What's this little ring?

vendredi 28 août 2015

I have a 2000 Jeep Grand Cherokee, Vin S.

I had 40 psi of oil, all the time, every time. Hot, cold, idle, WOT, Spring, Summer, Fall, Winter.
I got a weird knocking. Turns out the skirt on #6 cracked at 196k miles.

I tore the engine down. Did a rebuild. Block was punched .020 over, crank was polished, did a Comp cam and used the 96-99 timing gear set. I used a Melling high volume pump, gapped the rings, plastigaged all the bearing clearances.

Oil pressure was great for a week and then it started to fluctuate. As long as it was in spec (13psi at idle) I was happy. Then it started dropping to zero and "Check Gauges" would come on. I've read a ton about this. I did an electronic sender, I added a mechanical gauge, I covered all the bases. As a weird stroke of maybe luck I brought it to a friend of mine for an oil change. He stripped out the drain nut in the oil pan. I dropped the pan, removed the plug, welded the nut in. I did a brand new OEM from Chrysler oil pump. Same results. Once in a while, at a hot idle, the pressure dropped to zero. It did not happen every single time.

I was displeased.
Tore it apart. I had the crank rods and mains cut .010. Clevite 77 bearings all around, re-ringed the engine. Plastigaged it again and both rods and mains were at .001". New OEM oil pump. This will be my 4th oil pump. Pretty sure it's not the pump failing.

I was cleaning the oil pan just now, and a little ring with RTV on it fell out. I took my razor and removed the RTV. It's not a gasket stop from the oil pan gasket. (gasket stops are what I call the little rings that stop you from over compressing a gasket)
It almost looks like it could be an oil restrictor ring. I've experienced these on other engines but this is the first time I've seen it on this engine, and I already rebuild this engine once before... Although my exclusion of this ring the first time could be the cause?

So now I'm going through exploded diagrams of the engine. I don't see it anywhere. There is a distinct possibility it's not a Jeep part... but then why is there RTV on it, in a place I'm removing RTV from?
I had an extra block and head here. I inspected both but I don't see where any oil restriction ring would go between the deck of the block and the head. A Google search has yielded that there is an oil restrictor but it's for the crankcase ventilation system on a 2.5/2.5L
See the link here:
http://ift.tt/1KrXb3f

The next Google search revealed an eBay advert that says it installs new oil restrictors...
See that link here:
http://ift.tt/1KrXb3i

It's .101" thick, .4095" OD, .2815" ID. It has nice chamfers on both sides. It is made from steel (magnetic).

Just figured I'd check in with people more knowledgeable than me before I put the oil pan on.

Here is a picture of the part in question:


Thank you, anyone who bothers to read this. I plan on dropping the engine in the bay tomorrow so please, make my Saturday!


What's this little ring?

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