Engine/Transmission (1994 - 1998) Does Diesel expand in the heat?

[mattjj]

I have a 97' dodge and I topped the fuel tank off all the way to the cap. It was sitting in my inclined driveway facing uphill and I noticed diesel dripping from the bottom center of the tank. When I got underneath and looked for where it was coming from I saw it around the sending unit and also noticed a whistling noise coming from the vent nipple on top of the sending unit. It was 100 degress out today and I have not driven my truck since I topped off the tank 2 days ago. This is the first time I have ever noticed diesel dripping from the tank. The dealership thinks it the gasket around the sending unit, I tightened the plastic ring snug about a quarter turn and have not noticed any fuel leaking since and also drove it 50 miles today. Your feedback please?

 

[JHenry]

Just a quick reaction, I would say almost everything expands in the heat, except maybe ice. Water actually expands when it freezes.

 

[tp0d]

um topping it all the way to the cap isnt too good of an idea. The filler hose isnt made to hold pressure, just moving fluid.

Looks like you lost about 4. 98 on the ground... hmmm

I havent been filling mine up past 1/2 lately, pi$$ed off at the prices. .

-j

 

[Bob Cochran]

Yes it expands fact been a controversy about Flying J purposely heating fuel. Don't know the results but the idea is when fuel hot the pump registers more gallons than actually pumped. I would think the same goes for gas.

 

[Grizzly]

Diesel and gasoline expand with heat. So does steel beams, concrete and wood expand with heat. That's why we use expansion joints.

 

[AKaiser]

Any time you fill a fuel tank, especially if you're not going to burn off some, you need to leave sufficient "outage" space for expansion. Volatile fuels are more likely to expand than, say, motor oils.

 

[jtwcummins]

Fuel, gas & diesel, expand when heated. There is an issue about US gas stations not adjusting for temp when you buy fuel. If you buy early in the morning you get more fuel than if late in the afternoon. Pumps don't correct the price for the temp expansion. I think Canada has pumps that correct for temp, but not here. That means if you pay for 20 gallons in the morning when the tanks are cool you get what you paid for, after the tanks warm up during the day you pay for the 20 gals but get less than that.

 

[B.G. Smith]

50 gallons of diesel becomes 51. 3 gallons when the temperature of said fuel is raised 20 deg. celcius, (that would be like changing from 60 deg. F to 95 deg. F. ) This was from a search and didn't find much info. You really should not have a problem if you stop filling when the pump shuts off but I wonder about some of the modifications that allow you to put more than 35 gallons of fuel in the tank? bg

 

[QWaller]

As an aside, I too am finding myself running my tank lower and lower to bypass the $125station. What is the tank size on these trucks or better yet does anyone know where they typically run slap out?

 

[JDiehl]

I always fill my tank on the slowest setting and the pumps where i fill up are always not shutting off before the whole neck is full. So really this tells me that I am losing twice! Wish I could capture all the fuel and drops spilled in one day all over the US from just returning the nozzle.

 

[KLockliear]

When my fuel sender died at 1/4 tank, it took 36. 1 gals to fill it up from where it stalled.

 

[Andy Redmond]

The roll over valve and grommet are common leaky spots when "topping" off.

The replacement rollover valve fits to the tank module a little different.



52127666 = mopar number for rollover valve

4002149 = mopar number for grommet





Prior design was better.



Also the gasket/gasket skirt under the tank module sometimes gets jacked up, If you've changed your sending unit, then it leaks the large nut was over/under torqued or the gasket pinched damaged. (sorry don't have a part num. handy).



If you don't have the fancy nut wrench, a strap wrench from Lisle or the "plumbers" type rubber strap wrench available from Sears/Craftsman etc.



Tank modules have dropped a lot in price and are cheaper than the aftermarket now. MSRP $ 125 +/- vs. carter in the aftermarket $ 310, the numbers below are reman mopar numbers.



Good luck

Andy

R4798671 / 96-97 MY

R4864209 / 95

R4864735 / 94

 

[BigEasy]

Fuel, gas & diesel, expand when heated. There is an issue about US gas stations not adjusting for temp when you buy fuel. If you buy early in the morning you get more fuel than if late in the afternoon. Pumps don't correct the price for the temp expansion. I think Canada has pumps that correct for temp, but not here. That means if you pay for 20 gallons in the morning when the tanks are cool you get what you paid for, after the tanks warm up during the day you pay for the 20 gals but get less than that.

do you really think that the underground tanks change temp?