Dt466 oil leak mystery

[jhead64]

I have a friend with a 2004 Intl 4400 DT466 no egr. For the last several months he has been losing oil. At first he had no idea where or how but in the last month he is now finding oil on the bottom rear of the motor. He has been in the shop multiple times trying to get it fixed but still has the problem.

He had his air compressor replaced, the dipstick tube replaced, still losing oil. The truck runs great, doesn't smoke, has about 250, 000 miles on a new block. Fuel mileage is good, all is well except for the oil problem. The odd thing is that when the mechanic tries to locate the source of the leak, he can't find it. He will power wash the motor and let it idle for four hours. No oil leak. He took it on a 50 mile test drive, no oil leak.

My friend says that he fills it to the full mark. He will check it after 200 miles and sometimes there is no change, but usually after 400 or 500 miles it will be down to the add mark.

He says it never drops below the add mark. He thinks its the rear main seal but the mechanic thinks its an engine problem. Anybody have any ideas?

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[tknight]

Rear main oil seal I had that problem on my old international with the st 466 tranny needs to come out seal is under 50$ the laboratory gonna get ya though

 

[Deville]

I agree it could be the main seal. I assume the oil cooler was checked out. But yea rear main seal sounds like it's the issue. The oil will pool up than leak down.

 

[spongebox1]

There's a post on Google with the same symptoms and same mysterious oil loss, the guy replaced the rear main seal and 100k later zero issues.

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[jhead64]

Thanks for the feedback. He's going to have the mechanic replace the seal. Guess we will know after that if it fixes it.

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[BobWolf]

OK here is my tech lecture.

DT466 Most common Oil Leak suspects if your not losing engine lube.
Stop paying for the dealerships parts installer's guessing and look around.

Engine rear.

1) Engine breather tube. The engine vents to the atmosphere and vapor can accumulate on the transmission housing. You might have an after market recovery tank that simply needs emptying or is leaking.

2) Rear main seal or transmission pump/input shaft seal. Pull the inspection plug and check both the front and rear surfaces of the flywheel. Front is usually engine lube, rear is usually transmission lube/fluid. The smell will tell you witch one it is. If you find oil clean the inside and test again as oil will creep its way into the bellhousing.

Engine left side

3) Fuel filter, supply, and or return line. There is an O ring that eventually hammers a flat spot on the quick connecter. Supply is usually on the fuel filter housing Engine left side return is attached to the fuel regulator back of the fuel rail rear left. You will need to remove the doghouse to reach this. The return line will leak down the rear of the motor Unless the connector is damaged you only need to replace the O ring it's a fifty cent part. Using a zip tie to keep the connector tight also helps make sure you use Neoprene or Teflon o rings as they need to be compatible with diesel.

4) High pressure oil line a Braided lint that runs from the High pressure oil pump to the fuel rail. If it seeping replace it because when it goes it will drain all of the engine lube in a matter of seconds. Also check the fuel rail gasket common to leak near the rear..

5) Compressor oil line There is a hidden oil line behind the compressor it's a usually braided line. The compressor governor will also purge oil when it kicks off this is normal as long as you aren't seeing visible spray.

Engine right side

6) Turbo oil and return lines. Supply and return oil for the turbo. Some are solid some are a combo of solid and braided. You will drain all of the oil and destroy the turbo.

7) Breather tube O ring check the breather tube as described above and the O ring where it attaches to the valve cover. Remove the bolt pull out the tube remove and inspect the o ring.

8) Oil filter It is common for the filter to rattle loose over time due to vibration or if its not tight enough when installed. On occasion the filter seal be cracked, or if too heavy handed the filter housing can crack. Also check the oil cooler right behind the water pump.

9) Oil pan gasket. Try CAREFULLY retorquing them from the center out.

10) Transmission cooler lines. Allison transmissions have oil coolers on the front
the lines could be loose or leaking. Check the lines and fittings for looseness, tightness and seal rings if applicable.

11) Allison spin on oil filters It is common for the filter to rattle loose over time due to vibration or if its not tight enough when installed.

12) Transmission pan bolts. retorque them from the center out.

Engine lube. Are you using a CI 4 or a CJ 4 CJ 4 is a thinner lube esults in more blowby. I switched back to a CI 4 and I boil off less oil. Use a pre 2007 lube.

13) HOUSE KEEPING. Some engines simply need more house keeping than others If you do allot of city driving or allot if idling or even bigger culprit is sitting
A vehicle that dose not get driven will drip more oil. That's why Fire trucks often have drip pans under them. at 250,000 miles you will see some seepage somewhere.

Bob Wolf.

 

[jhead64]

Mechanic says seal on rear main was dry and not the problem. He says he's checked everything on the list and they are all good. Mechanic insists its the orings and will cost $7000 to fix.

Is that possible for the o rings to cause an external oil leak that severe without any loss of power or fuel mileage and no engine smoking?

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[tknight]

14) look for new mechanic!!!

 

[spongebox1]

Valve cover gasket going bad, I've seen a bad gasket leak under load while driving the air rushing through the engine compartment will blow the oil towards the back of the engine and look like a lower end leak.

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[jt1980a]

Pretty sure it's the flux capacitator. Unless you have a spare Delorian laying around for parts I suggest you bypass main transdimensinal diffuser through the secondary plutonium worm hole generation coupling. If you still have loss of oil then it has to be from the gravitation localizing solenoid. Hope this helps?

 

[SHARP327]

With my DT530 it had a rear engine oil leak...wasn't bad...and at the time it was under warranty or at least the rear main seal was, so I put it in the shop to get it repaired....the shop foreman called and said that since the trans was pulled back under warranty he recommended having the input shaft seal replaced for an additional $350..I let them do it and it turns out it was the shaft seal that was the problem...which is some type of o-ring....saved me a bunch cause they wrote it up for the main seal which they replaced.

 

[BobWolf]

Mechanic says seal on rear main was dry and not the problem. He says he's checked everything on the list and they are all good. Mechanic insists its the orings and will cost $7000 to fix.

Is that possible for the o rings to cause an external oil leak that severe without any loss of power or fuel mileage and no engine smoking?

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Will the mechanic at least give you a kiss and cook you breakfast afterwards? What O rings is this guy replacing for $7,000!?
Tell this guy to go play in traffic!
The list I gave you is pretty strait forward. An O ring should cost no more than a few bucks each
Most gaskets on a DT 466E are less than $50,00 a piece.
Oil and water have one thing in common. They can both leak in on location and appear on a different location because they blow around and travel on wires, hoses, and ridges. Loose the idiot working on your truck. PM me and give me some details.

Be safe
Bob Wolf.