OutdoorKing Repair Forum Forums Restoring, Customising and Modifying Tech Talk how do I fix my mower

The parts are available and not expensive.

1. Click HERE for the cylinder head gasket.

2. Click HERE for the crankcase gasket.

Note that all parts for the Rover Engines are available through the online store but at present we are working on the parts list and not all the items are listed at this stage.

One other thing is that a lot of Honda engines are also coming out of China so the difference in parts are minimal regarding quality.

Thanks Bruce.

charmaine, since Bruce is satisfied with the quality of the Rover bits, I suggest you get them from him. He has been running a professional mower repair shop for years. That way you know the parts will fit, and you can just get them before you begin the job.

One possibility I haven't mentioned, is that the main problem is not with the gaskets, it is with the quality control on the assembly line: someone may have forgotten to tighten the cylinder head bolts and the crankcase cover attaching bolts. There seemed to be quite a bit of that going on in some Chinese factories a few years ago. Joe Carroll has posted about some Chinese engines of that period not even having the connecting rod bolts tightened, and that tends to end very badly.

It is possible that you can fix your mower just by checking the cylinder head bolts and the crankcase cover bolts with a torque wrench. If you find them to be tightened well below the specified torque, just set them to the correct torque and see if the leaks go away.

Grumpy,

You are correct about the production line not torquing up the bolts. This has happened with the Atom engine as well. I only had one in last week where one side of the cylinder bolts were not torqued down properly which caused us major problems with the tuning (note that they now pressure test the cylinders).

The Chinese are still learning with lots of stuff and will eventually get it right providing the Companies guide them correctly.

Although charmaine may not return to this thread, due to switching her attention to a Briggs engine with smaller and simpler problems, I want to update it to cover a possibility I've overlooked up to now.

For two major gaskets to start leaking oil, simultaneously and in very high volume, is not really consistent with poor assembly of two different gasketed joints at the factory. It is much more likely that the underlying problem is a stuck Positive Crankcase Ventilation valve, which is causing a high gas pressure to develop in the whole crankcase. The two gasket leaks would then be the symptoms of the problem, not the cause of it.

Let's look at how the Honda and chonda crankcase ventilation works. If you remove the engine's top cover/cowl and the flywheel, you see the PCV valve's cover:

Removing this cover, we see the internal layout:

Note the round brown fibre disk, which is the actual valve. Underneath is is the exit port from the crankcase (circled in red in this next picture), which is located directly above the top main bearing ballrace:

Crankcase gas passes through the ballrace, then exits to the PCV valve chamber through this port. The idea is to minimise the amount of oil that goes into the PCV system. When the piston moves downward in the cylinder, it compresses the gas in the crankcase, and the gas flows through this port, lifts the brown disk valve, and then can't return to the crankcase because the disk valve closes until the next time the piston moves downward. Hence each time the piston moves upward, it creates a slight suction in the crankcase.

After passing through the disk valve into the PCV chamber, the gas passes through a fibrous filter (circled in red) to remove more of the oil droplets and mist:

The floor of the PCV chamber, under the filter, slopes along the length of the filter. At the low end is a tiny (1.8 mm diameter) drain hole to return liquid oil to the crankcase (circled in red), while at the uphill end of the filter is a large gas port (circled in green) which takes the de-oiled crankcase gas to the breather tube:

On the outside of the engine, a rubber hose connects the breather tube to the air cleaner:


So, if the disk valve is stuck, or the PCV cavity is blocked somehow, blowby past the piston rings will result in a high gas pressure in the crankcase. This pressure would build up until it was high enough to blow oil past the gaskets, to the outside of the engine.

Edit: Note that chonda engines may use different disk valve materials and designs. Here is one example of a chonda valve disk:



This seems the most likely cause of charmaine's severe oil leaks. Unfortunately, to check the status of the PCV valve requires removing the flywheel, which in turn requires brief use of a 6" gear puller. (Note that most Hondas and chondas have cast iron flywheels. Do not use a gear puller on an aluminium flywheel.)