Engine locking down on 2002 Grand Cherokee 4.0

SRQ941

SRQ941

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Oct 8, 2021
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Sarasota Florida
I got a 2002 Grand Cherokee 4.0. When I bought it it just sounded like a lifter tic. After a couple weeks I went to change the oil and what a surprise I got. 13 quarts of oil I drained out. Yep you read it right... 13. At the right amount the tic become a slap. I replaced the timing chain and gears. Still slapping so I dropped the oil pan. Piston skirt everywhere. Now when I put in new pistons and rod bearings (same rods.) I tried to turn the crank after getting 4 pistons torque down at 33 ft/lbs and it is locked up. I back the nuts off a little on the last 2 I dropped in and the crank turns fine. What have I got wrong? I'm just an old shade tree type mechanic with no shop and a bunch of wrenches.
 
If that's the case it should be the one I had the broken skirt on. Any tips on how to tell if it is out of round and would it be at the bearing or wrist pin?
 
SRQ941 said:
If that's the case it should be the one I had the broken skirt on. Any tips on how to tell if it is out of round and would it be at the bearing or wrist pin?
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It would have to be the bearing end since it loosens up when you backed off the nuts a little. A automotive machine shop would have to mike it and if it's out of round they can resize it.
 
SRQ941 said:
Thanks. I guess I'll go pull the Pistons back out
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The only other thing that would cause it to lock up when the rod bolts were torqued down is the bearing is wrong. Maybe try taking the rod bearing out of one of the rods that is ok and put in the one that is locked up.
 
BLACKJKU said:
The only other thing that would cause it to lock up when the rod bolts were torqued down is the bearing is wrong. Maybe try taking the rod bearing out of one of the rods that is ok and put in the one that is locked up.
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I'm headed out now and check into it. I'll let you no in couple hours. Thanks again
 
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Just watched a video and come to find out the notch on the bearing goes away from the cam. So it appears mine are backwards. Mine are on cam side.
 
There are notches in the rod caps and the rod arms for the bearings, that's what keeps them from spinning in the rod when the engines running.
 
Yes. I didn't no it mattered which way the rod went. The video tells me that the notches go opposite side of where the cam is. In other words noches to the driver's side and not the cam side.
 
SRQ941 said:
Yes. I didn't no it mattered which way the rod went. The video tells me that the notches go opposite side of where the cam is. In other words noches to the driver's side and not the cam side.
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Ok now I know what your saying, but yes the rods and pistons both have to be in a certain way. The rings have to be on the pistons so that the ring gaps aren't in the same spot also.
 
I finally got all 6 pistons in and crank turning fine. I removed the Pistons and one of the bearings looked like a a brake rotor with no brake pads. It was a scar on the top of the crank journal that I didn't see. Lock down problem solved. I have one more question. How to spin the motor and get oil to places it needs to be without starting the engine. Also how to bleed gas line
 
You shouldn't need to bleed the fuel, in this video it shows how to bleed your engine. It's about 1/2 way into the video where it's for your engine. Also did you coat everything down good with some kind of assembly lube, that will help protect it from a dry start?

www.melling.com

How to Prime Engines and Oil Pumps by Melling - Melling

Melling tech director George describes the proper method of priming engines and oil pumps. He shows how to use the Melling priming tools for in the pan pumps and our new MPL-101 Pre-Lube Oiler tank tool for engines with over the Crankshaft oil Pumps.
www.melling.com www.melling.com
 
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I got it together and all primed up. It started right up but wide open. I didn't have the breather on and the vacuum lines that connects to was unplugged. I'm hoping that's the reason. I disconnected the battery for the night. Gonna finish connecting things up in the morning.
 
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