CarTalk.com Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

Help on new plugs and wires

Mercedes 500E 4 matic 2005 model, 130K, runs great but I notice could use some pick up. Wondered if new plugs and wires would help. Dealer tells me its not running rough and wait till lights come on. I think its a good idea since it costs 1700$ to change plugs (16) and wires. What do you all think? Can I wait till next service? And why does it cost $17)) to change plugs and wires? Are those plugs made of gold or what? Can any one help? Suggestions? comments

Those kind of prices are why so many of us on here do our own work.

1 Like

If you can find them, do it yourself

3 Likes

The 3 biggest reasons it costs so much is:

  1. Mercedes-Benz
  2. Dealer
  3. Luxury Euro import.
4 Likes

That is it, most of the cost is labor. As far as a noticeable change in power, unlikely. Most manufacturers usually recommend plugs around 100K miles, but sure, no CEL, wait until the next time you drop it off for service.

Pretty much sums it up .That and the fact that you decided to get a car with an engine that has 2 plugs per cylinder . There is usually nowadays a ton of stuff that has to be disassemble just to be able to get at the plugs thanks to govt emmissions regulations .

1 Like

Plugs were changed in 2017 around the 75K mark. I guess I can wait for next time around. I don’t drive the car much. But I did make the mistake of using regular gas a bunch of times and then started noticing the lack of a pick up. With premium it seems to go away. You think thats the issue. These things are so much electronic that is hard to figure like I could in my college days with an oldsmobile cutlass supreme.

The picture sums it up.

But then even independent mechanics for MB and BMW cost the same in unit labor. Dealer is 150/hr. thee other shops are around the same. Might as well depend on original parts from dealer. This is SF mind you.

I guess with a Tesla I dont need to worry about plugs. One less headache. Actually the cost of a Tesla Model 6 is less than than my car when I bought it fully loaded.

Change them if you want, but I’d bet a donut there will be no improvement in performance. Of course, after spending those $$$ you’ll THINK there is…

I think you need to get another quote. An independent shop did the spark plugs (16) and wires (Bosch OEM) on my mom’s CLK 430, for less than half that price. The spark plugs aren’t especially expensive, they go for less that $5 a piece. The wires can cost upwards of $300 retail, and a shop will mark that up somewhat. Also the labor rate at MB dealership is going to be astronomical. With that said, the plugs should be replaced every 50k miles or so per the manual.

1 Like

you hit the nail on the head. LOL

My Cutlass Supreme required premium. Your MB may need premium, 91 or greater octane, for best performance. If so, when using lower octane fuel the computer will make adjustments to the engine such as less advance on the ignition timing, hence less performance.

When the car requires premium (which yours does) if you substitute regular the car will retard its timing to cope with the lower octane. You will have less power and poorer gas mileage as a result. Go back to using premium and performance and gas mileage should both improve.

Good advice. Saving a few dollars may not help in the long term.

When was that - I had my second hand one in the mid eighties. It was on regular leaded and then unleaded. The at 350 engine was a bullet when I pressed the throttle - the whole body stood up. It did fine with regular. Only downside - Rear wheel drive was terrible in snow and one time I did a full 360 on Route 128 in Mass and luckily did not hit anyone.

Good advice. I need to take it to an independent shop and get a quote.

Mine was a 1970 with the Olds 350 4bbl, pretty sure it was an Olds engine—not an SBC, I think the compression ratio was 10.5 to 1, required premium.

2016 Rolls Royce ghost everything up to and including the wipers need to be removed to do plugs, glad I don’t do many