Possible small fuel leak

[ajducote]

I just discovered that I may have a very slow small fuel leak on the passenger side of the engine. I have looked for evidence of where it could be coming from and so far I am unable to find the source. I am fairly certain it is not the fuel filters. The leak is so small that it left a small about 2" diameter stain on a piece of cardboard under the engine over a 24 hour period. I have cleaned that side of the engine with simple green and looked at it from all angles with a flashlight and I just do not see anything. I apears that the fuel MAY be coming down the side of the block and collecting on the lip of the oil pan.
So I am looking for suggestions on how to proceed in trouble shooting this issue. Has anyone else had a similar problem? Is there anything that can be used to find and trace the fuel back to its source?

[sawdust_128]

Dust the suspect area with talcum powder. Check it in the morning.

[Jon Wehrenberg]

Andre,

You are using the correct method. With a clean dry engine place cardboard beneath the coach and see where the drip is. With a small leak it is possible the fuel is seeping from somewhere and running down a fuel line or some other component to a low spot before dripping so you will likely have to find the origin of the drip, and then with your fingers follow the wet spot back to the origin. On the passenger side the fuel goes from the filters to the fuel pump on the rear of the compressor and then from there to the engine. It will just take some detective work on your part. Did you just have the fuel filters changed?

[Alek&Lucia]

Andre,

Also, check the fuel connection that is feeding your Aguahot,

Alek

[ajducote]

Jon,

The filters were changed months ago. I am almost certain that is not the problem. I have sorta / kinda narrowed it down to the hose that goes from the fuel filter to the pump on the back of the compressor. It almost seems as if fuel is "seeping" thru the hose and soaking the outside of the hose. But I need to let it sit for another 24 hours and check it. I have wrapped that hose in clean paper shop rags and if the rags get fuel on them I may have found the problem. I do not think it is the hose fittings. They are staying dry. So the next question, If it is that hose, is that something I can change or should Prevost or Detroit change it out?

[Jon Wehrenberg]

A hose is a hose. I suspect somewhere near where you are there will be a hose shop that specializes in making hoses.

Take the defective hose (if that is what the problem is) to them and on the spot they will make a new one equal to or better than the old one.

Remember how we got new radiator hoses when we were in OKC? Same thing.

[truk4u]

Be prepared to handle the stumble in the engine running, quitting and then restart as you will have air in the fuel system. It might pick it up pretty quick and it might not.

[ajducote]

Tom,

That is what I am concerned with, I guess it would be best to add this at the same time.
http://www.prevostownersgroup.com/public/index.cfm?fuseaction=articles.view&id=3734&publicationtype=Articles

Anyone have any idea how much pressure is on that hose?

[Jon Wehrenberg]

If it is up to the fuel pump it is likely vacuum. Downstream from the fuel pump will be pressure.

To eliminate the air use a pump sprayer or something similar to introduce fuel at the secondary filter fitting base. Leave the connection at the fuel pump loose and cause fuel to flow until it leaks from the loose fitting at the fuel pump. That will eliminate the air bubble.

If I were to guess I would say the problem is a fitting and not the hose. Fuel hoses are typically capable of withstanding a nuclear explosion and have one or two braided layers in addition to the normal hose material. I have a small fuel leak on my first bus and all it took was about 1/16th of a turn with a wrench to make it go away.

[bluevost]

Andre,

I too had a leak that was very hard to find. Turns out it was the aluminum check valve in the fuel line. It had a hairline crack at the threads. Also, the replacement part was hard to find, had to be sent from Tennessee. Give it a look.

Ken

[ajducote]

Ken,

Thanks, I a still looking at this and so far have found no source. I plan to spend a lot of time working this problem this weekend.

[ajducote]

Update,

While Tom (TRUK4U) was here at TGO he looked at this with me and we agreed that the short, large diameter hose that goes from the filter to the fuel pump on back of the air compressor looked like it was "weeping" thru the hose itself. So I went to NAPA here in Titusville, they have an attached machine shop, and had a new hose made. Took all of 5 minutes. So I will run the bus every day for the next few days and see if any fuel ends up on the clean cardboard siting under the engine. After I took off the old hose I look at it closely and it seems like the entire outside brad material is soaked in fuel. So in 3 or 4 days I should know if I guessed correctly.

[ajducote]

Well it looks like the hose was the problem. No fuel smell or fuel stains on the cardboard under the engine. So I think this problem is solved.

[phorner]

Andre,

I had a very similar problem with a 1998 Safari. The fuel hoses (the length of the coach!) would seep fuel right through them. You could squeeze the hose with your hand and get it wet with fuel. I was told at the time that they had received some defective fuel line and they replaced it under warranty.

However, this problem came to light within 8 or 9 months of using the coach. I had developed a diesel fuel odor in the basement storage area, but never noticed an actual leak.

Hope you have it resolved!