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Valve springs close the valves after the cam opens them. When a spring breaks or loses tension, the valve floats or does not seal, and you get a misfire that is often worse at higher RPM. Route 66 Auto Repair in Upland finds the weak spring with a visual check and testing, and on many engines replaces it with the cylinder head still on. ASE-certified technicians explain the method for your engine and put it on a written estimate before work begins.
Signs of a weak or broken valve spring
- A misfire that appears at higher RPM, like merging onto the 210
- A tick or clatter from one area of the valve cover
- Low compression on one cylinder that varies test to test
- A spring visibly broken or collapsed with the valve cover off
- Power loss after the engine was over-revved
How can a spring be changed with the head on?
With the valve cover off and the camshaft or rocker moved out of the way, we bring the piston to the top and fill the cylinder with shop air through the spark plug hole. The air holds the valve shut while a spring compressor removes the keepers and the old spring. The new spring and a new stem seal go in, and the keepers are seated. This method depends on engine layout, so we confirm it applies first.
If the valve itself has been damaged by floating, valve replacement is the next step.
Can springs be tested?
Yes. With the head off, springs are checked for free length, squareness and load at installed height. With the head on, a broken spring is usually visible. Our valve spring tension test page explains the bench check.
Our valve spring replacement process
Step 1: Identify the cylinder
Misfire data, compression and a visual check find the weak spring.
Step 2: Hold the valve
Cylinder air pressure keeps the valve closed during removal.
Step 3: Swap the spring
New spring and valve stem seal are fitted and keepers seated.
Step 4: Reassemble and verify
Cam or rockers go back to spec, valve cover resealed, and a road test at higher RPM.
What's included in valve spring replacement
Included on the work order
- 01Misfire and compression checks to locate the cylinder
- 02Valve cover removal and new gasket
- 03New valve spring as quoted
- 04New valve stem seal on that valve
- 05Keeper and retainer inspection
- 06Road test with misfire counter review
Need-now or need-later?
Need now: call
- A broken spring, since the valve can drop and contact the piston
- Misfire under load on the freeway
Need later: book
- Springs that pass testing on a high-mileage engine
- Valve cover gasket seep noted for a future visit
How pricing and timing work
Head-on spring replacement is much smaller than a head removal, but overhead cam engines may need the timing drive loosened to move the cam. If multiple springs are weak, a full set is often sensible. The written estimate explains the method and lines up each part. AAA members get 10% off parts and labor, up to $75, with the card at time of service.
Aftercare
The misfire should be gone. Avoid sustained high RPM for the first drives while we confirm the repair. If a tick remains, a valve adjustment check may be next.
Frequently asked questions
What breaks a valve spring?
Age and heat cycles weaken springs. Over-revving, a missed shift in a manual, or a bad batch of springs can also break them.
Do I need all new springs if one broke?
Not always. If the others test in spec, one can be replaced. On high-mileage engines or after over-revving, a full set is worth considering.
Can a broken spring damage the engine?
Yes. If the valve drops into the cylinder it can hit the piston and cause major damage. That is why a confirmed broken spring is need-now.