The owner checked what could be done themselves. It’s seeping quite a bit.
The surrounding seals and gaskets were replaced. Still not stopping? Liquid gasket was applied but it didn’t stop… This runs deep.
The push rod oil seal is also seeping, so we’ll replace that too.
The moment we removed the mounting bolts… oil came pouring out! This is probably it (*´ω｀*)
It became a tunnel, which was the cause
The cause was a bolt installed incorrectly, which punctured the crankcase. What was normally a dead-end became a through-hole, allowing oil to flow out.
Always use an M6 gasket bolt here and seal it.
We left instructions for the future, considering the possibility that someone else might work on it.
This shift cover is a bit tricky to remove and install
We gave it a wet blast treatment. *Bearing areas were masked Suddenly shiny and feels so good!
Honda’s OEM parts are amazing. They come with needle roller bearings from the start. To replicate this, you need to be careful—the material must be able to withstand the bearing rollers, or it will fail.
With older bikes, there can be similar issues, so be careful.
In this state, the cover cannot be removed. You must insert the cover and shift shaft together as a set, so it takes a bit of technique.
Replace the oil seal lip grease with fluorine grease
The OEM is thoughtful and comes with grease sealed inside. We remove this and replace it with fluorine grease.
The excellent lubricity and oil resistance of fluorine grease eliminate any seeping from around the oil seal lip.
We remove it like this and clean it thoroughly with cotton swabs before replacing it. It’s better to keep it from entering the engine side.
Fluorine grease separates from oil, so don’t use more than necessary.
That’s the idea. When inserting the shaft, it’s important to be gentle so the grease doesn’t splatter out.
We use DuPont’s MOLYKOTE® HP-500 Fluorine Grease. The consistency is just right.
After a test ride and one day of parking, no seeping was observed. We’ll just have to see how it goes. Well, it should be fine (*´ω｀*)
Fixing an Oil Leak on a 90s Legend: Honda RVF400 (NC35).
Vehicle: Honda RVF400 (NC35) – An iconic 400cc V4 sportbike. Issue: Engine oil leaking from the left side, specifically around the shift cover and shift shaft. Work: Over decades, rubber oil seals harden and lose their sealing ability. We removed the shift cover and found a massive buildup of leaked oil and old chain lube. The crucial (and time-consuming) first step is a thorough cleaning! Once spotless, we carefully extracted the old, hardened shift shaft seal and pressed in a brand-new OEM seal, along with fresh cover gaskets. Verdict: The leak is completely stopped, and the engine area looks factory fresh again. This beautiful V4 machine is ready to hit the winding roads with confidence!
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