Skip the auto shop - Our mechanics make house calls

Q: Engine shaking and knocking after spark plug replacement.

asked by on

I had a spark plug and ignition coil burn up. When I went to replace it the spark plug hole threads were stripped. Tapped and rethreaded and waited 24 hours before installing a new ignition coil and 4 new iridium spark plugs. When I started it, the engine was shaking badly and it sounded like something was knocking around inside.

A: This sounds to me like the cylinder head ha...

This sounds to me like the cylinder head has been severely damaged. If the burn of the coil and spark plug started on the plug end this would mean that combustion chamber temperatures from inside the engine were allowed past the electrode surface of the spark plug. The explosions from the fuel being ignited inside the engine must have caused the spark plug to burn up. I would first recommend having a qualified engine technician come and do an inspection of your engine. You may have a crack in your cylinder head. As for the knocking sound, a piece of metal from the cylinder head may have broken off during the rethreading process and fallen on to the piston. When the engine was started again the piece of metal must have been getting smashed between the valves and the piston itself. I would not run the engine anymore until the inspection is done to prevent any further damage.

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: I have a 2011 town n country. I was told by the service dept. that the left side cylinder head needed replacement which

As long as the cost of replacing the spark plugs on the right side is equal to half of the cost of doing it on the total engine I think it will be ok. Considering that the cylinder head is...

Q: SUV parked for three years

Hi. Parking a vehicle for that long is never good. Things like wiring, starter, fuel pump, and transmission can all go bad from lack of use. In severe cases, engines do seize up from rusting internally due to lack of...

Q: Trouble changing gears from park to drive

Hello. It sounds like you will need to replace the transmission. When you have trouble switching gears, the car won’t accelerate, or the engine light or traction control light is flashing, these are all indicators of a faulty transmission. ...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
How to Renew Your Car Registration in Oklahoma(DELETED)
Having your car registered with the Oklahoma Tax Commission is an important part of driving legally in this state. You will need to do this within 30 days of moving to Oklahoma...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...