Chris Paveglio

iTrader: (2)

My SCCA club is looking to buy a new truck. We are looking at some used rental trucks, GMC from 2008-2011 and they all have listed 4.8L engine (did they call that a Vortec in those years?).
What are the main issues with this engine? We looked at a few and several had leaks on the bottom and rear of the engine. Is this typically a rear main seal leak, pan leak, or head/top end leak?
What are the usual costs to do any of those repairs?
If there are any other typical issues with that engine, please let me know. I put it in Gen 3 b/c I am not even sure what version it really is.

truckdoug

iTrader: (25)

those are gen4. it's either an LY2 or a L20 if it has variable valve timing. They run for 300,000+miles with even a hint of a decent maintenance routine.

the rear mains and valve cover gaskets can begin to leak once the PCV system quits functioning

I part out work trucks for sweatpants money and what I do is run a few quarts of atf in the oil to work the sludge loose. then fresh oil and pcv valve, making sure the breathers are clear and the lines are not cracked. then I gunk the engine and check for leaks after that.

the weak spot in them is the 4l60e transmission.

00pooterSS

iTrader: (40)

I work on these for leaks often. The most common leaks are oil pan gaskets and the o ring on the cam sensor that is at the top of the engine at the back behind the intake manifold. Either of those will cause the leak you described. Both are quick and easy to do, they each call for around 2.5 hours labor and parts are not expensive either.

RockinWs6

o ring on the pick up tube is another sore spot. Should be changed after 5 years or 100k.