I searched for 3.0 oil leak info but nothing pertained to my problem.... had the 3.slow rebuilt a few weeks ago.... developed a pretty bad oil leak from the back side of the engine...oil all over the sides of the bell housing and front differential.... asked two Toyota service techs at different places about it and they said rear main seal or valve cover gaskets... stupid motor shop owner says it the seals at the back of the cam shafts... i have never heard of a leak here, but what do I know... the idiot tried to argue that his guys didnt attach the vacuum hoses wrong when 3 other 4runners confirmed that he was wrong... anyways... has anyone heard of oil leaking from the back seal on the cam shafts? how common versus rear main or valve cover gaskets? thanks! dealing with this guy is like this...

 

i gonna go with rear main seal on this one. My 3.0 is leaking in the same exact area, on the bell housing and front differential.

 

dont condem a rear main seal if it could be as simple as a valve cover gasket or cam end plug. I would try to clean the area of the leak, drive it around for a while, crawl underneath and look from top to bottom, remember it will leak down so look in the highest places first. My buddy had a 3.0 4runner and it was leaking like a civ from the rear cam plugs. The moron that rebuilt your motor probably gakked one of them.

 

ok sorry for my ignorance, but what is the rear main seal? Is that the seal btwn the engine and tranny?

 

I second that. It was a valve cover gasket on mine.

 

it's the main seal between the crank and the block, I'd guess if it were the rear main the outside would be fairly clean and it would be gushing from the bellhousing drain. To fix you need to pull the motor or trans.

Cam plugs are certinly a possibility, as are valve covers. Both fairly easy to fix w/ engine in the truck.

As the other user notes, CLEAN it, run it, look for the leak.

 

If there is oil on top of the bell housing it is coming from further up. A rear main seal won't put oil on top of the trans bell housing. Valve cover gaskets or cam seals is what I would check first. Still a rough job but not as bad as pulling trans for rear main seal.

 

I have run into this problem a few times on rebuilt 3.0's. If you recently had your engine rebuilt, there may be two main reasons why it leaks oil. Aftermarket valve cover gaskets, they're thinner, they don't seal as well as the factory gaskets and they suck. And two, not enough FIPG in the 4 corner areas on the head, the trick is to put the FIPG on the corners on the head first with your finger at the end of the half moon on each side and not on the valve cover itself.

RBMC

 

Also on the rear of the driver's side engine block you will have an engine oil cooler (if so equipped) that will play havoc on your mind when it leaks and runs to the back of engine but I wouldn't jump on the rear seal until all else was checked out!

 

If the tech used any silicone on the cam plugs( and you shouldn't)the silicone will block the oil drain back passage and leak like hell.If this happens on the front it will push the seal out.It will be very hard to fix ,with the engine in the truck.