Coolant Expansion Tank Upgrade?

[Roger Long]

The coolant on my Perkins 6.354's is very hard to check and top up. I have to move all the furniture and roll back the rugs.

Is there any reason I couldn't connect the overflow hoses to expansion tanks as on my new generator and cars?

[Larry M]

You should be able to but you will have to change your coolant cap to vented from a non-vented. A vented cap will suck the the coolant back from your overflow tank as the coolant cools where a non-vented one will not.

[O C Diver]

Try to keep the coolant level in the overflow tank at about the same level with the radiator cap when you install the new tank.

Ted

[Gabe n Em]

Let us know where you find a cap/ the model. I walked into auto zone here with the old cap and they looked at me like I had 3 heads.

[Airstream345]

Originally Posted by Gabe n Em

I walked into auto zone here with the old cap and they looked at me like I had 3 heads.

Well, some boats have three heads

We need to make this update when we take delivery of our Bluewater. Fortunately, American Diesel makes a kit for the Ford Lehman otherwise I'd be rummaging around NAPA.

[caltexflanc]

Originally Posted by O C Diver

Try to keep the coolant level in the overflow tank at about the same level with the radiator cap when you install the new tank.

Ted

This is important. Also make sure the hose twixt overflow tank and engine has no chance of kinking or getting obstructed. Not paying attention to either of these will lead to false readings of level.

[BruceK]

Originally Posted by Larry M

You should be able to but you will have to change your coolant cap to vented from a non-vented. A vented cap will suck the the coolant back from your overflow tank as the coolant cools where a non-vented one will not.

I`m curious, what do you mean by "vented"? I seem to remember a long while back adding an overflow bottle on a car and having to replace the old conventional "spring" cap with one which sealed the radiator opening.
My mechanic installed Mercruiser recovery bottle systems on my FLs, retaining the standard caps on the tanks, I have wondered how well that works.
Apologies if this overly diverts the thread but I think it relates.

[Cyclone]

Anything that will contain overflow pressure released antifreeze must be used. I housed a plastic gin bottle for years. Now the difference between most if not all marine closed cooling systems and the modern road vehicle. There is no means to take that overflow fuild back into the heat exchanger. To ensure that only a dribble comes out do not over fill the exchanger. I used my finger and kept the level at about 1/2 inch below the filler cap. Never a problem and never an over heating issue.

[DHeckrotte]

My 6,354s have their tanks mounted about 3" lower than the caps on the heat exchangers, and the level in the tank is well below the cap. (The caps are about 2" below the underside of the sole and all but out of reach for me.) There should always be enough coolant in the tank (minimum level is marked on the tank) so that there is plenty to be sucked back into the engine. Unless there is an air leak into the interconnecting hose or elsewhere in the system, I doubt it matters much how high the expansion tank is. (The hose is small enough so that a vacuum should be held in the coolant. Supposedly, up to a 3" dia. hose will hold a vacuum, thus the limit of hose/pipe size for siphoning.)

I think you will still need to fill up the system from the high point, but you'd be able to top up the system from the tank.

I'd bet a buck that if there were air in the system, that each time you heated the engine the air would travel to the expansion tank and bubble out, and when the engine cooled it would suck coolant back. Sooner or later, all the air would be gone. Or is that why I have an intermittent overheat problem???

[C lectric]

Originally Posted by BruceK

I`m curious, what do you mean by "vented"? I seem to remember a long while back adding an overflow bottle on a car and having to replace the old conventional "spring" cap with one which sealed the radiator opening.
My mechanic installed Mercruiser recovery bottle systems on my FLs, retaining the standard caps on the tanks, I have wondered how well that works.
Apologies if this overly diverts the thread but I think it relates.

There are two types of expansion or collection bottle systems

#1 One uses a Recovery type cap. It uses two spring loaded valves. One on pressure build up opens directing the excess coolant, from expansion, to a collection bottle or tank. The pressure is contained in the engine to spec.
This cap or the bottle will have a vent hole as it is not intended to maintain pressure, just hold the ejected coolant.

Upon cooldown the other valve opens as the coolant in the engine contracts creating a vacuum which pulls the excess coolant in the bottle back into the engine.

The bottle simply collects the spit out. Simply adding a collection bottle and using the original cap will not work as the old cap will not suck the expelled coolant back. It does not have the two valves. If it does suck back then he installed the recovery type caps.

For this system to work properly the recovery type cap on the exchanger must have good seals and those two valves.. The hose between the expansion tank and the overflow bottle must be fitted tight. An air leak will allow air, not coolant to be pulled back.

#2 Dead cap. The other system actually replaces the function of the engine mounted expansion tank cap , by installing a dead cap, but the overflow bottle now holds the pressure relief cap subjecting the overflow bottle and the hose between also to full pressure all the time. The overflow bottle now is fully part of the pressurized system. Of course the bottle must be more heavily built and must be designed to hold the pressure relief cap or A pressure relief cap.

They both do the same thing, just somewhat differently.
Both these systems will completely purge the engine of air and completely fill the heat exchanger. ALthough the bottles can be used to monitor coolant levels you must watch that the levels rise and fall with heat up and cool down. If not then there is something wrong. coolant loss or an air leak from a loose clamp, bad hose, or failing recovery type cap. I always look for a small leak or it needs a new cap.