me.

Full Rad + cold Rad/eng. as the engine warms up the coolant expands and thus the excess goes into the coolant overflow bottle. When the engine cools it creates a vacum and draws the coolant back into the rad.

1/2 or 3/4 full Rad + cold engine the coolant expands in the air space, but does not expand enough to push coolant into the overflow bottle. No vacum will be created to draw the coolant back into the rad as the coolant cools. the cooling system stays low and the engine runs hotter than normal due to lack of coolant.



Air will compress but liquids will not and have to have some where to go.

Hope this helps.

Sorry so long.

See Ya

Chris

 

[swamp rat]

Just be sure to do something with the excess coolant in the overflow, otherwise you will have a spill as the coolant in the rad and block expand into the overflow bucket. If the coolant is fairly fresh, I'd siphon about half or a little more from the bucket back into the rad/block then top off the rad with new coolant mix.

 

[drawson]

Sound like a Bad Rad Cap. Working on the pressure side but not on the Vacuum side.

 

[Loren]

I agree with drawson. It sounds like a bad cap. You can have yours tested, but it's probably just as easy to buy a new one.



Regarding expansion: When the coolant in the half full radiator expands, it forces the air out the cap and into the overflow bottle where it bubbles out. When that coolant cools and shrinks, the vacuum should draw coolant from the bottle back into the radiator. If it doesn't, there is something wrong with the system.



If it's not the cap, it might be a clogged line or something similar. The process is pretty simple and straightforward. I'm sure you'll be able to find the problem Dennis.



Loren

 

[Partyat33]

Not the Cap ?

Well, I replaced the cap and towed all week. Unless the new cap is bad, its not that. Its amazing that you can be loaded at 17+k in 95 degree weather, Air Conditioning on full, running 70 to 80 mph and be over a gallon low on antifreeze and not overheat this engine.



Amazing.



Prolly take it to the dealer.



Dennis

 

[Motorhead]

Check that the hose between the radiator and over flow tank doesn't have a pin hole in it. It would cause the radiator to suck air in when it cooled down instead of coolant. Chris

 

[GDouglas]

Hello all, I just purchased a 99 3500 quad cab a month ago based on what I have read on TDR. I am an ex ford dealer technician that had to work on the p. o. s power strokes the first 2 or 3 years they came out, which were the nightmare years for them. I love the simplicity of the Cummins and the overall design will definitely outlast the Ford/Navistar combination. I will always

race Fords when it comes to gas motors but the Dodge/Cummins combination makes a much more reliable and stronger combination for towing than a power stroke.





Well anyway, here's my 2 cents opinion on the full coolant bottle and low radiator. If you don't find any external leak in the cooling system or a bad cap then the only thing that comes to my mind is a cenario that I have seen alot on a few forced induction/nitrous gas motors. Sometimes under extreme cylinder pressures the head actually lifts enough to breach the head gasket/fire ring seal and actually pumps some cylinder pressure into the cooling system therefore pushing more coolant into the recovery bottle than just the thermal expansion of the cooling system by itself. Then when the cooling system cools down, only a certain amount of vacuum is created which is only enough to recover the amount of coolant discharged into the recovery bottle from thermal expansion, and not enough to suck in the extra amount of coolant that was pushed out by cylinder pressure leakage. In all the cenarios that I have seen/diagnosed there was no water found in the crakcase oil at all, just only the recovery bottle that never goes down and a radiator that can't stay full. In a lot of these cases, when the engine was not worked hard for a period of time, then there would not be near as much extra coolant in the recovery bottle if at all. Small block Chevys have less of a problem like this because they have 5 more head bolts than a small block Ford which helps with head gasket retention under extreme cylinder pressures. I don't claim as of yet to be an expert on Cummins engines, but I just thought I would share some of my head scratching experiences with you since what you describe yours is doing sounds familiar.