In a four stroke combustion engine, intake and exhaust valves play a critical role in a vehicle’s ability to turn fuel into power.

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What do Valves Do?


Engine oil is critical for the health of your engine. If the engine oil level is too low to deliver adequate oil pressure to the whole engine, any number of problems could occur. One of these problems is a valve getting stuck in the valve guide, which could bend the valve if it’s sticking out and a piston can make contact.

Few problems caused by oil starvation are cheap to fix, but checking and maintaining your oil level is very cheap. Don’t forget this critical step of your vehicle ownership.

How to Tell If Your Valves Are Bent

The best way to tell if you have a bent valve is to remove the cylinder head so you can physically get your hands on the valves. Since this involves a lot of work, most people will do a compression test or leak down test instead.

A compression test will tell you how much compression each cylinder is making. It is a quick and easy litmus test to gauge the health of your engine.

If you do a compression test and find the compression on one cylinder to be low, you can then move to a leak down test. A leak down test will tell you exactly where air is leaking out of your engine on the compression stroke, when the combustion chamber is supposed to be sealed.

A leak down test is performed by hooking up compressed air to the spark plug hole of a vehicle and turning the crankshaft until that cylinder is on the compression stroke. Once achieved, you should be able to listen for which part of the engine air is rushing out the fastest.

If you hear air hissing through the intake, you may have a bent intake valve. If you hear air hissing out of the exhaust, you may have a bent exhaust valve.

Please note that just because you hear air escaping from these places doesn’t necessarily mean you have a bent valve. You may simply have some carbon buildup around the valves causing air to escape from a poor seal.

This would still likely call for a valve job to fully correct, but you may be able to mitigate the issue with an additive like sea foam.

Related: Common Causes of Engine Ticking

My Valves Are Bent. Now What?

Depending on how low your compression is, you may want to have some head work done. The extent of the head work needed will vary in each case, so it would be wise to lean on your mechanic or the machine shop’s judgement for this.

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If you have other engine problems, sometimes replacing the engine with a lower mileage used engine is a reasonable option as well.