Well Ron,,
Tonight I installed the Stock Bosch Plugs.
Ive had a rough idle and never felt the best about the Bosch platinum 2's.
So I only ran them 5,000 miles. I think my mass air flow problems may have made them foul early.
At least they were only $4 per cyl each so I only blew $24 plus tax.
2/21/07 update. New stock $100+ plugs still did not take miss out of idle.
2-1-8 UPDATE : I replaced 3 of the ignition wires where my records show I picked up some misfires based on my code reader. I am down to a rare occational mis fire. I sat in my brother in laws 2007 Suburban and it idled worse than my 1999 with 130,000 miles. I decided my rough idle is so small I can ignore it.

__________________
Steve Danville
what i did myself.
CPS
rear shocks
MAS x 3.
SparkPlugs (twice)
Fuel pump & Filter
Window switch
replaced both failed horns with Honda horns.
Cleaned ERG Tube
Oil changes
Oil consumption Fix
Brake Pads
A/C Recharge
Anti-Freeze change X 2.
Front Shocks. Monroe. $90
Mercedes Warrenty Work:
Harmonic balancer,power steering clamp. Cat converters.Drive Shaft Bearing.s
Replaced Outer Lower Tie Rods and front lower ball joints at 156,000 miles

I think it is in keeping with the spirit of this forum, if I add the disclaimer that although the above worked for me, I make no representations whatsoever that this is the complete, correct, factory-approved procedure and will not cause damage to your vehicle and / or bodily injury to yourself. Always take all necessary safetly precautions before performing any work on your car.

Hope this helps.

Thanks for the great write up. Prying the plug wires off worked well using just a regular 17mm combo wrench, as you describe. My plugs were not that tight. I removed the driver's side coil pack for better freedom to wrench.

A WARNING, totally off the wall with regard to changing plugs. The surge line from the radiator to the expansion tank is very vulnerable to anyone climbing up on top of the engine to get a better pull on something. I broke the little nipple off the plastic header on the radiator and didn't even know it. It is unsupported and PLASTIC! luckily, i was able to tap some threads and then seal/support it with some JB Weld

Jim in PHoenix

I have changed the plugs on two 99 ML's in the last year or so; did not remove any parts of the fender, etc etc. I did have to use a pipe for leverage on the ratchet wrench to get several of the plugs out. They were very tight at 60K and 70K miles. I use Plats in all my Mercedes and they work beautifully ..... all of them run like deer!! Ben Carter

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Ben Harrison Carter
1999 Mercedes ML320 87K
1992 Mercedes 300CE 89K
1995 Corvette 29K -- Sold Dec 09
1989 Mercedes 420SEL 99K -- (Sold 4/08)
1968 Mercedes 230S (106K) (Sold 9/06))
1976 Mercedes 450SEL 130K (Just sold - 06)
1961 Mercedes 220Sb (sold years ago)

dont they take 12 plugs..

There are six coil packs; one for each two plugs -- and there are indeed 12 plugs. It is not really a tough job if done properly, except for some tight plugs in a few cases.

__________________
Ben Harrison Carter
1999 Mercedes ML320 87K
1992 Mercedes 300CE 89K
1995 Corvette 29K -- Sold Dec 09
1989 Mercedes 420SEL 99K -- (Sold 4/08)
1968 Mercedes 230S (106K) (Sold 9/06))
1976 Mercedes 450SEL 130K (Just sold - 06)
1961 Mercedes 220Sb (sold years ago)

99 ML 320 wih 207K miles

I changed plugs over the weekend. Took about 30 minutes of prep (check gap, anti-seize threads, dielectric both ends of each plug wire) and about 90 minutes to do the R&R. Thanks for the excellent write ups in this forum. My experience:

1) I was really surprised how deep the plugs fit into the side of the block. It's like a Hemi. I wasn't expecting to be working mostly by feel. But didn't run into any problems.

2) I read in multiple places a 17 mm wrench is used to pop the wires off the plugs. I checked and a 17 mm wrench may have worked but it did not fit around the metal shaft of the wire. I used an 18 mm. It fit perfectly.

3) I did not remove a wheel or inner fender. I did remove all coil packs as I went and removed the air box to do the passenger side.

4) I wasted about 20 minutes chasing a new plug I dropped into the nether regions of the engine compartment. Got smart and stuffed an old bath towel in the gap between the engine and inner fender. The towel trick saved me twice after that.

5) I bought Beru wires (part number ZEF 1442 and 300.891.442 on the box) and I have a concern for the next plug change in 100K miles. Look at the image. The old plug wire is on top. The new Beru is on bottom. The Beru has much less metal and no lip to grab onto. The only thing you see when they're installed is the rubber part of the connector. Not sure how I'll get those baby's off in four years. Hopefully the dielectric will enable me (or future owner) to pop them off by hand. I may proactively pop them off and re-seat them every six months or so (if I can remember to).



Notice also my old plug with right at 100K miles on it. The center electrode is worn to a nub. The gap probably opened from 1.00 mm to 2.00 mm. Amazingly, the truck ran smoothly with the old plugs. Wife needs to give me some gas numbers from before and after so I can see if it made a difference in mileage. But this is still hard evidence you should change them AT LEAST every 100K miles.

__________________


Behind every great man is a great woman. Behind every great woman is a great behind.

Don't bother with torque figure if you use antiseize on threads because it won't be accurate.

__________________
Kent Christensen
Albuquerque
'07 GL320CDI, '10 CL550. '01 Porsche Boxster
Two BMW motorcycles

I called the MBZ dealership today and they highly NOT recommended to use Bosch Platinum 2 or 4 spark plugs. Looks like your experience was also pretty bad with Bosch. Do you recomment any other brand for ML320?

__________________
1999 ML320
100,000 miles
77K - engine failure


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Nope. Just Origional Equiptment for me - regarding plugs.

__________________
Steve Danville
what i did myself.
CPS
rear shocks
MAS x 3.
SparkPlugs (twice)
Fuel pump & Filter
Window switch
replaced both failed horns with Honda horns.
Cleaned ERG Tube
Oil changes
Oil consumption Fix
Brake Pads
A/C Recharge
Anti-Freeze change X 2.
Front Shocks. Monroe. $90
Mercedes Warrenty Work:
Harmonic balancer,power steering clamp. Cat converters.Drive Shaft Bearing.s
Replaced Outer Lower Tie Rods and front lower ball joints at 156,000 miles

Could you please tell me if this is the OEM part:
Bosch Spark Plug Part Number: 4501

http://tinyurl.com/6pyj5r

I do not see this part number in the MBZ manual. Thanks!

__________________
1999 ML320
100,000 miles
77K - engine failure


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