04 WRX with burnt valve and cracked heads - Subaru WRX Forum
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#1 Old 04-26-2012, 02:21 PM
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04 WRX with burnt valve and cracked heads

Hey guys I recently lost compression in Cyl 4 so I took it to my buddies shop and we ripped it apart and sure enough it was a burnt valve. Just as we started cleaning everything up to reassemble, he noticed both of my heads have very tiny hairline cracks in between the valves. He was shocked that my car never overheated or was leaking coolant. I've never had a single problem as far as losing coolant or oil.

Here are my options, and I would like anyone's opinions;

1) Call junkyards and pull some off of another vehicle at ~$200 each.
2) Send the heads to a machinist and let him take a shot at welding ~$No idea
3) Nothing, replace the valve and put humpty dumpty back together again since I wasnt having any problems with it in the first place. ~Free

I have seen a couple of posts where #3 was done before and people never had a problem with the vehicle again.

I am running an 18g turbo, 680cc injectors, walbro fuel pump, FMIC, and about 20psi max boost in 2nd gear. I drive like a grandma nowadays anyway though since I had my daughter. I just want the car to get put back together and last for hopefully a few more years without any major problems.

Thanks again guys!
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#2 Old 04-26-2012, 05:30 PM
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Hey, welcome back WRXforME. I remember when you used to be on here a lot a ways back.

1) Hmmm...my opinion is if your pulling heads off a junkyard car. It'd be a good idea to get the heads tanked to make sure they're nice and cleaned up before you put them on your car. I couldn't tell you how much that runs but maybe your buddies shop can do that for free.

2) No idea either

3) You could roll the dice and give it a try. Does your buddy know a guy that could weld it for cheap?

I'm glad that your RA gears are still holding up...I remember when you broke the stock gears. Oh and congrats on having the daughter.

Kirt
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#3 Old 04-26-2012, 06:05 PM
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Yeah, its been awhile, which is a good thing, things stopped breaking for awhile.

I dont know anyone that I would trust to weld something so delicate other than a pro machine shop. My brother is a good welder but he wouldn't even want to touch it.

Yea the RA gears are still running strong, not a problem whatsoever with them.

I also drive like a grandma nowadays with the very, very rare WOT on the highway.

Thats why Im shocked I burnt a valve anyways, I was babying the car for a long time and all of a sudden while on the on ramp to a highway, I got the dreaded flashing CEL.

Who knows when my heads cracked, could've been like that for a long time for all I know.
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#4 Old 04-26-2012, 06:43 PM
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It is odd...you have a protune and everything. So, idk why it would've done that unless your plugs got all fouled up or something. Maybe Cullen will have a opinion....I see him lurking.

Kirt
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#5 Old 04-26-2012, 06:47 PM
 
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I don't know that welding would be the answer, necessarily. I rebuilt an '02 with some small cracks in the heads (around the spark plug holes, deck side) and straked them around the valve seats. That is a way of preventing the cracks from progressing to where they could cause damage. Engine is still running strong. You're going to need to do a good valve job anyway on both sides. You may find that the other heads are in similar condition.

Where are the cracks on yours, do you have pics ?

Sounds like option 3 may be your best bet.

Cullen
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#6 Old 04-28-2012, 11:04 AM
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I decided I definitely want to fix her up and get some good heads in there. The machine shop was going to be probably $500-$1000. And I want the piece of mind knowing the cracks wont be there.

The junkyard got back to me and they pulled the heads off a WRX they had and said they were good. I drove 1.5 hours to the junkyard and bought them both, as I put them in the car I wiped some of the grime off with a rag and sure enough, one of the heads had a hairline crack in it. After some bitching and moaning, I left with my right side head (intake side) for $200.

Now I need to find the left side head somewhere. And I also need to find a new turbo inlet because for some reason right next to the turbo it is shredded pretty bad. Back to the classifieds for me!


This is NOT my head, but my cracks look exactly the same as where those red arrows are aiming. I also found 3 of these hairline cracks on each of my heads
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#7 Old 04-28-2012, 06:48 PM
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#8 Old 04-28-2012, 10:37 PM
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Hope you find your other head.

Kirt
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#9 Old 04-28-2012, 11:41 PM
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Yeah if I cant, Ill lose another head, the one attached to my neck. :eek:
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#10 Old 04-29-2012, 09:19 AM
 
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The cracks pictured are pretty much identical to the ones I encountered on a rebuild. Like I said, we straked the aluminum, right next to the the valve seats, so they wouldn't spread. Been almost two years, and the car is running great.

I'm starting to think that cracks around the spark plug holes might be a common thing. Anyone else encountered these on a tear down ?

Cullen
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#11 Old 04-29-2012, 01:40 PM
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Yeah they are definitely common, as far as just how bad they are and if they are runnable, idk.
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#12 Old 05-04-2012, 09:20 AM
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After talking to a bunch of people on NASIOC, I think Im going to run with my current heads. Lots of people just threw them back in and never had an issue. And seeing as how I never had an issue with them, I should be OK.

Heres the pics.

You can see why I lost compression in Cylinder 4 (top right valve in left pic, its missing a good chunk)

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#13 Old 05-04-2012, 06:00 PM
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Tank those heads and clean them up so they shine.

Kirt
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#14 Old 05-23-2012, 01:33 PM
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Well I got my car back finally. She runs good and strong now but there is an annoying ticking noise coming from under the hood now. I've seen videos of a similar sound on Youtube and my brothers WRX had a louder tick than mine ever did, but, now mine is quite noticeable. Perhaps its because the mechanic used regular oil and my car has never seen anything but synthetic...? We are going to run this oil for a few hundred miles and then swap it out with synthetic and hopefully that ticking will go away.

It sound something like this (this is not my car)
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#15 Old 05-23-2012, 06:05 PM
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Did you get the heads cleaned and the valves redone? That sounds like valve tap to me.

Kirt
378awhp/373wtq Custom Dom 3 & CBRD tuned 2006 STI.
"When in doubt...flat out" - Colin McRae
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