Hi All, We have a 2015 Fleetwood Discovery with the subject chassis and ISL9 engine. I currently have a low coolant dash alarm and was wonder where the sensor for this is located in the cooling system. My overflow tank is practically empty, so I am guessing the sensor is located there, and I just need to top off ATF there? Also, I am reading that I must use Extended Life Coolant (ELC) that meets Cummings specs. Other than FleetGuard are there other off the shelf ATFs that you can purchase that meet the Cummins Spec? Thx, Jeff

Yes it's on the overflow tank and ATF usually means Automatic Transmission Fluid. Buy two gallons so you will have a spare one of ELC.

Best to check with Freightliner (give them your VIN)to verify exactly what coolant they put in at the factory and use that. Then you KNOW that there will be no compatibility issues.

The low coolant sensor pretty much has to be located in the overflow tank. And I highly recommend adding the official approved coolant, not any old generic coolant, and certainly not Automatic Transmission Fluid, aka ATF.Getting a low coolant warning may or may not signal a problem. It went off on our car the other day, and I had to add a half-gallon to reach the full mark. My wife, who is prone to panic when any car-related thing happens, was on it in a heart beat, demanding to know how much THAT was going to cost (how the hell should _I_ know?). Look, I said, it took 88,000 miles to lose the first half-gallon. If it takes another 88,000 miles to do it again, I won't care. If it loses that half-gallon over the next thousand miles, THEN I'll look into it.

Low coolant sensor problems with Freightliner is unfortunately a pretty common problem. Replacing the low coolant sensor usually solves the problem.

^^^^ Not when "the overflow tank is practically empty".

2015 Freightliner low antifreeze sensor | Good Sam Community

Tom_Barb
Explorer
Jan 26, 2018
Jim@HiTek wrote:
Tom/Barb wrote:
My coolant overflow tank will be empty, so I add coolant to the cold line, when it heats up, it will be right at the full /hot/ line, when it cools down again the coolant overflow tank will be empty.
I never see coolant in the oil, I've had it tested. and it shows OK. no coolant.

It's been doing it since new. no bad effects -- yet.

I don't think it's the way it should be but ?

Mystery coolant loss in a car is usually due to a leaking seal in the water pump. If yours has been doing it since new, perhaps it's either a defective pump OR a poor hose connection allowing it to drip out after the system gets up to pressure. A hose clamp loose or something. I'd check for 'telltale' type streaks of coolant somewhere under the engine around the rad or following the heater hoses to the dash comfort radiator...but outside the firewall otherwise you'd smell it inside.

That's what we thought, so we had all hoses changed to the new Teflon and kevlar type, no change. no leaks.
Jim
Explorer
Jan 26, 2018
Tom/Barb wrote:
My coolant overflow tank will be empty, so I add coolant to the cold line, when it heats up, it will be right at the full /hot/ line, when it cools down again the coolant overflow tank will be empty.
I never see coolant in the oil, I've had it tested. and it shows OK. no coolant.

It's been doing it since new. no bad effects -- yet.

I don't think it's the way it should be but ?

Mystery coolant loss in a car is usually due to a leaking seal in the water pump. If yours has been doing it since new, perhaps it's either a defective pump OR a poor hose connection allowing it to drip out after the system gets up to pressure. A hose clamp loose or something. I'd check for 'telltale' type streaks of coolant somewhere under the engine around the rad or following the heater hoses to the dash comfort radiator...but outside the firewall otherwise you'd smell it inside.
Tom_Barb
Explorer
Jan 25, 2018
janstey58 wrote:
Where do you DP owners buy the test strips I see mentioned in these forums?
NAPA
janstey58
Explorer
Jan 25, 2018
Thanks haddy1, that makes sense.
haddy1
Explorer
Jan 25, 2018
eHoefler wrote:
Sensor is located in the radiator tank, not the recovery bottle. If you fill the bottle and it goes down anfter cool down, the radiator needs topped off and refill the bottle. If low since new, all the air wasn't purged when built.

Not true. FL locates the sensor in the recovery tank, surge tank, or whatever else you want to call it. It is not located in the radiator.
wolfe10
Explorer
Jan 24, 2018
Stop by any shop that works on diesels. Because the strips have a relatively short life, buying a quantity is not reasonable unless you have a group of DP's at a rally, etc.

Here are the ones we use: http://www.wixfilters.com/Lookup/PartDetails.aspx?Part=22873

These strips test for:
freeze point
pH
SCA concentration

They are ONLY used with the older-generation "Low silicate for diesels with added SCA" coolant, NOT the new generation OAT-based coolants.
janstey58
Explorer
Jan 24, 2018
Where do you DP owners buy the test strips I see mentioned in these forums?
wolfe10
Explorer
Jan 24, 2018
EXCELLENT.

Much better than just grabbing one that MIGHT be compatible.

Also, a good time to test and adjust SCA concentration if needed.
janstey58
Explorer
Jan 24, 2018
FCCC filled my MH at manufacture time with Shell Rotella brand Ethylene Glycol and water 50/50 mix, Heavy Duty, with SCA. That is what I will use.
janstey58
Explorer
Jan 24, 2018
I will reply to FCCC's last email to request that info, thx.

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