Dealer installed different heat range plugs

[doitmyself]

About 18 months ago I reluctantly took my Caravan to a dealer to diagnose a pesky engine misfire. Turned out to be a bad plug wire and they replaced the wires and plugs.

My engine specifies copper Champion RC14MCC and they installed RE16MC.

According to the Champion site, the second plug is 1/4" longer reach and "hotter" heat range.

The plugs looked good after 30K miles, with only a few thousand's wear and a light whitish/tan color.

Should I be concerned or take this up with the dealer? Anything to worry about? Damage done?

Seems like the one place that should do it "by the book" would be the dealer.

 

[Colt45ws]

Chrysler may have changed the spec or consolidated inventory. You could call them and ask them..

 

[bdcardinal]

Originally Posted By: Onmo'Eegusee
Chrysler may have changed the spec or consolidated inventory. You could call them and ask them..


+1. we get that a lot at my work. the indy shops that dont have proper diag tools always say it does not match. the ones that have alldata etc get it.

 

[StevieC]

My dad is a retired mechanic/Chrysler employee. What engine and what year?

 

[doitmyself]

2005 (made in 5/04) Caravan SE short wheelbase, 4cyl. engine


The plug speced under the hood also has a 5 at the end: RC14MCC5, which the Champion site says designates a wide gap per federal and California standard.

I'm confused now. I checked the aftermarket stores (AZ, AA, Rock Auto and they all show the RE16MC!

What gives? Based on the factory service manual and the hood sticker (2005 Caravan SE) I installed the RC14MCC5 at .050 gap.

Has Chrysler determined the RC16 with .040 gap to be better and should I reinstall this? Or, am I good to go as is.

 

[StevieC]

Spoke to my dad, he says that it won't harm the engine, it will just cause the cylinder temperatures to run a tad hotter (not even noticeable) and may make a slight difference in emissions, but not enough to cause any problems or fail a smog test.

No worries he says!

(35 Years experience, you can trust!)

 

[swalve]

http://img27.photobucket.com/albums/v82/Sci-Fi/TSB/Picture_007a.jpg

 

[StevieC]

These new plugs are a good thing... They will contribute to better fuel economy because of a more complete combustion. I would leave them in and drive it!

I must add a word of caution though... Running plugs that are too hot for an engine (not these ones), can cause high NOX in the emissions and cause failed emission tests.

 

[doitmyself]

swalve,

Your picture is worth a thousand words. Yet, another lesson learned.

Thanks, everyone.

 

[mechtech2]

That 1/4" longer reach scares me. That would mean the threads are hanging in the breeze in the combustion chamber . Thos sharp threads are hot points that could cause preignition. Unless the old ones were too short, I don't get why they would do this.

If you plugs never fouled or misfired because of their heat range, then the heat range was OK. You want as cold as you can get, and never foul or misfire.

 

[doitmyself]

Originally Posted By: mechtech2
That 1/4" longer reach scares me. That would mean the threads are hanging in the breeze in the combustion chamber . Thos sharp threads are hot points that could cause preignition. Unless the old ones were too short, I don't get why they would do this.

If you plugs never fouled or misfired because of their heat range, then the heat range was OK. You want as cold as you can get, and never foul or misfire.


I will check the plugs tonight to see if there is indeed a reach difference. I'm just going on Champion's code for now.

The service bulletin shown in swalve's link says "The new plug is more resistent to cold engine carbon fouling". There must have been issues for them to change it.

The fact that the dealer put in the new style plugs and all the auto stores list the new style is convincing evidence that a change was made.

 

[BuickGN]

Hotter plugs are more resistant to fouling. Too hot and they can cause detonation. Fuel economy won't really change as long as they're not too hot or cold.

The longer reach doesn't necessarily mean the threads are sticking into the combustion chamber. Maybe the stock plugs don't use all of the threads in the head.

 

[doitmyself]

An addendum: The new style plugs have the exact same reach as the old ones. The champion code chart I read must be wrong regarding the second letter (RE vs. RC)and it's reach description.

I visited the dealer and the parts computer there still shows both plugs for this application. But, a mechanic said they follow the TSB which says:

"The new spark plug is more resistant to possible cold engine carbon fouling. The new style spark plug is now recommended and preferred for use in all 2004 model year vehicles and all prior year vehicles equipped with the 2.4L engine."

The 2005 models supposedly switched over to the new plug from the factory. Mine was made in 5/04, marketed as an '05, and slipped under the radar regarding this change.

Thanks guys. As always, I appreciate your input.

 

[StevieC]

Less carbon fouling = more complete combustion and that's what I said...

 

[mechtech2]

If threads are showing, whether they are on the plug or in the head, something is wrong. The same hot spots exist.
And if the correct longer plugs are even inserted, the threads need to be retapped first.