A reminder - Go easy on the silicone

A little history on my bike - the first owner had put about 60,000km on my kz250, and then had the engine rebuilt. It wasn't long until the engine was making a huge amount of noise, and so he sold it to the 2nd owner. The 2nd owner found that the camshaft had worn out and have enormous grooves in it, and replaced it. Then I bought it.

A worn camshaft to me says that there is some oil starvation, but the oil pump was replaced only 3000km ago. Either way I wanted a look, as I needed to replace the clutch anyway. The oil pump looked great, clearance was fine and little sign of metal particles damaging the surface. But while I had the cover off, I thought I'd give the sump a clean. There was a little grime, and some bits of the red and blue silicone used by the engine builder. Then I pulled out the oil strainer.



The oil strainer had been completely blocked by the pieces of silicone inside the engine, Whoever built the engine was far too liberal with the amount they used. I think this is what caused the oil starvation, as the mesh had been sucked flat from the oil pump draw, until the mesh had actually torn apart at the base, eventually allowing oil and anything else through. So the full engine rebuild was ruined just by too much silicone.

If you are rebuilding an engine, I would recommend using a non-hardening aviation gasket cement - and only enough for a thin, even coating.

Wow! Some people shouldn't be allowed to own tools.

Good advice to go easy on the silicone. It's fine if used "properly". Kawasaki specified a Threebond RTV material to seal case halves on at least some models in the past. In the present tense Kawasaki recommends Threebond 1105B, which is not silicone.

How badly damaged is the engine now? Salvageable or not worth the trouble?

Irish Yobbo wrote: A little history on my bike - the first owner had put about 60,000km on my kz250, and then had the engine rebuilt. It wasn't long until the engine was making a huge amount of noise, and so he sold it to the 2nd owner. The 2nd owner found that the camshaft had worn out and have enormous grooves in it, and replaced it. Then I bought it.

A worn camshaft to me says that there is some oil starvation, but the oil pump was replaced only 3000km ago. Either way I wanted a look, as I needed to replace the clutch anyway. The oil pump looked great, clearance was fine and little sign of metal particles damaging the surface. But while I had the cover off, I thought I'd give the sump a clean. There was a little grime, and some bits of the red and blue silicone used by the engine builder. Then I pulled out the oil strainer.

The oil strainer had been completely blocked by the pieces of silicone inside the engine, Whoever built the engine was far too liberal with the amount they used. I think this is what caused the oil starvation, as the mesh had been sucked flat from the oil pump draw, until the mesh had actually torn apart at the base, eventually allowing oil and anything else through. So the full engine rebuild was ruined just by too much silicone.

If you are rebuilding an engine, I would recommend using a non-hardening aviation gasket cement - and only enough for a thin, even coating.

Never use silicone, threebond only.


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Just to be clear, on my KZ750E Kawasaki used Three Bond 1207B to seal the case halfs, and that material is silicone. www.threebond.com/product/series/sealants/s_a1200.html

I learned long ago, If you use it, be sure to clear the bolt holes each time. I put in a bolt and cracked the journal around it. hydro-static pressure. If used wisely, it's the best stuff to use.
Steve

Nessism wrote: How badly damaged is the engine now? Salvageable or not worth the trouble?

The engine seems pretty good actually. The piston and bore are fine after a hone, and the new camshaft and valves are too. I think the saving grace was actually the mesh breaking. My theory is the mesh got clogged, rerstriced flow enough to damage the cam, but then the mesh broke, allowing the oil to flow again. The oil filter will still filter out the particles on the way to the engine, but if there were any small metal fragments floating around it could mess up the oil pump pretty quickly. But that's not the case, oil pump is fine.

I use silicone but i spread it real thin on gaskets ,fist lightly smear it on both sides, then let it dry slightly then put it on

I had the a similar issue with my 1300 project. Someone had tried to seal a leak on the left engine cover with silicone. There was a bunch of it on the oil pick up screen. No where near as bad as what Irish found. It doesn't take much at all to ruin an engine.

I used to see this from time to time in the shop. People would use silicone to seal the pan on an transmission. Its not easy or cheap to clean a pump and valve body out on an electric shift transmission. People would come in with a drivability complaint, as soon as we saw the red ( don't know why but they always used the red stuff) silicone around the pan... we knew what we were on for.

What pisses me off is they say form-a-gasket. If they had to pay for the damage caused, they'd stop this crap.
Steve