possible rod bearing issue

[transam89gta]

ok jeep has been parked, but cranked and maintained for around a year and a half.
got it registered again and drove for a week running good still looses a little water because of the freeze plug in the head leaking.
ok never ran hot had new oil and a good filter not fram
cranked it today and have a bottom end tap and low oil pressure.

so im thinking rod bearing and they seem not to bad to replace,
question does this sound right and never doing any motor work, all i should need is a torque wrench and do i get the standard size bearings

the jeep is a 94 4.0 auto

thanks
Aaron

 

[winterbeater]

You need to plastigage and test assemble the new bearings to make sure you get the correct fit. It sounds like this happenned all at once. Usually this doesn't happen with a rod bearing. What was your oil pressure before and what is it now? How fast did it change? Have you tried disconnecting different spark plug wires to see if the sound changes? This would help diagnose a rod knock.

 

[xj88kjetil]

Ouch....

Changing rod bearings is not the worst job. You just have to be very systematic, and extremely careful to put everything back together exactly as it was. Flipping one bearing cap 180 degrees can lead to rapid massive engine failure.... even to the extent of rods coming out through the side of the engine block. (I have seen this happen...)

Be shure to check that the crankshaft is OK. Without grooves and scratches. Mine hade some grooves, but I added a short prayer and installed the new bearings anyway; they lasted about one week and then the knocking came back worse than ever...

 

[transam89gta]

its not a knock its a tap and once i get it driving and oil pressure up it stops
oil pressure is at 10 idling and a little over 20 while driveing at 3000 rpms

 

[joe_peters]

its not a knock its a tap and once i get it driving and oil pressure up it stops
oil pressure is at 10 idling and a little over 20 while driveing at 3000 rpms

You should be getting 10 psi per 1k rpm, rule of thumb. Rent a mechanical oil pressure gauge and verify your readings.

What oil are you using?

 

[winterbeater]

Sound more like lifters if it goes away as the oil pressure goes up. Low oil flow to the lifters and they collapse.