2004 Mercury Grand Marquis. Car has 86-87 k on it. Love the car. Yesterday morning my check engine went on and the engine started running rough. The light blinked a few times, then just remained on.

Took it to a mechanic this morning and he found that the number 4 cylinder has coolant in it. He replaced the spark plugs along with the coil. Car runs fine now, it's just a matter of time before the engine tanks. Total repair for this is $2750. Car is almost 16 years old. And of course there are no guarantees the other cylinder head won't crack as well.

Very disappointed - did not see this coming. Low mileage and this happens. Is this a common issue with the car?

Any comments on this would be appreciated. Thanks.

 

More likely is a leak from the intake manifold which is leaking coolant into the spark plug cavity which is a common issue with the 4.6. I would seek another opinion because cracked heads and faulty head gaskets are much less common with the 4.6 and would likely foul the plug again before you got home. There are upgraded aftermarket units available which are improved over OEM versions.A pressure test of the cooling system while monitoring the #4 cylinder spark plug area would be a good starting point and possibly a cylinder leak down test would tell if you have a cracked head or a head gasket issue..

 

i agree with raski. good luck and keep us posted

 

The intake manifold was replaced last year. Spoke to the mechanic who did that job, he wants to see the car. Let's see what happens. I'll bring it to him this Tuesday (I'll let you know). Thanks to you both.

 

Well just got off the phone with the mechanic who replaced the intake manifold. He looked it over. Checked a couple of plugs, no issue. He noted that their was nothing coming from the exhaust system, as it was fine. If antifreeze was getting into the engine, you'd know it.

He also suggested if antifreeze was getting into the cylinder (as in a cracked cylinder head), your car would not being running the way it is. In short the car is fine.

Now what.

 

Thanks for the update! That sure is a head scratcher now

 

Yo, Bobba !! Welcome to the Mercury Forums !!
Regarding the coolant leak into #4 spark plug hole --
Mr. Raski told you right. I had the exact same problem in the 95 MERC.
Turned out to be a tiny leak from the intake manifold.
I re-torqued the manifold to 5 lbs. above the spec, using the factory bolt-tightening sequence.
Cleaned the #4 Ignition Wire thoroughly; applied Dielectric Grease to the inside of the spark plug boot;
Torqued the spark plugs to 175 inch-pounds.
No more mis-fire problems.
In passing:
I agree with Mr. Raski -- find another mechanic -- the dude you got ain't too swift ;>)