Rod Knock on startup

Alright, thanks for all the tips guys really helpful. Here is what I did.

10w40 Castrol high mileage (instead of 10W30 Valvoline)
resealed front cover, oil pump, etc and old one not in the best shape so swapped in a 1991 Wagoneer front cover with the different Chrysler style oil filter adapter from low mile car. Didn't change the gears as they were within spec when I measured as per my TSM
Bosch $7 filter (the smaller 1991 bypass one)

Knock is  G.O.N.E.



Next step is to put an oil gauge and sending unit on and check the actual pressure. Now that the knock is gone, I have begun to question the pressure might be too high as seems to be much online about too much pressure at idle, etc being an issue for these AMC engines and how very carefully the oil pump must be setup.

Run thicker oil and see what is does

How 'bout just pulling the pan and looking at the bearings.  Polish the crank with crocus cloth in place and then put in new bearings the same size.  You will need to flush the journals with a spray cleaner and then slide in the new bearings.  No big deal if the top end looks good.  Why are you doing the heads at 80,000 miles?  If it sat a year or two the heads may have corrosion on the open valves and seats but if not then there should be nothing wrong with them.

SEdmonds wrote: amx39068 wrote: After sitting for a long time in the miserable cold weather, they make all kinds of unpleasants sounds when you first start them up.  I resemble that remark..... Sorry - off topic - but this made me laugh this morning...as I watch it snow and blow outside - here in sunny, tropical Flagstaff.

Fluffy73 wrote: My 360 in my Javelin does this too.  I attribute it to just being a high mileage engine.   Except I would never run anything as thin as 10w30.  I'm usually running 20w-50 in my Javelin, but it's also strictly a summer cruiser.

IMO, running thicker oil is what is causing your knock. It takes longer for thicker oil to fully distribute throughout the engine, hence the knock on start up. Most engine wear occurs on start up because the oil hasn't had time to circulate yet. Using thicker oil can delay oil pressure build up causing the engine to run longer without proper protection. Think about it. If you load a syringe with water, it's easy to push it out. Now load it with peanut butter and try to push it out as fast as you did the water. In the March HMM, Ray Bohacz has an interesting commentary on the common "wisdom" of using heavy weight oils.

As has been previously stated in this thread, if your rods are knocking, it's only a matter of time before the engine fails. If this were a daily driver and you wanted to get one more year out of it before sending it the bone yard, then it makes sense to drive it like this. For a car that is essentially a toy that you drive infrequently and plan to keep, why put off the rebuild? Delaying will only cause more damage making the rebuild more expensive.

You can try changing the filter as suggested since it is a cheap experiment, but snake oil only masks the symptoms, it won't fix your engine.