OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Honda Engines GXV140: oil leak above cylinder

My post very smilier to a recent post by Kurb that Grumpy helped. (Thank you both for that post, it gave me confidence to proceed!)

I too have Honda HRB215 SXA lawnmower with GXV140 engine, more than 10 years old. The motor starts and runs perfectly. However just this year the engine is releasing oil from somewhere under the flywheel. It is possible that I put too much oil in the mower this past Spring.

My first effort was to replace the oil pan gasket as well as the cylinder head cover gasket, but when I put it all back together again still had the same issue. With the mower all nice and clean, I found that almost a mist of oil was covering the whole top of the deck within a couple minutes of running.

In my second effort, I have managed to get the flywheel off and upon inspection I am not sure what to do next. The top "seal" looks okay, and the breather assembly had oil in it but it did not look like it would leak from there. Any suggestions to help identify the source?

If the crank shaft upper seal is the most likely, should I replace anything else at the same time?



Any guidance is appreciated!

Hi Ricky, welcome to Outdoorking.

Your problem is an unusual one, at least in my experience, but you have described it very clearly and the description seems to suggest a starting point.

When you have the flywheel removed, you will see the Positive Crankcase Ventilation valve compartment - you have already referred to looking inside that housing. Your description of the problem suggests that it may come from that area. There should not be liquid oil in that compartment. Some of the ways it might get there are:
1. Excessive blow-by past the piston rings would carry oil from the crankcase, through the PCV valve, into the compartment. The system is not capable of dealing with much volume of oil, so some of it might then be forced past the cover gasket. If this is happening, the solution would be new piston rings.
2. The tiny (1.8 mm) drain hole from the compartment back into the crankcase might be blocked. You should check for this by pushing the tip of a 1/16" drill bit through the drain hole from above, then retracting it.
3. The mesh packing in the compartment might be clogged with crud, making the drain inaccessible and flooding the compartment.
4. The synthetic rubber breather hose that joins the compartment to the air cleaner housing might be blocked. This would pressurise the compartment and result in oil mist passing the cover gasket.
5. The brown fibre/phenolic disk in the compartment, which is the actual PCV valve disk, might be worn through, resulting in stronger puffs of crankcase gas and oil mist into the compartment, possibly leaking past the top cover gasket.

I suggest you focus on the PCV compartment at this stage, checking for those five possible faults, and report what you find.

I would suggest check you oil level, to insure that it is not over full and is the correct oil. Some oils not suited to air cooled motors froth and expand when engine going.

Thanks for the quick advice. Losing light here, so I went right out to work down your list.

1. Piston rings - I do not know how to check
2. Tiny drain hole - where? Do not see one.
3. Mesh is not dry, but to saturated either
4. Breather hose - the end to the carb comes off easily, other end resisted. can it be pulled off?
5. disc is thicker than I expected, not worn through.

Some pictures:
The breather compartment, a bit wet so I will dry it out. Gasket is old, but was not "blown out".


The disc is hard, black plastic:


The black rubber seal seemed a bit loose, it was not very hard to take out.


Looking down the shaft, I can see what looks like bearings - probably not good?

This shows, from inside the crankcase, the oil drain (red circle) and the breather gallery to which the breather hose is attached (green oval):


This is your picture of the PCV compartment with the drain circled in yellow:


I do not understand how you got that upper crankshaft main seal out without either removing the crankshaft, or destroying the seal. If it was loose, oil mist will blow out past it due to crankcase pressure. I suggest you fit a new seal, ensuring that it is tight in the crankcase.

That upper main bearing (a ballrace) looks normal in the picture. If it rumbles or has radial slack, it needs to be replaced. The oil seal relies on the crankshaft remaining precisely in the center of that bearing: oil seals cannot tolerate much radial misalignment, or eccentricity, of the shaft. A bearing with slack could cause your present problem. However if the bearing does not have slack, nothing is gained by replacing it.

Thanks again. I'll get more light in the compartment to find that drain.

I was just cleaning out the oil that I could see on top of the seal and it was clearly loose. I am going to clean out the breather hose, replace PVC compartment gasket and that main seal.

It will be a few days to get the parts, I'll report back.

Thanks Ricky. This should be easy to solve, and the GXV140 is a nice engine that went out of production in 2003. It's better to fix the one you have than to get a different model engine that may not be as nice.

Success! From my observation, the oil that was leaking out onto the engine and deck must have been coming out from around the top of the crankshaft main seal. The seal that was easily removed, once I got to it under the flywheel. Oddly enough, the seal was not damaged - I compared it to another new one.

I put the same seal back in, it fit nicely, and put the whole works back together. After cutting the yard, the deck is free from oil (although some of the old oil on the block and exhaust is slow to burn off.)

The question remains: how did the seal get dislodged to begin with? As I mentioned above, it is very possible that I added too much oil to the motor this Spring after I emptied the old. But the seal was dislodged toward the engine block, not away. I have one photo of the seal where I found it. When I put it back in it is now flush with the metal ring that you can see around it.



I am certainly not an experience mechanic, but it does not make sense to me! If it blows out (or in) in the next week weeks, I will report back.

Thanks again to this board, I enjoyed my lawn mover project and I know much more about small engines than I ever knew before!


RickyT
Woodstock, GA USA

Thanks for that report Ricky. It is more common for crankshaft seals to blow out than in, but both are possible if the seal fits fairly loosely. There are pressure pulsations in the crankcase due to the piston moving up and down in the cylinder, which causes the volume of the crankcase to change very rapidly. The PCV valve opens when the pressure is positive, to allow blow-by (gas leakage past the piston rings) to escape, then closes when the pressure is negative, so that there will be no escape of blow-by overall: most of the time, there is a slight vacuum in the crankcase. So, a stuck PCV valve will result in a high positive pressure in the crankcase, and this will blow out either a seal or a gasket. A properly-functioning PCV valve will maintain a slight crankcase vacuum, encouraging a loose-fitting seal to be sucked inward. In Honda engines there is some space between the upper crankshaft bearing (a ballrace) and the top oil seal, because that space is used to separate oil from gas, before the gas passes into the PCV chamber on top of the engine. The oil seal should be a tight fit in the crankcase, so it has to be driven into position, not pushed in under finger-power. For you to have been able to remove the seal (from the outside, without drilling through it to allow you to use a hook), after it had dropped down into the cavity below its normal position, sounds very much as if it fits very loosely and should be replaced.

The fact that the seal moved down, not up, indicates that your engine has a low rate of blow-by resulting in negative crankcase pressure, as it should be.