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07/14/2009 02:58:20 PM · #1
I know there are some decent mechanics on the site and I know they grit their teeth when I try to do things myself. Well, this time I took it promptly to the mechanic, but I'm in a dilemma over what to do.

2004 Subaru Outback.
Sunday AM started it up to pull into the garage. Everybody noted a strong exhaust smell, but that was it.
Yesterday I noted it idled in drive mildly roughly, otherwise drove normally.
This AM I drove it to work to take to the mechanic and the check engine light came on.

The independent mechanic says it is a "burnt valve" which they have only seen one other time outside of a broken timing belt or something else which isn't the case. The cost will be about $1400. Nobody really knows why it would do this although the gal I spoke to was talking a bit about non-OEM sparkplugs (put in by my mechanic in Vancouver at the last tune-up) being "bad for the car". They replaced them and the wire. Right now I'm in for $150 to drive it away. $1400 to replace the valve and head gasket on one side.

I called the Subaru dealer. He says he's never experienced a burnt valve on an Outback. He's not sure how the independent guy diagnosed it as a "burnt valve" and has some question that that's the right diagnosis. He says it would be a minimum of $99 and potentially more just to diagnose the problem. He says there is no way in his mind spark plugs could have been the cause.

Here's my question. I feel helpless not having enough knowledge about things to know who to trust. The last thing I want is to do the $1400 repair and then have a similar problem in 20,000 miles (or sooner) because the root problem was not discovered. Then I have to do it all over again plus fix the root. What questions should I be asking the independent guy to get a feel for how sure we are this fix will fix everything? Should I take it to Subaru for a second opinion which will cost me time and money? I'm planning on driving to Whitefish, Montana on the 23rd and I want this fixed by then, so time is a bit of an issue.

Reaching out to the mechanics! Give me your best shot there ' . substr('//www.dpchallenge.com/images/user_icon/21.gif', strrpos('//www.dpchallenge.com/images/user_icon/21.gif', '/') + 1) . ' MattO!

Message edited by author 2009-07-14 15:00:26.
07/14/2009 03:10:48 PM · #2
Not a mechanic, but if Subaru will do a diagnostic for 99 bucks, it may add 99 to the cost, but if the total repair fixes the root and is less than 1400, you saved a bunch of money and you didn't even need Gieco to do it.
07/14/2009 03:20:01 PM · #3
Originally posted by CEJ:

Not a mechanic, but if Subaru will do a diagnostic for 99 bucks, it may add 99 to the cost, but if the total repair fixes the root and is less than 1400, you saved a bunch of money and you didn't even need Gieco to do it.


You didn't note the mechanic parlance of "a minimum of $99"...
07/14/2009 03:24:02 PM · #4
I would just outright tell the mechanic where you have it that your research isn't collaborating with their diagnosis, and that you'll have to take it for a second opinion. Also, if they replaced something that you didn't give your consent to, you aren't actually liable for those costs. Anything beyond the initial inspection needs your OK.

Get it looked at by someone else, but not a dealer! heh.
07/14/2009 03:34:21 PM · #5
Originally posted by K10DGuy:

I would just outright tell the mechanic where you have it that your research isn't collaborating with their diagnosis, and that you'll have to take it for a second opinion. Also, if they replaced something that you didn't give your consent to, you aren't actually liable for those costs. Anything beyond the initial inspection needs your OK.

Get it looked at by someone else, but not a dealer! heh.


Well, this is my dilemma. :) I like the independent mechanic types, but being in Eugene only a year these guys are the closest I have to a "trusted source". I usually avoid the dealer mechanics like the plague.

I guess I'm a bit annoyed that he changed the plugs, but in the end he's probably goofed with it for an hour and it would be lame to drive it away for nothing, so maybe $150 is reasonable. What I don't like is goofy talk about spark plugs being able to do this if that's not the case. That doesn't inspire trust or confidence.
07/14/2009 03:36:53 PM · #6
Originally posted by DrAchoo:

Originally posted by K10DGuy:

I would just outright tell the mechanic where you have it that your research isn't collaborating with their diagnosis, and that you'll have to take it for a second opinion. Also, if they replaced something that you didn't give your consent to, you aren't actually liable for those costs. Anything beyond the initial inspection needs your OK.

Get it looked at by someone else, but not a dealer! heh.


Well, this is my dilemma. :) I like the independent mechanic types, but being in Eugene only a year these guys are the closest I have to a "trusted source". I usually avoid the dealer mechanics like the plague.

I guess I'm a bit annoyed that he changed the plugs, but in the end he's probably goofed with it for an hour and it would be lame to drive it away for nothing, so maybe $150 is reasonable. What I don't like is goofy talk about spark plugs being able to do this if that's not the case. That doesn't inspire trust or confidence.


It most certainly doesn't. I've been bitten way too much lately, and had to change mechanics myself right over the last little while. Now I'm way more careful. The fact that they're so quick to take advantage of people that don't know any better makes me so darn freaking angry.

Message edited by author 2009-07-14 15:37:07.
07/14/2009 03:50:32 PM · #7
Pay $99+ and go have someone else look at it!! If it's emissions related, you should still have some warranty left. (Most are 8/80,000 on the exhaust.(Called my hubby - mechanic) Thoughts are the car would have been running rough and the check engine light would have come on before this if the valve truly were burnt. (You wouldn't really smell anything with a burnt valve.) Just from reading this to him, he said it could be an O2 sensor issue. If it's sensing a lean condition, it's dumping fuel into the engine to try and correct. He definitely said something sounds odd with this.

His disclaimer is that it will depend on whether or not you smelled exhaust or smelled raw gas. Guess that indicates different things.

Don't know if this helps, but I'd pay the diagnosis for someone else to look at it!!! THEN decide what you want them to do. Sounds like the Independent is doing things and then telling you how much you owe.
07/14/2009 03:50:41 PM · #8
A duff spark plug will cause lumpy running. There was a time a few years ago when a certain make of spark plug just would not spark properly in Vauxhall or Ford cars. Both manufacturers used Bosch and cars would run as smooth as silk. Stick a *..* plug in and you had a car that ran like a tractor diesel engine. So, there is an element of truth that a plug could be part of the problem.

I am not a trained mechanic, but have spent most of my life repair, rebuilding and generally mucking about with cars, tractors, motorbikes etc. However, if the engine/ignition light comes on, it could be the engine is close to stalling, or is pointing towards an electrical problem. A failing altenator will cause the engine light to come on.

It is possible to burn out a valve which would make the engine running roughly. I don't see that a burnt valve would necessitate a new head gasket?? Check oil and water to see if there is a mixture of both in sump/radiator, this will indicate that the head gasket is blown allowing water to seep through the break into the oil channels.

Just my thoughts:))
07/14/2009 04:05:01 PM · #9
firstly I am not a mechanic, nor have I had any training but I have re-built a few engines in my time.

A faulty plug could cause the engine to run lumpy but there should be nothing wrong with non-oem plugs at all. A faulty plug can't really cause any damage I can think of at all, one cylinder just would not fire properly, the engine would idle poorly and you would get a smell. In fact I would be surprised if any car manufacturers actually made their own plugs, they will have someone like NGK, champion etc make them for them.

I have to admit I've never heard of a "burnt valve" before but I cannot see how that could set off the engine check light. The engine check light is an electronic check on the ecu and sensors and if one cylinder is not firing correctly the lambda sensor (in the exhaust) could be getting odd readings though that sensor is really is only used when cruising at a steady throttle. Maybe there is another sensor that has been set off.

If the plugs have been changed again then I would drive the car away and see how it goes. If the engine check light then pop it to subaru who will plug it in a read off the fault code and reset the light. Personally I would drive the car and if it is running ok I would wait and see if the light goes off. Often once triggered they will stay on until reset or they will reset themselves after a few days.

You would need to change the head gasket if the head is taken off to change a valve, you could not reuse the head gasket. The price will be mainly labour, the gasket itself would be fairly cheap.
07/14/2009 04:07:22 PM · #10
I'm certified to work on motorcycle motors and small engines, and have worked "unofficially" on larger vehicles for years. So, take my advice for whatever you think it is worth...

First, I'd ask for much more detail on the original diagnosis. Are you sure he said "burnt" value vs. "bent" valve -- one is much worse than the other. Assuming it is "burnt" valve they are asserting is wrong...

- How did they come to this conclusion, specifically? To completely isolate a valve leak around the stem seal (which is the actual issue with what some call a "burnt" valve) takes a lot of work.
- Which valve or valves, specifically are supposedly "burnt"? The actual timing position is not as interesting as to if they are intake or exhaust valves.
- What is the underlying cause of the valve seal issue? Has the stem seal completely failed? Is the valve/rocker clearance out of spec (if so, is it too tight or too loose? Has the clearance issue caused damage to the cam face?)? Does the valve have significant, obvious deposits along the stem?
- Is there other evidence of what may have caused the stem seal failure (obvious signs of overheating, etc)?

If the diagnosis is correct, and you have a leaking valve stem seal, it's very important to isolate and correct the underlying cause. Simply replacing the valve may not be "everything" you need (although the actual activity of replacing the valve may include the appropriate action, such as correcting the valve/rocker clearance). However, if there is further underlying damage (such as the cam surface, for example), simply adjusting clearances will only cover-up a much more serious issue, and you'll be in the same position again very soon.

Some shops/techs may just throw around terminology like "burnt valve" without really meaning the strict definition as well (intentionally or not), and they might really mean you have any number of other valve-train related issues.

The assertion that the wrong spark plugs would cause burnt valves is not entirely without merit. If, for example, you used the wrong heat-range plug... and mis-sized it... and had a bad cable... and a timing issue... errrrr, let me pile on some more stuff here... that caused enough of a timing and/or overheating issue, that *could* cause a valve stem seal to fail... But that's a real stretch, and would require a LOT of really specific "proof" before I'd believe it.

That aside, you just paid $150 for new plugs and a wire? (Hopefully a whole set of wires, not just one)? Whew, that's like MAYBE $50 of parts and 1/2 hr of labor. Thus, I'm reminded why I do all my own work. ;)
07/14/2009 04:32:08 PM · #11
So, ok, an update. (Thanks so far for the information. I at least learn stuff on threads like this.)

I talked with the owner who was also the guy doing the diagnosing. He agrees it's a weird thing. He has no confidence it's the sparkplugs or wires, but he says over the years when he sees Autolite plugs he's always been best to throw them away. There was a mild abrasion on the #2 wire which is also the misfired cylinder. What he says is interesting is there is only one error code on the computer and that was the misfired cylinder. He says burnt valves usually come from a lean mixture but the Subaru computer is quite sensitive about this that the check engine light would have been on longer. I am positive it only came on this morning when I came to work.

So his price so far is $1400ish, but he will also replace the timing belt and water pump and other smaller tubes or seals because the engine has been removed and it makes little sense not to do those things. After a bit of talking I understand what he's on about there and agree with him. I kept coming back to whether there was an underlying problem that we aren't seeing and he kept saying he doesn't think there is one partly because there were no other error codes on the computer.

He diagnosed the burnt valve with a "leak down" test. He said he couldn't get smoke to go through the system but could definitely get compressed air through. He checked the valve on the other side and while I can't remember the specific numbers there was a large difference in the compression. This last paragraph is mainly me just parroting stuff I don't quite understand.
07/14/2009 04:44:10 PM · #12
You'd notice a distinct faltetr in the performance and possibly a dead flat miss with a burnt valve.

In these days of variable valve timing, multi-valve engines, and emissions, cylinder leakdown tests are VERY hard to perform and don't always tell the truth.

You're better off having an engine power balance test done by a competent driveability specialist.

Like it or not, the Subaru dealer is best equipped to tell you what's wrong with the car, and despite the natural inclination to mistrust dealers, they have access to proprietary information they do not have to release.

BTW, with OBD II, a burnt valve would probably have set a good half-dozen trouble codes.

Personally, I would check around for the local witch doctor.......there's ALWAYS one guy around who is the go-to guy for all of the regular shops in the area.....he's that person who is intuitive, knowledgeable, and gets off on the problem children that scare the crap out of the rest of the techs in the area.....try and get your guy to refer you to get an accurate diagnosis.

The second best idea would be to have Subaru look at it.

BTW, and I know this is closing the barn door after the horse got loose potentially, but the entire time I worked on cars, I *ALWAYS* used OEM parts......it's REALLY hard to get into trouble using what the manufacturer recommends.......and ensures that any warranty consideration won't be kicked to the curb for using Brand X stuff.

There are some exceptions, but they are so few and specialized that using the OEM guideline really does keep you out of the woods.

Of course, this is just my opinion....YMMV....
07/14/2009 04:51:14 PM · #13
I bet people feel like this when they go to the doctor...
07/14/2009 04:58:39 PM · #14
Originally posted by DrAchoo:

He diagnosed the burnt valve with a "leak down" test.


Incomplete diagnosis, or at least incomplete information. Compression and/or leak down tests will give a positive confirmation you have a broken seal in your compression chamber, but it does not show you where the leak actually is. The compression chamber could leak from the piston rings, valve stems, valve seats, or even (although unlikely) a crack in the cylinder wall itself. I'd press him to understand how he conclusively determined it was a valve stem seal failure (I'm not saying he didn't -- but so far you haven't repeated enough information from him to conclusively isolate a stem seal in my opinion).

I will say this (and it's not good news) -- assuming the test was performed correctly, and you do have a substantial compression-chamber leak, whatever the cause, you've got a moderately series problem. Regardless of what this first technician comes back to you with, I could get a second or even third opinion. If you have someone else fix this (vs. doing it yourself, which I don't recommend if you don't work on motors), you're going to be paying for a heap of labor time, and I'd get at *least* two "matching opinions" from independent sources before sinking that much money into it.
07/14/2009 04:59:55 PM · #15
I am betting on the skip being the chafed wire and your rich idle and off running being an o2 sensor. Take Jeb's advice and if you want it fixed correctly, take it to the dealer.
07/14/2009 05:02:11 PM · #16
Heh. I'm a do-it-yourself guy to the core, but there's no way I'd even think about something like this. So maybe the mechanic is using "burnt valve" loosely. We know the problem is in cylinder #2. We know it doesn't have compression.

The problem with taking it to the dealer is the unknown expense of diagnosis plus the time factor. They can't look at it today and maybe can look at it tomorrow and I want it by the 23rd.
07/14/2009 05:02:28 PM · #17
I googled the issue and got sent to a Subaru owners group website, and a number of threads there would suggest that the likely root culprit is the O2 sensor, for what that's worth. I've lost the site now, but I googled "subaru outback burnt valve" and found a wealth hits.

R.

Message edited by author 2009-07-14 17:02:53.
07/14/2009 05:04:06 PM · #18
Originally posted by Notroubles:

I am betting on the skip being the chafed wire and your rich idle and off running being an o2 sensor. Take Jeb's advice and if you want it fixed correctly, take it to the dealer.


Wouldn't a bad O2 sensor send off codes galore and wouldn't the check engine light have been on longer?

Another issue with taking it to Subaru is, in my limited understanding, to REALLY diagnose the problem you have to see the valve itself which involves taking things apart anyway which involves $$$, so I'm not really ahead of the game.

Message edited by author 2009-07-14 17:09:00.
07/14/2009 05:39:31 PM · #19
Just to be clear, assuming the leak-down/compression test was done correctly, that's done with the engine physically "off" and actually rotated to a timing position where the cams are in position to physically close the valves so the combustion area is sealed.

In other words, assuming the test was done correctly and accurately, there is no possible relation to any other sensors or engine components -- it's a failure to have a sealed compression chamber, which is a physical issue; not the effect of any other system.

The shorting plug wire, faulty O2 sensor, or any other cause of timing or air/fuel mixture issues, might have contributed to the failure (and should be investigated and repaired), but the failure to have a sealed compression chamber is a pretty serious issue that will need to fixed independent of any other system.

I hope the test was performed incorrectly, and you had a valve open due to an incorrect timing position during the test itself. But that's just me hoping.

ETA:

Originally posted by DrAchoo:

Another issue with taking it to Subaru is, in my limited understanding, to REALLY diagnose the problem you have to see the valve itself which involves taking things apart anyway which involves $$$, so I'm not really ahead of the game.


The stem of the value may be observed and inspected superficially by removing the valve covers, assuming your motor design allows that (I'm not familar with the specific motor for your vehicle -- some of the newer designs make some, ummm, "compromises" for accessibility to gain space savings...), and could thus be inspected for any obvious issues, and the superior surface of the valve seal could be observed during a pressure test to verify the actual leak. You cannot inspect the *entire* contact-length of the stem using that method of visualization, but it is much easier than pulling the head to physically remove the valve for inspection.

Alternatively, the valve would have to be removed by pulling the head, and dropping the value into the head/chamber. That's some serious work at that point.


Message edited by author 2009-07-14 17:52:43.
07/14/2009 05:45:35 PM · #20
How many miles on the car? Or did I miss that?

A failed compression test can be many things but is bad news either way. For $30 you can get a compression tester at harbor freight and test the compression yourself in as much time as it takes you to pull the spark plugs and put them back. If you have any doubts about this mechanic i'd do that. it's an easy process (I checked my boat Friday, horrible access and 8 cyliners and it took 30 minutes). You may be able to rent a compression checker from your local auto store also?
07/14/2009 05:55:52 PM · #21
72,000 miles. Just past the warranty. :)
07/14/2009 06:05:54 PM · #22
If it's just past the warranty I'd take it to the dealer and be very angry. I've heard of them extending a warranty a couple thousand miles for major problems that should not happen (like a burnt valve!).
07/14/2009 06:06:13 PM · #23
Well, I'm going to make the assumption he did the leak down test correctly. It does me little good to start questioning him on this stuff when I got no clue myself. In my 20 minute talk with him I at least judge him to be a honest guy. Competence is harder to guess at when you have little experience yourself.

I told him to go for it with a large dash of "cross your fingers". I'm giving it a 50/50 we find something else when it gets opened and I am also 50/50 as to whether that would be a good thing. On the good side it might mean a cause and a completely picture, on the other hand, who knows the price...
07/14/2009 06:21:03 PM · #24
At least they have good reviews on Car Talk which is where I found them in the first place.
07/14/2009 06:29:48 PM · #25
Hmm...gotta love Car Talk!
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