Knocking in engine on 931b

[Long John]

Got a 931b that has a small knocking noise in engine when it gets warmed up. Is it possible that rod and main bearings could correct this or do I need to pull engine and have crank turned. Machine shows 4936 hours and previous owner said started doing this after running over a steep pile of dirt. TIA

 

[Nige]

Have you tried hooking up an oil pressure gauge to see what you have and how it changes between a cold and warm engine.?

 

[Dave Neubert]

wrist pin bushing

 

[OzDozer]

Wrist pin bushing is certainly the weak point on the 3204 engines - but it could also be a big end bearing.
Big end bearing knock is generally a little heavier sound than a wrist pin bushing knock.

Remove and cut open the oil filter and spread out the filter media, looking for metal. Big end bearings are tin coated aluminium, wrist pin bushing is copper.

 

[Nige]

Remove and cut open the oil filter and spread out the filter media, looking for metal. Big end bearings are tin coated aluminium, wrist pin bushing is copper.

If you have never cut a filter before click this LINK for a good "how to" video.