how do you know if you bent a valve

[1990talonmatt]

I am unsure if I bent a valve or just broke it but it feel that there is a lost of compression but what would be a good sign that the valve is broken or bent

 

[99gst_racer]

Please don't use the Regional forms for tech questions. Please use the newbie forum.

Thread moved.

 

[BurrowZ]

Do a wet compression test. Squirt the little bit of oil in the cylinder, and if you get better compression than before, your piston rings are worn. If nothing changes you could have bent a valve.

 

[19BLACKGST98]

Perform a leakdown test.

 

[docb002000]

A loss of power? I would start with a boost leak test, double check your timing marks and leak down test would show if you have valve piston issues.

 

[99gst_racer]

A loss in compression would indicate compression is leaking past a broken/bent valve, past the head gasket, or past the rings. You would have to do a leakdown test to verify which of the three places it's leaking out.

I would recommend against a compression test if you think you may have piston-to-valve contact.

What makes you think you have a valve issue?

 

[1990talonmatt]

Well when I was driving home last night I got on the I5 and the car just loss power my fuel to air gauge started to go back and forth and the car won't pick up speed like it was be for I got on the I5 once I felt the loss in power I pulled over to let the car idle.... I saw that the car was normal idling at 800 rmp and it would drop down low to 500 then go back up to normal it just sound like the exhaust valves wasn't opening enough for the pressure to leave the engine so I think it might of happen when I went to down shift and the speeded up on to the freeway so...I am thinking is a valce not a ring so I am thinking I should buy a new head or try and save this head which one would you guys would be the pest way to go if I fine out that it is the valve that is bad

 

[99gst_racer]

At this point, you don't even know if you have low compression or a damaged head. Start testing and ruling out possibilities before you start buying replacement parts that you may not need.

 

[19BLACKGST98]

Do a boost leak test. Did you atleast look to see if you blew off a coupler? What have you actually checked?

 

[1990talonmatt]

Ok thanks ill start checking I haven't checked anything I am just guessing but I am going to start checking tp day after I get off work

 

[BigBeans]

It's obvious if you seriously bend one. This was my car about a year ago with a bent valve.

YouTube - ‪bent valves‬‏

 

[1990talonmatt]

It's obvious if you seriously bend one. This was my car about a year ago with a bent valve.

YouTube - ‪bent valves‬‏

Well the video is what the engine sound at idle so that's why I was think a bent valve

 

[robertseber]

As everyone stated earlier start with a compression test.

 

[1990talonmatt]

Ya I am going to do that then go from there

 

[FearlessNick]

It would sound like its camed and you would hear it missing and a CEL came on. Thats what happened to me. It was funny because my dad was like did you put cams in it while I was gone. No dad I bent a valve or two ;( and I did bend a exhaust and intake.

 

[9thgencorolla]

First thing I would do before anything is a boost leak,and Check all the connections to the innercooler,turbo,and throttle body. Alot of times this is the problem, then if all checks well move on to a compression test. And write down all the numbers per. Cylinder. This is to rule out a bent valve. Start with these two test before guessing. Then get back to us!

 

[FearlessNick]

Well like I said if it sounds like its camed and you have a CEL for a misfire. Then it is a bent valve.

 

[L train]

Well when I was driving home last night I got on the I5 and the car just loss power my fuel to air gauge started to go back and forth and the car won't pick up speed like it was be for I got on the I5 once I felt the loss in power I pulled over to let the car idle.... I saw that the car was normal idling at 800 rmp and it would drop down low to 500 then go back up to normal it just sound like the exhaust valves wasn't opening enough for the pressure to leave the engine so I think it might of happen when I went to down shift and the speeded up on to the freeway so...I am thinking is a valce not a ring so I am thinking I should buy a new head or try and save this head which one would you guys would be the pest way to go if I fine out that it is the valve that is bad

if you have a funny idle and your afr gauge is flipping out i would tend to think its a leek after your air has been metered out by your maf. i bent the valves in my gsx and trust me ya know when they bend ( catastrophic failure in my case) your timing belt would have to slip so check that also when i bent mine the rockers fell off the lifters. A mild bend in the valves will sound sort of like it has a big cam with some extra ticking. You could just have a sticking valve. compression check would point you in the right direction you can also take your valve cover off and look.
best of luck man

 

[DSM1G90]

could have a plug wire shorting out, or arcing to ground ... think electrical also...

Plus, I've seen plug wells somehow get full of water-mainly from condensation of sorts and that'll play some fun as well..

 

[JayRome]

if you bent a valve.... take the rocker cover off and check if any of your roller rockers have fallen out of place........ should take you 10mins....

 

[BigBeans]

if you bent a valve.... take the rocker cover off and check if any of your roller rockers have fallen out of place........ should take you 10mins....

That doesn't tell you anything. You can bend valves without throwing rockers.

 

[JayRome]

That doesn't tell you anything. You can bend valves without throwing rockers.

he may also just have a rocker thats come off... considering he just thrashed his car before the issue begun..... ruling out one thing at a time...

 

[hoby0316]

Do a compression test and post the results.

 

[docb002000]

Well like I said if it sounds like its camed and you have a CEL for a misfire. Then it is a bent valve.

Never threw a cel, and had six bent vavles

 

[TexasTurbo]

Take a compression tester, disconnect the gauge from it, connect that to an air compressor and use that to blow air into a "closed" combustion chamber. If that leaks air you will be able to hear where it's leaking from. It will not show you percentage lost like a real leak down test, but it will show you where the air is leaking from.