Cummins 8.3 low coolant light...

[engelstad]

I am a few hundred miles from home and the low coolant light has started to flicker more and more frequently. Should I first just add in distilled water in the coolant tank, which has some fluid in it but is not very full. Any trick or do I just add in the distilled water (not sure if need to bleed or do something special?). Thanks, I don't want the family to get stranded on our fun trip...

[opus]

There should be a level line on the coolant tank. You should be fine putting water in it...provide its operational and has a hose connected to it going to the radiator.

[engelstad]

Thanks! I don't see any level markings... should the tank be half full? Three quarters? Almost full? I will add water but am just not sure how full it should be. Thx!

[opus]

I'd go half. You could go more. If it expands too full it will just blow out the road tube.

[engelstad]

Thanks, I put a bit more into the tank, such that it was probably 3/4 full (or more). I kept getting the intermittent "low coolant" light flashing on occasionally. Today, after the bus sat all day, I checked the electrical connection to the sensor, and it seemed good. I opened up the cap to the tank, and fluid gushed out, until I put the cap back on. At this point, I'm not sure if I still have bad sensor, or where the coolant goes when the engine is running a while, etc. ?? Any other ideas or suggestions?

[Azuleslight]

Originally Posted by engelstad

Thanks, I put a bit more into the tank, such that it was probably 3/4 full (or more). I kept getting the intermittent "low coolant" light flashing on occasionally. Today, after the bus sat all day, I checked the electrical connection to the sensor, and it seemed good. I opened up the cap to the tank, and fluid gushed out, until I put the cap back on. At this point, I'm not sure if I still have bad sensor, or where the coolant goes when the engine is running a while, etc. ?? Any other ideas or suggestions?

you checked that the ground for the wiring is secured? do you have any pictures?

[engelstad]

I am not sure how to verify the wiring ground. The 2 wires from the sensor disappear into the rest of a wiring harness. ?

[Azuleslight]

Originally Posted by engelstad

I am not sure how to verify the wiring ground. The 2 wires from the sensor disappear into the rest of a wiring harness. ?

I also just found a story, if this sounds familiars it might have the same cause. the person was going uphill when the light came on. Turned out that the coolant was 1 gallon low. If the coolant is above the max line (as it is needed to fill the other segments, supposedly), you should be ok. as for the grounding wire, it was a guess, others may have better info.

[Robin97396]

I think you got a big bubble of air in your cooling system, in the block.

[2kool4skool]

Bleed it. My FE has a small black plastic tube with a shut off on it. the inst. are under the rad. access cover. Warm engine, heater valves open, coolant should come of the valve.

[engelstad]

Hi, me again... Well, I think I might actually have a leak, as I've had to add another gallon of coolant to the reservoir. I don't see any obvious leaks, and it's likely about 1 gallon of coolant needing to be added per 1k miles or so. Any ideas or clever ways to find the leak? Is it advisable to use some of the coolant dyes on the market to help? How about some of the stuff added to the system to help seal any minor leaks? I don't want to make the situation worse, but I figured maybe some of this might help...

[opus]

If you havent yet, get an oil sample done. This will tell you if you are leaking coolant into the oil or not. Blackstone Labs is where to get that done, $28.

[engelstad]

Thanks. I just changed the oil recently, and I was encouraged by the fact that I didn't see any water or anything "non-oil" in the oil. Also, the exhaust doesn't seem to ever be whitish, which I was thinking was a good sign. I've not smelled coolant either out the exhaust. Do these make it sound more like leak in the lines somewhere, rather than in the block, etc?

[Robin97396]

If someone worked on your bus heaters and got a bunch of air trapped in the lines it might be working it's way out over time. Just a guess.

[opus]

Those are all good signs. Nothing around heaters, front heaters? Its got to be going somewhere if you are using that much. Unless someone did some work on it and its working out air bubbles still.

[Booyah45828]

Did you pressure test it?

[2kool4skool]

I just fixed a coolant leak, the top rad. hose was leaking at the rad. Replaced to hose and all is Ok....for now. After I added makeup coolant I did bleed the system via the factory bleed hose at the rad. It's a very small tubing with a brass shut off valve on it. Warm engine, all heater valves open, open the bleed valve until coolant appears. Close the bleed valve.

[engelstad]

does anyone know where I can find procedure to replace the coolant/filter, for Blue Bird RE Cummins 8.3L? I had been planning to do this already, but am not sure of how to do the bleeding, and where the bleed valves are, etc? Thx!