Seneca DEF Concerns

[thirdktm]

A semi-related question: I top off the DEF after every trip. Some trips are less than 300 miles, which means I'm adding perhaps two quarts of DEF. The DEF tank holds 4 gallons or so, I seem to recall.
Question: By topping off so often, is old DEF still in the tank and thus could cause problems?
I suppose an option would be to add fresh DEF every 1,000 miles or so...???

[Mad5581]

Your okay topping off with some systems. Freightliner your fine. GM, Ford not so fine. Ram I'm not sure. Me personally I dont top off my DEF. I only put it in when the truck tells me to or when the gauge is down to about ¹/⁴ tank. This insurers i have fresh DEF. Also the way to get the freshest DEF is to go to the truck stop pull around back and put it in from the pump. The cases may have been sitting for weeks or months before they even get to the store. The bulk def in the big truck tank is likely much fresher. Oh its its cheaper too... just make sure you pull away from the pump when your done. The super truckers will have a fit if you hang out too long at the pump.

[Duke4857]

Originally Posted by dramo77355

Since we may not be using our Seneca much this year, we need to worry about DEF getting old in the tank. DEF is stated to have a life of 1.5 to 2 years, but high heat can reduce the decrease the life to much less than that. For those of us living in the south, we need to be concerned due to the summer heat. This is especially true if you have a full tank that has been there for an extended period of time.
I went by my Freightliner dealer today and asked if there was a way to drain the DEF tank and was told that you can only syphon the DEF out through the tank filler. From what I have read, this is not viable option do to the check valve.
Does anyone have a viable option?

I do not own a diesel engine, but with all the trouble that it could be to get the DEF out, just drive it until the def tank is empty. The engine will go into limp mode and then you park it. Driving 500 miles around town might be cheaper and easier. The way I understand it, there is also a algae that likes to live in diesel tanks and plug up things.

[Gunfighter]

Originally Posted by Johnynorthland

If you start it up with an empty def tank To suck the lines dry will you set a code or just warning a light?

Originally Posted by dramo77355

I would not try starting on and empty tank. The outcome is unknown, with a worse case of a hard stop light that requires a tow to the nearest shop......

Do not run your DEF tank empty, in fact I would recommend that you not run it so low that the "Low DEF" Warning light comes on. If this light comes on you are at about 10%. This light will not reset unless you FILL the DEF tank. If you don't refill you will DERATE eventually. I was in Colorado and the Low DEF light came on. I put in a couple gallons, light didn't go off. Read the manual - Aha moment have to fill. Filled it and light didn't go off. The tank was full so I figured it would clear up as I drove. Bad guess. Went about 40 miles and received a Flashing dash that I would DERATE in 50 miles. You do not want to see that Flashing message on your dash about the speedo. Long story short I ended up a few days waiting for a new sensor in Grand Junction Colorado. I could go into greater detail but I would not recommend getting so low as to trigger the LOW DEF as you will have to fill the tank with 11.5 gallons on the S2 Chassis according to the manual. I too worry about old DEF and would recommend not filling your DEF tank unless you put on a lot of miles.

[Shokyle1]

The pump module goes into a evacuation mode at key off this is so the def in the pump and lines does not freeze and damage the system.

[Johnynorthland]

Originally Posted by david a judd

When I picked up my Seneca with Freightliner M2 it had not been driven for a year. When I stopped for fuel the engine light came on and the power was down substantially. I immediately took it to my local diesel mechanic. He drained the DEF tank and replaced it with fresh DEF. Has run like a top since. Short answer is you will be down about 25% on power. When the computer senses an exhaust fault, it reduces the output to 75%. When the DEF tank runs dry you will be reduced to "limp home" mode.

What is the starting year requiring DEF?

[TOS]

Originally Posted by Johnynorthland

What is the starting year requiring DEF?

DEF started in 2010...
I had problems with mine recently. My monitor went to only 10 starts left, tank was full. My research said, problem may be contaminated DEF, which would be discolored (it should look like water). I placed a small hose down the filler spot and used a turkey baster to start the siphon. Fluid was clear, and easy to siphon from DEF tank.
So, I decided to take to M/B shop for diagnosis under warranty. Problem was a bad heater in the DEF tank. The replacement tank and labor was near $3500 . So glad this happened at home and before warranty was out.

[Pops&Dee]

Originally Posted by Robbbyr

The fear of someone introducing a foreign substance into my fuel or DEF tanks is why I replaced the caps with locking versions. Just something else to think about!

Robbbyr, where did you get your locking DEF cap? Thanks

[Rustynuts]

Originally Posted by Pops&Dee

Robbbyr, where did you get your locking DEF cap? Thanks

I had just messaged Robbbyr a couple weeks ago asking him this. The is is the brand and I got it off Amazon and it fit perfect. Freight Defense 100302 13-19 Ford... https://www.amazon.com/dp/B01AJUJVFU...p_mob_ap_share

[Pops&Dee]

Originally Posted by Rustynuts

I had just messaged Robbbyr a couple weeks ago asking him this. The is is the brand and I got it off Amazon and it fit perfect. Freight Defense 100302 13-19 Ford... https://www.amazon.com/dp/B01AJUJVFU...p_mob_ap_share

Thanks!!

[Robbbyr]

Originally Posted by Rustynuts

I had just messaged Robbbyr a couple weeks ago asking him this. The is is the brand and I got it off Amazon and it fit perfect. Freight Defense 100302 13-19 Ford... https://www.amazon.com/dp/B01AJUJVFU...p_mob_ap_share

Sorry, I was working outside. Wife and I building a retaining wall. Fun, fun, fun!

[Pops&Dee]

Originally Posted by Robbbyr

Sorry, I was working outside. Wife and I building a retaining wall. Fun, fun, fun!

No problem. I am glad I am not having all of that “Fun, fun, fun!”

[ed4ster]

I purchased a Stant 10525 DEF cap for our 2016 Seneca that is also locking for about $24.00 on Amazon a few years back.

Ed

[Pops&Dee]

Originally Posted by ed4ster

I purchased a Stant 10525 DEF cap for our 2016 Seneca that is also locking for about $24.00 on Amazon a few years back.

Ed

Thanks Ed. I looked and this one will work on mine!
Ricky