Valve Stem Seals?

[Diesel Tom]

I've got a 2007 4.6L V8 with 95K miles. I have had it for 6 months. Oil consumption has been about 1 qt per oil change (4,000). I have changed to oil three times. There are no external oil leaks (clean garage floor).

I noticed today that there is a puff of blue smoke when it is first started in the morning. No other smoke while the engine is running.

Could the problem be bad valve stem seals? How much trouble are they to replace on this engine? (I have replaced valve stem seals a number of times on OHV engines)

Thanks.

 

[michael loibl]

I can tell u I sure wouldn't mess with it over a quart of oil over 4,000 miles! The older early '90's 4.6L were common to have worn valve stem seals. Often they would blow a puff of blue smoke first acceleration flowing a high vaccume deceleration event.
I seriously wouldn't worry about that little consumption

 

[Flag Gibby]

If you are really that worried about it perform a leakdown test on all the cylinders and check to see if it is leaking out the valve seals. See here for some insight on the test: http://www.hotrod.com/how-to/engine/116-0406-cylinder-leakdown-tester/
If it really is in the head then its not going to be that difficult to take care of. However, since you have an 07 I would be looking very closely at the exhaust manifolds to make sure that they are sealing good and don't have any broken studs since that can cause the valves to not seat properly.

 

[Explorer_PL]

I am not sure a quart every 4k miles is acceptable, maybe it is within specs.
My old engine was not taking any oil at 200k, but it's probably cheaper to add that quart every few weeks rather than do the valve job.

 

[Diesel Tom]

I wasn't talking about doing a complete valve job, just replacing the valve stem seals with the heads on the engine. Other than having to buy the valve spring compressor, I already have all of the tools.