Common oil leak locations on '96 3.4 engine?

I'm preparing to dig into one or more small oil leaks at the front of the 3.4 in my '96. Could use some advice on common oil leak locations on these engines.

Background - all stock 4x4, 274k miles on original engine. After any short drive, I get a couple drips off the skid plate at the front. Planning to pull things apart so I can see what's in there, and will do some basic maintenance (belts, etc.) while I'm at it.

Please advise me if there are some common things I should look at. Thanks!

 

Valve covers are a common culprit. Mine was also leaking from the front main seal. Valve covers are a PITA on the 3.4 compared to older yota engines I've worked on... Front main seal is easily done when swapping timing belt.

 

Most common oil leak by far are the valve cover gaskets, cam plugs, and 1/2 moon plugs.

 

Ahh. The valve covers and cam plugs makes perfect sense, because the truck's normal parking spot is nose-down on a sloped driveway, and I don't think the valve covers have ever been off since new (never needed a valve adjustment yet). I'll start making my parts list now, will probably just do the front main seal while I'm in there.

 

FWIW, while you're down that far, it's worth doing the injectors (highly suggest motor west "denso upgrade" injectors), and vacuum lines. There are a few lines you can only get to while the intake manifolds are off and main wiring looms are freed up.

 

If you're not due for a timing belt then I would wait on the main seal until then... most timing belt kits come with a new main seal plus all the other goodies that are easily accessible once the timing belt is off.
Check out Aircabinman on eBay for parts kits. He is highly recommended around here and I had great luck with him. 100% OEM and speedy shipping.

 

I think it'd be worth your while to check the valve lash while you're in there, if you end up doing the valve covers. Did mine at 278k miles and if I remember correctly 9 of the 24 valves were out of spec. Subjectively felt like she ran a lot better afterwards (pulled stronger and ~2 mpg increase that remains at nearly 290k miles).

 

FWIW, there is an updated crank pulley bolt that has a loose washer as opposed to the fixed washer. It is $15 ish bolt and is probably the most important bolt on the motor. The torque is rather high (217 lb ft) on this for a reason. If you dont torque it and the bolt is loose the woodruff key will wollow out the crankshaft groove and now you need a motor/crankshaft.

 

Well, this project has escalated quickly. Good ideas, everyone. Thanks!