Rear Valve Cover Leak

[jclemen]

I had some misfire CELs appear on my 94 es300 so I replaced all the spark plugs as well as cleaned the TB and ICV. I thought I'd change the rear valve cover while I had the plenum off to address a problem where I'd smell burning oil in the cabin at idle.

I did all the work and put everything back together, I had a major leak so I tore everything down again. This time I used a thin layer of high temp rtv around the head where the cover mounts. This time no major leak, no puddles on the garage floor but still the smell. I drove around to burn-off the oil from the first attempt. Still had the smell, still no puddles. I can put my hand on the back of the motor and feel up and down, my hand stays dry. I drove the car about 18 miles yesterday, still stinky at idle, no puddles/drips in the garage.

I put the car out last night (-10 overnight) and then started it this morning. I let it run for a few minutes then moved it into the garage (heated to be around 45 degrees) and left for work in another car. I got home tonight and went out to 'run' the es and backed it out into the driveway. There was a puddle of oil about a foot wide. I drove it for 15 miles and its back in the garage. I'm waiting for it to drip, but so far nothing.

I'm getting pretty good at tear down, took me about 35minutes last time to get to the point where to take the rear cover off. Doesn't mean I want to do it again though. ;)

I can deal with the smell but not the puddle. Any tricks on the rear cover? Should I use a thick layer of rtv?

[925benjie]

Just to be sure, I would take the rear valve cover off again. This time, put it back together using a NEW gasket and also a thin layer of the same high temp. sealant you're using. Good luck.

[jclemen]

Thank benjie, I think you may be right on the redo. I forgot to say I used a brand new cover gasket and installed a brand new pcv valve as well.

I just went out to check. The back of the motor is dry but the rubber mount near the cat is very wet with oil.

[George_Jetson]

Did you also replace the spark plug tube gaskets? Sorry to hear that it did not fix it the first time, but sooner or later it happens to all of us.

[jclemen]

I did not replace the spark plug tube gaskets. That the culprit?

[George_Jetson]

Most likely, over the years the seals will dry and harden. When you remove the cover, it is very hard to get it on exactly the same position. It is a good practice to replace them every time you take the cover off (especially the rear cover, considering the amount of work required to remove the cover).

[jclemen]

I have the cover off, the leak was coming from the timing chain 'hump'.

The spark plug seals disintegrated when I attempted drive them out with a socket. I sprayed some PB and will try to gently get the rest of the seal out. Seems like theres a metal ring within the seals. Any tips on doing this job?

[homemechanic]

it is not metal rings holding the gaskets in place. there are two small tabs holding each gasket in place. you have to sort of bend/ply the tabs out in order to remove/install gaskets. after installing the new gaskets, you need to bend the tabs back in. make sure you go gently on the tabs, or they might break on you.