Help reading spark plugs!

[sattech2000]

Afternoon All!

99 Explorer 4.0 OHV
The short version, has 291k on the motor and still running pretty good (although I did start to notice a little spark nock recently.) I put new heads on it 4 or 5 years ago otherwise the bottom end and tranny are original.

I'm a little puzzled on reading these plugs and looking for input from all of the smart people here! Lol. Cylinders 1-3 look great but 4-6 have something going on. Also did a dry compresion check (readings in pics) and thinking about running a wet one shortly.

What are they telling me?

I put these Autolite Iridium's and wires in last summer or fall I think it was, (am looking for my notes and will update mileage if I find them) but don't think it's that many.

Unfortunately I DIDN'T pay attention to my coolant level in the last month or when I drained it. Ughh. Was in a hurry unfortunately and that hasn't been an issue for a long time now.


The long version:
I put new heads on her 4 or 5 years ago. Trucks running great before I started this, (extremely reliable!)
Its abused for 47 miles 5-6 days a week delivering the mail as my primary truck. also reliability is a huge concern since my job depends on it so I'm being very proactive with maintainance and repairs.

This project started with an AC compressor clutch failure and has snowballed into a fairley substantial project so far. (FedEx delivered 22 shipments last week lol.) Entire AC system is being replaced including water pump and fan clutch. Since I had that tore off I wanted to replace pushrods/rocker arms (noise was killing me) and left valve cover (for rust/leaking) Figured I may as well do the timing chain since I was that far, not sure what these are rated at but couldn't hurt. Basically wanted to do everything that didn't require pulling the heads or oil pan BUT would do a Compresion check once I got that far just to get an idea of what shape the lower end was in and 'possibly' go ahead and do a rebuild on it so I can fix the rear main leak, hv oil pump and I do hear the mains talking every once in a while. It's always something I tell yeah! Lol
(BTW I do have a backup explorer so I can be without for a little bit)

 

[Explorer2.0]

Possibly due to "Opposite Firing Order"?

OEM Motorcraft Platinum Spark Plugs

Okay all you "rocket scientists", let's see if you can figure this one out: I just got thru re-gapping my OEM Motorcraft spark plugs on my '96 4.0 XLT. How come the plugs on the right side are different from the left side. Left side is AWSF-42P and the right side is AWSF-42PG. The right...

www.explorerforum.com

Team TARDIS

 

[Mbrooks420]

How much oil does it burn between changes? How many miles on these?

I think all 6 look pretty poor. Way too many deposits on those.

Wasted spark ignition does tend to beat up the one bank more than the other.

 

[koda2000]

You compression test is all over the place. Was this done on a warm engine with the throttle body plate held open? Your readings ideally should be w/in about 10% of one another. You appear to have multiple cylinder sealing problems. The only cylinder that looks good is #4 at 180 PSI. On an engine with near 300k you'd expect to see loss of compression due to wear. If I saw 150-160 PSI with no more than 10% difference I'd say your compression was adequate, but seeing a high of 180, a low of 100 (with your mid readings between 130-160) you're loosing compression somewhere. Are you sure the compression gauge your using was sealing in the spark plug hole? Is it one of those cheap gauges with the rubber plug you have to press & hold into the spark plug hole?

As you've replace your heads recently, you shouldn't be loosing compression through you valves. All a wet compression test will show you is if you're loosing compression through your piston rings.

As far as your spark plugs, they all look pretty bad. The 3 black ones look oil fowled, the 3 white ones look somewhat fowled but also look like you're running lean on that bank. How much oil are you burning between oil changes? A normal plug reading on spark plugs with say around 20K on them should show no deposits and a tan coloring on the insulator.

 

[sattech2000]

Engine ran great before disassembly, not even a slight miss to it, good power and could do 80 on the hwy without a problem 9except for recently noticed a bit of spark knock). the was cold engine and the upper intake removed. (Test was an afterthought). honestly was very surprised to find what I did when I removed the plugs. I am not able to accurately say what/if oil consumption might be due to both valve coveres and rear main oil leaks. (one of the many issues I'm resolving from this project.)

(gauge is new and I double checked readings a second time. Everything was very accurate from the first reading. Have also been rebuilding engines for 20+ years so I have a little bit of experience performing compression tests. Going to go run the wet test as that will help pinpoint the condition of the rings/bottom to help decide if I want to just pull it and do a rebuild.

1, 2, 3 are misleading if looking at the oil/gese that is shown which is from the removal process but the ceramic is clean, possibly lean if anything but that's not where my concern is.

to be more specific I'm mostly a little puzzled by the cause of the tan discoloration on 4, 5, 6 as I have yet to find a chart that indicates this condition.

 

[sattech2000]

also had battery charger connected and all plugs removed before starting first reading.
I also suspect my very worn rocker arms are playing an issue on the readings which I'm in the process of rebuilding as we speak.

 

[Gary Crist]

4,5, and are oil burning.look e

http://c4owners.org/plugins/forum/attachment/1/1412690921_1_FT112778_petrol_plugs.jpg

Top 3rd over in above example.

What weight oil 'r ya drinkin'?
You might go a little heavier.

 

[Mbrooks420]

What’s heavier oil going to do?

 

[koda2000]

Engine ran great before disassembly, not even a slight miss to it, good power and could do 80 on the hwy without a problem 9except for recently noticed a bit of spark knock). the was cold engine and the upper intake removed. (Test was an afterthought). honestly was very surprised to find what I did when I removed the plugs. I am not able to accurately say what/if oil consumption might be due to both valve coveres and rear main oil leaks. (one of the many issues I'm resolving from this project.)

(gauge is new and I double checked readings a second time. Everything was very accurate from the first reading. Have also been rebuilding engines for 20+ years so I have a little bit of experience performing compression tests. Going to go run the wet test as that will help pinpoint the condition of the rings/bottom to help decide if I want to just pull it and do a rebuild.

1, 2, 3 are misleading if looking at the oil/gese that is shown which is from the removal process but the ceramic is clean, possibly lean if anything but that's not where my concern is.

to be more specific I'm mostly a little puzzled by the cause of the tan discoloration on 4, 5, 6 as I have yet to find a chart that indicates this condition.

 

[Gary Crist]

I have used heavier oil to patch up some oil burning.
Had a '87 Bird that drank light dino like a Saidi Skiekh.
50 weight slowed the spark plug fouling till
I put in anti-oilers on the plugs...

FE's looked like 4,5 and 6 that when the valve guides were worn , usually about
the 30Kish range. By then an ex valve or 2 was burned too.
I