Oil on spark plug threads, what does it mean? - Ranger-Forums - The Ultimate Ford Ranger Resource


4.0L OHV & SOHC V6 Tech General discussion of 4.0L OHV and SOHC V6 Ford Ranger engines.

Reply
 
LinkBack Thread Tools Search this Thread
  #1  
Old 11-21-2009
winks's Avatar
Member
Thread Starter
iTrader: (5)
 
Join Date: May 2005
Location: Jackson, New Jersey
Posts: 4,872
Oil on spark plug threads, what does it mean?

I'm at 105,000 miles on my Ranger, it's a 2004 4.0L V6. Today I ran Seafoam through the brake booster and changed out the plugs and wires, they've probably been on the truck now for about 40,000 miles. All of the plugs looked fine, there was no fouling to them, they were still at the gap I originally set them at, just a little bit rounded at the electrode. What caught my interest was a wet looking thread on my 2, 3, 5 and 6 cylinder plugs. It's not really bad, just slightly wet and smelling of oil. Does anybody know what this might mean? I am not hearing any engine knock or valve tapping, if that helps.
Reply With Quote
  #2  
Old 11-21-2009
Lazler's Avatar
Senior Member
iTrader: (18)
 
Join Date: Dec 2008
Location: Brantford, Ontario
Posts: 5,526
oil/compression rings on the pistons are done?
Reply With Quote
  #3  
Old 11-21-2009
edgeman4.0's Avatar
Member
iTrader: (2)
 
Join Date: Oct 2008
Location: All Over
Posts: 1,475
Quote:
Originally Posted by Lazler View Post
oil/compression rings on the pistons are done?
not entirely laz, unless op's truck has been dogged on for all of those 105k.

op, do you have a rough idle issue?
Reply With Quote
  #4  
Old 11-21-2009
winks's Avatar
Member
Thread Starter
iTrader: (5)
 
Join Date: May 2005
Location: Jackson, New Jersey
Posts: 4,872
No, idle's fine... nothing seems to be out of the ordinary with the truck.

I don't think it would be the case, but could it have anything to do with running the Seafom through the engine an hour and a half before I pulled the plugs?
Reply With Quote
  #5  
Old 11-21-2009
God,Country,FORD's Avatar
Member
iTrader: (1)
 
Join Date: Nov 2007
Location: Red Oak, IA
Posts: 2,468
I had the oil on the threads, and it turned out to be a cracked head.. Now i also had other symptoms as well though..
Reply With Quote
  #6  
Old 11-21-2009
Lazler's Avatar
Senior Member
iTrader: (18)
 
Join Date: Dec 2008
Location: Brantford, Ontario
Posts: 5,526
u got an air filter u oil up? only other way i see oil getting on the plugs
Reply With Quote
  #7  
Old 11-21-2009
MudSlanger's Avatar
Member
iTrader: (4)
 
Join Date: Jun 2007
Location: Phoenix, AZ
Posts: 1,462
leaking valve seals?
Reply With Quote
  #8  
Old 11-21-2009
winks's Avatar
Member
Thread Starter
iTrader: (5)
 
Join Date: May 2005
Location: Jackson, New Jersey
Posts: 4,872
Nah, paper air filter.

How else could I tell if I had a cracked head or leaking valve seals?
Reply With Quote
  #9  
Old 11-21-2009
God,Country,FORD's Avatar
Member
iTrader: (1)
 
Join Date: Nov 2007
Location: Red Oak, IA
Posts: 2,468
compression test. Also your local mechanic should have a scope he can stick into the spark plug hole and look at the internals
Reply With Quote
  #10  
Old 11-21-2009
countryboy_110's Avatar
Member
 
Join Date: Mar 2008
Location: Edenton NC
Posts: 182
being on the threads i dont see it geting there from the cylinder, more likely from an exterior leak. the op did say the electrodes were fine
Reply With Quote
  #11  
Old 11-21-2009
God,Country,FORD's Avatar
Member
iTrader: (1)
 
Join Date: Nov 2007
Location: Red Oak, IA
Posts: 2,468
Quote:
Originally Posted by countryboy_110 View Post
being on the threads i dont see it geting there from the cylinder, more likely from an exterior leak. the op did say the electrodes were fine
Never said it was from the cylinder. Said it was from the head.. You do know that the spark plugs screw into the heads, right?
Reply With Quote
  #12  
Old 11-21-2009
winks's Avatar
Member
Thread Starter
iTrader: (5)
 
Join Date: May 2005
Location: Jackson, New Jersey
Posts: 4,872
Quote:
Originally Posted by countryboy_110 View Post
being on the threads i dont see it geting there from the cylinder, more likely from an exterior leak. the op did say the electrodes were fine
An exterior leak would be visable around the area the spark plug is threaded into, wouldn't it? It would be odd also to have that on the rear 4 of my 6 cylinders. I didn't notice anything that looked stained around the plugs.

Is there a tool that I could possibly rent to do the compression check myself, and how difficult is it to do?
Reply With Quote
  #13  
Old 11-21-2009
Member
 
Join Date: Mar 2007
Location: Upstate,NY
Posts: 2,598
Quote
It would be odd also to have that on the rear 4 of my 6 cylinders.

Not if the valve cover gaskets were seeping.
It may not be obvious , no large oil runs down the side of the engine ,no puddles around the spark plugs, but try tightening the valve covers down.
Reply With Quote
  #14  
Old 11-21-2009
winks's Avatar
Member
Thread Starter
iTrader: (5)
 
Join Date: May 2005
Location: Jackson, New Jersey
Posts: 4,872
Alright, I'll take that on for tomorrow. If anybody has any other ideas, please post them up.
Reply With Quote
  #15  
Old 11-21-2009
Blhde's Avatar
Member
 
Join Date: Oct 2005
Location: Northern IL
Posts: 2,804
If the plugs were not tight enough or the gasket did not seal the oil will be pushed out.

There is oil in every cylinder and its supposed to be there. Every engine burns oil. The amount it burns is the key.

If your covers are clean it had to come around the threads. Or a spill from a long time ago.

If the electrodes looked good on the old plugs you should be fine. If your **** compression and leak down tests are in order.
Reply With Quote
  #16  
Old 11-22-2009
God,Country,FORD's Avatar
Member
iTrader: (1)
 
Join Date: Nov 2007
Location: Red Oak, IA
Posts: 2,468
I had oil on 2 of my 6 spark plugs.. There was stuff inside the spark plug hole as well if you stikc your finger in there and pull it out, you whould be able to get something out of the threads..

You probably dont have a cracked head.. But i would still get a compression test done.. any ford dealership can do it shouldnt cost more than 30 bucks.
Reply With Quote
  #17  
Old 11-22-2009
winks's Avatar
Member
Thread Starter
iTrader: (5)
 
Join Date: May 2005
Location: Jackson, New Jersey
Posts: 4,872
The plugs may not have been tightened up enough. Though it could do with the oil lubricating them, those 4 did come out much easier than the other 2 plugs. I'll get a compression test done soon. Thanks for all the info guys.
Reply With Quote
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Oil on top of the spark plug 215ranger General Technical & Electrical 6 10-14-2008 08:51 AM
Lots of oil on every spark plug - Ranger 2.3L macm General Technical & Electrical 1 06-23-2008 07:58 PM
Oil on spark-plug threads FlyboyZR1 4.0L OHV & SOHC V6 Tech 4 05-25-2008 10:00 PM
spark plug gap, how much does it matter? otterboy_99 4.0L OHV & SOHC V6 Tech 1 11-25-2006 08:24 AM
stripped spark plug threads Ranger1 General Technical & Electrical 30 06-10-2006 01:47 PM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -6. The time now is 12:59 PM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.