Similar to other timing cover oil leaks we’ve written about, the 4.6 liter 1UR-FE V8 engine in the Lexus GX460 can develop oil leaks where the timing chain cover meets the cylinder block and cylinder head. While the problem is similar, the repair of the GX460 is done in the vehicle as opposed to the teardown of some Toyota V6 engines that can also have issues.
The issue is fairly simple: where the engine block, cylinder head and timing chain cover all meet they form a T shaped junction. Slight irregularities in machining of these parts can lead to small differences in their surfaces in regards to depth (ie. they don’t line up totally perfectly). This is normal, however over time the flexible gasket that seals these surfaces together is subjected to more stress at this location, potentially leading to leaks. The solution? Replace the failed flexible gasket with more carefully applied flexible gasket and the issue shouldn’t reoccur.
The scope of work is large: the front bumper, radiator, all the accessories, and most of the emissions control system on the engine are removed simply to gain access to all the timing cover bolts. Here’s a GX460 totally torn down with the cover off:
And a frontal view of the engine highlighting the two places the heads meet the block where they can leak from:
…and up close of the driver’s side spot that was leaking on this GX460:
Simply cleaning the old gasket material off the engine and timing cover, renewing gaskets as they are disturbed as well, corrects this issue and prevents it recoccuring. CARspec technicians normally apply a small amount of extra gasket material in the groove picture above to help seal the junction as well.
As Minneapolis, Minnesota’s premier independent Toyota and Lexus specialist, we see more than our fair share of GX460s and are extremely familiar with all kinds of timing cover resealing procedures like the above. If you’ve been told your GX460 timing cover is leaking, don’t hesitate to make an appointment by calling (952)426-4798 for a second opinion or to schedule a no charge inspection today!