XJ XJ8 / XJR ( X308 ) 1997 - 2003

Um, why is there oil inside my air intake manifold???

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Old Mar 31, 2023 | 07:03 PM
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Default Um, why is there oil inside my air intake manifold???



 
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Old Mar 31, 2023 | 07:30 PM
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Because the Gov't does NOT want the crankcase vapors to be vented to the atmosphere and the vapors collect in the intake passages?
 
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Old Apr 1, 2023 | 01:12 AM
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I think that the crancase ventilation back to the engine intake is great. The hot oil smell is bad. Oil separator is also great thing in the ventilation flow.
One japanese/french car manufacturer puts the vent tube to the air filter casing just before the filter. Quess what the filter looks like after 10 thousand miles..
 
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Old Apr 1, 2023 | 01:18 AM
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Originally Posted by Vauxi
I think that the crancase ventilation back to the engine intake is great. The hot oil smell is bad. Oil separator is also great thing in the ventilation flow.
One japanese/french car manufacturer puts the vent tube to the air filter casing just before the filter. Quess what the filter looks like after 10 thousand miles..
I think the smell I have been smelling is indeed burning oil. It smells like what some have stated it smells like, acidic and sort of "plasticy". I have found a lot of oil spilled on the bottom of the oil pan but no leaking on the floor. Also obviously. Oil in the intake manifold. Why does it only smell when I accelerate?
 
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Old Apr 1, 2023 | 08:52 AM
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^

Just a guess but possibly increased air flow moving some of the oil to hotter surfaces?

Which makes me wonder if it’s healthier for these cars to be driven a bit more aggressively a bit further than they’re used to? I know my mechanic used to complain about my Series III not being exercised enough and said I should take my wife for coffee in Red Deer once a week (Red Deer is about 150 km from Edmonton so a nice little 80 minute run) which I never managed to do as often as it should have.
 

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Old Apr 1, 2023 | 10:30 PM
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Originally Posted by Ken Cantor
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Just a guess but possibly increased air flow moving some of the oil to hotter surfaces?

Which makes me wonder if it’s healthier for these cars to be driven a bit more aggressively a bit further than they’re used to? I know my mechanic used to complain about my Series III not being exercised enough and said I should take my wife for coffee in Red Deer once a week (Red Deer is about 150 km from Edmonton so a nice little 80 minute run) which I never managed to do as often as it should have.
Yeah, seems like this car has been sitting for months. If not years. From what the previous owner said, the car was only driven a few miles on the weekend, to get breakfast and such.

I drove the car all day today (about 241 km) It runs fine and unbelievably smooth. No overheating or smoking. Did start to see some weird stuff after 8 hours. First of all, I think the transmission is starting to slip between gears, I stopped at a Stop sign around 6 hours in, and when I pressed the gas (slowly), the car immediately jolted forward, as if it was releasing built up tension, even burning rubber. Then the transmission knocked very loudly and the car went back to normal. I also noticed that the 3rd and 4th gear seem to jolt the car backwards, and it shakes me back. All this makes me assume it's early transmission failure symptoms.

Another thing, the car gets hot. VERY hot. I can see heat shimmer coming out of the edges of the hood and the exhaust. It's very visible. But, the temperature gauge says it's at normal temperature.

I also cleaned the MAF sensor and some of the loss of power and shaking went away, however, the car goes down to 500 RPMs in reverse, and sometimes while idling, the engine starts to vibrate. This only lasts a second at most, although it's very noticeable.


Lastly, the car is making two strange noises now (Boy oh boy the problems keep on piling), the first sounds like the sound of a dead battery, like when you turn the key and it goes "brrrr-pew" when you press the gas. Then, I can also hear a quiet knocking sound after acceleration. It's always two knocks. I step on the gas and then after releasing it goes "knock knock".
 

Last edited by ericnunez; Apr 2, 2023 at 12:40 AM.
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Old Apr 2, 2023 | 01:23 AM
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Originally Posted by ericnunez
I think the smell I have been smelling is indeed burning oil. It smells like what some have stated it smells like, acidic and sort of "plasticy". I have found a lot of oil spilled on the bottom of the oil pan but no leaking on the floor. Also obviously. Oil in the intake manifold. Why does it only smell when I accelerate?
Burning oil smells different than boiling oil. Both smells are bad though. Why it smells more or only when you accelerate? Exhaust manifolds get way more toasty when engine is under load. Maybe because of that that spillage that you have found hits the exhaust pipe via airflow when driving. Or you have engine that breaths heavily. Or there is leak in the pcv system and when engine is under load, it does breath more.
"few" possibilities.

But basically every engine likes longer drives and good mainteance.
 
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Old Apr 2, 2023 | 08:38 AM
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Make sure your 'part-load-breather' is cleared of sludge and carbon.
 
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Old Apr 3, 2023 | 07:37 AM
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What motorcarman said, possibly a blocked breather valve causing it to blow out out the vent pipe.
 
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Old Apr 3, 2023 | 08:39 AM
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The crankcase vapors are 'supposed' to flow from the FULL LOAD breather (at the air cleaner) to the PART LOAD breather and into the throttle elbow.

A clogged part load will not let the vapors 'flow' properly.
 
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