Comanche County Posted February 27, 2015 Share Posted February 27, 2015 Guys, recently rebuilt a 2.5. Oil pressure is just a little low. My buddy has put about 500 miles on it since I assembled it...new everything except crank and rods, .030 over pistons. Dropping to 10 psi when warmed and idling. The machine shop polished the main journals and clearance was a little on the high side of the spec .003. I'm gonna drop the pan and roll in some .001 oversized bearings...but I can't find any? I know there out there guess I'm looking in the wrong places. Anyone recommend a source? Thanks Jay Link to comment Share on other sites More sharing options...
Jeep Driver Posted February 27, 2015 Share Posted February 27, 2015 http://www.quadratec.com/products/52449_0671.htm?sgsc=C6Z06ZR1C6Z06ZR1&utm_medium=compshop&utm_source=googlemerchant&gclid=Cj0KEQiApbunBRDs0fba3dz484cBEiQAMsx-p7Ex_imL8baO2u0MTwcZIF-EHZsfHsI9xyDfT-vHxxkaArjN8P8HAQ Link to comment Share on other sites More sharing options...
Eagle Posted February 27, 2015 Share Posted February 27, 2015 You're looking for the wrong thing. The crankshaft was polished, so the crank is UNDERSIZED, not oversized. You need UNDERsized bearings. What's the oil pressure at 1500 RPM? 2000 RPM? Link to comment Share on other sites More sharing options...
Comanche County Posted February 27, 2015 Author Share Posted February 27, 2015 :doh: It jumps to 20 and up with any throttle. Until its warmed up completely its idling at 40, then drops when hot. Link to comment Share on other sites More sharing options...
Jeep Driver Posted February 27, 2015 Share Posted February 27, 2015 At 500 miles it's now broke in. Has he changed the oil yet? with what? I'd go with a straight 40 and a Pure1 filter before you go changing bearings. Link to comment Share on other sites More sharing options...
HOrnbrod Posted February 27, 2015 Share Posted February 27, 2015 Jay, measured the clearance on each main journal with a plastigauge? Unlikely each journal will require the same spec bearing on a crank polishing job. Link to comment Share on other sites More sharing options...
Comanche County Posted February 27, 2015 Author Share Posted February 27, 2015 Yes, checked with plastigage. You're correct Don, there was some variance. The thrust bearing was good, the other mains were just a little big .0025 - .003. Rods were spot on. New head and valve train components, timing chain, cam, cam bearings, lifters, Melling oil pump, pistons, rings. My renix 4.0 has been running low oil pressure like this for years. I wouldn't sweat it, but this isn't my Jeep and it is bugging me. Its a mystery and there can't be mysteries in engine building, things are either in spec or they're not. I triple and quadruple checked everything during assembly, torque specs checked with 3x wrenches. I put it together correctly, the thing fired right up on the first turn of the key, but obviously something isn't right. I'm trying to rundown causes in my head and my first culprit is the bearing clearance. Perhaps its bleeding off oil out of the mains and that could be disastrous later on for the rods if it gets worse. Maybe the new oil pump isn't up to task. I admit I didn't check the pump gerotor clearance. Not sure but I'm gonna find out. Link to comment Share on other sites More sharing options...
Jeep Driver Posted February 27, 2015 Share Posted February 27, 2015 Have you checked with a mechanical gauge? Link to comment Share on other sites More sharing options...
Comanche County Posted February 27, 2015 Author Share Posted February 27, 2015 Bearing journals? Link to comment Share on other sites More sharing options...
Jeep Driver Posted February 27, 2015 Share Posted February 27, 2015 No, oil pressure? Link to comment Share on other sites More sharing options...
Comanche County Posted February 27, 2015 Author Share Posted February 27, 2015 No, good idea though. Link to comment Share on other sites More sharing options...
cruiser54 Posted February 27, 2015 Share Posted February 27, 2015 No, good idea though. What if it was just a crappy oil sender or an inaccurate dash gauge? The bearings are within tolerance. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now