miglia-spyder

This started about 3 months ago...When i go to start my jeep in the morning or when its cold, it will knock. I thought that it might have been the torque convertor bolts coming loose, but today i turned my radio down and found that the noise became faster under load while the revs went up. I beleive the loose torque convertor bolt noise would go away under load or when in drive... Mine noise does not. I am still going to check the torque convertor bolts today though!


However it does go away when the engine gets warm. So im leaning more towards a rod bearing. It does


I run 10w30 and my oil pressure at a warm idle is about 21 and 55 when under load. The motor is a 4.0 and has 135K on it.


What do you guys think?

Donnie_K

do you have a mechanics stethescope? a burnt up rod bearing will egg out the rod pretty quick and blow a motor... better find out where that knock is coming from. That seems like alot of oil pressure too, how much are you putting in that thing?

miglia-spyder

I put six quarts in it. But from what ive seen and heard, that oil pressure is pretty close to normal.

Abovetimberline

I have found only a few things will cause a knock like this, (1) bad main bearings,bad rod bearings,or thrust bearing is going out. However it could be a crack in the flex plate,i doubt it would be a loose converter bolt. If it was a crack in the flex plate or a loose converter bolt I doubt it would go away when warm. I just replaced the the mains and rod bearings on mine,the thrust had went out due to lack of oil,the previous owner ran it out of oil.
The clearances on your bearings maybe getting worn and after it warms up the oil is enough to take up the space. If it is a bearing it will not last long.
I assume you know the difference between a rod knock and lifter noise?
The oil pressure on my jeep is just the same as yours. I put 20-50 in it