Burning Oil?

[psychos2]

While I do think some of the oil burning is PCV related, there is another theory than the several presented here - this is what Jerry Lemond, who used to train Isuzu mechanics, told me:

The 3.5L is a stroked version of the 3.2L. Because of the deeper crankshaft necessary for the 3.5L, the pistons had to have relatively short skirts to avoid impacting the crankshaft, leaving less room for piston rings. As a result the 3.5L pistons only have one oil ring. The oil ring's job is to squeegee oil from the cylinder wall. The oil ring also has drain-back holes for any oil that gets trapped between the oil ring and the compression ring. The oil ring for the 3.5L only had 4 drainback holes, which apparently was inadequate for the job, so some of the trapped oil ends up going the other way, up into the combustion chamber and is burned.

The improved design 3.5L, identifiable by the screw-in PCV valve, has oil rings with additional drainback holes.

[shrug] I dunno which theory or combination thereof is correct, just thought I'd pass this one along. Have a nice day

The pistons have 3 rings like any other piston. And the theory about the drain back holes would be ok if all 3.5L engines had the same oil consumption amount. shawn

[JHarris1385]

Here is my repost on this issue:

Hi John,

Its not actually oil loss that’s a problem its oil pressure loss. Where the oil filter bolts onto the engine you will see that it does not bolt directly to the block. It bolts onto a cast metal item which is attached to the block. This cast piece that sits between the block and the oil filter is one of the main problems of oil pressure loss. Inside it there is very sharp bends which restricts oil flow and therefore oil pressure.

We solve this issue by removing this cast piece and have it replaced with another fitting that allows the oil filter to be remote mounted. This will be available for purchase shortly.

The other issue is only when the engine is pulled down. The oil feed system to the main bearings comes in at the number 1 piston and travels along feeding the others. This means that the number 6 piston is the last one to get any oil fed to it and is why the number 6 bearing is prone to failure. We have a modified oil delivery system available which rectifies this problem and gives even oil flow and pressure to all main bearings.

[BigSwede]

The pistons have 3 rings like any other piston. And the theory about the drain back holes would be ok if all 3.5L engines had the same oil consumption amount. shawn

You may be right about the number of rings, I wasn't sure about that part and was going from memory of a conversation over a year ago. But the change in oil ring drainback holes is the main point and is factual. Whether it is the main cause of oil burning is another question.

I also meant to say there is an oil-burning connection with the EGR system more so than PCV. My old 99 Trooper didn't burn any oil (at least until it got totaled), which I suspected had to do with the Mobil One I used and it's tendency not to gum up the EGR system. But I have no way to prove it.

[iamironman]

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Done!!






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