I have a 2003 with the 5.4 litre V8. A short while ago, it started misfiring in the #4 cylinder, mostly when cold. Generally the misfire disappears when the engine temperature comes up to normal operating range. Then for a little while it went away completely.

The misfire came back so I figured it must be the COP assembly. (This is my Wife's rig, by the way). She fired it up to come home from work, experienced the misfire so she shut it down, paused and restarted the engine. It backfired on her once and then she said that steam and vapor which smelled of coolant was coming from the tailpipe. The next morning I drove the "Beast" to work and saw the steam coming from the exhaust, like an old Steam Locomotive. Soon it disappeared and has not come back.

I have now replaced the coil pack on the #4 cylinder. I still get a misfire within the 1st 1000 revolutions code, in the #4 cylinder. There is a faint smell of coolant from the exhaust. Most of the time, once the engine warms up, she runs smooth as the day we drove her off the lot.

We have 120,000 miles on her.

If anyone has experienced this, please share your results. My suspicion is that there is either a gasket problem or even worse, a crack in the cylinder head...

Best regards and thanks in advance,

Jeff

 

Is your car using up coolant? Do you need to refill it often? To me, it sounds like a head gasket that almost "healed" itself somehow after a major failure (the hole got plugged with some debris during the big steam show you witnessed so it leaks a lot less now)

I hope I'm wrong, but the faint smell of coolant in the exhaust tells you that some coolant gets into one of more cylinders and comes out the tailpipe, and the only way for this to happen so softly is via a shot head gasket. A cracked head should manifest itself in a more radical way.

I only had one blown head gasket, but I still remember that the cabin heat went dead right away, and all I could see in the rearview mirror was a cloud of white steam. An almost lovely sighting if it were to happen to someone else instead of me

Let us know how it goes!

 

I have discussed this with a former Ford Mechanic, who now is employed by my company. He stays in contact with many of his peers who still work for Ford. It seems that the head is cracked in a spot where coolant is allowed to leak into the cylinder (when cold) near the exhaust port. There is no water in my oil, neither is there oil in my coolant system. It only manifests itself with the engine cold and not all of the time does the exhaust plume out steam like an old steam loco.

The interior heating still works normally, which at this time of year is important!

My plan is to use Blue Devil to attempt to seal this flaw in the head. If this does not work, I am going to invest in a long block as I see little point in just replacing heads. The cost seems to be about the same.

I will send an update as soon as I have some results.

JWS

 

Blue Devil treatment has been applied. So far it looks good. I'll be able to tell in the AM when it is completely cold.

 

am wondering now if Blue Devil will help me and my 02 X. I have to check my overflow tank every time I drive it and add coolant if needed. I don't have any white smoke pillowing out the back, I don't see any coolant under the X, my oil is clean but I'm still losing coolant somewhere. Looking forward to your next post and result.