The vehicle was running fine last week.

Stood for a few days and then when put under load (flooring it) the 2nd cylinder was found to be misfiring. Popped off the engine cover and removed the 2nd cylinder's ignition coil, found the well had coolant water in it.

Drained the well and cleaned the coil. The misfiring problem was resolved. (For now)

Does coolant fluid in the cylinder well indicate gasket failure again?

enter image description here


Vehicle running fine after removing all water (with paper towels) and replacing two coils damaged by (I assume) water. See conclusion below for more info.

Vehicle Information

  • 2010 Ford Focus ST 2.5
  • Engine: B5254T

Head Gasket Service

Date: Approximately 2-3 months ago

Cylinder head testing and reconditioning. (passed pressure test but found a slight warp in the head which was corrected)

Parts replaced

  1. Head bolts
  2. Head gasket
  3. Cam seals
  4. Intake gasket
  5. Exhaust gasket
  6. Thermostat housing

Questions and Answers

  1. "Any coolant pipes running close to that location?" No nothing.
  2. "Are you sure it's coolant?" Yes.


Excuse my delay in responding back. The problem I tracked to the flushing process which resulted in coolant/water spilling over onto the engine cover protecting the ignition harness and coils. Water quite easily makes it passed the engine cover and pools up and then leaks passed the ignition coils into the plug holes causing spark problems.

  • 1
    Pull the plug and (assuming you have a bore scope or something) look at the piston. If the top is clean, it's likely the head gasket. Honestly, I'm not sure how else you'd get coolant there. I'd start with a compression test.
    – 3Dave
    Oct 19, 2020 at 16:40
  • Are you sure it is coolant? I can see how oil could get in there from the rocker cover, but not coolant.
    – HandyHowie
    Oct 20, 2020 at 8:29
  • What is the make/model/year/engine of the car?
    – HandyHowie
    Oct 20, 2020 at 8:30
  • Are there any coolant pipes running close to that location?
    – HandyHowie
    Oct 20, 2020 at 8:35
  • Thanks for the interest everyone. I'll update my post shortly to answer your questions. Oct 20, 2020 at 9:24

3 Answers 3


Does coolant fluid in the cylinder well indicate gasket failure again?

Indeed it does! Or it may also mean that the original problem was not actually a head gasket. The next likely causes are warped or cracked cylinder head or engine block.

  • 1
    I can’t see how a leaking head gasket could leak coolant to the plug hole. Maybe I am missing something, what am I missing?
    – HandyHowie
    Oct 20, 2020 at 8:43
  • @HandyHowie First water leaks from the water jacket into the cylinder. Next the compression stroke forces it through the spark plug threads. That water collects in the well. Happens all the time and yes, it can cause engine damage as you might imagine.
    – jwh20
    Oct 20, 2020 at 9:54
  • @jwh20 very interesting. Oct 20, 2020 at 10:56
  • I find that very hard to imagine. Surely the high combustion pressure would force exhaust into the coolant via the gasket leak and pressurise the cooling system long before pushing water past the gas sealing ring fitted on a ignition plug. The threads are not used to seal the plug. But I may be wrong. Maybe others have seen this.
    – HandyHowie
    Oct 20, 2020 at 11:33
  • @HandyHowie I'm not the only one who imagines this is a possibility. I've actually seen this happen myself where you could see the coolant bubbling up around the spark plug hole. See this link for a 2nd opinion on this topic: 2carpros.com/questions/coolant-in-spark-plug-well
    – jwh20
    Oct 20, 2020 at 11:51

Were the heads decked (checked and milled perfectly flat) when you last had the head gasket replaced? This indicates that they weren't, and you'll never get a good seal if there is any warping on the heads.

  • 1
    I can’t see how a leaking head gasket could leak coolant to the plug hole. Maybe I am missing something, what am I missing?
    – HandyHowie
    Oct 20, 2020 at 8:44

Unless there is something different about your engine, I can’t see how a leaking head gasket could cause coolant to get to the the plug hole. Maybe a crack in the head would allow coolant there.

Often the plug hole is surrounded by oil in the rocker cover and a leaking seal will let oil get to the plug, but not coolant.

Are there coolant pipes running near this plug hole?

If there are no coolant pipes nearby, my guess would be a crack in the head.

  • The gasket was recently replaced. No, there are no coolant pipres near the plug hole. Only an oil pipe which connects on the top of the head. Oct 20, 2020 at 9:54

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .