99custom

I changed my valve covers 4 years ago with all factory parts, new bolts and washers. Yesterday while changing my oil I noticed almost all of them were loose (not leaking though). I tightened them up all backup, used my stubby ratchet for the back (really handy). I was pretty shocked since I torqued them properly the first time and it's only been a few years. Everyone be sure to check their valve cover bolts....

LeX2K

Common problem, the design is simply poor. Plus torquing them is not an accurate method need to go by feel but this is risky.

Arsenii

Hello,

There is a shoulder on those bolts designed such that you won't be able to compress the gaskets too much no matter how hard you tighten those bolts. Some people suggest putting additional washers to offset the bolts and rely on torque readings to achieve right compression on the gasket for one reason or another. I would argue that this is not the right way to do it, and will result in those bolts getting loose over time, not to say that you will never know how much you will compress the gasket.

If you didn't use the washers described above, then the bolts are likely not torqued to the right amount, they have to bottom out and sit against the engine block, otherwise they will keep getting loose. If that's good, try using some threadlocker on the bolts to see if that will help.

Hope this helps and best of luck!

99custom

I'm just gonna check every oil change I suppose.... Love my Lexus but this is something I'd expect from Kia or Nissan...

LeX2K

I RTV the entire mating surface of the rear cylinder head I know this will trigger some people. It sucks for the next person but guarantees no leaks. Valve cover should have been cast/machined with a much deeper groove. And this.......
On one job I used some spring washers only time will tell if it works.

Arsenii

Strange, it's not like they should need it, considering that the bolt does torque up against the engine block, just like any other bolt would. I've done my gaskets about 3 years ago by now, no signs of those letting up yet..

LeX2K

This is necessary on the 3VZ-FE for sure. If you don't do this it will leak.
Instead of adding flat washers I used spring washers.

Arsenii

I don't think that system needs any washers though, other than the factory ones that are already on all the bolts, Part Number 90902-02001. I just kept the old ones, but might as well replace them, at least for the rear bank if that becomes a problem. The thing is that those bolts have a specially designed shoulder to control how much the gasket gets compressed every time, it is very reliable and ensures that the bolts won't be coming out on their own, unlike the older designs in 1UZ for example where those bolts only had the rubberized washers to keep them in place, and as the gasket was setting, the tension would get looser, and the bolts would start backing out on their own.

LeX2K

In Canada those are $6-7/each from a local dealer. Better online but with shipping it costs more.
Those washers are crush style one time use. Even with new washers they still come loose in my experience unless I do it by feel.
2VZ/3VZ has the rubber style washer. Horrible design.