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U320 rh fuel tank hot after full day of travel

April 01, 2020, 06:55:47 pm

I never checked the fuel tanks before, Tonite I did and the right side fuel tank on my U320 was hot to the touch. The aqua hot water tank sit behind it. Is this normal?? This was after 8 hours of travel.
Thanks for the heads up, Cummins confirmed this was normal for the older coaches with out the coolers.
Special thanks to Pierce

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Re: U320 rh fuel tank hot after full day of travel

Reply #1 – April 01, 2020, 07:12:02 pm

Normal as the fuel tank gets hot from the returning fuel. Diesel engines only use part of the fuel to the injectors and return a good portion to the tank. This also cools the injectors. The lower the fuel in the tank is, the hotter it will get. Normally on a big rig with exposed diesel tanks, the fuel is cooled by the airflow. But ours are out of the airflow. You can install a return fuel cooler as some have done.

Every diesel manufacture has a spec for maximum fuel temperature when it enters the injection pump.

When low, our fuel tank gets too hot to keep you handr on it in summer.

Pierce

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Re: U320 rh fuel tank hot after full day of travel

Reply #2 – April 01, 2020, 07:19:36 pm

AND, some of us on older coaches and OE on many newer Foretravels, there is FUEL COOLER on the return line to the tank.

If yours does not have one, not difficult to add-- Hayden transmission coolers work well in the return line.

Been there, done that.

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Re: U320 rh fuel tank hot after full day of travel

Reply #3 – April 01, 2020, 07:56:05 pm

The fuel cools the ECU on the m11

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Re: U320 rh fuel tank hot after full day of travel

Reply #4 – April 01, 2020, 10:02:13 pm

Get a laser thermometer when you can. Easy to check temps in tire's, metal, anything else. If you drive 8 hours straight then yes the fuel will get warm. The U320 has a fuel cooler in front of the radiator. Don't know your year coach. Fill out your signature with your info. Makes it a lot easier for us to answer your questions.

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Re: U320 rh fuel tank hot after full day of travel

Reply #5 – April 01, 2020, 10:38:43 pm

Quote from: Caflashbob – April 01, 2020, 07:56:05 pm

The fuel cools the ECU on the m11

Through the ECU on the Detroit. That's why it's good to keep the fuel fairly full in summer so you don't go over the Cummins/Detroit temp rating for the fuel. The ECU is cooled before it gets to the injectors.

Pierce

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Re: U320 rh fuel tank hot after full day of travel

Reply #6 – April 01, 2020, 10:57:34 pm

I had a unusual event happen to me twice,  totally filled fuel tank including leaning the coach to get it fully filled.

Then Banzai up from grapevine, ca to Lebec, ca.  Tenon grade. 

Fuel pouring out of the take overflow. 

Wrong cap.  Non vented.

Fuel expanded from the hot recirculation

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Re: U320 rh fuel tank hot after full day of travel

Reply #7 – April 02, 2020, 05:42:23 am

Thanks for the replies, this was the first time I have traveled that long. I will check and see if it has a fuel cooler and if so that is working properly. They don't say anything in the manual about it.

Steve G

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Re: U320 rh fuel tank hot after full day of travel

Reply #8 – April 02, 2020, 07:41:47 am

Steve,

I just looked at your build number and unless someone added a fuel return cooler aftermarket your coach was built before they started OEM coolers.

Mike

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Re: U320 rh fuel tank hot after full day of travel

Reply #9 – April 02, 2020, 09:39:56 am

With our Detroit the pro link tells me my fuel temp  128 degrees with a half a tank of fuel as soon as I fuel up and start driving again it drops to around 95 degrees and as I use more fuel the temp starts coming up.

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Re: U320 rh fuel tank hot after full day of travel

Reply #10 – April 02, 2020, 09:43:35 am

The time fuel temperature gets really high is with low tank level after driving for a long time.

Before adding a fuel cooler to our coach, the tank could get hot enough it was uncomfortable to touch.  A Hayden transmission cooler is pretty easy to plumb in to the fuel return line.  Had a cover with Velcro for it so it did not over-cool in the winter.

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