Hi, I am working on a Cat 3306 engine in a D6D dozer. The oil pressure was dropping off when the engine ran for ~1hr, however it was in the green region when the engine was cold. I pulled out the sump, oil pump and the first main bearing and connecting rod bearing to check them. Can anyone with experience give me any feedback on what they think about the condition of these? Should I replace them? (pictures below). I also saw the oil pump drive gear (not the pump gear itself) has a tooth with a small chip, also the crankshaft drive gear also has a small chip on one of the teeth - is this critical? Also should I polish the crank journals before putting it back together? I saw 3M has a crankshaft polishing tape and was thinking to try it. Right now the engine is still in the machine. Thanks
Is it copper that I see in the bottom most picture of the main bearing cap. They do not look like genuine Cat Bearings . One of the caps looks like it moved some. Simon C
Remove a couple of connecting rod and main bearing shells from their caps and take a look at what’s stamped on the back. In my opinion the bearings definitely need replacing but first the crankshaft bearing journals should be measured and compared to the specifications in order to determine whether the crankshaft will go again without re-grinding. If you have the Serial Number of the tractor and the engine I can probably find them without too much trouble.
Those grooves in the bearings are an indication some trash has started going through the system. What does the inside of the oil pump look like. I agree with Nige on removing more caps. I would also pull the oil filter out and cut it open.
So, why did you take it apart? Did you actually measure the oil pressure, or trust a 50 year old red/green gauge?
I would probably put new rods and mains while you’re there and definitely polish the crank while you’re at it. Depending on what the customer wants. Its not too bad but you’re not too far from a full rebuild. All depends on what the machine does and what it will be doing.
Depending on how long it is since the engine was last rebuilt, or even if it has ever been rebuilt before, the condition of the crankshaft bearings may prove to be the least of you problems. You mentioned the condition of the oil pump drive gear before, but have you opened up the pump itself for a look inside it.?