First, some disclosure. I was recently offered a set of Bosch Iridium plugs for free in return for doing an objective review and posting it here at FTE. Liking anything free, I figured, what the heck?

I haven't done my plugs in around 5 years, so it was definitely time, although I've probably only put around 20K miles on it since them. This year, I took a new job and have been commuting about 50 miles round-trip with the V10, and already put 8K miles on it since earlier this year. It was definitely time.

Now, I know all about the reports of Ford modulars not liking Bosch plugs, and I myself have even suggested never EVER use Bosch plugs in the V10 based on all these people having problems.

But the plugs I received are the new Iridium plugs, which are "original equipment" replacements. Bosch Iridium Spark Plugs

I'll attach a picture or two below of one old plug and the new Bosch plug side-by-side. They have a rounded-off ground electrode, and a very fine-wire center electrode. See the website link above for all the other marketing information.

Now while I've only just installed them and driven the truck for 4 days back and forth to work, and I know that's not a long time to make any real comparisons in terms of longevity and what will happen down the road, I will say this.

The engine idles like glass in drive. It's NEVER done that in it's entire life, whether it be with the original plugs when I first picked it up with 25 miles on it brand-new from the dealer, or the first time I changed out the plugs with Motorcraft and replaced all the boots. If I didn't have to keep my foot on the brake to keep from rolling, I wouldn't even know it's running. Again, it's never EVER idled that smooth. It hardly drops RPM at all going from neutral to drive, another indicator that something is different.

Power at all RPMs is smoother, and when the tranny shifts the engine doesn't balk like it used to. It just keeps applying torque like nothing happened.

Over the next few weeks and months, I will try to report back if I notice any MPG changes or any degradation in performance, but so far I am very pleased. I have not noticed any misfires or any other problems.

The next post in this thread will be a more technical description of changing the V10's plugs, and what I found while doing it.

 

A more technical description of changing my plugs and some comments/tips.

Removing all the COPs, I found some dirt/crud had found it's way past the top boot seal.

Even worse, when I pulled the #4 COP, I smelled gas. Yes, gasoline. #4 was loose. It must have just recently happened because there was no buildup of any soot or other deposits on the boot, the seat of the plug, or anywhere else. But I definitely smelled gas, and when I removed that plug, it was not tight at all. It was still on it's seat, but definitely not tight. I checked the plug threads for aluminum, checked the hole with an inspection mirror, and when reinstalling the Bosch plug, it tightened up just like the rest of them when I torqued it, so no damage was done. PHEW! that was close! Although looking at the pic below at #4 (second from the right), it definitely looks like SOMETHING was going on there.

So let this be a lesson. Even when done right, a plug can still come loose, and if you have waited more than 2 or 3 years since the last time you checked them, CHECK THEM NOW. Don't put it off. I didn't hear any ticking or feel any misfire, but that one plug was definitely loose. Now that I think about it, because I have headers, I might have overlooked some noise from that loose plug. Now that all of them are in tight again, the engine does seem quieter.

Removing the old plugs, I didn't use any penetrating oil because I knew I used anti-seize on the plugs I put in last time. They came loose easily, I backed them out 1/2 turn, and then blew all the holes out with compressed air. I then backed them out another 2 or 3 turns, and blew out all the holes again. I used a thin piece of vacuum hose attached to my air chuck to get down to the bottom of the hole. Some crud came flying out, so wear safety glasses

Pulled all the plugs out one by one, marked with a magic marker to keep track of which cylinder they came out of, and took pics. See below.

I bought Duralast spark plug boots from Autozone, after checking them out at the store. Something like $36 for a box of eight, and had to buy two more singles. They were EXACTLY the same molding as the Standard Motor brand boots I used 5 years ago except for some lettering. Decent rubber, they seemed good quality, and the springs were also identical to what I took out.

Pulling the old boots off the COPs, I wiped down and inspected every COP for cracks around the top, around the tip where the spring attaches, and corrosion on the contacts. Some of the COPs had slight corrosion on the tip where it meets the spring, so I cleaned them up with a wire brush by hand.

First, I assembled the spring to the COP and make sure they were firmly attached and completely seated.

Then applying dielectric grease to the boot where it seals to the coil, I assembled the boots to the coils. I applied another good bead of dielectric grease to where the boot seals to the head, and a very thin coating at the tip where the boot seals to the plug insulator itself. I also applied a very thin coating around the connector at the top of the COP where the wiring harness plugs in. This can only help keep water out of the connector.

Putting the COPs aside, I went about installing the new Bosch plugs. Checked the gap, they all seemed right around .052" which is right at the small end of the spec, .052-.056". A coating of anti-seize was applied with an acid brush to the threads of the plug, trying not to get any on the electrodes, and keeping to a minimum the amount on the tapered seat of the plug itself. The idea is to keep the threads from corroding, and NOT getting any between the plug seat and the head taper.

Threading the plugs into the holes was easy, no surprises there. Bottomed out the plugs by hand. Set the torque wrench to 14ft/lbs, and found that the plug just sort of stopped dead. No ramp-up of torque to reach 14ft/lbs, just stopped dead. I thought, well, there should be SOME tightening, so yes, I did it. I went to 20ft/lbs and got a nice "feel" of the plug actually tightening up.

So yes, in my case, I used 20ft/lbs. I have to say I never suggested that in the past, but in this case 14 just wasn't enough. Maybe that's because the taper in the head has been hardened with so much time and cold/hot/cold cycles. I would definitely say to anyone doing this, go with your gut. If the plug just stops dead at 14ft/lbs, I would definitely say go a little bit more and see what happens. Because #4 was loose, I checked how it torqued down compared to the rest of the plugs, and it tightened up just like the rest of them so the threads and seat seem to be OK.

After all 10 plugs were in, it was time to reinstall the COPs. Align the COP with the bolt hole in the intake, keeping it centered in the hole, and push it home. It should go down easily and stay. It's really a "feel" type of operation, and there is some faith required that you got the spring down over the top of the plug.

Using some more anti-seize on the hold-down bolts, I bolted down the COPs trying to keep them centered while doing so. Reconnected the wiring harness to the COPs, and it was time to put the air intake back on.

Got it all buttoned up, fired it up, and was very pleased with the results. No misfires, no extra noises, in fact, it seems there is LESS noise, as I think that loose plug was definitely leaking at least when the engine was cold.

As I say above, I am very pleased with the Bosch plugs, at least for the time being, and I will report back if I do (or don't) have any problems.

For now, it looks like another 2 or 3 years before I go through THAT again

First pic is #1 through 5, second is #6 through 10. Notice the anti-seize still on the threads, the shiny area where the plug seals to the head, and that it was definitely TIME to do them overall based on appearance.

 

Thanks for the write-up Art. For all the negative comments on Bosch plugs in the past, this will be an interesting experiment......

 

Subscribing.

 

I have used 2 sets Bosch plugs with multiple electrods for the past 150K miles. I am very pleased with them. The set that i have in the truck now, has nearly 50K on them and as Art said, they are smooth. My truck is a 99 F350, V10, 3.73 gears, DRW, 4x4, sc lb, with 350K on the clock. I marvel every time I drive it, how smooth it runs. Also getting 13 mpg when driving 65 on highway.

nice wright up Art. thanks

 

i wonder if that tiny tip on the electrode will last..

seems like its gotta be prone to disappearing..

be intersting to see/read ur future updates.

ps i wonder if the loose plug was due to using only 14lbs the previous time.. that number seems awful low (unless you have the 3thread heads). i used 24lbs dry when i did my 03 V10.

 

Iridium plugs are supposed to last 100k+ miles. I put NGK iridium plugs in a past suv and they were great. Sold it 15k miles later so I don't know for sure if they last.

 

I put iridiums in my bmw 80k miles ago.brkeix7. still runs smooth as glass. I noticed a difference as soon as i started it.. I think my excursion is going to get a set.

 

Also subscribing Art-------thanks for posting this! It will be interesting to any modular V8 or V10 owner seeing how another brand of plug performs over the longer term.

The center electrode does look woefully smaller than MotorCraft---I also wonder about its longevity, if it'll be burned away soon.

Another question is the plug body threads matching Ford's in the heads? I've read somewhere Ford saw fit to have a different thread profile wihch was a suspected issue with blowing or spitting of plugs earlier on. I don't know this to be the case and from the side-by-side photos its tough to tell.

Looking forward to seeing how this plays out------certainly a game changer if its a benefit!

 

I will definitely check one or two for wear after the winter is over.

I have the 3/4 thread heads.

 

Any updates on these plugs? Im going to be putting new plugs in my truck soon, just seeing what good options are available.

 

Yes, any updates?

 

No issues so far, just like OEM plugs.

 

I have tried the Pulstar Eco-MPG Series Spark Plugs in my wife honda civic. they are nice and smooth.... has anyone have any opion on the Pulstar Performance Series Spark Plugs and find them cheaper that $134.95
they really maybe but maybe a half of a half of a half of something but her 5 speed pick up was nice. then again i never raod in it before hand.. we just got it about 3 months ago



K&N air intake, BBK Dual 65mm throttle body, Jet Mass air flow, Jet spacer, Royal purple engine, Royal purple trans, Royal purple rear diff, Fitch Fuel Catalyst. took off my luggage rack, removed that big black rubber piece under the hood, ditched the running boards, took out the 3rd row seat and bass system, kick the wife out! purchase just now a jet therm stat.... anyone have any problems!!! .... thanks and happy holidays

 

Art, have you noticed any change in MPG?