Precisionag
New Member
Greetings all,
I was hoping for some expert opinions from Volvopaul. I am a diesel mechanic in the agriculture industry and last year purchased a 1999 Grady white 274 with a KAD44P-A in it. The ecu shows just shy of 2000 hours. Since purchasing the boat we had issues with crankcase fumes. At first just thought the breather tube had become displaced and was routed back to the air inlet (why is there no place for this to connect to the air box after the filter?). Anyway after a trip that involved a 4.5 hour run and three days of trolling on the main, we picked up to run to anchorage for the night and got an alarm. Low oil pressure. Opened cover - oil everywhere. Discover it was coming from the breather pipe (thankful no hole in the block!). Added oil (5 litres) - routed breather into empty jug in case we needed to add it back to engine to get home. Watched oil level and had to add another litre and monitored the oil from the breather. Had another 4.5 hour run home. Nearing the end of the trip the engine seemed to have a bit of a rattle to it. Pulled the boat to my shop and started investigating the rattle. Did a valve adjustment and several were quite loose. Ran engine - knock still there. (Rattle at cruising speed. Cracked injector lines - thought #4 seemed to make no difference - all others seemed to give misfire out of time with knock. Pulled #4 injector - had tested - perfect. Pulled all injectors (looked freshly replaced) and did a compression test 220-260 across the board. Ok - motor is coming out - ordered liner and piston kit from Swedish lorry parts - tore down engine.
Findings:
-#1 cylinder wrist pin bushing worn and sloppy (this was the knock) - 1/8” of play probably
-2nd compression rings on all but #2 cylinder broken in 2-3-4 pieces.
-#6 big end bearing shows some circular scoring - might need to be ground under size
-all top rings and piston margins ok
- oil rings ok
I have sourced a used good rod to replace #1 since bushing is not readily available and rod small end shows some heat damage. Source has torn down many kads and said he had never seen a broken ring in any.
My question for Paul is what could cause the breakage of the second rings like this? Do I have a problem with oil flow to piston jets? (They are all clear and show no damage).
Through this whole ordeal the engine ran with plenty of power and pushed the boat to 32 mph at 4100 wot (cruise at 25 mph at ~3500 rpm). Swinging a set of b3 duoprops on a DP-E drive. Just purchased a set of c3 stainless to try to get rpm down by 200 (haven’t run them yet).Had no issues getting it up on plane. Other than the blow by and slight rattle everything seemed fine performance wise.
I’m thinking I may need to reprop again once we get the full performance back.
I was hoping for some expert opinions from Volvopaul. I am a diesel mechanic in the agriculture industry and last year purchased a 1999 Grady white 274 with a KAD44P-A in it. The ecu shows just shy of 2000 hours. Since purchasing the boat we had issues with crankcase fumes. At first just thought the breather tube had become displaced and was routed back to the air inlet (why is there no place for this to connect to the air box after the filter?). Anyway after a trip that involved a 4.5 hour run and three days of trolling on the main, we picked up to run to anchorage for the night and got an alarm. Low oil pressure. Opened cover - oil everywhere. Discover it was coming from the breather pipe (thankful no hole in the block!). Added oil (5 litres) - routed breather into empty jug in case we needed to add it back to engine to get home. Watched oil level and had to add another litre and monitored the oil from the breather. Had another 4.5 hour run home. Nearing the end of the trip the engine seemed to have a bit of a rattle to it. Pulled the boat to my shop and started investigating the rattle. Did a valve adjustment and several were quite loose. Ran engine - knock still there. (Rattle at cruising speed. Cracked injector lines - thought #4 seemed to make no difference - all others seemed to give misfire out of time with knock. Pulled #4 injector - had tested - perfect. Pulled all injectors (looked freshly replaced) and did a compression test 220-260 across the board. Ok - motor is coming out - ordered liner and piston kit from Swedish lorry parts - tore down engine.
Findings:
-#1 cylinder wrist pin bushing worn and sloppy (this was the knock) - 1/8” of play probably
-2nd compression rings on all but #2 cylinder broken in 2-3-4 pieces.
-#6 big end bearing shows some circular scoring - might need to be ground under size
-all top rings and piston margins ok
- oil rings ok
I have sourced a used good rod to replace #1 since bushing is not readily available and rod small end shows some heat damage. Source has torn down many kads and said he had never seen a broken ring in any.
My question for Paul is what could cause the breakage of the second rings like this? Do I have a problem with oil flow to piston jets? (They are all clear and show no damage).
Through this whole ordeal the engine ran with plenty of power and pushed the boat to 32 mph at 4100 wot (cruise at 25 mph at ~3500 rpm). Swinging a set of b3 duoprops on a DP-E drive. Just purchased a set of c3 stainless to try to get rpm down by 200 (haven’t run them yet).Had no issues getting it up on plane. Other than the blow by and slight rattle everything seemed fine performance wise.
I’m thinking I may need to reprop again once we get the full performance back.
