Spark plug condition and idle? | Ford Explorer Forums - Serious Explorations

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Spark plug condition and idle?

AGodlyCanuck

Well-Known Member
Joined
June 13, 2018
Messages
196
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City, State
Nelson, BC. Canada
Year, Model & Trim Level
1992 Explorer 4dr 4x4 XLT
So I whipped out my spark plugs and wires and thermostat to see if that would smooth out the slightly rough idle. Seemed to make a difference.

But there is still a bit of a studder in the idle.
Every 10ish or so seconds the rpms wiggle.
And you can feel a little shake in the vehicle.

Any ideas?

I've also got questions about the spark plugs I pulled out. What do you think of the condition?

I either need to replace the seals on the valves or the valve cover leak is leaking into the combustion chamber through the spark plugs.
Is that possible?

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Oil isn’t leaking in past the plugs. Those looks pretty oily except for the two. How many miles on them?
 






Oil isn’t leaking in past the plugs. Those looks pretty oily except for the two. How many miles on them?
No clue, the diodes seem pretty worn.
I'm assuming they were only ever changed once.

I was really Hoping I wouldn't have to do the valve seals lol
Everything I've done on this vehicle has been a learning experience lol
 






Does it smoke on a cold start?
 












Yeah it does puff a bit of greyish smoke at idle and blue when I stomp on it, I honestly would suspect a headgasket leak. Except there isn't any coolant in my oil and no blowby. The exhaust does smell a bit sweet and there seems to be a lot of condensation. My family is suspecting valve seals.

And no, it's not the Ac as for some reason it doesn't cycle. Either its that low or something else...
 






Those plugs look like NGK G-Power plugs. Good plugs - when new. Try the Same plugs or some OEM’s as they seen to work well too. Maybe utilize a can of Seafoam in the tank to cut down on some carbon accumulation in the cylinders, if any.
 






Smoke at start-up would lean towards valve seals. Smoke when stepping on it would be more like the rings not sealing.
I honestly would suspect a headgasket leak. Except there isn't any coolant in my oil and no blowby. The exhaust does smell a bit sweet and there seems to be a lot of condensation.
I had a '91 BMW 318 that had a crack in the head. It would blow out white-ish smoke on start-up (looked like condensation vapor), but it would go away once warmed up. Started losing coolant and would overheat in traffic. Never, ever had signs of coolant in the oil. I eventually pulled the head off and the crack was between a coolant passage and the cylinder. I also didn't have any performance issues - it ran strong the entire time!
 






Compression test and block test would be helpful too at this point.
 






after you go down a long hill and then step on the throttle if it puffs blue smoke it is the valve seals and maybe some rings
roscoe
 






I'd change out those plugs. How hard were they to break free? I have new ones, and new wires, once I get the darn underside done.
 






after you go down a long hill and then step on the throttle if it puffs blue smoke it is the valve seals and maybe some rings
roscoe

Out of curiosity, why would a hill affect it?
 






I'd change out those plugs. How hard were they to break free? I have new ones, and new wires, once I get the darn underside done.

Oh I replaced them with NGK and Napa Premium wires.
 






If you have access to a bore scope or even look through the spark plug hole, try to see if you can see carbon buildup. With the plugs in that condition, I can only imagine how much carbon is on the top of your pistons and top of the combustion chamber in the heads directly around where the spark plug enters the combustion chamber. I had a vacuum leak for a few months and the internal carbon buildup was significant.

I poured Seafoam directly into each cylinder and let it soak overnight. I'm talking about two tablespoons max. I also am running Seafoam in my gas tank for the next few fill ups to help keep the carbon down and out while I plug up any remaining vacuum leaks. There's a product I just discovered, it may be new - not sure, called Seafoam Top Engine Cleaner and Lube. It's marketing advert states that is "helps" remove intake valve and combustion chamber deposits. I just purchased it so I can't give an opinion yet.

My plugs looked new vs yours after I removed them. Here's pic of the inside of my head after I removed it. The carbon isn't too bad. You try some Mystery Oil too directly into your gas tank.
 






coming down the hill your foot is off the throttle making more vacuum in the cyls and pulling more oil in the cylinders
roscoe
 






If you have access to a bore scope or even look through the spark plug hole, try to see if you can see carbon buildup. With the plugs in that condition, I can only imagine how much carbon is on the top of your pistons and top of the combustion chamber in the heads directly around where the spark plug enters the combustion chamber. I had a vacuum leak for a few months and the internal carbon buildup was significant.

I poured Seafoam directly into each cylinder and let it soak overnight. I'm talking about two tablespoons max. I also am running Seafoam in my gas tank for the next few fill ups to help keep the carbon down and out while I plug up any remaining vacuum leaks. There's a product I just discovered, it may be new - not sure, called Seafoam Top Engine Cleaner and Lube. It's marketing advert states that is "helps" remove intake valve and combustion chamber deposits. I just purchased it so I can't give an opinion yet.

My plugs looked new vs yours after I removed them. Here's pic of the inside of my head after I removed it. The carbon isn't too bad. You try some Mystery Oil too directly into your gas tank.

What was the vacume line that was broken?
 






So, Here is where I am At now...
I am worried I may have a cracked head.

How would I check that?
I'm fairly certain that I need valve seals but I don't want to replace those just to have to replace the heads afterwards. There is no oil in the coolant but the exhaust does smell a hit sweet.

I will definitely try the seafoam though.
 






What was the vacume line that was broken?

The elbow at the PCV had deteriorated. And, the gasket between the EGR and the Intake Manifold had slipped from one of the bolts when I was installing a new EGR. So the EGR gasket was only held in place by one bolt and hung downward from that bolt - essentially no gasket where it was needed. I fixed the PCV elbow and thought I was fine until months later that I found the EGR gasket out of place. Gas mileage sure did shoot up once those were fixed.
 






So, Here is where I am At now...
I am worried I may have a cracked head.

How would I check that?
I'm fairly certain that I need valve seals but I don't want to replace those just to have to replace the heads afterwards. There is no oil in the coolant but the exhaust does smell a hit sweet.

I will definitely try the seafoam though.

Have a leak down test performed. And, a block test. Swapping heads at a machine shop is not that expensive. It's all about time and tools - OTC 6488 in particular. A good machine shop is extremely important too.

What do your dry and wet compression numbers look like?
 



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Have a leak down test performed. And, a block test. Swapping heads at a machine shop is not that expensive. It's all about time and tools - OTC 6488 in particular. A good machine shop is extremely important too.

What do your dry and wet compression numbers look like?

No idea lol this is my first time doing anything this in depth. The vehicle isn't on the road yet. Everything I am doing is just backyard stuff.
 






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