Changing plugs on a 300M

[G-MAN]

I had to drive to Columbia to interview some witnesses on Sunday and I could really tell my engine needs a tune-up. So I picked up a set of Champion platinum plugs yesterday and I'm going to put 'em in this morning. Anyone who has looked under the hood of a 300M would think replacing the plugs would be a relatively quick and straight forward job. In theory, it is. The problem usually comes when you try to remove the Torx screws that hold the coils down. They are put in WAY too tight at the factory and tend to strip off when you try to remove them. I went out earlier this morning and sprayed all the screws good with PB Blaster. I'm letting that soak in. I'll be going out in a little while to do the change. Wish me luck.

 

[JTK]

Nice pics and write-up! It's always the small fasteners that give you the grief. I found a similar nightmare with the
Joel

 

[mechtech2]

Put a torx bit in the bolt and tap on it. This will break it free, or at least allow the loose juice to get in better.
Tap a little harder on it if it's stubborn - it will seat the bit and loosen the bolt.

 

[G-MAN]

Well, that was a relatively painless procedure. The Torx screws on the coils were no problem. I don't know if it's because I used PB Blaster, but I was able to take all but three of them out using nothing but a T-27 screwdriver.

The SNAFU came when I tried to use my 5/8 spark plug socket to remove the first plug. Because these plugs are longer than normal, my spark plug socket was too short. So I had to drive down to Carquest and get a longer 5/8 spark plug socket. I get back and discover that the longer socket is 1/2 drive while all my ratchets and extensions are 3/8. So I drive back to Carquest and get a 3/8 to 5/8 adapter. Thus the first plug took about 2 hours to do and the remaining five plugs took about 10 minutes each.

Judging from the condition of these OEM plugs I'd say 50,000 miles is really the useful life. Mine have almost 80,000 on them and there is no way they could go 100,000, IMO.

It's 100 degrees here right now and I'm dripping wet. I'm going to cool off for a few minutes and then take her for a test drive.

 

[surfstar]

Quote:

---

The SNAFU came when I tried to use my 5/8 spark plug socket to remove the first plug. Because these plugs are longer than normal, my spark plug socket was too short. So I had to drive down to Carquest and get a longer 5/8 spark plug socket. I get back and discover that the longer socket is 1/2 drive while all my ratchets and extensions are 3/8. So I drive back to Carquest and get a 3/8 to 5/8 adapter. Thus the first plug took about 2 hours to do and the remaining five plugs took about 10 minutes each.

---

Sounds like so many DIY jobs. It would be soooo much easier to have a garage full of tools at home.

 

[G-MAN]

Just got back from a 20 mile jaunt down the Interstate. Wow, what a difference! I hadn't realized just how badly the performance had deteriorated.

 

[Oldmoparguy1]

Nice job G-MAN. What brand plugs did you use? Text says Champion, but pic is of NGK, & Bosch.

 

[Dr_No]

EDIT: Sorry my vision didn't detect the link in there

 

[Merkava_4]

Why the [censored] would a company make a 1/2 inch drive spark plug socket? That's whacky as all [censored].

This is what you need: a 3/8 drive Snap-on S9720KA

 

[Camu Mahubah]

Hey we got a lawyer not afraid to get his hands dirty! Bitog is the place to be...bet other sites can't claim this! How many miles were on those plugs your honor?...

 

[G-MAN]

Quote:

---

Nice job G-MAN. What brand plugs did you use? Text says Champion, but pic is of NGK, & Bosch.

---

The pic is not mine. It's from a fellow member of the 300M Club who did a "how to" page on changing spark plugs.

I used the same Champion platinum plugs that came in it from the factory. My factory plugs had 79,900 miles on them. I think I pushed them about 29,900 miles too far.

 

[JTK]

It's especially great when the rubber grommet in the spark plug socket, slides out and stays on the newly installed spark plug! I love that. It helps to have a pic set or long skinny needle-nose pliers on hand.

Joel

 

[Ed_T]

Why aren't you guys just using iridiums?

 

[Merkava_4]

Quote:

---

Why aren't you guys just using iridiums?

---

That's probably what I'll do when it comes time to do mine. AC Delco iridium 41-101's. The stock double platinum 41-921's are twice as much money because they'd have to be special ordered.

 

[G-MAN]

Quote:

---

Why aren't you guys just using iridiums?

---

Why use them? Do you think I would be able to detect any performance difference that would justify the roughly 3X price difference?

 

[Jonny Z]

Is the 300M a rear wheel drive? I thought it is a clone of the Dodge Intrepid.

 

[wavinwayne]

This reminds me; I need to change the copper plugs in my VW 1.8T, which have around 25k miles on them.

 

[G-MAN]

Quote:

---

Is the 300M a rear wheel drive? I thought it is a clone of the Dodge Intrepid.

---

The 300M wasn't a clone of anything. It was based on the LH platform, as was the Intrepid, Concorde, and LHS. The LH platform was designed to be FWD, RWD, or AWD with a minimum of changes needed on the production line. In the end Chrysler chose to go with FWD across the board for all LH models. Though at the time of the Mercedes takeover, development of the LX platform was well underway and it was based on the RWD variant of the LH. When Mercedes came in they scrapped that LX and started a new LX design from scratch based on the E-Class Benz platform.

 

[Jonny Z]

Quote:

---

Quote:

---

Is the 300M a rear wheel drive? I thought it is a clone of the Dodge Intrepid.

---

The 300M wasn't a clone of anything. It was based on the LH platform, as was the Intrepid, Concorde, and LHS. The LH platform was designed to be FWD, RWD, or AWD with a minimum of changes needed on the production line. In the end Chrysler chose to go with FWD across the board for all LH models. Though at the time of the Mercedes takeover, development of the LX platform was well underway and it was based on the RWD variant of the LH. When Mercedes came in they scrapped that LX and started a new LX design from scratch based on the E-Class Benz platform.

---

So is this FWD or RWD? Web searches indicate it is a FWD but from the photos, the engine is NOT transversely mounted.

 

[JTK]

Quote:

---

So is this FWD or RWD? Web searches indicate it is a FWD but from the photos, the engine is NOT transversely mounted.

---

It's front wheel drive with the north/south engine. It's been that way since the inception of the Intrepid/Eagle Summit (I think that's what it was called) Pretty cool design IMO.

Joel