2003 Expedition 5.4L Cylinder #1 Misfire

mchan68 · July 29, 2010

I got this one passed down to me from our tune-down department. Apparently this vehicle has had an ongoing issue with cylinder #1 eating spark plugs. Also has an ongoing issue with coolant loss and overheating. Vehicle has had two spark plugs and one COP replaced. No external coolant leaks. Vehicle definitely runs with a slight miss to it. T-stat appears okay. Overheating appears to be due to level getting low enough to require top ups. Pulled intake on it. Nothing appears to be wrong with the intake gasket. I remember replacing a lot of 4.6/5.4L heads/gaskets back in the day for external oil leaks, but never heard of any issues with cylinder heads cracking. There is a lot of coolant staining on the degas bottle (like a 6.0L with stretched bolts). Vehicle is a 2003 Expedition 5.4L with 139,000 kms. on it.

Aaron · July 29, 2010

Some Irontite. Posted Image

But seriously, if it's been overheated...aluminum heads....ehhhh....I dunno about this one, but I am thinking that you may be getting some water into that #1 hole, if it's eating spark plugs and misfiring. Just my opinion.

mchan68 · July 29, 2010

Some Irontite.

But seriously, if it's been overheated...aluminum heads....ehhhh....I dunno about this one, but I am thinking that you may be getting some water into that #1 hole, if it's eating spark plugs and misfiring. Just my opinion.

That's my point. Where we're at with this truck, is it's loosing/drinking coolant. It has something wonky with cylinder #1. Tune-down department diag'd a POSSIBLE intake gasket leakage into cylinder #1 (since the coolant passage at the front of the intake happens to be adjacent to the intake port to cylinder #1). After completing my retail 6.0L harness replacement, I rolled it into my bay to rip the intake off, and the gasket appears to be okay. NOW, is when I'm wondering if anyone else has ever had an issue like this before with one of these. This is a 5.4L 2-valver by the way. Also the first year for the 2nd generation body style Expedition.

Jeff_E · July 29, 2010

Well I haven't seen a cracked head on a 5.4 yet... But last week I had a 2.5 Ranger with the same symptom, and it had a cracked head. I hadn't seen one of those either - but it happened.

Jim Warman · July 30, 2010

Well I haven't seen a cracked head on a 5.4 yet... But last week I had a 2.5 Ranger with the same symptom, and it had a cracked head. I hadn't seen one of those either - but it happened.

OMG... Jeff is starting to get the message...

Years ago, back when I knew everything there was to know, I was absolutely sure that if I hadn't seen it before, it was never going to happen....

An open mind and a logical thought process will take you a long way.... OPEN mind should not be confused with a hole in the head...

Ah... I WAS so much older then... now I am MUCH younger....

What does Mike think it is?

Aaron · July 30, 2010

^^ Agreed. I had a hotline guy tell me the other day that he had never seen that before. So I asked him, so does that mean it can't happen? The phone got real, real quiet.

RickB · July 31, 2010

I have seen head gaskets leak on earlier tritons. The symptom was always overheating on initial warm-up cycle - to the point of guage pegged, loss of heat, coolant out degas & ck engine light on. after a few seconds it would be good for the rest of the day. They usually came to me after having water pumps,heater cores & rads replaced.

Fredsvt · July 31, 2010

I've seen only 1 with a cracked head, but it was a 4.6 in a Grand Marquis. When I was at the limo company, it had a cracked right head. Initial cold start, misfire, slight steam, it would stop misfiring, then do the over-temp, stat snap open and be fine until next cold start.

I think it was in cyl 3 on that one, you could pull the plug pump it with pressure and next morning have the cyl full of coolant. Luckily it never hydrolocked. That car only had about 30k on it, and had a head put on it. Was fine for the next 750k afterward.

Mbl35 · August 1, 2010

^Had a few of them as well.

Aaron · August 29, 2010

OK Mikey... What was the repair?

mchan68 · September 3, 2010

OK Mikey... What was the repair?

R & R right side cylinder head. Send head out to be checked and machined as needed. Turned out that the upper side of the firing ring on cylinder #1 showed evidence of coolant breaching, as verified by machine shop findings. Buttoned up, and drove home for a night. No problems ever since. First time ever pulling a head on a 5.4L for THAT reason.