JAB

1999 RX300, 210K, original owner. My valve cover gaskets are leaking and after reviewing the excellent threads on this forum have determined that its a repair I can do myself. Will also do spark plugs and plug tube gaskets. But should I replace the knock sensors and the coolant bypass hose while I'm in there? They are all original, and no reason to suspect that failure is imminent, but at 210K anything can happen, and I would kick myself if one of those failed after I passed up the easy opportunity to replace them prophylactilly. (Yes, I realize that the intake manifold must come off, which is a significant additional step.) Regardless, a complete timing belt/water pump job by my independent mechanic will immediately follow, which I am not comfortable doing myself. TIA.

salimshah

Time labor and money ...

If time is your own (you are not paying for labor), we are are only talking about removing the air-intake. I would wait. The cost is substantial for knock sensors and the gaskets.

I inspected the coolant bypass hose and saw no reason to replace it.

Other thing to consider is the water-pump replacement would involve coolant drain and knock-sensor replacement would require coolant drain.

Do you plan to change the cam and front main seals?

Also please do not under-estimate the amount of work in doing the knock sensor replacement work. It is more involved than t-b replacement.

Salim

JAB

Salim: Thanks for your prompt response but I'm confused. Am I wrong in my belief that the air intake needs to be removed in order to replace the rear valve cover gasket? And am I wrong in my belief that the intake manifold needs to be removed (steps 16-21 in your excellent thread) in order to replace the knock sensors?

salimshah

Till some one finds out a way to do the rear valve cover without removing the intake, you have to remove it.

What I meant was that if decide not to change the knock sensors now, the repeat work will be the air-intake.

Salim

JAB

Got it; thanks.