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One of the BW Old Guard/R129, W204 Moderator
1997 SL500- 40th Anniversary
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7,166 Posts
Discussion Starter #1 (Edited)
Changed plugs a coupl'a weeks ago, due to an incident with Seafoam. In short, car had been setting for a while, so I thought I'd treat it to a dose of clean-out. A day or so later, she developed a dead miss... When I pulled the plugs, guess what I found: #4 fouled out/completely bridged...

Three things were noted: 1) Fouled plug(s), perhaps from the carbon/seafoam treatment (as no oil consumption but could have been a tad rich). 1-4 in bottom row, 5-8 on top row.
2) Plugs wrong heat range... Note W8DC, non-resistor, made in India
3) Plugs came out easily, with removing only the breather to make room for tools :)

Replaced with NGK BP5ES non-resistor, of course.

Second pic is the result of today's shake-down run; the first chance I have gotten to take her out for a good romp. Purring like a sewing machine :) Note temp, oil pressure, mileage, and idle rpm. I'm a happy camper... for now! Should I mention HT is on, and A/c is ice-cold...

PS... no grief needed for the faded needles. "That's just patina, son..."

Oh, and the little tops on the plugs... I removed them from the new and screwed them to the old.
 

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1987 Mercedes-Benz 560 SL
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973 Posts
So is the improvement due to the new plugs or the Sea Foam?

(I'm skeptical about most additives--except maybe Techron, used as needed--but Sea Foam does have a following.)

Good road,
 

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'71 250, '78 450SLC 5.0, '78 450SL, '81 380SLC 5.6, '89 260E, '15 Kia Sorento
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5,269 Posts
Changed plugs a coupl'a weeks ago, due to an incident with Seafoam. In short, car had been setting for a while, so I thought I'd treat it to a dose of clean-out. A day or so later, she developed a dead miss... When I pulled the plugs, guess what I found: #4 fouled out/completely bridged...

Three things were noted: 1) Fouled plug(s), perhaps from the carbon/seafoam treatment (as no oil consumption but could have been a tad rich). 1-4 in bottom row, 5-8 on top row.
2) Plugs wrong heat range... Note W8DC, non-resistor, made in India
3) Plugs came out easily, with removing only the breather to make room for tools :)

Replaced with NGK BP5ES non-resistor, of course.

Second pic is the result of today's shake-down run; the first chance I have gotten to take her out for a good romp. Purring like a sewing machine :) Note temp, oil pressure, mileage, and idle rpm. I'm a happy camper... for now! Should I mention HT is on, and A/c is ice-cold...

PS... no grief needed for the faded needles. "That's just patina, son..."

Oh, and the little tops on the plugs... I removed them from the new and screwed them to the old.

Those are the same plugs I just pulled out of the 026. I wonder who was recommending them because they are incorrect for my car as well.
 

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One of the BW Old Guard/R129, W204 Moderator
1997 SL500- 40th Anniversary
Joined
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7,166 Posts
Discussion Starter #4
So is the improvement due to the new plugs or the Sea Foam?

(I'm skeptical about most additives--except maybe Techron, used as needed--but Sea Foam does have a following.)

Good road,
Plugs made the difference most definitely... #4 was bridged closed with "contaminants", which resembled carbon... Not sure if the seafoam was the culprit or not. Car has only been used locally around town on short runs for he last several months, so it could have been a combination of things, ie running rich/incomplete combustion due to the cold plugs and other things. The old gal needs run more... Can anyone say, "Italian Tune-up"?

Techron from now on... Save the seafoam for the lawn tools, etc. Incidentally, I treated my '88 ranger with seafoam according to instructions before I changed the plugs/wires/rotor and cap. The plugs were coated with carbon as well. In a few months, I'm gonna remove #4 again to inspect... That may be a caveat with seafoam treatment.
 

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1978 450SL--117K
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1,374 Posts
I changed from the resistive Bosch plugs to Champions on the 560 and believe it is getting worse MPG--certainly no better performance and was considering going back to the Bosch platinums.

I swear by Techron. And I used to use Slick50 in all of my heavy stuff. My diesels started easier in the Winter time than anyone else's did. I have thought about on the 107's, but I am hesitant.
 

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1981 380SL
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256 Posts
Did you just add Seafoam to your gasoline, or did you do the hardcore intake system cleaning by feeding it into your intake manifold through a vacuum port?

If the latter, it sounds like it worked as advertised and thoroughly degunked your intake and valves (or, at least, the #4 runner). Unfortunately, that gunk had to go somewhere. Never thought that running gunk through a running engine was a great idea -- you may have just confirmed it for me.
 

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1987 MB 560sl, Champagne/Burgundy, 83K miles, decent shape
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658 Posts
I had a very similar experience with the Seafoam and my 560sl.
I have had beneficial results with Seafoam in other engines, cars, equipment, etc.
However, when I used Seafoam in the fuel of my sl, the thing ran like crap...really bad!
It was so bad that I ended up siphoning about half a tank of fuel out (at almost 4.00 a gal!!!) and added fresh fuel. Then, I used Techron and gave it the Italian tune-up, and all has been fine since.
Rule: No Seafoam for the sl, ever.
 

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It Is What It Is, Dude
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22,841 Posts
...



An Italian tuneup usually refers to a process whereby the operator of a motor vehicle runs the engine at full load for extended periods in order to burn carbon buildup from the combustion chambers and exhaust system. It is performed after a traditional tuneup and often accompanied by an addition of fuel system cleaner to the fuel tank. It is particularly useful for vehicles that are only operated at low speeds on short journeys, and for diesel vehicles prior to emissions testing.
 

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1987 MB 560sl, Champagne/Burgundy, 83K miles, decent shape
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658 Posts
Not sure if IsThisDave has any ItalianAmerican heritage in his blood, but he is correct as to the definition of the Italian tune-up. Essentially, put in fresh gas, get out to the highway or wherever you can really push it, and hit the throttle hard and long. That should do it!!!

If you need to know anything further about the Italian tune-up, just ask! Not only am I 100% Italian, but I also am very experienced in driving the piss out of cars, motorcycles, boats, etc.....
 

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One of the BW Old Guard/R129, W204 Moderator
1997 SL500- 40th Anniversary
Joined
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7,166 Posts
Discussion Starter #11
Did you just add Seafoam to your gasoline, or did you do the hardcore intake system cleaning by feeding it into your intake manifold through a vacuum port?
I had a very similar experience with the Seafoam and my 560sl.
I have had beneficial results with Seafoam in other engines, cars, equipment, etc.
However, when I used Seafoam in the fuel of my sl, the thing ran like crap...really bad!
It was so bad that I ended up siphoning about half a tank of fuel out (at almost 4.00 a gal!!!) and added fresh fuel. Then, I used Techron and gave it the Italian tune-up, and all has been fine since.
Rule: No Seafoam for the sl, ever.
Dosed as above, but did not siphon out... Still in there, but almost gone :)
 

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One of the BW Old Guard/R129, W204 Moderator
1997 SL500- 40th Anniversary
Joined
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7,166 Posts
Discussion Starter #13
I changed from the resistive Bosch plugs to Champions on the 560 and believe it is getting worse MPG--certainly no better performance and was considering going back to the Bosch platinums.
Can you elaborate?

1) What "resistive" bosch plugs specifically?
2) What Champions specifically? Resistor?

I read "somewhere" (probably within the tomes here) that Platinum were a No-No... Don't remember why. Seems like it had to do with destruction of the platinum tip, resulting in Fm in the combustion chamber...
 
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