Skip the auto shop - Our mechanics make house calls

Q: I replaced 2 spark plugs in cylinder 5 to fix a misfire.

asked by on

Had a code scan not to long ago cylinder 5&6 had misfire so I did the spark plugs for it car started up but it did have oil in cylinder 5&6 now my car won't start up don't know if replacing the value cover gasket would make it start up again

My car has 265000 miles.
My car has a manual transmission.

A: Leaking valve covers on this engine allow o...

Leaking valve covers on this engine allow oil down into the spark plug recesses as you note. Besides shorting the plug, the oil degrades the boot portion of the coil which plugs onto the spark plug, creating other opportunities for a short and misfire.

By all means, replace the leaking valve cover gasket and, given your mileage, replace all the plugs and coils if the boots show any sign of oil contamination. Replacing only 1 or 2 plugs/coils doesn't always cure misfire problems especially once oil is introduced. I would recommend having your valve cover gasket serviced by a professional mobile mechanic, like one from YourMechanic to start with. A certified professional from YourMechanic can replace the valve cover gasket, and can also perform spark plug and ignition coil replacement services if necessary.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Save up to 30%

Get a quote

What others are asking

Q: Bank one and two in rich conditions, CEL on

If the mass air flow sensor has failed, unfortunately cleaning will not resolve the issue. I would recommend having your mass air flow sensor tested with a digital multimeter or scan tool using the manufacturer's suggested procedure to determine if...

Q: My car starts to misfire really rough after running it for about 30-60 minutes, shutting it off then starting it up

You have taken some great steps to try and resolve these issues. Looking to the spark system was a good choice. Plugs were a good start, but the distributor and wires may be causing the plugs to not receive the...

Q: no key

Hello. The only way to start any vehicle is with a key that matches the ignition cylinder installed in the steering column or dash; which sends an electrical signal to the ignition relay and starter. You should have a professional...

Related articles

How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.