OK, I've been chasing an on-and-off leak for about a year. I was thinking fuel, but now I'm not so sure... I'm thinking... engine oil? Does this sound possible, or is there a plausible leak source that I haven't found?

I've had several issues, and chased down all but this one. I had a power chip connection issue, and had a massive leak from the fuel bowl cover... either I didn't get the cover seated when I checked the filter while limping home, or the fuel pressure went wacky and blew the o-ring partway out. That saturated the foam in the hood liner and on the rear of the passenger side fender liner. I had a bad leak in the cylinder valley, replaced fuel pump and all the soft fuel lines last year. The valley has been dry and bright orange (rust) ever since.

But I'm still frequently getting a leak that saturates the foam on the inside rear of the passernger side fender liner. The leak runs down the inner edge of the liner, and drips from the rear inside corner.

I thought "fuel". The fluid is a bit viscous and sticky, and fairly clean... about what I would expect evaporating, gumming diesel to be. It's not the black stuff dripping off my oilpan drain plug (plug gets a new copper washer with next change ), so I was figuring "gummy diesel" not "fairly clean oil".

But can I find a leak source? No! The cylinder valley is dry and orange. The fuel line fitting in the rear of the right cylinder head is dry and dust/dirty. Everything I can see on the valve cover and head above the exhaust manifold is dry. I see nothing on the manifold.

The front of the engine has a bit of seep below the HPOP... but I cannot see that anything is going anywhere. Looks like just enough to be wet, but not enough to drip. I see no sign that the front fuel line fitting is leaking.

Where I DO see some wet is the dipstick fitting on the oilpan... that has some gummy seap around it, and it's running down under the pan. This stuff is dirtier than what's saturating the foam on the fender liner. I also noted when I checked the oil today that I didn't get the dipstick fully seated on the first try. Hmmm... it looks like I may have had some oil coming out the top of the dipstick, and running down the tube. I do have some wet grime along the bottom of the transmission and transfer case.

If I'm losing oil, it's not much. It's about time for a change, and I'm half a quart below full. I would expect any engine oil seep to look as dirty as what comes out of the pan on an oil change.

So is it possible that the "fuel" leak I've been changing, is either the dipstick pan fitting, or a not-seated dipstick? Since the leak is getting into the foam on the fender liner first, is the foam "filtering" the oil, adding some diesel odor from prior leaks, and letting the oil gum up a bit, while it seeps through the foam and eventually drips off the lip of the fender liner?

This sounds really implausible, but I can't figure out any other source for what's dripping off the fender liner lip.

Anybody have any ideas? Or any hidden fuel leak locations that I missed?

 

How about the pwr steering - I know these can be deceptive and only spray every now and then. Also what about the Diesel lines that run inside the front wheel yoke?
Or the AC line with a leak.

Just a few more to check

Also if its the pwr steering you may have to rev test for leaks while someone looks and you turn the wheel

 

Are you positive it's fuel? Could it be coolant from a heater hose or maybe even winshield washer fluid? Just a thought.

 

The fluid dripping off the bottom is yellow-golden, a bit more color than new Rotella-T, and a bit stickier.

The fluid seems to be getting into the foam on the inside rear of the passenger side fender liner, from somewhere high and middle or rear of the engine. The inside of the passenger side frame rail just has a bit of wet mark near the dipstick tube, and is dry forward. The inside top and inside front of the fender liner are dry, forward part of frame rail is dry, exhaust manifold is dry. It's like a point source is dropping it straight onto the foam on the inside of the fender liner, and not getting anywhere else.

No sign of red for it to be transmission fluid (this IS an auto). I do have a drip at the front from one of the auxilliary cooler lines, but that's obviously RED.

It's not blue and watery like windshield washer fluid.

It's not opaque bright green and watery like my coolant. I siphoned some out of the overflow today to add SCA so I know the color is bright green enough for St Patrick's day. And the leak happened before I siphoned today, so it's not spillage from today that changed color.

I doubt brake fluid... as of today, I was only down a couple of teaspoons over 2 years, and my guess of the amount that's under the truck and in the foam on the fender liner right now is at least half the reservoir volume. If my leaks over the past year were brake fluid, I expect that the master cylinder would be sucking air.

A/C oil... hmmm... there's one I haven't thought of. But doesn't Freon evaporate at atmospheric pressure, and there's only a bit of actual oil in the system? But the location is right; I guess it's the dryer, accumulator, and evaporator coils that sit right above the leak. My AC does work, but I haven't done anything to it in the 9 years I've had this truck. On the shopping list: can of R134 with leak detector. All the R134, run it, then check for glow.

Power steering fluid... pump is on the wrong side of the engine; even the cooling line doesn't get near the fluid accumulation, and I don't see any sign of fluid spraying or blowing around to the passenger side. I will check level; if it IS power steering fluid, I should be well down.

DRRXR- what diesel line "through the wheel yoke"? Do you mean the balljoint yoke on the front axle end? The only thing I see there is the soft brake line. And I thought the tank lines are all on the driver's side frame.

 

A/C dryer could be a good place to check. It possibly could hold enough oil in the bottom to make a substantial leak.

 

Yep that the lines. For the life of me I cant place where your talking about insulation and passenger side.
the only insulation on mine is the wrap around the AC Air plennum and the insulating board mounted to the hood.

So if its the plennum insualtion you could have a heater core leak and its driping out the AC blower drain. You should be able to find that drain 2.5 ft below the blower in the engine compartment 1inch hole ---- Just another WAG

 

Passenger side front wheel well, the plastic fender liner, on the engine side of the liner, towards the rear, my truck has a piece of rigid foam, moulded to the shape of the plastic fender liner.

It's pretty much underneath the heater core/blower/AC components. So if the leak is oil from the AC components, this foam is where it will land. My guess is that the leak, whatever it is, IS landing on the foam, and eventually oozing out after the foam is pretty well saturated.

AC oil would explain this leak rather nicely. So off to the store for a recharge kit with leak-detection dye.

I'm guessing that the foam is sound insulation. It's not wrapped in metal, like the firewall insulation around the downpipe. It reminds me of a moulded layer of Great Stuff- the urethane spray foam in a can for sealing air leaks in houses. It's also crumbling from all the solvents (diesel, whatever this leak is, engine degreaser...) it's absorbed over the years.

 

Did you find that drain hole for the AC duct? If you eye ball no 7 cyl near the rear fire wall then look over about 7 inches down and 1 ft left of the cyl on the fire wall there is a 1inch hole. The fluid from there can run inside the fire wall insulation and then down to where your speaking of.

I was eyeing mine today and it had worked back to where the insulation was pulled out from it. I was working on the ground wire that is attached to the VC at the back side near cyl 7. I suggest checking it before the trip to the store. These have also been known to plug over time with whatever and you can route some plastic tubing in there to rod it some and some have used a little low pressure shop air too.