Why Inspect the Valves When Compression and Leakdown Are Good?

Persistent misfire cyclinder 1.  Trusted independent mechanic diagnoses bad engine control module (ECM); take it to dealer.  Dealer (with a decent reputation) says pull the valve cover to check the valves.  That's $370 just to look and see.  7,000 miles ago compression was 140# and 5% leakdown in all cylinders.  Car is a 2006 Subaru Outback XT, now with 129,000 miles.

Why inspect the valves if the compression and leakdown are good?

First thread on this issue.  Does This Coil Look Bad?

Second thread on this issue.  Bake My ECM?

Thanks for your thoughts.  I have to respond to the dealer this afternoon with my decision what to do next.

Was it misfiring 7000 miles ago? If not, something changed.  If you had just gotten those leakdown results yesterday i would say don't bother 'inspecting valves'.  But, things change and every breakdown occurs inside some 7000 mile span. You just don't know which 7,000 until it happens. 

Agreed, when the test were done, the problem was not there. SOMETHING changed in 7000 miles and it could be something that would show if the test were repeated.

What exactly is the mechanic going to see by removing the valve cover unless he is somehow looking at a worn cam? I would have to hear the exact explanation before I could say one way or the other if he is on the right path.

A vacuum gauge will try and tell you if you have a bad valve.

Pete

In reply to NOHOME :

I have seen broken valvesprings cause running misfires but good compression tests.

Not likely on  4 valve engine but I have also seen bent valves that the valvespring would bend/stretch enough to seal.

Unless the dealership is aware of a pattern failure, compression issues causing misfires is quite rare. 

Vigo said:

Was it misfiring 7000 miles ago? If not, something changed.  If you had just gotten those leakdown results yesterday i would say don't bother 'inspecting valves'.  But, things change and every breakdown occurs inside some 7000 mile span. You just don't know which 7,000 until it happens. 

You are absolutely right.  And those 7,000 miles cover about two years.  So yes, something could have changed.

Maybe another compression/leakdown test would be a cheaper than $370.

or a nice Sears compression tester for 45.00,get it while you can.

Dealer says valves are tight.  They want $2,200 to pull the engine and adjust and "hopefully" the head isn't warped.  I think they are taking me for a ride.  Help?

I think I would buy a vacuum gauge and see what it tries to tell me.

Pete

What’s the year make and model of this car and what’s the mileage

DWNSHFT said:

Dealer says valves are tight.  They want $2,200 to pull the engine and adjust and "hopefully" the head isn't warped.  I think they are taking me for a ride.  Help?

Tight, as in binding in the guides? Then pulling the engine makes sense, but sounds expensive  

or

Tight, as in the clearance is out of spec? If it’s this why aren’t they suggesting to adjust the valves?

on edit: why does the engine need to come out to adjust the valves? If they could check them they should be able to adjust them, right?

Subarus are one of the easiest cars to pull the engine out of and if the heads are warped (from what? a misfire? is there a major overheat involved somehow?) then you machine them for ~$20-40.  I'm deeply suspicious of their quote.

No Time said:

DWNSHFT said:

Dealer says valves are tight.  They want $2,200 to pull the engine and adjust and "hopefully" the head isn't warped.  I think they are taking me for a ride.  Help?

Tight, as in binding in the guides? Then pulling the engine makes sense, but sounds expensive  

or

Tight, as in the clearance is out of spec? If it’s this why aren’t they suggesting to adjust the valves?

on edit: why does the engine need to come out to adjust the valves? If they could check them they should be able to adjust them, right?

Makes me think tight guides.  I don't think any mid-00s have mechanically adjustable valves.

In reply to Knurled. :

I was thinking they were like the 2003 forester I had where the valve could be adjusted once the valve covers were removed. 

Thanks, everyone, for your comments.  Car is a 2006 Subaru Outback XT with 129,000 miles and a persistent misfire in cylinder 1, error code P0301.  These have the EJ257 turbo engine and the internet tells me that yes, you have to pull the engine to adjust the valves.  They are bucket-type.

Should I have them do a compression and leakdown test?  I think they are trying to scare me with a bill so I trade in the car and buy a new one, which I won't do.

Based on the background i would do a leakdown on that cylinder only and see what happens. If you're going to do a leakdown, a compression test is semi-superfluous, but that's just my .02.