1988 Yamaha Radian - Oil leak issues.

3436 Views 4 Replies 3 Participants Last post by SemiFast, Jun 13, 2018

Crashmk1

Discussion Starter · Jun 12, 2018

Before diving into this, I have to mention that this is my first motorcycle, and even before this, I was never too mechanically savvy. However, I can manage to stumble my way through researching things. I'll ask that people be a little gentle with responses, as I'm still figuring things out (and I won't know the technical terms for every piece).

I recently purchased my radian in running and driving condition (after installing a new battery), with 9,800 miles on it. The engine head was completely blackened, and it looked as though it was painted at some point. Much to my dismay, this was what appeared to be years of baked on oil. The previous owner had mentioned that there was a slight oil leak, and he wasn't outright lying, but it was a little worse than I had intended. I've only put about 15 miles on the bike since I've owned it, scared that I may have a big fix in my near future. I was able to trace the leak back to the source (relieved to find out that it wasn't the head gasket), and it appears to be coming from the half moon sections on the right side of the valve cover gasket. When I got the bike, two of the bolts from the valve cover were missing, which I promptly ordered and replaced. Although, that clued me into thinking that the valve cover was probably replaced once before, and by my best guess, they didn't use any sort of sealant to seal the gasket properly.

Am I on the right track, or is there something that I'm missing entirely?

Thanks in advance, and cheers!

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Dodsfall

· #2 · Jun 12, 2018

Replace the gaskets. It should be a simple fix.

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SemiFast

· #3 · Jun 12, 2018

I looked up the price of the cam cover gasket... Be ready for sticker shock.

It's common practice to use a sealant only on the half moon ends of the gasket. Yamabond or (aftermarket) ThreeBond 1184 Gray is the right stuff.
Do not use an automotive sealant that hardens or silicone.

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Crashmk1

Discussion Starter · #4 · Jun 12, 2018

SemiFast said:
I looked up the price of the cam cover gasket... Be ready for sticker shock.

It's common practice to use a sealant only on the half moon ends of the gasket. Yamabond or (aftermarket) ThreeBond 1184 Gray is the right stuff.
Do not use an automotive sealant that hardens or silicone.

On yamahapartshouse.com, it looks like it runs about $86.00, which is relatively steep for an OEM gasket. I've seen others available online in the $20 range, which I'm guessing are not OEM. Being that I've never really messed with it before, how true should I stick to OEM? I mean, I paid $800 for the bike, just for an older machine that I can learn to ride on. I know that they can be money pits, but I don't plan on this being my "forever bike".

As for the sealant, Yamabond was what I was planning on using. And by using it on halfmoon portion of the gasket, is it just used on the underside of the gasket (the part that lies against the head?). This would make sense as to why it may just be leaking there.

Would there be any reason to just try opening it up and re-applying the sealant, instead of just replacing the gasket itself?

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SemiFast

· #5 · Jun 13, 2018

Considering the age of the machine the original gasket may be hardened and/or shrunk up enough that getting it to seal may be a problem.
I like to use OEM gaskets mostly because they'll fit on the first try... most of the time.
Something else to look at is the rubber grommets on the cam cover bolts. If they are flattened too much they will not apply enough down force to seal the gasket.

Clean the head mating surface free of ALL oil and apply the Yamabond to the head itself at the cutouts (and a little too each side) where the half moon portion of the gasket goes.
You should not need to put any sealant on the gasket.

Understanding this is not a keep it forever bike you could try just cleaning the gasket, cover and head real well then use Yamabond on the entire mating surface.
If (when) that doesn't work you'll get to spend a bunch of time cleaning the parts to re-do the job. :surprise: LOL :devil:

Sorry, not funny. :angel:

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