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Coolant in only spark plug hole #3 in 2000 V10 Excursion
I've been having a slight misfire at idle, but severe misfire under load, i.e. accelerating on the freeway around 3rd and 4th gear.
The spark plugs and boots were all replaced around 173k miles, and it is now at 196k. I purchased 10 spark plugs and boots to replace all of them at once.
However, when I pulled COP #3, the boot looked like this:
I put a spark plug socket on the spark plug, and it came out with coolant on it:
Not a great picture, but here's what the hole looks like:
Given that the spark plugs and boots are all fairly new, I'm considering simply cleaning out hole #3, replacing only that plug and boot, and then putting O rings on all 10 spark plug boots with dielectric grease. They all had grease when I put them in, however I did not put O rings on them.
My concern is that this is an intake gasket leak. What are the changes of that? Would coolant be in more than one cylinder in that case? Given that only #3 has coolant, it seems more likely that coolant has been slowly dripping from the heater hose or something? Although that all seems dry to me.
The coolant in the intake is only at the front and back, nothing close to the middle. It would be in a front or back cylinder, if that was the case.
Check for leaks of the heater hoses around there. Does the X have a heated PCV? That would be right above #3.
What happens is water or coolant get on the spark plug boot seal, and as the engine cools off, the air in the spark plug hole contracts, and it sucks the coolant down the hole. Takes just a few drops a day, and suddenly you have a tablespoon of coolant in the hole. Same thing for water too - my V10 with something like 30K miles on it had a mix of dirt and water down the #10 and #9 holes.
Indeed it does have a heated PCV right above #3. So that definitely could explain the pool of coolant. I'm going to replace those hoses. I'm not even sure they are necessary though, considering this truck has been in Texas its whole life!
I seem to remember a thread around here, if not here than in the X forum, about the heated PCV. Might want to check that out before you go nuts all on your lonesome
I think it was leaking vacuum or something, not coolant, but still a good read.
By the way, it just rained, and I am seeing where water is getting into plugs 3/4/5. I did notice some water (not coolant) in #4 and #5 after creating this post. I'm going to seal the plug boots better this time, but is there a good way of keeping water from reaching the valve cover in the first place? Besides just throwing a tarp over the hood when parked?
Isn't there a piece of weatherstrip between the hood and the firewall/cowl/whatever?
What I did was always use a generous helping of dielectric grease at the point on the boot where it seals to the head. Never had water intrusion after that.
Isn't there a piece of weatherstrip between the hood and the firewall/cowl/whatever?
While not the least expensive part to replace it was installed to keep water from leaking on the engine--if its worn out or has become compressed with time/age it would be wise to replace it with a new Ford part.
Sealing the plugs & boots is a great idea but its good to stop water from getting to them in the first place.
Sealing the plugs & boots is a great idea but its good to stop water from getting to them in the first place.
Absolutely. Even my coil-pack 4.6's got a good bead of dielectric grease right at the part of the plug boot that seals to the top of the head. But given enough water laying up there, and enough heat cycles, something's bound to be pulled in.
This is the first time I've heard of using an o-ring though... what's up with THAT?
By the way, it just rained, and I am seeing where water is getting into plugs 3/4/5. I did notice some water (not coolant) in #4 and #5 after creating this post. I'm going to seal the plug boots better this time, but is there a good way of keeping water from reaching the valve cover in the first place? Besides just throwing a tarp over the hood when parked?
Check out the "water intrusion at the cowl" threads (2 parts) in the Excursion Tech Folder, it covers how and where the water makes it past the weatherstripping and a few methods to combat it. Mine has been completely dry under the hood following a little RTV work a few years back.
This is the first time I've heard of using an o-ring though... what's up with THAT?
Sounds like a good idea but I'm thinking or guessing with new good quality boots and stopping the hood leak would work just as well---and save a step for future plug swaps.
Sounds like a good idea but I'm thinking or guessing with new good quality boots and stopping the hood leak would work just as well---and save a step for future plug swaps.
If you don't give the air in the hole somewhere to go as it expands, it'll pop the boot out of the hole.
If you don't give the air in the hole somewhere to go as it expands, it'll pop the boot out of the hole.
I'm currently 25K miles into a set of MC plugs, Denso boots with O rings and dielectric grease, no boot popping here and our Ex sees plenty of engine bay heat as most of its miles are with the 12K TT on the hitch. Attachment 281576
