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Discussion Starter #1
Ok, here is what happened, FIRST this is a 2002 7.3 PS with a little under 250k miles. We were pulling a horse trailer and on the way home noticed a huge puddle under the engine. It was engine oil and was dripping from the plate between the tranny and the engine. Assume a main seal ... so we put 2 gallons in it and the leak started up. We were 50 miles from home so decided to get the horse home and safe. Had to put 2 more gallons at 30 miles but it made it home.

So today I decided to track down the leak, first think I noticed was engine oil sprayed the the back part of the motor and the "valley" was full. So cleaned everything up and put another gallon and a half in and fired it up. NO LEAK.

So ran it 50+ miles on the freeway, and NO LEAK.

My next test is to hook up and run the thing, but does this sound like anything.

The HPOP lines look clean, there is no dripping off the back ... I DON'T KNOW!!!
 

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Here's the normal leak spots.

HPOP line fittings
Plug on back of HPOP
turbo pedestal o-rings
HP oil rail plugs (back and front of each head)
Rear main seal (very rare)

There's a drain hole in the back of the valley that makes lots of people with leaks in the valley think rear main seal.

Since your leak has stopped at this point, you'll just have to keep it clean and keep checking.
 

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Like klhansen said check HPOP lines because the rear main seal very seldom goes out on the 7.3
 

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I would guess hpop reservoir gasket.

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Discussion Starter #5
I am just wondering why I would lost 5.5 gallons of oil in less than 75 miles, yet 2 days layer I fire it up and drive 60 miles and absolutely no oil is lost. Doesn't make sense.

The only flaw that was fixed was a fitting on the fuel filter right near the top was loose and dripping diesel. I did tighten that up ... was that the leak and I was confused? The fitting should be the high pressure relief for the fuel system.
 

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Discussion Starter #6
MORE INFO

OK, this morning hooked up the trailer and ran it around the drive and backed it up a small hill. OIL IS GUSHING OUT.

Does not appear to be from the High Pressure Oil system ... the two lines in the HPOP look clean, where they go into the "fuel rail" look clean, all 4 plugs on the rails are dry ... cannot see it moving oil, but the "well" between the heads/cylinders is full of oil.

Looking closely at the rear of this valley it looks as though there may be a seeping between the valley and a cast piece that looks to be a pedistal for the turbo. Again a crap load.

Will also check the vents ... assume they are on the valve covers.
 

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The oil usually won't move forward from the turbo to under the hpop. The drain is at the back of the engine.
I'm still betting hpop reservoir.

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I am just wondering why I would lost 5.5 gallons of oil in less than 75 miles, yet 2 days layer I fire it up and drive 60 miles and absolutely no oil is lost. Doesn't make sense..
OK, this morning hooked up the trailer and ran it around the drive and backed it up a small hill. OIL IS GUSHING OUT.

Does not appear to be from the High Pressure Oil system ....



It makes sense to me. When you lost the 5.5 gallons of oil in less than 75 miles, you were pulling a trailer. The engine was under load. When you later test drove it on the freeway, you weren't pulling a trailer. The freeway was likely more or less flat. Your engine was not under a real load. Later still, when you hooked the trailer back up, and then backed the trailer up hill, the engine was under load again.

The power that the engine needs to motivate a real load (truck and trailer) from a stand still up a hill, is enabled by fuel. In the 7.3L, more fuel per millisecond of the injector being open is delivered by increasing the oil pressure to the injectors. The higher the oil pressure, the higher the fuel pressure, the higher the fuel pressure, the more fuel is expressed into the cylinder, the more fuel, the more fire, the more fire, the more power.

From the Monday morning quarterbacking recliner where I sit, the correlation between your leaking operation and non leaking operation is straightforward.

However, the more you leak, the more you will leak, and eventually load will cease to matter, as the oil that has already passed through your leak at high pressure will have done enough damage to the seal in it's passing to now pass at lower and lower pressure. This is very common with an HPOP leak. It is the same failure modality I experienced with mine. No leak under no or light load, lots of leak under high load, eventual leak under any load, ultimately leak even at idle. And this cascade all happened within a very short period of time from discovery (less than 24 hours in my case).

You can poke and prod and hem and haw and guess all day as to where your leak is coming from. You can unbolt every part on the engine and replace every seal if you want to. But if you'd rather know exactly where your leak is coming from, without throwing parts, time, frustration, and more forum posts at the problem, then you need three ounces of diesel oil compatible Dye-Lite Tracer Dye, part number TP-3100, from Tracer Products. This product was specifically approved by Ford and International for the 7.3L crankcase, and is chemically compatible with all the seals and gaskets and sealants contained in that motor as built. Use of the dye is how Ford directs service technicians to diagnose oil leaks in Ford's Workshop manual.

A professional leak detection light is called for to locate the leak once the dye is poured into the crankcase. That light used to cost over $300 twelve years ago. There are probably copies from China that are a lot cheaper now, but you don't need the professional light if you do the leak test at NIGHT. The lack of ambient light at nighttime greatly assists the human eye in detecting fluorescence. And if you use a black light (black light bulbs in both compact fluorescent, tubular fluorescent, and incandescent in Edison screw base form factors are available at most hardware and home improvement stores), then you will have no trouble at all seeing the clear lime green effervescing stream of dye pouring from the leak source.

At that point, you will know with certainty where you leak is coming from.

I don't know what kind of oil you use, but I use full synthetic 5W-40. It costs $20.00 a gallon. So for me to lose 5.5 gallons on the roadway would mean a loss of $110.00... nevermind the guilt I'd feel about needlessly drowning the ground in oil. The cost of the tracer dye is negligible by comparison. And the time saved in diagnosis is worth even more. Highly recommended you start with the dye. If I had to place a bet, I'd say a plug seal on your HPOP gave out, so once your dye is in the crankcase and night has fallen, aim your blacklight at the HPOP first.
 

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Discussion Starter #9
Looks like we found it!!
The FRONT HPOP fitting ... it looked fine within a few seconds of running it. But crawled into the engine compartment and took a little ride and tried to find the leak. The turbo was clean so looked at the HPOP and sure enough there was a black flow coming from the front fitting.

Thanks for the sounding board!! Will report if it works.
 

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Discussion Starter #10
I have 2 part numbers ...
F81Z-9C402-AA
F81Z9N332AA
Both look the same, but one is $55 and the other is $27 respectively. I assume the more expensive ones go on the pump and the others go on the rail.
 

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All you need is the oring. Doubt the fitting is bad.
Careful tightening.

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I have 2 part numbers ...
F81Z-9C402-AA
F81Z9N332AA
Both look the same, but one is $55 and the other is $27 respectively. I assume the more expensive ones go on the pump and the others go on the rail.


I can't tell if this is a question that desires an answer, or an assumption you are bouncing off this sounding board. And, of the two part numbers listed, you don't identify which one is more expensive. And, in your previous post, you said "front HPOP fitting". But that doesn't say whether or not you found the leak on the plug, or the left head line, or the right head line. Knowing if the leak is coming from the plug fitting or a line fitting would make a material difference in cost of parts and complexity of repair.

For example, if the leak is in the HPOP plug, then you could fix it with one O ring. You could purchase an O ring kit from Ford that would have 3 O rings included, plus the Loctite 680 that Ford recommends applying to the threads once removed. The part number to that O Ring kit is 2C34-9G804-AB. The cheapest genuine Ford price I've noted is $24, but plenty of aftermarket sources can provide similar O rings for as little as $6. Substance of aftermarket sources could be suspect, depending on the vendor.

On the other hand, if the leak is coming from the fitting on the HPOP where the hose is actually attached, then it would be to your advantage to replace the fitting itself, in addition to the O ring that is leaking. The fitting itself has internal seals, and at 250K miles, it is not unreasonable to replace them. The pump mounted fitting is the first part number you listed, F81Z-9C402-AA . The second number you listed mounts to the head.

I'm not certain, but I don't think the O rings provided in the 2C34-9G804-AB kit are included with the F81Z-9C402-AA fitting, so if it were me, I'd order both, if an only if the hose line fittings on the HPOP were the source of the leak. If it is just the plug fitting, then I would only get the 2C34-9G804-AB O ring kit that includes the vile of pricy and hard to find Loctite 680. But if a hose fitting on the HPOP, I'd get both kits... especially because the O rings in the O ring kit are of an updated design than original equipment. Presumably, they will last longer. But I don't know that.

 

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Discussion Starter #14
found a seal kit for 6 bucks that has 5 seals, the ford oring kit and fittings appear to have duplicate orings ... $90 bucks vs 6 dollars is a bunch. If i can replace all the orings would that be enough? or do the fittings actually crack often?
 

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He has oil in the valley. No way in hell the rear main can do that. Unless he's driving upside down.

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Yes, I had this same problem leaking massive amounts of oil. I ordered the o-rings online, made the installation, and that solved my problem. Do this search 7.3 oil rail o-rings and you will find the companies that sell them online.
 

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found a seal kit for 6 bucks that has 5 seals, the ford oring kit and fittings appear to have duplicate orings ... $90 bucks vs 6 dollars is a bunch. If i can replace all the orings would that be enough? or do the fittings actually crack often?

Being stranded on the highway with a trailer full of horses is "a bunch" more.

The fittings could come with external o rings, and the external o rings could be the exact same size as the o rings in the Ford updated o ring kit that I recommended and posted the part number to above. But that doesn't mean that the orings in the fitting kit and the o ring kit are "duplicate". The orings in Ford's 2C34-9G804-AB kit might be a lot better material than the same size o rings on the fitting kit. It really depends on if the fitting kit that you obtain has the updated o rings or not. So the safest bet is to get both, in the absence of being able to determine what might be shipped to you. If you buy genuine Ford parts over the counter at a local dealer, then you might be able to see the difference, and reject or accept parts, depending on what is presented to you.

Generally speaking, the updated O rings are magenta colored. Color isn't the exclusive determining factor if buying in the aftermarket, but coming from Ford, the original O rings for this application were black. So if the fittings from Ford have black o rings, then I would buy the duplicate O ring kit from Ford, in order to get the updated material O ring (magenta in color)... because I don't like failures. And clearly, the original o rings material was very prone to failure. Why sign up for more of that headache down the road?

On the other hand, if the fittings from Ford already have magenta o rings fitted, then I wouldn't buy the O ring kit. That indeed would be duplicate.

Most people just change the external o rings to fix the leak, as that is what fails. The internal line seal inside the fitting isn't known to leak. But, since your truck has 250,000 miles on it, and since you're going in anyway, it is not an unreasonable practice of preventative maintenance to go ahead and replace the fitting, as then the internal seal will be renewed simultaneously with the external seal being replaced and updated.

You can also throw in those 99 cent each o rings that you reported finding, which will probably fit just fine and get you by for a while. For even more savings, you might be able to trim the inflatable bladder off of a party balloon, and use the rolled edge remainder that you blow through as an o ring. I saw a whole bag of 50 party balloons at the dollar store for 99 cents. Some of the balloons were magenta colored, too.
 

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For even more savings, you might be able to trim the inflatable bladder off of a party balloon, and use the rolled edge remainder that you blow through as an o ring. I saw a whole bag of 50 party balloons at the dollar store for 99 cents. Some of the balloons were magenta colored, too.
:surprise::crying::crying::bang::dunno::yikes::yikes::domotwak:
 

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MX-Stroker... I've actually done that balloon trick, but not in a vehicle, and not on anything important. The example given is just a memorable way to emphasize the point that the materials used in o'rings that will endure petroleum, pressures, and heat are not everyday cheap elastomeric materials. What does it cost in downtime on the side of the road? What does it cost to do it again? Pennywise and pound foolish? I'd be very suspicious of low cost orings on eBay.
 

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found a seal kit for 6 bucks that has 5 seals, the ford oring kit and fittings appear to have duplicate orings ... $90 bucks vs 6 dollars is a bunch. If i can replace all the orings would that be enough? or do the fittings actually crack often?
Hey cvs, do you mind posting what o-rings you replace and if you actually removed the HPOP? Just wondering if it's the high pressure line o-rings only. Thanks.
 
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