Radiator surge tank

[Adam Hicklin]

I have the white plastic (long and flat) surge tank in the engine compartment.  It always looks empty.  There is an “add” mark at the bottom, and a “full” mark towards the top.  What does that mean?  Should it be full when hot?  Add when cold?  Or hot?  It’s almost impossible to tell from the engine access door because the thing is so opaque, you can’t see the fluid.  Since I had the bed out and the top access cover open I was able to take the cap off.  Sitting cold, there is a slight bit of fluid in the bottom. Below the add mark.  Any ideas?

Thanks

[Bill Lampkin]

Add when cold (its pressurized, just like your car) so that its below the full mark when hot.

My tank (different shape than yours) was also made of the impossible to see thru plastic. I would add a gallon of coolant and the next thing (after running awhile) same tank level. Finally had the tank replaced this June with a welded aluminum tank with a real sight glass. Haven't added a drop of coolant since, and I can clearly see the level in the sight glass thru the engine cover.

[Steve Huber Co-Admin]

Adam,
The OEM C12 surge tank is from a Ford Truck and is prone to discoloring, cracking, and leaking. Many of us changed the radiator cap from the OEM 13lb unit to a 7lb unit to reduce the amount of stress on the tank from expansion since the C12 runs relatively cool and the 13lb is overkill. http://beaveramb.org/forum/index.php/topic,8558.0.html

The real fix is to replace the plastic tank with a metal one. http://beaveramb.org/forum/index.php/topic,6140.msg45426.html#msg45426
If you want to replace the existing with another plastic one: http://beaveramb.org/forum/index.php/topic,853.0.html

You may want to search the Forum too. I seem to remember a post about a shop in IN that made the metal replacement tanks for a bit cheaper than BCS, but I couldn't locate it.
Steve

[Bill Lampkin]

Northwest RV Supply in Eugene has coolant tanks, steel, a bit cheaper than the al tank I choose. Also, Source Engineering also in Eugene has tanks.

[Gerald Farris]

Adam,
If your coolant surge tank is not leaking, you can just replace the radiator cap with a 7 PSI cap and install a coolant recovery tank in a convenient location. That way your surge tank will remain full at all times, and you can check the coolant level in the recovery tank. The recovery tank needs to be a one gallon tank. There are several links on the forum about this addition to your cooling system.

Gerald