How do you get to the rear valve cover gasket

Try tightening the valve cover. I don't know your skill level so hard to say if it is a DIY job for you.

did you try tapping it with a rubber malot

One gasket for each valve cover, you have 2 covers. Upper intake manifold must be removed to access rear valve cover and all wiring that is in the way.

remove air intake chamber firts

Its kinda hidden at the back.. you can take off the upper intake plenum to gain a bit more access.. some people also take off the washer arm housing.. theres a few bolts under the cover that mount it to the firewall

support engine and remove front engine mounts, you'll have to remove your upper intake and some EVAP hoses, some other parts mounted to your intake and your ignition module from the rear valve cover the bolts should be either 8mm or 10mm, make sure to clean the valve cover of all old gasket material before reinstalling with new gaskets!

Hello. Let me try to assist you the best I can, with the hope of achieving a FixYa rating from you for my assistance.

Changing the rear valve cover gasket on your vehicle would be not considered a "real" big job, but IS a time-consuming job.
In order to remove the rear cover, you first have to remove the intake plenum. If you do not remove the plenum, you can't get to the valve cover bolts that are under the plenum. After the plenum is off, the valve cover is easy to access. You will also need to replace the intake plenum gasket, if you do the job yourself.

I hope this information has satisfied your question.
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the only way to replace the rear valve cover is to remove the upper intake....there is no easy way

The best way to remove the rear valve cover is to remove the intake plenum. There is really no other way to do it. It is not a hard job, removing the intake plenum, but, trying to tackle the rear cover without taking off the plenum is almost impossible. If he does remove the plenum, make sure he replaces the plenum gasket. Hope this helps.
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To replace the valve cover gaskets on a Sienna: The front one is easy. The difficult one is the other side, closest to the firewall. You will need to purchase a new intake plenum gasket, when you buy the new valve cover gaskets, because you MUST remove the intake plenum to remove the rear valve cover. You can NOT get the back side valve cover off of the engine without removing the plenum. Trust me.
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