Rear main seal and valve cover gasket

[jsmuir]

I recently bought a 2004 Toyota Sequoia. I knew it had an oil leak. I sent it in for a comprehensive inspection and was told there were leaks from the valve cover gaskets and the rear main seal. I am going to do these myself, but it may be about 6 weeks before I can get to both of them. So I have two questions:

1. Should I do them both at the same time?
2. If not, which should I do first?

Thanks for your help.

 

[Snagglefoot]

The rear main seal is a ton of work because you have to pull the transmission. The valve covers are relatively easy. I would do the valve covers to warm up for the main event.

 

[t1snwrbrdr12]

Not familiar with this engine or vehicle, but if you aren’t fixing both at once…first verify the valve covers are leaking, if they are, do them first because they are higher. Replace your crankcase ventilation as well in case it’s clogged. Then clean the entire engine and monitor for your rear main seal leak. Maybe the valve covers were leaking down onto it making it appear to leak, maybe your pcv was clogged and replacing it will clear up the rear main leak. I’ve seen both (seen plenty of rear main misdiagnosis and seen Pcv repairs clear up rear main leaks).

 

[PontiacHO]

Valve covers first, degrease engine, high mileage oil. Watchful waiting to confirm the rear main seal is leaking. As said above, the VC leak may be running down and creating the appearance of a rear main seal leak. Good advice already given on the vent system check as well.

 

[jsmuir]

Thanks for the input. It is VERY helpful.

@t1snwrbrdr12 By crankcase ventilation, do you mean replace just the pcv valve or more?

 

[Finklejag]

You will be amazed how far an oil leak can end up on an engine. The valve covers on my V6 Acura were leaking and the rear bank leak covered the whole back side of the engine and transmission. Yes, install a new pcv valve also when doing the valve cover gaskets.

 

[t1snwrbrdr12]

Thanks for the input. It is VERY helpful.

@t1snwrbrdr12 By crankcase ventilation, do you mean replace just the pcv valve or more?

Yeah, pcv. I’m not familiar with that engine, some manufacturers don’t necessarily use or call it pcv but they will have some system to accomplish crankcase ventilation.

 

[The Critic]

Valve Cover Gaskets are easy on that truck. Do those first, degrease and pressure wash the engine, then re-evaluate.

 

[ripcord]

Like everyone said, do the valve covers first and clean the block. You might find that the rear main is a slow enough leak that you can live with it. Pulling the transmission (or engine) to reach the rear main is a big job.