Radiator Max/Min Fill Lines

[ecurb74]

Dang Man, I'll make a stab at it. Look just beyond the dip stick in the foreground you'll see a plug in the pipe. I suspect it may be it so that you can bleed the air from the system since it's the high spot. Follow the pipe right and down past the elbow and that should be the the thermostat housing. If I'm wrong it will not be the first nor the last.


Bruce & Teresa
2000 Foretravel U320 4010
Cummins ISM 450hp
Allison HD4060R 6 Spd W/Retarder

[dennis45]

Is this not where it's going now? Just as it should be.....

[96 Wideglide]

Cant go by color of antifreeze.

The Texaco fully formulated diesel antifreeze with SCA, that came in my coach from the factory, is lime green colored!

[Pexring]

Originally Posted by dennis45

Attachment 128023

Is this not where it's going now? Just as it should be.....

Nope, not a drop has gone in that reservoir since I bought the unit last summer. Hopefully my new cap will be in at Napa tomorrow and that will fix all!

[dennis45]

Originally Posted by Pexring

Nope, not a drop has gone in that reservoir since I bought the unit last summer. Hopefully my new cap will be in at Napa tomorrow and that will fix all!

Sorry, I meant the hose below the pressure cap looks like it's going to the bottom of the reservoir now, as it should be.
Any air entrained in the system will make its way to the top of the expansion tank and then the cap will allow the air to escape through this hose into the plastic reservoir. If you look just below the cap on the reservoir, you will see a small hole where the air is allowed to escape to atmosphere but leaving the coolant in the reservoir.
When you trace that hose, does it connect to the bottom of the plastic reservoir?

You need to maintain a level in the reservoir between the Min Cold and the Max Hot. This prevents air from being drawn back into the expansion tank when you shut the engine off and the coolant contracts. As mentioned before, no need to remove the pressure cap to add coolant after the initial fill. Just maintain the level in the reservoir. Very Important.
Keep a close eye on this level initially and add coolant as necessary. Once the air has been expelled from the system you should not see much change in the level if everything is as it should be. Remember, air is the enemy of cooling systems.

I'm surprised the engine did not overheat. You must have still had enough in the expansion tank to keep the low coolant alarm from sounding. You might want to pull the connector off the sending unit to test it.

[Pexring]

Originally Posted by dennis45

Sorry, I meant the hose below the pressure cap looks like it's going to the bottom of the reservoir now, as it should be.
Any air entrained in the system will make its way to the top of the expansion tank and then the cap will allow the air to escape through this hose into the plastic reservoir. If you look just below the cap on the reservoir, you will see a small hole where the air is allowed to escape to atmosphere but leaving the coolant in the reservoir.
When you trace that hose, does it connect to the bottom of the plastic reservoir?

You need to maintain a level in the reservoir between the Min Cold and the Max Hot. This prevents air from being drawn back into the expansion tank when you shut the engine off and the coolant contracts. As mentioned before, no need to remove the pressure cap to add coolant after the initial fill. Just maintain the level in the reservoir. Very Important.
Keep a close eye on this level initially and add coolant as necessary. Once the air has been expelled from the system you should not see much change in the level if everything is as it should be. Remember, air is the enemy of cooling systems.

I'm surprised the engine did not overheat. You must have still had enough in the expansion tank to keep the low coolant alarm from sounding. You might want to pull the connector off the sending unit to test it.

Yep, I found the hose is connected to the bottom of the reservoir tank. I do see little air bubbles coming up by the viewing glass. If my new cap comes in tomorrow at Napa, I will put it on the expansion tank and then fill up the reservoir tank to the minimum and see what happens. So far I have had no issue with overheating and a low coolant alarm has never sounded.

I read in another thread that the arrow on the cap must be pointed to the tube leading to the reservoir? That is not possible on my cap. Does that matter?

[dennis45]

No on the arrow thing. Just make sure it is turned into the second slot. There are two stops so that when you remove it, especially if the engine is warm, it will stop at the first slot to allow pressure (if there is any) to release without the cap coming off completely. Then push down and turn to the next notch to remove the cap. No arrows required....

[TwelveVolt]

I see there are several different radiator cap types (aside from size). Which one is used on the ISC?

[palehorse89]

Originally Posted by TwelveVolt

I see there are several different radiator cap types (aside from size). Which one is used on the ISC?

Cummins repair manual for the ISC it states:
Normal duty - 15 psi
Light duty - 7 psi

I had been running the 15# cap for years, changed the coolant over to "Final Charge this spring, and put a 7# cap on it.......working well as for my travels and use........it is light duty for this cooling system.

[Pexring]

Originally Posted by TwelveVolt

I see there are several different radiator cap types (aside from size). Which one is used on the ISC?

My cap is a 15#, but I did see in my Spartan manual where it said to use a 16#.

[TwelveVolt]

I thought there was another spec for the radiator cap to do with how it is constructed and how it handles the return vacuum to suck coolant back into the radiator as it cools.

[Pexring]

Originally Posted by TwelveVolt

I thought there was another spec for the radiator cap to do with how it is constructed and how it handles the return vacuum to suck coolant back into the radiator as it cools.

My Spartan manual says this about the radiator cap.
"Located on radiator fill neck. 16psi stant R-30 or equivalent."

The one I use is located on my surge tank.

Otherwise Napa was an epic fail today. Got in a cap that was physically too big. Not wanting to wait for them to order another, I found one at Car Quest (part # 10231).

Having supper with the DW then I'm about to go take the coach for a spin and see what happens.

[dennis45]

Originally Posted by Pexring

My Spartan manual says this about the radiator cap.
"Located on radiator fill neck. 16psi stant R-30 or equivalent."

The one I use is located on my surge tank.

Otherwise Napa was an epic fail today. Got in a cap that was physically too big. Not wanting to wait for them to order another, I found one at Car Quest (part # 10231).

Having supper with the DW then I'm about to go take the coach for a spin and see what happens.

Good luck, Let us know how it goes. Don't forget to keep an eye on the coolant level in the reservoir.

[Pexring]

With my new radiator cap and the reservoir filled to the minimum line, I gave Huba about a 30 mile jog. Motor stayed right at 180 degrees (and damn my new Koni shocks rock!). As soon as I got back home, I popped open the engine hatch and was a bit mythed to find that the level in the resorvior never changed by one drop. I felt the coolant and it was warm but not overly warm. Could have been warmed by heat off the motor as far as I know.

But as the motor began to cool, it began sucking the coolant into the surge tank which dropped the level below the minimum line. To be sure it wouldn't suck air, I added more coolant at 2 different times. Oh, I never did burp the system because I couldn't find that bleed hose.

So hopefully on my next trip there is no adding coolant to the reservoir. If I do then I'm still at square one. But this is the first time the reservoir tank has had coolant in it since I bought the unit last summer so hoping things have balanced out now.