what are the symtoms of a bent valve?
Thread Starter
On The Tree
Joined: Jun 2008
Posts: 183
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From: new orleans to houston
what are the symtoms of a bent valve? i was just curious about it because my mechanic said i might have a bent valve. I just paid to get a new coil in because my car was missfiring badly to the point where i was scared to drive it. now its still missfiring but drives a tad bit better, but he is saying that cylinder 8 is weak which is causing it to missfire and backfire all the time. as for the opti, there was nothing wrong because cylinder 7 has no missfire, which is for the opti (i guess). so the main thing is i would like to know whats the symptoms of a bent valve and how much should i be looking at spending and how long does it take?
If that's the problem, might as well do a valve job.. like $100-$200 for a 3 angle valve job. Good time to upgrade valve train too (=
Just try and get the car scanned to narrow down the possibilities and make sure its not something stupid like a plug wire arcing or anything. Don't draw conclusions so fast.
Just try and get the car scanned to narrow down the possibilities and make sure its not something stupid like a plug wire arcing or anything. Don't draw conclusions so fast.
Thread Starter
On The Tree
Joined: Jun 2008
Posts: 183
Likes: 0
From: new orleans to houston
If that's the problem, might as well do a valve job.. like $100-$200 for a 3 angle valve job. Good time to upgrade valve train too (=
Just try and get the car scanned to narrow down the possibilities and make sure its not something stupid like a plug wire arcing or anything. Don't draw conclusions so fast.
Just try and get the car scanned to narrow down the possibilities and make sure its not something stupid like a plug wire arcing or anything. Don't draw conclusions so fast.
A modern valve job is done with a carbide bit that cuts all three angles at once (hence, 3-angle). The 45 degree seat angle is sized and positioned by the 60 degree throat and 30 degree top angle. In other words, just do it. You will get some kind of performance increase too. (=
Plus most places that work on cylinder heads do 3 angle valve jobs standard. Anyone doing a 2 angle valve job these days is using a chisel and hammer, so to speak.
Plus most places that work on cylinder heads do 3 angle valve jobs standard. Anyone doing a 2 angle valve job these days is using a chisel and hammer, so to speak.
FYI - Your Opti or OPTISPARK is your distributor and it controls all cylinders not just #7. Are you throwing any codes - getting an SES or Check Engine light? If so get it scanned by your local autoparts store and let us know the codes so we can help you diagnose the problem. As to the misfiring this could be due to the opti as they typically fail over time on our cars and you can also check the ECM (plugs into and mounts behind the coil) as this might be an issue as well, but once again your local ap store can tell you if it's good or not by testing it. Let us know if you have any codes and let's go from there.
A relatively simple and quick compression test should help isolate the problem. If you have a bent valve on one cylinder the problem will be locatable.
A valve job requires removal of both cylinder heads. The labor for R & R will be more than the cost of repairing the damage. Timeline? Unless you do the R & R work yourself or have an amazingly responsive shop, count on three days at the fastest, a week or more in some cases.
A valve job requires removal of both cylinder heads. The labor for R & R will be more than the cost of repairing the damage. Timeline? Unless you do the R & R work yourself or have an amazingly responsive shop, count on three days at the fastest, a week or more in some cases.
Well depending on his valve condition, it'd be best to get a valve job instead of replacing just one. And yes it does require removal of both cylinder heads but that can be done in less than 3 hours..
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You're right on both counts but being able to isolate the problem to a loss of compression on one cylinder would eliminate a lot of other potential causes to the same problem. Bending one valve is not an particularly easy thing to do on a unmodified motor. A burnt valve or a damaged seat would make a little more sense as would the same scenario that involved an aftermarket camshaft. I'd want to know it was a bent intake (backfiring in the plenum) or exhaust (backfiring in the pipes) before I pulled the head.
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On The Tree
Joined: Jun 2008
Posts: 183
Likes: 0
From: new orleans to houston
in my opinion i think i will just shoot for the opti since bought the car used and really have any history on it...i believe that it might just be the opti because my voltage drops and the missfires, but as for the backfires, it sounds like its coming from the exhaust since i hear it behind me
