Diesel Leak

[Dave Porter]

Hi all,

Need your thoughts on our latest problem with our 2005 40' Beaver Monterey that is leaking diesel fuel.  We recently got back from 2 short weekend trips, having filled the fuel tank before leaving on the first one.  No other fuel has been added since and we were registering about 3/4th of a tank remaining upon our return.  As far as I can tell, we never leaked any fuel at the two visited campgrounds nor was there any sign of a leak in our storage area.  So getting ready to go out on the 3rd weekend (Labor Day), I noticed fuel on the ground....I'm guessing less than a gallon... puddled under the fuel tank.  I could see fuel dripping off the bottom of the tank but have no idea the real source of the leak.  I cleaned up the area the best I could using cat litter as an absorbent, swept it up and put another fresh layer down over the impacted area.  I also filled an aluminum roasting pan with cat litter and placed it under the area that I saw leak.  So after the Labor Day weekend, I inspected my pan and the area under the coach and couldn't see any evidence of further leaking.  The fuel tank was still registering at the same 3/4th level.  So my assumption was that wherever the leak originates is close to the area that equates to about 3/4th of a tank remaining.  Our local repair facility has diagnosed the problem as cracked/old fuel fill lines.  I'm not sure where the fill lines enter the tank nor where the fuel line exits the tank to wind it's way back to the Cat C9 but it really sounds as a guess rather than a diagnosis.  And this is where my question is.  Do you agree with their diagnosis?  Only six years usage from a fuel line seems a pretty short life to me.  Do the fill lines enter the fuel tank at someplace other than the top of the tank?  The fuel sender is about 1/2 up the side of the tank as I remember....and if so and it is the source I would think it would still be leaking.  Or is there another area I should suggest they look.

I now bow to the experienced members of the forum and I look forward to your ideas.  Many thanks!


Dave

[Joel Ashley]

I also doubt that the fuel lines are old enough to have cracked, Dave.  That's not to say a fitting may not be loose.  But there should be no fitting leak at 3/4 tank, regardless.

I was finding some leakage on our pad nearly under the tank a few years ago.  Forgive my dimming memory, but I recall there is a vent tube, apparently from the fuel tank, that winds forward over some framing, and I thought it was from that, since everything around was oily.  I try to always park the coach at home with a full tank, and figured it was fuel expansion in warm weather out a vent tube.  

But I eventually determined it was probably from when I'd recently had the generator serviced;  the tech hadn't properly tightened the filter.  Driving down the road caused a very slight leakage to "spray" over time back over the fuel tank area and adjacent parts, then when I parked, it gathered and dripped to the ground.  What appeared to come from the tube was in actuality coming from the generator immediately in front of the tube end.  As I recall, there was a fitting or housing under the generator filter acting as a catch basin of sorts, so the puddle wasn't directly under the filter.

I'm not sure you'd get anywhere near a gallon, or even a cup, out of such a scenario, but just a thought for you to check.

Joel

[Bruce Benson]

My thought is that they are referring to the fuel fill lines, not the fuel output lines that go to the engine.  Perhaps it is a little early for you to have this problem but the large rubber lines that run from the fuel cap to the tank are apt to leak at some time or another.  My failure occurred when the coach was 8 years old.  I know that I had to siphon a lot of fuel out of my tank to make mine stop leaking after filling it and discovering the problem.  I did not look at the gauge but 3/4 full may be close to correct.  The hose used was not the best quality.  One side has leaked on mine and the other side has not.

You should be able to slip between the side wall and the tank from under the coach to check these hoses.  You might try wiping the attachment point to the tank with a paper towel to see if you come up with some oily dirt.  Otherwise, it might be necessary to bring the fluid level up to find the leak.  You will have to siphon back out to a point below the bottom of the filler flange to stop it from leaking again and to replace the hose.  

The replacement is a rather tough job but can be done if you are handy.  The hose can be sourced locally and you should buy the best quality that you can find.  You should remove the old one first and have the new one cut to the correct length.  This is not a material that you can use your pocket knife on.  

[Gerald Farris]

Dave,
Fuel filler hose leaks are fairly common on coaches between 5 and 10 years of age. If the hose is leaking it will be pretty obvious and found easily with a visual inspection.

Gerald

[JimCasazze]

There is another thread on here regarding the hose problems.  I remember because I had to replace me driver side hose earlier this year.  On the earlier PT's (maybe others as well) it seems the driver side hose rots out.  When this happens you will leak fuel if you fill the tank beyond 3/4 to 7/8.  I was able to do mine without removing the front wheel, but it was a bear.  If I have to do this again, I will remove the wheel to save my knuckles, back, etc.

Jim