How To Find Out if Your Engine Has Bent Valves

If you have an engine miss or performance problem, don’t forget to check for a mechanical problem, such as compression loss, with the engine. This video covers compression testing which will help you determine if your engine has a mechanical problem like mine did.

The video links below will also help you.

To find a specific cylinder that’s causing a problem, perform a Power Balance Test:

How To Perform a Compression Test:

How To Perform a Leak Down Test:

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Thanks for watching!


Compression Tester:

Ingersoll Rand 3/8″ Impact:

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36 thoughts on “How To Find Out if Your Engine Has Bent Valves

  1. Hi Eric,
    I have a car with noisy valves KIA Sportage :(,
    in your example why would three cylinders be OK and only one have bent valves. What would cause that?

  2. You can have a bent valve and it still seals duded. Leak down and compression test will not tell you anything in that case. A valve with a slight bend can seal but cause excess valve noise.

  3. Hey Eric! I’ve owned my Infiniti 05’ G35 6MT since 2006 currently with 123k miles. It’s making the ticking sound but has no leaks around gasket and block. I changed out new sensors, solenoids, spark plugs, brakes, etc. should I spend the extra money to get the ticking sound checked and then have it fixed? Or sell the car and drive it into the ground? How much would a job like this will run? Any advice will help. Thanks.

  4. I believe the service manual says anything under 150psi is poor on this engine. My identical car gets slightly over 200psi on my cheap gauge.

  5. Suppose it isn't a bent cylinder head but a sticking one that is dirty in some way? Could that cause low compression in Cylinder number three?

  6. I have Subaru which is a interference engine and it had 0 comp on cyl 3 and 1 which are on the right side of the engine I checked the timing belt and it was off by 5 teeth. I realigned the belt and it now all cyl show 150. Is it possible to have bent valves and good compression? Do I need to do the leak down test?

  7. I measured Valves on a 2010 Hyundai Accent to see if any were bent, timing belt broke. Visual they look fine however I found 2 valves with stems out by .010. Do valves stems have to be perfectly straight with no deflection?

  8. Question…lots of people machine the valves,… but why not just get the valves off another cars engine??? Exact Same engine size of course…jw???

  9. I have a 2.3 l Ford , crank no start .0 compression on 4 cylinders . I pulled the cover and found the cams were out of time ,possible tooth jump. Is it possible on this interference motor that timing jump bent all or half the valves and still continues to crank? I know this is a crap motor . I will try a leak down.

  10. Without doing wet compression we can't conclude either it's piston rings issue or valve leaking…
    If in wet compression, reading improved not improved that means from valve it's leaking..
    If reading improved means rings have leak.
    If two cylinder HV low compression then gasket burnt..

  11. Hey man love you videos been watching you for more than 5 years now, where can I find a good mechanic like you any tips I live in Canada Toronto

  12. I just bought a used head for $70,the guy said he pulkled it from a running engine,when I got home i poured water into the intake and exhaust ports and all were slightly leaking,I tapped on the valves and that sealed it more spo my first 3 thoughts were eather bad springs/bad valve guid or seal causing valves to misalign/or bent valves,When I took them out they were kinda hard to remove but once removed I can see just by looking they were bent.Ths guy even told me he didnt clean the head to show me its condition as it was but after cleaning it up there were obvious dings from a broken or skipped timing belt,The same reason why I needed this head to begin with.what other tecjniques can you do by visual once there out?do you roll them or something because for me just standing them up i could see they were bent to one side then I would rotate and they were now bent to the other side,I also cleaned the carbon off the top so that wasnt making the valve tilt.

  13. I have a 09 R56 JCW with the same problem. Took it to Mini and they said cylinder 3 has 0 compression. They told me I needed a new engine. Once I got the car back the paper work said it is possibly a bad piston ring. I am pretty sure I have bent valves too that don’t require a new $10k engine.

  14. Always a pleasure to watch and learn from your uploads Eric. No heavy metal, expert knowledge/teaching and a sense of humour make your channel my first stop. Thankyou, and greetings from Western Australia.

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