Chrysler Repair: Aclaim Noise after changing engines, connecting rod bearing, coolant temp

Question
I installed a used engine into a 1990 Aclaim.  The engine has good oil pressure hot and cold (50lb).

4 Door, Automatic.

It started and ran fine for a few hours and then a noise started up and increased.  A knocking sound especially as engine is decreasing speed.  So gently reving the engine and it rattles loud on coming down.

The sound is definitely coming from lower in the engine... or maybe the bell housing.

The sound is getting worse but locating is dificult even with stethescope.

Is there something common I may have done?  I used seize it and tourqued the Ring gear.  tightened all four tourque converter bolts.

sigh

Mick


Answer
Hi Mick,
One possibility crossed my mind: could you have the spark too far retarded? My experience is that when you have the spark too late, you can get firing of the charge when the exhaust valve is opening which makes quite a racket. All Acclaim engines have a spec for the timing at idle with the coolant temp sensor disconnected that is supposed to be 12 BTDC, with the engine up to operating temp. So why not check that out?
Roland





Hi Mick,
I am not that familiar with internal engine malfunction noises so I can't really give you a diagnosis based on your very adequate description. I only know that there is a characteristic sound of a connecting rod bearing, and a very characteristic sound of a main bearing problem but whether what you described fits either of those two is an unknown for me.  I'll bet a machinist at an auto machine shop would be able to tell you though if there is such a shop near you.
I'd be interested to know what it turns out to be, and best of luck.
Roland