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Rich cylinder causing blow by?


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I was at a friends house trying to slow my blow by problem. 1qt every other day which is 200 miles for me. I checked all the lines and steam cleaned my valve cover. No change. I have a 4.0. So when he got back we did a compression check. Looks like the front cylinder is running rich (dark plug) and a little lower on compression 120 psi if I remember. Others were around 135. His first diagnosis was that the cylinder is running rich and causing oil to blow by the rings. Does this make sense? Can I adjust the richness on just one cylinder?

Thanks

Mike

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You can't really "adjust" one cylinder, but you could exchange that injector with a different cylinder to see if it makes a difference. But I think your friend's diagnosis is backwards. The lower compression suggests that the low cylinder may allow more oil to get into the cylinder, and the burning of that oil is likely what's making the plug read dark.

 

That said, I've seen older cars that literally trailed a smoke screen behind them that didn't use a quart in 200 miles. It doesn't take a lot of oil to make a smoke generator. If you're going through a quart in 200 miles, there's something going on besides one cylinder with marginally low compression.

 

How's your rear main seal?

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Thanks for the answer. I might try switching the injectors around this weekend.

 

I replaced the rear main earlier in the summer. The oil seems to be draining out of my air box and running down into my drivers side wheel well. I don't have a lot of smoke other then at then end of my commute. 52 miles each way and its almost exclusively smoking on the drivers side. I assumed that the oil had made its way from the blow by back to the exhaust.

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I've got a gallon jug collection the oil that comes out the top of mine. :roll: This is obviously not acceptable if you have vehicular inspections. Oh, and whatever you do, don't dump that oil back into the engine. The stuff collecting in my jug is about the nastiest oil I've ever seen.

 

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I've got a gallon jug collection the oil that comes out the top of mine. :roll: This is obviously not acceptable if you have vehicular inspections. Oh, and whatever you do, don't dump that oil back into the engine. The stuff collecting in my jug is about the nastiest oil I've ever seen.

 

 

I did something similar with my BMW 2002Tii, using a spare washer bottle (see upper left corner):

 

 

 

87709049-M.jpg

 

Fortunately, it's old enough that it's exempt from Calif. inspections. jamminz.gif

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