1999 Subaru Legacy Outback no compression in #4

[wjsinger]

First off I would like to say hi and thanks for any help you all can offer! I have looked all over this forum and don't see an issue quite like mine. If I am posting this in the wrong spot, or there is a thread already made that will help me out please let me know.  

 

So my wife's BFF just moved to Las Vegas from Washington State. She has a 1999 Subaru Legacy Outback with the 2.5L DOHC motor in it, that she recently purchased before her move. The seller told her that they did a full tune up just before putting it up for sale. After she got here to Las Vegas she took it to get smogged so she could get NV plates for it. It failed the smog test. They gave her a list of the OBD2 codes (too many to list). Basically misfire in every cylinder, knock sensor, and a few others.  And told her it would cost about $1,000 to get it fixed.  That's where I come into the story. I looked into it and decided that I would help her out.

 

What I did 1st:

 

 1)   Full tune up, consisting of new NGK plugs and wires, pcv valve, oil change, air filter, gas filter and ran some Lucas fuel injection cleaner through the system.

 

2)   Replaced the knock sensor (per the OBD2 code)

 

When replacing the "NEW" spark plugs I found that it had 3 different spark plugs in it.... and that the #4 cylinder was cross threaded. 

 

What I did 2nd:

 

1) I went and bought the proper sized tap and fixed the threads and finished the tune up.

 

2) Reset the CPU.

 

After a couple of days I rechecked the OBD2 codes. At this time we found only 2, P304 and another that I can't remember (No check engine light present). After some tinkering I found little to no spark in the #4 cylinder and decided that the coil pack was bad. 

 

What I did 3rd:

 

1) Replaced the dash light bulb, found that someone had removed it so it didn't show that it was on when selling it. They couldn't even be nice and put the little bulb holder back into the instrument panel (What nice guys).

 

2) Replaced the bad coil pack with a new one

 

3) Reset the CPU

 

After a couple of more days I rechecked the OBD2 codes and found just one, that evil P304 code! Not sure where to go next I told the owner that I would have to do some more research on it. She decided to take it to a Mechanics shop and have a full diagnostic done on the issue. $100 later he told her that cylinder #4 had no compression and that it was a bad motor. She called me at this time to let me know what he had said, I had her ask if it could have to due with the spark plug not being seated properly due to the previous cross threading issue. He said "Nope" it needs a new motor...

 

Now if this had been any other cylinder than the one that had been cross threaded I would have been less likely to question his findings and opinions.

 

Please if you have any ideas or suggestions please let me know, also if you think that I am barking up the wrong tree I would like to know that too. Again thanks for any and all help you may be. 

[lmdew]

Start it up and put a $1 bill up to the exhaust pipe.  If it sucks up against the outlet you most likely have a bent valve.

 

Easy fix for a bad 96-99 DOHC engine is to swap in a good old 95 2.2 with EGR.  Plug and Play for the most part.  You can use other years as long as you get the single port y-pipe and or put the correct intake on it.

[john in KY]

Could be a burnt exhaust valve. #4 cylinder has a history of this for some reason. 

[idosubaru]

Could be a burnt exhaust valve. #4 cylinder has a history of this for some reason. 

this.  i would suspect a burnt exhaust valve. 

 

if it was the spark plug cross thread you'd still have some compression, it would just bleed some of it off but still make some compression.  it wouldn't be zero. 

 

if it's bleeding pressure through the spark plug you should be able to hear it when turning by hand or feel it by putting your finger over the spark plug hole.   but again, i highly doubt that it would have a slight leak and show zero compression, this would only be for an ominous spark plug failure which seems unlikely.

 

EJ22 swap is the best bet.  can probably reuse the knock sensor on the new EJ25.

 

 

alternately and possibly a little cheaper is to install a used head on that side of the engine.  ideally the heads are resurfaced and new Subaru headgaskets installed on both sides due to the proclivity of that engine to have headgasket issues. 

[wjsinger]

this.  i would suspect a burnt exhaust valve. 

 

if it was the spark plug cross thread you'd still have some compression, it would just bleed some of it off but still make some compression.  it wouldn't be zero. 

 

if it's bleeding pressure through the spark plug you should be able to hear it when turning by hand or feel it by putting your finger over the spark plug hole.   but again, i highly doubt that it would have a slight leak and show zero compression, this would only be for an ominous spark plug failure which seems unlikely.

 

EJ22 swap is the best bet.  can probably reuse the knock sensor on the new EJ25.

 

 

alternately and possibly a little cheaper is to install a used head on that side of the engine.  ideally the heads are resurfaced and new Subaru headgaskets installed on both sides due to the proclivity of that engine to have headgasket issues. 

Thanks all for the info, I will try the dollar bill trick and try to turn it by hand to see if I hear it. I was not there when the guy did the compression test, so it could be just low and told her that it had "no compression". For all I know it could be like one of them telephone games we all played in grade school, he may have said low compression. 

 

Anyone know if that harbor freight compression tester is any good? I don't have a compression tester of my own and can't see needing one often. Only once every few years...

[Bushwick]

A more reliable way of checking for bad valves is to connect a $15 vacuum gauge (get it at parts store, they can be used for LOT of future engine diagnosis issues) to the engine (use a " T " connector if needed, do NOT connect to the fuel pressure regulator line) and observe what the needle does at idle after engine is fully warmed up.

 

Use this as reference: http://www.gregsengine.com/using-a-vacuum-gauge.html  scroll down as they have a generic chart. Dunno how far above sea level you are, but that can alter vacuum readings slightly vs. what that chart lists. Big thing is what the needle tells you.

 

If her plates are still current from Washington, tell her to leave them on and keep it insured. Technically, if stopped by police (assuming they aren't expired from Washington sticker) she can say she travels back and forth between states and is considering a permanent move. This will/should stop her from getting ticketed while the engine is sorted.

 

In the meantime, you need to figure out if the issue is in the head (bad valves, etc.) or piston ring related. If it's not puking burnt oil out the pipe, it's hopefully head related and easily fixed.

 

You can replace the head yourself, for little money. Would need a new head gasket, and an exact head match for ease. Dunno if cam profiles are significantly different across various EJ25 heads or not, so ask around. Biggest thing with a used head is making sure it's not warped, and make sure is has oil on the important bits before installing.

 

I'd replace the head before replacing the entire engine. On the other hand, I can get EJ22 and EJ25 engines all day long for $150 from a local Pull-A-Part. Being the state you are in where everyone owns new cars, you might get lucky with inexpensive engines abound in your area, so a full engine swap isn't too painful.

 

Good on you though for being a stand up helper. Sounds like she got scammed from an jerk offloading (she probably would have been better off taking you with her to buy a car, go with her on next buy ) a car he new was going out of state. My mom did a cross country move once, so I can't help but feel sorry for this woman as that's a big deal to up and move, and having a car with serious issues has to be really stressful for her.

[Fairtax4me]

No compression on one cylinder would create a dead misfire and make it shake like crazy at idle and feel very underpowered when driving.

 

You can unplug fuel injectors one at a time and see if the idle changes.

Buy or rent a compression guage set and do a compression check yourself.

 

Not uncommon for that engine to burn exhaust valves, but If nothing else I would take it to another shop and get a second opinion.