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NCRog · 02-14-2019, 08:58 AM

Does anyone know at what point the ISX15 coolant low level warning comes on? I'm pretty sure the total coolant capacity for my Spartan K3 chassis is 15 gallons, but I recently had a major coolant event (requiring around 4 gallons of new Final Charge 50/50 mix) and yet there was no low level warning (or high coolant temperature) beforehand.

We made a short 75 mile trip the other day, checked the coolant level, etc beforehand, but upon arrival the towed vehicle was covered in dried coolant and there was a puddle of coolant under the coach, getting larger by the minute. The leak was coming from the general area of the coolant filter ... which had been changed by a Cummins service shop about 1,500 miles earlier. If you look at the attached picture you'll see the shut-off valve shaft in the filter housing is sticking out about 1/4 inch from its seated position, presumably pushed out by coolant pressure, until the coolant leaked past the seals. The shaft is supposed to be held in place by a flat washer and set screw, which you can just about see. The flat washer engages in a slot around part of the shaft's circumference, this both retains the shaft and also limits the rotation for the on-off function to just 90 degrees. You can see the set screw has backed off, allowing the shaft to move out and leak. The screw was within 3 turns of completely dropping out, which probably would have caused further outward movement of the shaft ... with complete coolant loss. Ugh! It's tough to know what happened, I see no wrench marks on the set screw, so I don't think it was touched during my recent service. However, the flat washer has an area where there's no red Cummins paint (the area that was engaged in the shaft), so maybe the act of shutting off the valve to change the filter caused the flat washer to also turn and loosen the set screw. I now have everything back in place and torqued to the Cummins recommended 70 in.lbs. When I get home I might remove the set screw and apply some loctite, I've also added a "feel" check of the set screw to my pre-trip engine bay checks!

The scary part of this episode is I was completely unaware of the situation unfolding. Just dumb luck that we only took a short trip! The low level sensor is at the bottom of the coolant expansion tank, does this mean the expansion tank has a capacity of more than 4 gallons, or that I have a defective sensor? Has anyone else had an issue with this set screw?

GaryKD · 02-14-2019, 11:05 AM

Hi NCRog,
Could be several things.
1. bad sensor
2. bad connector(s)
3. bad design letting enough coolant stay in the tank when the rest of the engine runs dry
4. bad on the other end of the sensing wires

Consider unplugging the low coolant sensor and start the engine. Is there a low coolant warning light/sound?

bokobird · 02-14-2019, 02:23 PM

Last year on my trip back from FL, I ran into this problem. Thought, oh, just need some coolant. Nope, the service guy came by, put 1/2 gallon in and it started to overflow. Started up, light was off, went down the road no more than 20-30 miles, low coolant back on.

Turned out to be the sensor, cost me about $150 and the great guys at Jacksonville Cummins installed it right there on the spot (didn't even pull into a bay).

Reading your issue - did the original problem perhaps have any impact to the sensor?

NCRog · 02-15-2019, 12:43 PM

Sensor appears to be more complex than a simple NO/NC switch. There's a line item on my SilverLeaf master screen for coolant quantity, currently reads 100%, disconnecting the sensor at its connector on the expansion tank changes it to 0%. I cannot tell whether lowering the level in the tank provides an intermediate number ... maybe I'll try removing coolant to perform that test when I get home. For now I will change my SilverLeaf display line items to include coolant quantity ... I can then monitor en-route, providing more peace of mind. I didn't have the engine running when I did this check, just the ignition in the run position, but I wasn't aware of any coolant level warning on the dash when I removed the connector.

bokobird - I can't think of a scenario where the leak location would prevent the low level warning from being energized, namely to loose 4 gallons from the system but the tank retains some of its capacity. But never say never ... with these vehicles I learn something new, and stay humble, every day! The expansion tank is on the other side of the engine bay from the filter leak, the sprayed coolant was pretty much confined to just the LH (radiator side) of the bay.

NCRog · 02-15-2019, 12:52 PM

Gary - #3 is an interesting idea, let me think that through!

tom chelbana · 02-15-2019, 08:09 PM

We had a problem with our Essex low coolant check engine light coming on because we had a different anti-freeze then what Cummins approved. Had to drain cooling system and replace coolant with the Cummins anti-freeze to stop check engine light from coming on. The anti-freeze that wasn't approved by Cummins also effected the engine temp gauge that was giving high readings. No issues with K3 605 on 18 LA with check engine light so far.
Newmar Man

lakebuster · 02-17-2019, 08:34 AM

Looking at picture has me concerned as a do it yourself person. I have the filter and was about to change out. So seeing large plug and red bolt with washer in picture which one is the shut off? So to change this filter a person would not just remove old filter and install new filter?
As far as sensor have no clue!

Lault · 02-17-2019, 03:26 PM

I just had mine done at Spartan, did not want to screw up.

NCRog · 02-19-2019, 05:54 AM

Quote:

Originally Posted by lakebuster

Looking at picture has me concerned as a do it yourself person. I have the filter and was about to change out. So seeing large plug and red bolt with washer in picture which one is the shut off? So to change this filter a person would not just remove old filter and install new filter?
As far as sensor have no clue!

If you just remove the filter without turning the shut-off a lot of the coolant will leak out. Turning the shut-off means you lose nothing, except you need replace the quantity of coolant that's left in the removed filter. The shut-off is the larger, shiny hex fitting in the photo ... as best I recall it's a 20mm socket. To shut off the coolant you need turn it 90 degrees counter clockwise, there's very little friction. Just remember to turn it back on after you have the new filter installed!

By way of an update, I received a lengthy, detailed response from Spartan to a series of questions I emailed them. At the factory they fill the system with 64 qts (16 gallons). Their assessment is my system didn't drain enough, even with a loss of 4 gallons, to trigger the low coolant level. If it had, I would have received both visible and audible warnings, plus there would be fault code of SPN111 on my dash. They also added that checking the security of the set screw (the smaller red item in the photo - it takes an 8mm socket) should be part of the regular maintenance check. I wonder how many other "regular maintenance" items there are?

Since the problem we have now put a 400+ mile day on the coach, the smell of burning leaked coolant has gone and the system was just fine ... the level is unchanged and I did do another torque check on the set screw, still holding.