I put these plugs in my car a while ago and have not really noticed much difference. Are they supposed to be a lot better than the single tipped ones?</P>


Now that I've had them awhile, I noticed theyget dirty and caked up with black hard residue very quickly. I used the dialectric grease and stuff, but it doesn't help. Does this mean something in my engine is dirty, or thatI just need to replace the plugs? Also, would you reccomend the +4's or the regulars?</P>

 

You may be due for some valve work or maybe it's just running too rich. Take itto a MB hospital or mechanic you trust and show them a dirty plug. If they don't all look the same, tell them which cylinders the dirty ones come from.</P>


Just my opinion, mind you.Platinum spark plugsare a salesgimmick.I stay way fromthem. Some reasons off the top of my head:</P>


- Someplatinum plugs will drop their platinum disc into thecombustion chamber after just a few thousand miles. Viola. You no longer have a platinum plug, the spark gap is now way off, and who knows what the disc will do.</P>


- Copper plugs provide a better performance spark. How many race car enginesuse platinum plugs?</P>


- Platinum plugscost four to six times more than copper plugs, but don't return four to six times the value. The plug manufacturers are laughingall the way to the bankholding your money.</P>


- Manufacturers tell you to change your platinum plugs after 100,000 miles. If you wait that long, you risk having a spark plug seized into the cylinder head. If you plan to wait 100,000 miles, take them out right now and put anti-seize on the threads. You'll thank me later.</P>


</P>

 

I fitted bosch platinum 4 plugs to my 87 w124 200. It has had a fully rebuilt 2.3l engine fitted. I found that they were great in cold mornings when the engine was warming up it has a little more pull compared to the normal plugs. I didnt feal any noticable power gians but the car seemingly idles better... The way these plugs differ from conventional ones is that they allow the spark the chose the tip with the best earth. They therefore provide the best spark available, at diffrenet egine loads and rpms.

The problem that lugnut has highlighted is indeed an important one. This is where cheap replica plugs with multible tips, detach one or more of them into the engine when they overheat. This is why they MUST NOT be used in turbo cars! But Bosch plugs NEVER do this anyway so i can assure you it is nothing to worry about.

To solve the carbon build-up on the plugs use a fuel aditive like (in UK anyway)"Redex petrol treatment" these really do eventually keep the plugs clean. But it is normall anyway for cars to soot the plugs and it shouldnt be anyrthing to worry about. Spark plugs can give indications of the fuel mixture as follows,

Richness are normally black (sooty)deposits,
leanness (weak mixture) are white deposites
and normall deposites are grey/ tan colours!