Seeking Guidance on Spark Plug Change - 2006 Lincoln Town Car Designer Series

[Sl4b]

Hey all!
My Lincoln Town Car spent most of it's life in Michigan, and it's been in Arizona for the last 3 years.
It has 112k Miles on it, and no service record for having the spark plugs replaced.

I am going to replace my spark plugs when my parts come in the mail, I have all the right sockets, extensions, and gap tools.
I have an air compressor for dirt, and a flexible inspection camera to look inside the holes.

I bought 8x OEM Motorcraft SP-493x Spark Plugs, and 8x Motorcraft DG-508 Coils. I also have high temp anti-sieze, and dielectric grease.

My Haynes manual says 13 ft lbs of torque for the plugs, but some facebook groups are saying go anywhere between 18-21 lbs, some say use anti-sieze, some say dont.
I was looking for some guidance here on this, and any tips/things to watch out for.

 

[Jryan]

Given the shorter-than-desired thread engagement of spark plugs to cyl head on the 4.6L, I followed the online advice and torqued to 24 ft*lb without use of anti-seize on threads with intent to prevent future loosening and blowout. This was at 72kmi, car sits in the parking lot today with 89.2kmi and all is well thus far.

I also vacuumed out the area once coils were removed to keep debris from falling into the pots. I found the vehicle-side-wire-harness connectors for the coils to be rather brittle - a broken connector snap retainer required some attention. Else the accessibility for the job is quite good, and I'm glad I have the 4.6L and not the long extended plugs of the 3-valve 5.4...

anyways...

-2004 UL black

 

[Sl4b]

Given the shorter-than-desired thread engagement of spark plugs to cyl head on the 4.6L, I followed the online advice and torqued to 24 ft*lb without use of anti-seize on threads with intent to prevent future loosening and blowout. This was at 72kmi, car sits in the parking lot today with 89.2kmi and all is well thus far.

I also vacuumed out the area once coils were removed to keep debris from falling into the pots. I found the vehicle-side-wire-harness connectors for the coils to be rather brittle - a broken connector snap retainer required some attention. Else the accessibility for the job is quite good, and I'm glad I have the 4.6L and not the long extended plugs of the 3-valve 5.4...

anyways...

-2004 UL black

Do all the 4.6 have the short plug threads? I have read that the 06' does have the longer threads

 

[Action]

Opinion - the coil replacement is not needed. Coils have been very reliable for a couple of decades. Plus they do not wear out. If anything negative happens with a coil, it just stops working.

I have a 5.4l 3V and a 4.6l 4v. Both have over 200,000 miles with no negative events after the first plug change.
Very high temp anti seize has been a huge blessing on the 5.4l. Not sure it was needed on the 4.6l 4v. And it did not hurt as long as the correct toque is used. The torque is different for the different modular engine configurations. I have never owned a 4.6l 2v.

Action

______________________________

 

[etinpa]

From what I've read over the years, the thread count was increased on the change from 2002 to 2003 although there is some question whether it was the change of model year or closer to the change of the calendar year. Either way, well before your car was made.

Although anti-sieze might be useful on three valve engines, the Town Car only ever had the two valve. I do agree with tightening above spec (I use 20 lb-ft).

 

[driller]

Opinion - the coil replacement is not needed. Coils have been very reliable for a couple of decades. Plus they do not wear out. If anything negative happens with a coil, it just stops working.

Agreed.

As for the torque on the plugs, never trust Haynes manuals... get the OEM manual. I can't remember the factory specified torque and my manual is in the garage. Next time I'm down there I'll look it up and post it here unless someone else beats me to it.

I've never had issues using anti-sieze (very sparingly) on spark plug threads on any modular engine. I'm old school and was trained to use anti-seize on steel to aluminum fasteners, which would by definition include spark plugs.

As @Jryan pointed out, use caution with the harness connections on the coils. If you break a retaining tab, you will want to be sure to secure the harness connector with a small nylon zip tie.

 

[Blueox]

OEM manual and Haynes are the same.

 

[Action]

A word on plastic connectors. (Coils and injectors) Another application where I use a spray conditioner/treatment.
Helps the plastic from not getting brittle. Plus I am wiping off any surface dirt that might cause an issue.

Action

______________________________

 

[driller]

The 2006 Town Car manual shows 11 lb-ft for the spark plug torque.

 

[Sl4b]

The 2006 Town Car manual shows 11 lb-ft for the spark plug torque.

View attachment 24312

Thank you for this! This is the Haynes Manual right?

 

[Sl4b]

The 2006 Town Car manual shows 11 lb-ft for the spark plug torque.

View attachment 24312

NVM I think this is from the Workshop manual, I was able to go to Operation Charm and get an offline version. Thank you again

 

[Blueox]

I have the Lincoln Workshop Manual and can confirm the torque is 11 lb-ft as shown on page 303-07-1.

______________________________