- - a lesson in spark plug reading - -( ROUND 2 )

[lurtch]

Take a look at what is happening in my cylinders. (M130.980)

# 1 is a nice toasty brown

#2  looks like the result of a fouled injector ( bad spray pattern = uneven atomization )

#3  and #5  both have evidence of oil fouling
 
#4 is also running too rich

#6 appears to be just OK



 The obvious presence of  oil  in the threads  of four of the plugs  indicates there is considerable  ring blow-by on those cylinders. It works its way up  into the threads on the compression stroke after being drawn into the cylinder on the intake stroke. This is a rebuilt head from Metric Motors without any Heli-Coils in it. However, I am sure these threads are at the outermost tolerance limit, because there is a little too much wobble when screwing them in.

I guess this is to be expected from a vehicle that had no maintenance documents , unknown mileage and had been abandoned and sitting idle for five years.

I installed a rebuilt head, leaving the bottom end untouched, and crossed my fingers - - .  

 - -  oh curse those  German Gremlins ! ! !      Larry in  CA


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[ja17]

Hello Larry,
The presence of oil on the spark plug threads is probably a result of the ball stud adjusters leaking oil through their threads and onto the spark plugs. Feel directly above the spark plugs on the outside of the head. The valve adjuster "ball studs" are actually threaded through the head and  may be seeping oil. You will notice some oil dampness on the outside of the head around the spark plugs if this is the cause.

Don't give up on the engine yet. Make sure to check your spark plug wires and wire ends. You can do this with an inexpensive ohm meter. Who replaced your head, are you sure everything is set up correctly? How about a little more history.

Joe Alexander
Blacklick, Ohio

[Benz Dr.]

You have a mess there.
Only one plug seems to be firing right. The black ones are too rich and it looks like you have low voltage going to the plugs. What heat range plugs are you using? I'd go to W9DC and see if that helps. Think your wires could be junk.

I tend to agree with Joe. Looks like the ball studs could be leaking oil on to the plugs ( I use a teflon sealer ). It would get burned up in the cylinder and most would be carbon on the threads if it was coming from inside the engine ( it would look different than what you have - that much oil would make it a James Bond car ). Even the plug that is firing well is still wet from oil around the threads. Some plugs show oil fouling as well which could be a valve stem seal that poped off.
Does the engine smoke at idle or just after start up and then clear away? If it smokes all the time that's head problems. If it comes out in regular puffs at idle that's a valve stem seal.

Maybe Metrics isn't as hot as everyone says.........

Dan Caron's
 SL Barn
benzbarn@ebtech.net
 slbarn.mbz.org
  1 877 661 6061