Coolant in spark plug well

SEAN CONGDON

MEMBER
1999 TOYOTA TACOMA
2.4L
4 CYL
2WD
MANUAL
196,000 MILES

I am getting coolant in the spark plug well of cylinder two.
Five hundred miles ago I flushed the radiator.
One thousand miles ago I changed the plugs and wires.
Also about one thousand miles ago I changed the tube seals because I was getting a little bit of moisture in cylinder two. Not sure if it was coolant. But it was giving it a misfire.

The head gasket was done less then ten thousand miles ago.

The coolant is only in cylinder two. It looks like it had been still leaking but the new wire plug kept the spark plug dry enough to not misfire. I do not know? Why do you think there is coolant in the spark plug well? Any and all possibilities would be helpful.

1 Reply

STEVE W.

MECHANIC
13,452 POSTS

About the only ways for coolant to get there would be an external leak that is following the ignition wire into the well. Or for there to be coolant in the cylinder being forced up past the plug. It might be a crack in the head letting coolant into the plug area but that would be very rare.

I would blow it out, remove the plugs and compare them all. If number two is substantially cleaner than the others it is likely coolant in the cylinder, especially if the piston top is clean as well. You could also pressure test the cylinder. To do that you use a spark plug to air hose adapter and put the cylinder at TDC and lock it in place. Then apply 120 psi air and look in the coolant for bubbles.
For an external leak look at anything that has coolant in it and is weeping. You could wrap the top of the plug wire with a paper towel and see if it gets damp.

It is not unheard of for a new gasket to fail, especially if the head was warped and resurfaced with the wrong finish.