Thank you for your help!

I have an oil leak from our91 4Runner V6 w/145k miles, 5spd. that I would like to repair. The leak appears to becoming from the rear of the motor, on the passanger side,roughly in the area ofvalve cover (best I can tell).

The oil drips off the back corner of the motor and onto the exhaust pipe that crosses behind the motor causing smoke. The oil seems to leak worse just after I shut off the motor. About 2 tablespoons ofoilwill leak down onto the exhaust pipe and down to the flooor.

I suspect the valve cover gasket, even though they where replaced last year.

Question:
- Is there anything else in passenger-side rear corner ofthe motor that can cause an oil leak?

- Any tricks in how to better identify the source of the leak?

The motor idles and runs fine, and hasno unusual color or smokein the exhaust.

Thank you for your Help!
Sincerely,
R.K.Graves

 

Clean the motor first and thats the first start. Also an oil change will help make it leak more and make it easier to see.

 

Yes, Thank You. Have done both.

On the passenger side of the motor there is a lot of hoses and hardware that makes it difficult to see this area. The intake manifold covers this side of the motor making it difficult to see much of the valve cover. I'm concerned something besides a leaking valve cover gasket could be causing the problem and would like to know before I remove the intake manifold.Once I remove themanifold I can't start the motor to search forthe leak.

I'm hoping someone with a lot of knowledge of the 3VZ V6 can tell me ifanything else on the passenger-side-rear of the motor could likely cause the leak, other than the valve cover gasket.

Again, Thank you,
R.K.Graves

 

For anyone searching "oil leak" in the Archives, here is what I learned.

-On the 3VZ 3.0L 6 cyl. of all the things that could cause an oil leakfrom the top of motor the valve cover gaskets are the most likely suspecect.The gasketsare not flat, but havehumps at each end topass over the top of the camshaft.The bends in the gasket atthe humps is a likely spot for an oil leak, particularly on thebackside of the motor as the motoris lower in the back, allowing oil to pool in these areas. The motor manual suggests a spot of RTV at the bends to help avoid leaks.

- Therear of the right camshaft and front of the left camshaft have large bearing/caps that could also cause a leak, but this is less likely as oil does not collect or pool in these areas. These bearing/caps use RTV as their gasket.

- (If I identified it correctly) The oil sending unit is in the valley between the two cyl heads. If it where leaking it would not leak off the back corners of themotor. It can be viewed by removing the Throttle Valve assembly.

- To replace the left valve cover gasket you only need to remove the Throttle Valve assembly. To replace the right valve cover gasket you need to also remove the Intake Pentium. The intake manifold is in two pieces; the top section which covers the right valve coveris called the Plenium and can be removed seperatly from the lower half (intake manifold).

- To replacethe valve cover gaskets you need; valve cover gaskets ($25),Intake Plentium gasket ($5),Throttle Valve assembly gasket ($5). No special tools are required.

- The hardest part of the repair is working with all the hosesattached to the Intake Plentium.Many of the hoses can stay connected,as you can swing the plenium out of the way and access the right valve cover.

- The motor manual says to remove the EGR valve at the exhaust connection. On our motor there is a large 1"or so nut just below the EGR which is much easier to get to and loosen.

The repair took about 16 hours, will take much less time next time.

Hope this helps,
Sincerely,
R.K.Graves