Should I change plugs at 100,000 miles?

[terryl]

A slight variation on the various spark plug threads. My 2004 Ford V10 just turned 100,000 miles. Ford recommends that the spark plugs be replaced at this point. Also, that the serpentine belt be "inspected."

Right now, the RV runs like a top. It always has, since I purchased it 8 years ago with 38,000 miles on it.

One side of me says "if it ain't broke, don't fix it." The other side acknowledges that here in AZ, I have to pass a smog test every year. It has always passed, and I have no reason to expect it will not pass this coming April. But I have no way of measuring whether it is getting close to failing the test. There have been fluctuations in the test results over the years, but I attribute that to not warming it up enough before running it through. Would new plugs reduce the engine emissions?

I do know that I will get this job done at a Ford truck dealership. I don't mind paying the extra dollars to have V10 experienced mechanics, rather than using the local auto repair shop who has limited experience with them.

Should I also replace the serpentine belt, tensioner and pulley, even if they appear to be fine? I will be heading out on a 5800 mile round trip that will keep me on the road for all of July, and don't want to be worried about these things while on the road. I do carry a spare serpentine belt with me, but changing it is not a one man job, and I travel solo.

Thanks for any advice!

[JohnRR]

I’m in the camp of leave well enough alone with the spark plugs.

[Taffeys]

If it was me I would not "leave well enough alone" as far as the spark plugs go. Your SOHC V10 is prone to spark plug ejection; this design flaw has been well-documented by Ford and publicly. Ford issued TSB 07-21-2 in July of 2007 addressing this failure. http://www.blownoutsparkplug.com/images/tsb07-15-2.pdf

[Taffeys]

And from a fellow Lazy Dazer's experience, he noticed a slight misfire with his 2003 E450 V10 but decided to chance taking a 500-mile round-trip to meet-up with friends. Half-way home on his return trip the engine went into limp-mode then died. Diagnosis was a blown spark plug which in-turn destroyed one piston/cylinder. Cost him a new Ford remanufactured V10 and time and labor to remove and replace his original blown one.

[twinboat]

I would change the plugs, using Ford's recommended procudure for replacing them. If having it done, they should be experienced. Its not just the V10 that had the spitting plug issue, It was the modular engine series.

I would replace the belt now. Ford recommends it be changed at 90,000 miles and having that fly off on the road will stop you in your tracks, when it goes.

A few misfires from old plugs will set a Check Engine Light, but you can keep going.

[450Donn]

Plugs are cheap replace em. Same for the belt. Loose a belt on the road could cost you a motor.

[Bill Gail]

I had the plugs on our V10 changed at a Ford dealer service center.
Cost for spark plugs and labor - $600 . They did say they charge $60 for each heli-coil needed if any holes strip threads
They did it without stripping any plugs and we have put on 15K since without any issues.
Not cheap but worth every penny .

[wildtoad]

I too am in the camp of replacing them per manual. 100k miles is a lot.

[oldeguy]

don't know about the V10 fords...but the V8 stuff had a poor plug/head design. I would replace the plugs. But before...spray some penetrating lubes to the top of the plug and run some "gas additives to the fuel. broken plug or stripped threads in the head are not good!

[Waiter21]

"Leave well enough alone" can be restated as "Run it until it breaks". OK, but my luck, these things always seem to break at the absolute worst possible time..

You are in a different boat than I am. I do the vast majority of work on my vehicle, so I don't incur the $100 / hour labor charge.

On my 20 year old F53, I want a reliable, dependable vehicle. I do not want to be broken down beside the freeway hunting for a part. So I tend to weigh the cost of preemptively replacing low cost components that have high consequences if they failed.

Preemptive replacement components:
Plugs and COPs
Cam and crankshaft position sensors
Starter
Water pump and thermostat
Belt, idlers, and tensioner
Fan clutch

[Pirate]

Changed mine at 85K. None broke off (2 piece time frame issues) but one had ground electrode almost gone.

[tiffy2000]

I would change them, now for some spark plug info: I've seen pictures of plugs changed in these engines at 200,000 + miles ...looked pretty good and owner reported that it ran great .....seen some changed at 340,000 miles ....those looked a little rough but was still running OK... just found a ford v8 modular in a van with 740,000 + miles on it, changed plugs at 429,500 and still running OK .......kind of interesting I'd say

[wildmanbaker]

We are talking V-10s in a MH are we? They probably spend more time above 3,000 RPM than the average pick-up. When I changed ours at 34,000 miles, the average gap was .015 above the limit. Its more the number of sparks per mile to consider rather than the actual mileage. I'm with Waiter, I don't like problems to find me on the road, or away from home.

[TonyMac]

Many a good plane crash has been caused by "if it ain't broke..." If Ford says replace xxx at yyy miles, replace same