MJ Comanche Tech. Stock & Modified. MJ (86-92)
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Oil issue- Comanche 4 banger.

Old 12-21-2015, 01:02 PM
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Default Oil issue- Comanche 4 banger.

I'm a little confused about what's going on with this little engine in my MJ. I bought it to upgrade from the renix system, so it has a '93 wrangler computer and MPI. After the rebuild I put about 1000 miles on it- good power and gas mileage etc. One morning (after a sub-zero night) I started it up and it was running really rough- gave it some gas and heard a pop and then it died. Turns out the collar that holds the distributor in place had snapped- perhaps as a result of my gorrillahands buddy tightening the retention bolt too much. The distributor was ejected from the block. New dizzy went in, fired it up, and after 10 seconds the Wix oil filter blew off. ~4 quarts of oil all over the garage floor.


New K&N filter went in with a lighter weight 5w30 oil (was 10w30) and it runs but there's a sound of marbles in a coffee can coming from the oil pan. Not marbles shaking around, just rolling. My thought process was that the oil pump had seized or picked up something it couldn't pump, and since the distributor drives that, it had ejected from the drive slot, breaking the collar. Therefore, I rebuilt the pump. Is it possible I have a clogged oil passage? What route does the oil take after it goes through the filter?
Attached Thumbnails Oil issue- Comanche 4 banger.-img_7170.jpg   Oil issue- Comanche 4 banger.-img_7172.jpg  
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Old 12-22-2015, 06:13 AM
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http://www.machinerylubrication.com/...in-your-engine

From the pump, it goes to the outside of the oil filter, and there it is forced through the filter media to the center, where it exits into the oil galleries inside the engine. The oil filter also has a bypass valve to keep the pressure from dropping too low if the filter becomes clogged. The first and most important job of motor oil is to lubricate the rotating components of an engine, and it must be under a good pressure to do its job.

Oil is forced into the space between the bearings making contact with the crankshaft journals and the journals. The bearings are simple metal sleeves encircling the rotating components of the engine. The block has main bearings on the crankshaft, and connecting rods bearings are on the crank throws. This thin space, usually one-thousandth of an inch on newer engines, holds a thin film of oil between the bearings and the moving surfaces on the crankshaft. Under pressure and within the correct operating temperature, the oil protects and prolongs the life of the machined parts. Metal should never touch other metallic surfaces while it is moving.

It is important to note that some of the oil is forced out of the sides of the bearings and drips back into the sump. If the clearance is too much, say 0.004 of an inch or better, pressure starts falling in the upper end of the engine. A flickering oil light or a slight tapping sound in the rocker arm area on the topside of the motor is a good indication that not enough oil under pressure is reaching the top end of the engine.
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Old 12-22-2015, 01:56 PM
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Can the post-filter journals become clogged? I have 40-50psi under engine load, 20-30psi at idle.
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Old 12-22-2015, 06:00 PM
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Your pressure is the same as mine....2.5 also.


Doubt you have a clogged galley.......you'd have spun bearings by now.
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