coolant over flow jug......why? how?

[Capt. Tobb]

I do not understand how with all of the pressure in the cooling system, that plastic tube and the plastic jug stay together. Why are they there, other than the tube coming off and water pouring all over me when I am crawling around front of my 892's. Can I take them out? I check coolant level in the tank before I go out.

[(Nobody You Know)]

The tube is protected by the pressure cap which the system must overcome before the jug can begin to fill.

It's there to recover coolant as the hot engines want to discharge small amounts while cruising. I think diesels, since the early 80's, are set to run slightly hotter than those before (someone correct me on this?). And fortunately the physics of the situation allows the engine to suck some of the coolant back into the "jacket" upon cooling down.

[SKYCHENEY]

This is another one of those points of argument. I installed coolant overflow bottles on my 6v92's because it helps keep air out of the system and keeps the coolant system full at all times whether hot or cold. Others believe that allowing the coolant to sit in the overflow bottle exposes it to the air and is worse than if you just run them without an overflow bottle.

To each his own. Which means that you can get rid of them if you choose to do so.

[Brian Degulis]

Think of it this way with no overflow the engine heats up the coolant expands the pressure cap opens and some coolant drains off to allow room for expansion. Engine cools coolant contracts and level in the tank drops a little.

The overflow or recovery tank captures the coolant that otherwise would drain off when it expands. Then when it cools it sucks the coolant back into the expansion tank.

With a recovery tank you can always see the coolant level without removing the pressure cap which is pretty handy when your running.

Brian

[Nonchalant1]

The problem with only checking the bottles is that you have to know that your overflow pipes are OK and working. My pipes are plugged up from 28 years of living in the engine room so I just always check the tank level every morning. I normally fix everything that's not working as it should, and it would be easy to replace or rod out these tubes, but the way I see it is that the fluid always expands when the engine is hot, so if it sucks any back up when it cools down, it'll just push it back out when it gets hot again. I just leave it at about an inch below the pressure cap when cool and I have never had to add any coolant until I change it annually.

Doug

[Jim_n_Naples]

PV=K boyles law or a basic thermomter....gets hot expands...get cool contracts

[Trojan]

I use my expansion tank all the time. I put them on. I don't need to dump any antifreeze into my bilge. You also need to make sure you have the correct pressure cap on your system. 5 to 7 lbs is all you want to run. If you run more pressure than that on a 6-71 DD. You stand a big chance of rupturing your heat exchanger. They are only rated for 14 psi.. If I remember correctly. Its quit low.

BILL

[yachtsmanbill]

When I went to the motor parts for caps they didnt even flinch at the 7lb caps for DDs ! ws