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Discussion Starter #1
You guys were so helpful in my last thread I'm going try this one here. It's a bit of a riddle.

Backing up a 8000lb RV up a steep gravel driveway in my V10 Excursion. While under load the truck catches fire. Get under it with an extinguisher and oil is pouring from the back of the motor, seemingly from the rear main seal onto the hot exhaust.

Put the fire out. Pull the truck out onto the road and several quarts of oil pour into the street. Zero oil on the dipstick. Tow it to mechanic thinking it's a rear main seal. Mechanic fills it with 5 quarts. No leaks anywhere. Let's it run for an hour. No leaks. Drives the truck for 30+ miles. Zero leaks.

Dyes the oil and checks it with a black light. No leaking anywhere. Truck still has all five quarts.

Where did all the oil come from?

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Discussion Starter #2
PS I don't know the answer and the mechanic who knows his stuff doesn't either. lol

The only thing he can thing is the truck was under so much load that the rear main seal flexed and leaked oil into the bell housing and then re seated itself.

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Well a V10 holds more than 5 quarts , mine holds 7 in my 99 super duty super cab short box 4x4 .
You should have your mechanic , simulate the exact circumstances, that caused the fire.
Only way to verify that theory, that i personally don't think holds water .
I have towed 20k pounds , backed it up , etc , never had such an event .
 

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None of this makes sense. If oil was pouring out and you ended up putting 5 quarts (that's 1.25 gallons BTW) in to get back to normal oil level you would have had an 1/8" deep (and that would be a thick depth) oil slick that was about 54.25" in diameter. It would be an enormous mess. And if it caught fire it'd be a fairly big fire.

And how does oil from the rear main seal pour onto the hot exhaust? Is this magic gravity defying oil? The main seal is not above the exhaust and is well to the side away from the exhaust. By the time the exhaust system is on the same plane as the exhaust the exhaust tubing is back past the leading edge of bell of the transmission. For oil to get on the exhaust it would have to spray onto it or be slung onto it some how or come from above. Like from the cam cover area. It couldn't pour down on it or even get slung onto it because the transmission is a closed system against the back of the engine. The flexplate would not be able to sling oil.

And if the rear main did leak, the oil would run down the back of the pan and then under toward the front of the truck if it was backed up an inclined driveway.

No oil on the dipstick would indicate you were down at least about 2 quarts. If you were 5 quarts low out of 7 you aren't following maintenance guidelines at all.

Not making any accusations. Just saying this makes no logical sense as the story was told.
 

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Discussion Starter #5
None of this makes sense. If oil was pouring out and you ended up putting 5 quarts (that's 1.25 gallons BTW) in to get back to normal oil level you would have had an 1/8" deep (and that would be a thick depth) oil slick that was about 54.25" in diameter. It would be an enormous mess. And if it caught fire it'd be a fairly big fire.

And how does oil from the rear main seal pour onto the hot exhaust? Is this magic gravity defying oil? The main seal is not above the exhaust and is well to the side away from the exhaust. By the time the exhaust system is on the same plane as the exhaust the exhaust tubing is back past the leading edge of bell of the transmission. For oil to get on the exhaust it would have to spray onto it or be slung onto it some how or come from above. Like from the cam cover area. It couldn't pour down on it or even get slung onto it because the transmission is a closed system against the back of the engine. The flexplate would not be able to sling oil.

And if the rear main did leak, the oil would run down the back of the pan and then under toward the front of the truck if it was backed up an inclined driveway.

No oil on the dipstick would indicate you were down at least about 2 quarts. If you were 5 quarts low out of 7 you aren't following maintenance guidelines at all.

Not making any accusations. Just saying this makes no logical sense as the story was told.
The only thing I miss spoke about was being down 5 quarts. If no oil in the dipstick means 3 quarts down then fine. The vehicle is maintained appropriately and checked a few days before the incident.

Otherwise the situation is exactly as I described it. my brother in-law who has been a heavy equipment and vehicle mechanic for 25 years was there for it, and can't understand how it happened either. I know it seems impossible that's why I'm posting here, because there are alot of guys with alot of experience.

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Discussion Starter #6
My current theory is....the extreme weight and angle the vehicle was at going up hill, with 200k miles on the clock...being under so much load the input shaft flexed enough to push down in the rear main seal. Truck is facing down hill so oil is filling the bell housing which has weep holes from what I understand. let off the gas and remove the load and the rear main seal re seated. Pulled off the hill with the truck and the oils poured out of the bell housing through the unsealed flex plate literally right onto the exaughst right before the cat.

If there is any way to debunk this please let me know. Again this is a theory trying to explain the impossible, not factual

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You zaid you were backing up , up hill .
Oil would be at the front of the engine .....
 

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I decided I had to see if I could find what the exhaust under these trucks looked like. WOW! Got a weird crossover that's right under the bell of the transmission. I did not think they were like that. Where it came from I'm not sure, but the way it got on the crossover is totally within the realm of possibility. And likely probable.

Dumb question (sometimes they need to be asked) but you're sure the fluid was not transmission fluid right? if engine oi lis not leaking anywhere, maybe it wasn't engine oil to begin with.

EDIT: Just noticed the proximity of the oil filter to the cross over. Could it have sprayed oil on the pipe? From the filter or filter mount perhaps?
 

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Discussion Starter #9
I decided I had to see if I could find what the exhaust under these trucks looked like. WOW! Got a weird crossover that's right under the bell of the transmission. I did not think they were like that. Where it came from I'm not sure, but the way it got on the crossover is totally within the realm of possibility. And likely probable.

Dumb question (sometimes they need to be asked) but you're sure the fluid was not transmission fluid right? if engine oi lis not leaking anywhere, maybe it wasn't engine oil to begin with.

EDIT: Just noticed the proximity of the oil filter to the cross over. Could it have sprayed oil on the pipe? From the filter or filter mount perhaps?
Yes definitely not ATF, several quarts of oil poured out in the street. ATF is full and clean. Dip stick was dry.

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Discussion Starter #10
You zaid you were backing up , up hill .
Oil would be at the front of the engine .....
Yes but the engine being under load trying to back up a steep gravel drive way pushing 15k lbs, the oil is going to be under pressure no?

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Yes but the engine being under load trying to back up a steep gravel drive way pushing 15k lbs, the oil is going to be under pressure no?

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The pressue is regulated to the level determined by the oil pump. I'd guess around 50 psi but just totally guessing. Pushing 5,000 or 50,000 lbs won't matter to the pressure in the oil system. Nor will any angle a vehicle might normally see effect anything.
 
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