Drivetrain No Compression cyl#3
No Compression cyl#3
Driving in to work this am check engine light comes on and throws P0303 code.
Pull plug on cyl # 3 and the entire center post has fallen out and disentegrated.
Compression check on cyl 3 is 0.
What's the easiest way to tell if it is a head/valve issue or piston without completely tearing the head off? Or is that pretty much impossible to tell without taking the head off.
Pull plug on cyl # 3 and the entire center post has fallen out and disentegrated.
Compression check on cyl 3 is 0.
What's the easiest way to tell if it is a head/valve issue or piston without completely tearing the head off? Or is that pretty much impossible to tell without taking the head off.
6th Gear
Joined: Jun 2006
Posts: 4,165
Likes: 400
lemme see if i heard you
1. when the plug was removed it was substantially damaged, including a missing center electrode
2. a compression test of the same cylinder pumped zero pounds
questions...
a. did that plug get so chewed up that the cylinder was essentially open to the atmosphere? in other words, was the hole in the plug right out to the lead?
b. any odd noises at cranking speed?
suggestion...
the usual way to try and determine whether low compression is valves or rings is to first test the compression without adding anything to the cylinder (the "dry test") and then secondly to place a few cc's of motor oil into the cylinder through the plug opening, and then turn the motor over using the starter to distribute the oil to the edges of the cylinder - on the top of the rings - and then finally to repeat the compression test again
if the rings are worn, the 2nd test (the "wet test") will pump a significantly higher number than the dry test
if the valve seats or valve operating mechanisms are the problem, the two numbers will be close or identical
FWIW my guess is the head - which will have to be pulled anyway. with the head off you'll know, and if the piston is eaten the repair work is at that point well started...
bloody pain mate - sorry
1. when the plug was removed it was substantially damaged, including a missing center electrode
2. a compression test of the same cylinder pumped zero pounds
questions...
a. did that plug get so chewed up that the cylinder was essentially open to the atmosphere? in other words, was the hole in the plug right out to the lead?
b. any odd noises at cranking speed?
suggestion...
the usual way to try and determine whether low compression is valves or rings is to first test the compression without adding anything to the cylinder (the "dry test") and then secondly to place a few cc's of motor oil into the cylinder through the plug opening, and then turn the motor over using the starter to distribute the oil to the edges of the cylinder - on the top of the rings - and then finally to repeat the compression test again
if the rings are worn, the 2nd test (the "wet test") will pump a significantly higher number than the dry test
if the valve seats or valve operating mechanisms are the problem, the two numbers will be close or identical
FWIW my guess is the head - which will have to be pulled anyway. with the head off you'll know, and if the piston is eaten the repair work is at that point well started...
bloody pain mate - sorry
lemme see if i heard you
1. when the plug was removed it was substantially damaged, including a missing center electrode
*******correct
2. a compression test of the same cylinder pumped zero pounds
*******correct
questions...
a. did that plug get so chewed up that the cylinder was essentially open to the atmosphere? in other words, was the hole in the plug right out to the lead?
*******no just the electrode and insulating material
b. any odd noises at cranking speed?
********none.
suggestion...
the usual way to try and determine whether low compression is valves or rings is to first test the compression without adding anything to the cylinder (the "dry test") and then secondly to place a few cc's of motor oil into the cylinder through the plug opening, and then turn the motor over using the starter to distribute the oil to the edges of the cylinder - on the top of the rings - and then finally to repeat the compression test again
if the rings are worn, the 2nd test (the "wet test") will pump a significantly higher number than the dry test
if the valve seats or valve operating mechanisms are the problem, the two numbers will be close or identical
FWIW my guess is the head - which will have to be pulled anyway. with the head off you'll know, and if the piston is eaten the repair work is at that point well started...
bloody pain mate - sorry
1. when the plug was removed it was substantially damaged, including a missing center electrode
*******correct
2. a compression test of the same cylinder pumped zero pounds
*******correct
questions...
a. did that plug get so chewed up that the cylinder was essentially open to the atmosphere? in other words, was the hole in the plug right out to the lead?
*******no just the electrode and insulating material
b. any odd noises at cranking speed?
********none.
suggestion...
the usual way to try and determine whether low compression is valves or rings is to first test the compression without adding anything to the cylinder (the "dry test") and then secondly to place a few cc's of motor oil into the cylinder through the plug opening, and then turn the motor over using the starter to distribute the oil to the edges of the cylinder - on the top of the rings - and then finally to repeat the compression test again
if the rings are worn, the 2nd test (the "wet test") will pump a significantly higher number than the dry test
if the valve seats or valve operating mechanisms are the problem, the two numbers will be close or identical
FWIW my guess is the head - which will have to be pulled anyway. with the head off you'll know, and if the piston is eaten the repair work is at that point well started...
bloody pain mate - sorry
1. when the plug was removed it was substantially damaged, including a missing center electrode
*******correct
2. a compression test of the same cylinder pumped zero pounds
*******correct
questions...
a. did that plug get so chewed up that the cylinder was essentially open to the atmosphere? in other words, was the hole in the plug right out to the lead?
*******no just the electrode and insulating material around the electrode
b. any odd noises at cranking speed?
********none.
I'll try the wet test. Thanks for that suggestion!
Just pull the valve cover and take a peek. Put it in 1st gear and pull/push you MINI(rotate crank) to see if you've got valve issues in cylinder 3. You could pop it up on jack stands and put a socket on the crank pulley in neutral to rotate your motor too. Sorry to hear of your nil compression.
Jeremy
Jeremy
6th Gear
Joined: Mar 2006
Posts: 1,710
Likes: 1
From: Northampton MA
Trending Topics
what was the compression in the other cyl.? or did you discover the bad plug and immediately throw your gauge on it ? just thought maybe to check the gauge . 0 is awful . that's like a hole in piston type territory . sorry to hear it ,.
2nd Gear
Joined: Jun 2007
Posts: 143
Likes: 0
From: Lindenhurst, Long Island NY
I had low compression on cylinder#4 80lbs verses other cylinders being 130. thought we cracked an exaust valve but when we got the head off the piston had a chunk missing from it. this was due to running lean. had lots of mods, but no higher injectors to compensate
6th Gear
Joined: Mar 2006
Posts: 1,710
Likes: 1
From: Northampton MA
A 0303 is a misfire, you knew that, but, it is suprising there were no other codes.
Any piston damage from detonation will leave some evidence on the plug. A valve or seat would not.
You would think the upstream o2 sensor would have detected a lean condition before this failure. A valve or seat would not cause a lean condition = 0303.
Either way the head needs to come off.
Any piston damage from detonation will leave some evidence on the plug. A valve or seat would not.
You would think the upstream o2 sensor would have detected a lean condition before this failure. A valve or seat would not cause a lean condition = 0303.
Either way the head needs to come off.
6th Gear
Joined: Jun 2006
Posts: 4,165
Likes: 400
Oh Sh*t mate -- hope I'm wrong...
Ouch ouch ouch.
I'm afraid that looks like way too much heat and shock to be ought but severe detonation. That tells me that my hope of finding a burnt valve seat or something jamming a valve ajar was too optimistic.
I'm very sorry to say that I expect when the head comes off you'll find the need to at least replace a piston.
I am stunned by the damage, the symptoms, and the very short time frame. The only thing I could imagine could cause such a selective and immediate failure would be a clogged or problematic fuel injection nozzle. In such a case I could imagine an extreme lean condition arising fairly suddenly.
Ouch again!
Hope I'm wrong.
I'm afraid that looks like way too much heat and shock to be ought but severe detonation. That tells me that my hope of finding a burnt valve seat or something jamming a valve ajar was too optimistic.
I'm very sorry to say that I expect when the head comes off you'll find the need to at least replace a piston.
I am stunned by the damage, the symptoms, and the very short time frame. The only thing I could imagine could cause such a selective and immediate failure would be a clogged or problematic fuel injection nozzle. In such a case I could imagine an extreme lean condition arising fairly suddenly.
Ouch again!
Hope I'm wrong.
6th Gear
Joined: Mar 2006
Posts: 1,710
Likes: 1
From: Northampton MA
That plug was WAY hot.
If you look at the melted parts on the end of the plug there is more material than just the plug. There should be some aluminum, in the mix, from the piston. cmt52663 has a good theory in that the #3 injector failed, have it tested, I'd bet it's bad. Are your injectors JCW's ( 380 )? I am assuming they are from your sig.......
The bad news is you need a piston. With some luck the cylinder wall is not damaged ( this would happen if the ring lands melted & left the ring to score the cylinder ). By the looks of the plug, the heat was in the center of the combustion = hole in the piston.
If you look at the melted parts on the end of the plug there is more material than just the plug. There should be some aluminum, in the mix, from the piston. cmt52663 has a good theory in that the #3 injector failed, have it tested, I'd bet it's bad. Are your injectors JCW's ( 380 )? I am assuming they are from your sig.......
The bad news is you need a piston. With some luck the cylinder wall is not damaged ( this would happen if the ring lands melted & left the ring to score the cylinder ). By the looks of the plug, the heat was in the center of the combustion = hole in the piston.
Joined: Feb 2003
Posts: 1,754
Likes: 36
From: Metro Detroit Area, Michigan
look at the oil also and see if it smells like raw fuel. if you have a big hole in the piston, it will be just dumping fuel into the oil pan. it looks like you are going to have to pull the head to see what is going on, but a bore scope will help without pulling the head.
but a bad valve will need the head to be removed. if you have to replace a piston, replace all 4 with better ones and depending on the miles, your better to replace the bearings and upgrade to some ARP rod bolts.
but a bad valve will need the head to be removed. if you have to replace a piston, replace all 4 with better ones and depending on the miles, your better to replace the bearings and upgrade to some ARP rod bolts.
__________________
6th Gear
Joined: Mar 2006
Posts: 1,710
Likes: 1
From: Northampton MA
"if you have to replace a piston, replace all 4 with better ones and depending on the miles, your better to replace the bearings and upgrade to some ARP rod bolts." very good advice.
Either way, the head is going to come off. Unfortunately I don't think there was a valve failure, there is too much evidence on the pulg that suggests piston.
Either way, the head is going to come off. Unfortunately I don't think there was a valve failure, there is too much evidence on the pulg that suggests piston.
Joined: Feb 2003
Posts: 1,754
Likes: 36
From: Metro Detroit Area, Michigan
you know it's also better to just upgrade to a RMW head and not rebuild the JCW head.. lol 
if that is what it is...
if that is what it is...
__________________
Why guess when you can find out for sure.
4th Gear
Joined: Aug 2002
Posts: 510
Likes: 0
From: Orange Park, Fl.
A Friend lost number 4 cylinder!! dry was 40 psi/wet was 60 PSI!! He NEVER went to a colder plug when he went to 17% boost!! He has a CAI/ cat back exhaust ported head..blah blah!! The issue here is you have to drop the heat range when you boost!! HAVE TO!! colder t-stat also, and get a read on your a/f!! Not that this was your issue... but detonation will kill ya!! yes??Just me..........................Thumper
other 3 plugs had minor damage.
I have the unichip with a tune for jcw. CAI and larger intercooler.
I don't have the jcw injectors since mine aren't blue in color but tan.
I belive the pistons are probably shot so I've contacted Webbmotorsports and will get it in to him for complete diagnosis and repair.
I agree that it probably isn't the head now.
Thanks for all the input.
I'll keep everyone posted as to results.
I have the unichip with a tune for jcw. CAI and larger intercooler.
I don't have the jcw injectors since mine aren't blue in color but tan.
I belive the pistons are probably shot so I've contacted Webbmotorsports and will get it in to him for complete diagnosis and repair.
I agree that it probably isn't the head now.
Thanks for all the input.
I'll keep everyone posted as to results.
6th Gear
Joined: Mar 2006
Posts: 1,710
Likes: 1
From: Northampton MA
With a JCW tune you need the JCW injector. This would be the "how". The "why" would be the duty cycle of the "S" injector. The plugs were also a big contribution as they ran much too hot. It's strange that there was no run on after shutting the car off. Those plugs got very hot........
Why the ECU did not see such a lean condition is of note. The EGT had to be way high given the look of the plug posted. There should have been a code & possibly "limp mode".
Possibilty 2:
When the engine is taken apart look for an air intake leak. A broken hose, old cracked hose... This failure, as you describe, is more sudden than the spark plug is telling me & the ECU reaction is not what I'v seen.
You'll know more after you get it apart. If it's not too much trouble have the injectors tested.
Why the ECU did not see such a lean condition is of note. The EGT had to be way high given the look of the plug posted. There should have been a code & possibly "limp mode".
Possibilty 2:
When the engine is taken apart look for an air intake leak. A broken hose, old cracked hose... This failure, as you describe, is more sudden than the spark plug is telling me & the ECU reaction is not what I'v seen.
You'll know more after you get it apart. If it's not too much trouble have the injectors tested.
6th Gear
Joined: Jan 2005
Posts: 2,223
Likes: 0
From: DC
Ouch! Confiming what others have said:
1. Lacking adequate injection was the primary cause of failure.
2. The warm plugs contrbuted significantly.
3. The bore scope will help you determine the extent of the damage, but you might as well just start pulling pieces. At the very least either the engine ore the head or both will need to be rebuilt. With the detonation you have experience (not to mention the big chunk of spark plug sucked into the engine) at least one if not all of the pistons will need to be replaced.
You might want to consider a used engine salvaged from a wreck. Or if money is not an option, pull the engine and have it built into a monster by a good builder.
1. Lacking adequate injection was the primary cause of failure.
2. The warm plugs contrbuted significantly.
3. The bore scope will help you determine the extent of the damage, but you might as well just start pulling pieces. At the very least either the engine ore the head or both will need to be rebuilt. With the detonation you have experience (not to mention the big chunk of spark plug sucked into the engine) at least one if not all of the pistons will need to be replaced.
You might want to consider a used engine salvaged from a wreck. Or if money is not an option, pull the engine and have it built into a monster by a good builder.