lexuscars5

I am new to the Forum but have lurked for years after owning several Lexus Vehicles. I currently have a Mis on my 2010 LS460L AWD. This car has 56K miles and was always maintained at the Lexus Dealer every 5K since new. It has been at 2 Different Lexus Stores with no confirmed diagnosis. Plugs have been changed, Coils Swapped and Replaced, Injectors swapped and seals replaced, Injector Harness replaced, Injector boxes swapped, intake gaskets replaced, all with no movement or change. Both completed compression and leakdown test with no reported concerns. Taken to an independent and they tried several things but again no confirmed diagnosis. It appears it is going to be an issue with the head itself but the amount of labor to replace the heads by the book is almost 36 hrs. Has anyone dealt with this or Lexus Techs have any suggestions. I currently have the valve cover off to make sure the valves were opening and closing and that the rocker wasn't off or anything. It appears the motor would need to be dropped out to pull the head, but would like to hear if anyone has removed a head in one of these cars without removing the engine. Thanks in advance for your thoughts and help!

Anfanger

What makes you think that the problem with the engine and not the wiring?

Have you inspected the cylinder #2 with a camera?

lexuscars5

I replaced the injector wiring as was unable to test while running as it’s under the intake and checked the coil wiring all good signal. Yes the cylinder has been inspected nothing unusual even checked the valves for possible carbon buildup. Serval different mechanics have said bad head, valve seat, head gasket, ect. But no one can guarantee. I’m open to try about anything. I did a cold leak down test myself today and something on 2 is not sealing with all the plugs out air is moving from cylinder 2 when pressurized to 4. This is the first time I have tried to verify myself.

Striker223

If you are sure it's leaking across 2 into 4 it's likely a head gasket.

Anfanger

I agree, if there is a leak between cylinders, most likely is due to a failed head gasket. Which means, the engine was likely overheated before.

What makes no sense to me as how the dealer did not catch the issue.

swfla

iTrader: (1)

Has the car ever shown a check engine light? Did you immediately turn the engine off or keep driving. Even a few miles to get to a safe place can warp heads. Was the coolant level ever low? Has anyone tested the coolant reservoir with the blue fluid that checks for combustion gases? It's a simple and fast test. If it's positive, that supports the pressure bleed that you measured between cylinders. Head warp or gasket.

Striker223

If you are 100% certain there is a cross cylinder leak I would drop the engine out and swap in a known good one. Too many risks trying to replace the headgasket if the engine was overheated.

It is relatively easy to drop the engine out the bottom, if you have a "table" and lift you can get it out in a day and a new one in in like a day and a half. Should be around 24 labor hours max