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Old 09-28-2010, 10:17 AM   #1
jays05
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Default Help read my plugs (aka, complete engine destruction)




Last edited by jays05; 05-02-2011 at 04:52 PM.
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Old 09-28-2010, 11:17 AM   #2
CatfaceType-R
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lol...poor j
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Old 09-28-2010, 11:30 AM   #3
juanmedina
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I haven't seen jay post in a long time, I was wondering the other day if everything was ok

Whats the damage? are you going to rebuilt again? or sell the thing?

I am very very
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Old 09-28-2010, 11:34 AM   #4
jays05
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The motor had 5k miles on it. We were gonna pull it to fix a minor HG leak. I drove the car for the first time in two months, and that happened while I was rolling away from a stoplight. There's no coolant in the oil or anything so I'm guessing it dropped a valve again (coated supertech valves, ferrea springs).

I'm ready to pull the motor and as soon as a buddy lends me his cherry picker I'll have it out and apart. I'm probably going to rebuild it myself this time.
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Old 09-28-2010, 11:43 AM   #5
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ok, this is motor number 6, correct?
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Old 09-28-2010, 11:48 AM   #6
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This is really only the second built motor, but the first one had a number of failures... a broken cam, a blown hg, and then a dropped valve.

My intervals between failures have been 6k, 2k, 5k, and 5k miles.
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Old 09-28-2010, 12:00 PM   #7
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Quote:
Originally Posted by jays05 View Post

My intervals between failures have been 6k, 2k, 5k, and 5k miles.
Ever get the feeling you're doing something wrong?
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Old 09-28-2010, 12:47 PM   #8
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^^no, he runs them like a built motor should be run. It's the design and tuning of the motors at big power that we still haven't figured out. Sleeving and pinning will help, but it's all crap they should last way longer. If someone like micktheginge has failures, anyone can.


he's having problems with the valvetrain, a place where we are usually fine. Could have maybe been assembly error?
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Old 09-28-2010, 01:49 PM   #9
jays05
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I've used different builders, different installers, different tuners, and different parts. Now I'm just going to make my car a DD and stop dragging it every weekend.
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Old 09-28-2010, 09:10 PM   #10
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Best thread title ever!!!

Jay read below, this was the stuff I was telling you about. See ya when you drop off the motor!!


Quote:
Originally Posted by DJIMPREZA View Post
Guys

A friend of mine, running his 10 sec sti on a cosworth large valve head/cam kit have lost one of his cylinder number 2 intake valve after 8K miles of street use and some runs at the drag strip, here it is the answer from cosworth, wich makes sense, so you guys running larger valves, next time make sure you use the subaru procedure for installment, and turn the intake and ex LH head cam sprockets in the right direction, and turn them with the less angle possible and do not make them move, wich is difficult, but can be done..

so here it is

"The main issue is that it's difficult to keep the cam gears in the proper position when installing the belt and that you don't open intake and exhaust valves at the same time causing contact. As long as you follow the factory service manual instructions exactly, you will be fine. I've attached a PDF copy of the timing belt procedure. On page 5, they explain the importance of the steps and rotation directions. With +1mm valves and higher lift cams, the danger of valve to valve contact during timing belt installation is even greater.
once the valve is slightly bent, the higher spring rate and constant contact of the valve to the valve seat tries to straighten the valve. Plastic deformation sets in, like bending a paperclip back and forth, and then the valve head falls off causing failure. We inspected a number of these valves and the material showed evidence to support our diagnosis.
It's always number #2 that fails, so we're confident this is the problem. Some people argue about piston to valve contact with the AVCS full advanced or retarded, but we've bolted on a cutaway head and manually clocked the avcs cam to each extreme and never came close to piston to valve contact. If the cam timing is phased properly you don't have to worry about the AVCS.
Hopefully the customer in Venezuela can elaborate.
Thanks"

So be aware with the timing belt on high lift/large valve heads

Cheers

DJ

Quote:
Originally Posted by BallPeenHamr View Post
Thanks DJ. I'd like to add some additional insight on this particular type of failure if you don't mind?

The following pictures are of intake valve stems from two different failed engines with cosworth cylinder heads... and guess from which cylinder they're from? Yep, cylinder #2!



Uploaded with ImageShack.us

Notice, first of all, the valve stem is still straight after the failure- which means the failure wasn't a result of piston contact, or foreign debris in the cylinder. If that were the case the valve stems would have bent. Instead what we have here is a clean break, like the valve head said, "later man, I'm outta here", and took a vacation.

Secondly, look at the beach marks on the broken surface of the stem. See how the half-moon lines on the face begin on one side of the stem and get bigger? This is a sign of fatigue, and in this case, plastic deformation. It happens when a slightly bent valve tries to straighten itself out over many miles of operation. And at the weakest point of the stem (in this case where the stem is necked down, just before the radius into valve head begins) a microscopic crack appears then gets bigger and bigger over time. Eventually, POP goes the valve head.

Note this will always happen to the intake valves and not the exhaust due to the thinner (weaker) stem, and the larger head diameter- they bend easier.

Also, if an engine failure such as this happens at a low rpm and the driver shuts the engine off quickly enough (like the examples above), it is likely you will see only one, not both intake valves in cylinder #2 that will look like this because both valve heads will never decide to pop off at the same time, and it is always that first popped valve head that takes out the other intake valve (and everything else for that matter) before it has a chance to do it on it's own. However, a said failure at higher rpms will just obliterate everything, including the chance you'll find a relatively clean valve stem break to look at such as the ones you see above.

When it comes to installing a timing belt, I imagine the common logic of some engine builders/mechanics is to think the cam sprockets should only be rotated in the direction of engine operation, and that you always begin with the intake cam gear first... because after all, the mechanical cycle of engine operation is dictated by the intake valves opening before the exhaust valves do, right? So when it comes to lining up your marks to install the belt, it would make sense to phase the cam gears in the same manner, right?? WRONG WRONG WRONG!! Especially if you are running +1mm over-sized valves, be warned that you WILL bend the intake valves when they come in contact with the exhaust valves, in cylinder #2, on an EJ engine if you adapt this logic.

This is why it is very important to refer to the factory service manual when phasing the cam gears before you install the timing belt. If you don't, you run the risk catastrophic engine failure, and not to mention a very expensive repair.
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Old 09-29-2010, 10:23 AM   #11
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I give you props for sticking with it...............I would have burned the car by now.......
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Old 09-29-2010, 10:39 AM   #12
juanmedina
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Quote:
Originally Posted by JMK508 View Post
I give you props for sticking with it...............I would have burned the car by now.......
+12345

Jay have you thought about going to the dark side?
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Old 09-29-2010, 10:47 AM   #13
jays05
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Quote:
Originally Posted by JMK508 View Post
I give you props for sticking with it...............I would have burned the car by now.......
Quote:
Originally Posted by juanmedina View Post
+12345

Jay have you thought about going to the dark side?
I'm stubborn and I just want to drive my freakin subaru.
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Old 09-29-2010, 12:38 PM   #14
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jay did you have any symptoms before this failure? ex. rolling over funny, not normal tapping, idleing funny? just interested in some tell tail signs.
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Old 09-29-2010, 03:01 PM   #15
JMK508
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Quote:
Originally Posted by juanmedina View Post
+12345

Jay have you thought about going to the dark side?
It would be the easier thing to do........


I remember when i had my Subaru and it was always something. I was always listening to everything. Every single pull i felt like could be its last one. I wish you the best of luck .....but unless u have found the tree that grows money its got to be getting expensive.

I hate to tell you to do it......but.....maybe its time to move on.......DARK SIDE.

With my EVO i have none of this............... 0 problems.....0 issues......just a hell of faster car with no issues. just food for thought.

Last edited by JMK508; 09-29-2010 at 05:43 PM.
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Old 09-29-2010, 12:30 PM   #16
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4g63 subaru???
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Old 09-29-2010, 12:35 PM   #17
jays05
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Ready to pull the motor.

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Old 09-29-2010, 12:45 PM   #18
jays05
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There was nothing that concerned me. It idled nice and smooth at 875rpm with cosworth cams and ID2000's on the stock ECU + UTEC. Drove smooth and had no funny noises besides the normal built motor sounds.

When it let go, I was rolling away from a stoplight in 1st gear. Around 4500rpm it felt like I hit a rev limiter (I was thinking "stupid utec"), and as soon as I shifted to second gear it made a really expensive noise... one of those noises that costs a couple grand to make. I shut the key off so fast that the steering wheel locked as I was turning off the road and I almost took out a small tree.
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Old 09-29-2010, 01:05 PM   #19
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ugh. Ive seen what those expensive noises do... thats terrible to hear i hope you have better luck with your next build.
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Old 09-30-2010, 12:08 AM   #20
Junior2JZ
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lol, I love Jay.. Only a seasoned destruction vet can calmly say "expensive noise" lol..

You guys have no idea how bad I fight the urge to just buy an 9 RS and go 9s on pumpgas.. I could have built 2 with the money my RS has cost me
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Old 10-11-2010, 03:54 PM   #21
jays05
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The motor's out and on an engine stand. Since nasioc loves carnage pics, here it is.

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Old 10-11-2010, 04:41 PM   #22
juanmedina
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..........

poor Jay
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Old 10-11-2010, 06:32 PM   #23
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What do you think happened? Piston took out a valve which took out the spark plug? What a mess.....
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Old 10-11-2010, 07:23 PM   #24
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Sad to hear! I know how it feels. I had a motor assembled, drove it like 200 miles and found out it had a cracked head. Had to pull it out again :S
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Old 10-11-2010, 09:16 PM   #25
Junior2JZ
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Jay check out my post up above.. Notice how the valve broke exactly the same in exactly the same head...

See ya soon!!
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