Spark Plugs I pulled - What are They Saying?

[Rotor]

2005 RT with less than 20,000 miles on it.  The more I dig the more it’s apparent that it wasn’t well cared for…  I test road it several miles.  Put it through some moderate paces and it performed as expected.  Accelerated fine, set cruise and it was stable, idled well and never saw any signs of burning oil.

I could go on about the work I’ve done and the lack of maintenance it received; but I’d really like an opinion about the appearance of these plugs and what it says about the condition of the engine.  The pic of the one I’m holding is secondary plug from the right side.  Never seen one that full of carbon/oil/fuel or whatever that crud is.

Fire away (pun). 

[Hosstage]

Just off hand, I'd say it needs an air filter change (I'm sure you have, or will) and a fresh set of plugs. Ride it for a few hundred miles and take another look at them.

I'm sure others will jump in with deeper diagnosis, I'm a simple plan kind of guy.

[Rotor]

Hi Hosstage,

Yup, air filter already replaced, all brake circuits flushed, clutch fluid replaced, drive shaft rebuilt, final drive oil changed (that was some nasty stuff too).  Today was adjust the valves and replace the plugs and then on to the throttle body removal.  After seeing those plugs I didn't get to the throttle bodies...

[dirtrider]

Quote

 

2005 RT with less than 20,000 miles on it.  The more I dig the more it’s apparent that it wasn’t well cared for…  I test road it several miles.  Put it through some moderate paces and it performed as expected.  Accelerated fine, set cruise and it was stable, idled well and never saw any signs of burning oil.

I could go on about the work I’ve done and the lack of maintenance it received; but I’d really like an opinion about the appearance of these plugs and what it says about the condition of the engine.  The pic of the one I’m holding is secondary plug from the right side.  Never seen one that full of carbon/oil/fuel or whatever that crud is.

Fire away (pun). 

 

Afternoon Rotor

 

They tell you something but not enough. That right lower look like it was burning some oil in that cylinder. Being the lower plug any oil that gets by the rings after shutdown goes right to the bottom where that spark plug is. 

 

You can't tell lot more as the plugs were not removed after a very long hi-way run to clean the cold-starting crud off of them. 

 

Put new plugs in then ride the heck out of it, then pull the plugs in 1000 miles & inspect them (that will tell a better story). Do not pull/inspect them after a lot of cold starts or just idling around, do it after a nice 50 mile hi-way run (after it cools down of course).

[Rotor]

OK D.R.  Thanks for the reply.  We'll see where this take me.  Probably not going to put much more into it until I figure out what's going on (no throttle body work or additional accessories).  While it did seem to run well, I've never seen plugs like that in a healthy engine.  Think I'll run a compression test first.  Any idea what the specifications are?

[Hosstage]

The important spec on a compression test is that both cylinders be within at least 10% of each other, preferably much closer. Make sure the battery is fully charged when testing each cylinder. I like to test cold and then warm, sometimes helps show a problem. If the reading seems extremely low, then I'd start looking deeper. I don't know what to expect for a reading, I hope DR can help with that, and I don't mean to interrupt his help here.

Personally, if you say it runs good, I'd just throw the plugs in it and ride it, then check compression later if there still seems to be a problem.

I've tried to get away from the "I'm going to fix it until it's broken" strategy.

[dirtrider]

36 minutes ago, Rotor said:

OK D.R.  Thanks for the reply.  We'll see where this take me.  Probably not going to put much more into it until I figure out what's going on (no throttle body work or additional accessories).  While it did seem to run well, I've never seen plugs like that in a healthy engine.  Think I'll run a compression test first.  Any idea what the specifications are?

Evening Rotor

 

Compression depends on cranking speed plus air getting in so test compression with fuel injectors & coils disconnected & a fully charged battery.  

 

Throttle must be held wide open to allow max amount of air to enter cylinders. 

 

With oil burners sometimes the compression will show high on the oil burning side due to carbon buildup. 

 

 

[Hosstage]

I had to look it up.

1 bar is approximately 14.5 psi. 

[Rotor]

So, 140-145 PSI per side would be ideal.  135 or better would be good.  Pretty sure there's carbon in the right cylinder so I'll take that into consideration.

Thank you both for your help!!

[Rotor]

So, compression test looked pretty good to me.  First pic is the right side and second is the left.  These numbers came from spinning the engine about 12 revolutions per cylinder.  I wasn't watching the gauge so I don't know what the first two or three revolutions produced, just the end result.  Could this be a lower stick coil issue?  Just asking, I haven’t checked them yet.

[dirtrider]

54 minutes ago, Rotor said:

So, compression test looked pretty good to me.  First pic is the right side and second is the left.  These numbers came from spinning the engine about 12 revolutions per cylinder.  I wasn't watching the gauge so I don't know what the first two or three revolutions produced, just the end result.  Could this be a lower stick coil issue?  Just asking, I haven’t checked them yet.

 

 

Afternoon John

 

Could what be a lower stick coil?

 

That spark plug has oil on it so probably some oil getting into  that side cylinder after engine shutdown.

 

As rule compression test won't show this as your compression can still be OK,  just a little oil control issue. 

 

 

[Rotor]

Thanks for the reply D.R.  Regarding the stick coil:  The plug didn't appear to have been firing well enough to burn the residual oil off - it was just a WAG.  Based on what I'm seeing I think the engine is healthy and probably not an oil burner under power, we'll see.

Thanks again for your time!

[dirtrider]

21 minutes ago, Rotor said:

Thanks for the reply D.R.  Regarding the stick coil:  The plug didn't appear to have been firing well enough to burn the residual oil off - it was just a WAG.  Based on what I'm seeing I think the engine is healthy and probably not an oil burner under power, we'll see.

Thanks again for your time!

Afternoon John

 

The lower spark plug firing won't burn any oil off as it is just a very small spark across the electrode gap. It is the combustion heat of the cylinder firing that burns the oil off. Obviously that cylinder is firing OK or you would be complaining about a poor running engine.  

[Rotor]

Thank you D.R.  Now more comfortable with the condition of the engine, I'm proceeding with other repairs and maintenance.

[Rougarou]

70,000 between plug changes

[Rotor]

Dang Richard, those looked great!

[Rougarou]

3 hours ago, Rotor said:

Dang Richard, those looked great!

ya, its only “recommended” for most service, not “required”.