DRAFT COPY. COMMENTS INVITED. Send to B. O'Sullivan - 47 The Avenue Morwell VIC, 3840.
These Howard Engines use a dry sump lubricating system. Oil from the oil tank is pumped through the hollow timing side main shaft then through several oil ways into the big end roller bearing. The oil, after it leaves the big end, lubricates the other components by splash. A second oil pump removes the surplus oil from the bottom of the crankcase and pumps it via a filter back into the oil tank.
This system has one serious defect. Whatever is placed into the oil tank is forced into the big end bearing. If the oil is contaminated with dirt etc., it will damage the bearing and block up the oil ways to the big end bearing.
Ball and roller bearings only need a small quantity of oil to lubricate them, but the oil flow must be regular and the oil perfectly clean. The HOWARD system does not filter the oil before it is pumped into the big end. In other words, the filter is in the wrong place.
Over the years that I have been playing with HOWARD engines, I have noted that a large number have blown up with broken connecting rods and fractured crank cases. When these engines are dismantled, the big end bearings are found to be seized solid and frequently the rollers will be jammed side ways and worn into a square shape and look as if they have been heated to a brown colour. Lack of lubrication>
A second problem is sometimes found in that, the bolt that clamps the gudgeon pin into the connecting rod, has fractured or is loose. The connecting rod has a vertical slot at the little end that allows the bolt to clamp the pin into the connecting rod. If this bolt becomes loose or fractured, the connecting rod may break.
*********The elbow that feeds the oil into the timing side hollow mainshaft drilling, if the crankshaft is out of alignment for any reason, the elbow will break just inside the timing case, the oil will bypass the hollow mainshaft and drop directly into the bottom of the crankcase. In this situation, the Rotary Hoe operator will see oil returning into the oil tank but the big end bearing will not receive oil.
*************I suggest that the following test be carried out on each engine before operating.
1. Remove the cam box cover and the oil supply elbow that fits into the cam box cover. Check that the elbow in NOT broken. 2. Undo the four bolts that hold the barrel onto the crankcase and lift the barrel up, about 50mm. Turn the engine over till the big end can be seen at the top of the stroke. 3. Using a pressure oil can, force oil into the hollow timing side mainshaft. (You may need to make up a fitting to connect the oil can to the hollow mainshaft.) As you force the oil into the hollow mainshaft, observe if oil can be seen emerging around the big end. If oil can be seen and it is easy to force oil into the mainshaft, the oil ways are open and everything is fine. 4. If oil cannot be injected into the hollow mainshaft, or it needs considerable force to inject oil, the flywheel assembly must be dismantled and the oil ways cleaned out.
Another defect than can sometimes be found on these machines is that the oil pipes fracture because of vibration. I suggest, at least once a year, the oil pipes be annealed to prevent fracture.
If a big end bearing is found to be worn, it is advisable to replace it as the worn rollers can turn sideways and lock up the bearing, also smash the connecting rod and crankcase.
Over the years, I have dismantled about twenty Howard Junior engines. All of them had the oil channel to the big end obstructed to some extent. The oil tank should be cleaned out to make certain that no grit, rust etc. is present. If it is, sooner or later, it will be pumped into the big end with disastrous results.
Two years ago, I bought the bottom half of a Junior engine at a Swap meeting, because the big end bearing felt good. When I got home, I tried to force oil through the timing side mainshaft. No oil could be forced into the mainshaft. I dismantled the crankshaft and found that the oil channel to the crankpin was completely blocked up with metal particles. The big end bearing was perfect - still filled with packing grease. The bearing was installed back to front, which meant that the big end bearing would never receive any oil. I am certain that this engine had never been started after the bearing was installed.
Actually, there are four ways that the bearing can be installed - only one of these is correct. The other three will block the oil supply to the big end.