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Chat Area => General Car Chat => Topic started by: Webby the Bear on 07 March 2014, 09:54:36

Title: Theory question re oil in plug wells
Post by: Webby the Bear on 07 March 2014, 09:54:36
Hi guys, doing a mini assignment for school and as ever I like to use my car as a case study where possible. mine's not leaking but for the purposes of the assignment I have to say why leaking CC gaskets causing oil in the plug wells would/could cause misfires.

whats the reason? is it simply that the oil gets in to the ht lead/spark plug connection and severs the electrical contact? or is it something to do with the extra heat?  :-\
Title: Re: Theory question re oil in plug wells
Post by: chrisgixer on 07 March 2014, 10:01:57
Oil eats the rubber that insulates the spark. Spark then escapes outside, via the porcelain insulator on the top. A classic fail will see black etch marks in the porcelain leaving a track down the side of the spark plug. There's pics on here of one somewhere.
Title: Re: Theory question re oil in plug wells
Post by: Webby the Bear on 07 March 2014, 10:04:16
Got ya, Chris. Thanks. So essentially the failure is ''voltage leak''.
Title: Re: Theory question re oil in plug wells
Post by: Webby the Bear on 07 March 2014, 10:07:33
oh one more q...sorry lol

once you have a misfire from the oil in the wells.... is a ''clean up'' of the ht lead good enough or is replacement recommended... im thinking replacement based on the fact they've brken down
Title: Re: Theory question re oil in plug wells
Post by: chrisgixer on 07 March 2014, 10:18:55
That's certainly the case ime.

Assuming plugs are not damaged...Once a missfire starts, just cleaning up any oil doesn't cut it. Water will clean up and dry out, provided the iron core isn't damaged/rusted and swelling, but once the oil has eaten the rubber and a miss is present, new leads or boots are needed.

See what others say though, I can't provide viable answers on voltages etc. There's others here far more qualified to help you. :)
Title: Re: Theory question re oil in plug wells
Post by: Marks DTM Calib on 07 March 2014, 11:00:11
Right.

For one, you dont get 'voltage leaks', the only thing that flows in an electrical circuit is current so the 'current' will track down the side of the spark plug.

In essence, what happens is that the oil gets around the spark plug insulator, the voltage is raised across the plug and the current then takes the path of least resistance.

As the oil is not as good an insulator as the ceramic insulator, the current tracks down the side of the plug rather than jumping the gap on the plug.

The question of if you can re-use the leads etc is very dependent on how long its been in the condition, oil will over time attack and damage most rubbers so catch it early and degrease the rubber well and it will be fine.

For info, voltage is the difference in potential (PD) between two points....
Title: Re: Theory question re oil in plug wells
Post by: TheBoy on 07 March 2014, 11:48:33
In laymans terms, the 2 reasons this will cause a miss are (as DTM says, explaining it technically):

1) The oil (partially) shorts the HT to the head (ground/earth/0V)
2) The plug leads (or plug caps on those with coil packs) get damaged over time by hot oil, causing a high resistance (which tends to arc, and will eventually burn the cable
Title: Re: Theory question re oil in plug wells
Post by: Marks DTM Calib on 07 March 2014, 12:17:10
In laymans terms, the 2 reasons this will cause a miss are (as DTM says, explaining it technically):

1) The oil (partially) shorts the HT to the head (ground/earth/0V)
2) The plug leads (or plug caps on those with coil packs) get damaged over time by hot oil, causing a high lower resistance (which tends to arc, and will eventually burn the cable

Corrected  :y
Title: Re: Theory question re oil in plug wells
Post by: TheBoy on 07 March 2014, 12:21:21
In laymans terms, the 2 reasons this will cause a miss are (as DTM says, explaining it technically):

1) The oil (partially) shorts the HT to the head (ground/earth/0V)
2) The plug leads (or plug caps on those with coil packs) get damaged over time by hot oil, causing a high lower resistance (which tends to arc, and will eventually burn the cable

Corrected  :y
Earth bit went in because some peeps insist on calling it that. And for your benefit :P ;D

Lower resistance? Are we talking about the insulation (in which case I agree) or the conductor (in which case I don't think I do)?
Title: Re: Theory question re oil in plug wells
Post by: Marks DTM Calib on 07 March 2014, 12:24:10
In laymans terms, the 2 reasons this will cause a miss are (as DTM says, explaining it technically):

1) The oil (partially) shorts the HT to the head (ground/earth/0V)
2) The plug leads (or plug caps on those with coil packs) get damaged over time by hot oil, causing a high lower resistance (which tends to arc, and will eventually burn the cable

Corrected  :y
Earth bit went in because some peeps insist on calling it that. And for your benefit :P ;D

Lower resistance? Are we talking about the insulation (in which case I agree) or the conductor (in which case I don't think I do)?

Insulation, the conductor wont increase in insulation (although its length may get compromised as it errodes) but either way, tracking is down to finding a lower resistance path . :y
Title: Re: Theory question re oil in plug wells
Post by: Webby the Bear on 07 March 2014, 15:37:03
Thanks for the info boys, very well explained.  :) :) :)
Title: Re: Theory question re oil in plug wells
Post by: Toledodude1973 on 07 March 2014, 20:02:44
i'm learning on here all the time, thanks for info :y
Title: Re: Theory question re oil in plug wells
Post by: chrisgixer on 07 March 2014, 22:24:01
Yeeeep, they lost me at the start of ....   Well, the electrical bit. I'm still on "electricity flows, like water" ;D

Title: Re: Theory question re oil in plug wells
Post by: Marks DTM Calib on 08 March 2014, 09:11:12
Yeeeep, they lost me at the start of ....   Well, the electrical bit. I'm still on "electricity flows, like water" ;D

Sort of, consider the flow as the current, the difference between the top and bottom of the pipe as the voltage (potential difference) and the bore of the pipe (e.g. the resistance to flow) as resistance
Title: Re: Theory question re oil in plug wells
Post by: Entwood on 08 March 2014, 12:20:01
Yeeeep, they lost me at the start of ....   Well, the electrical bit. I'm still on "electricity flows, like water" ;D

Sort of, consider the flow as the current, the difference between the top and bottom of the pipe as the voltage (potential difference) and the bore of the pipe (e.g. the resistance to flow) as resistance

That brings back memories !  When I started my flight engineer training way back in 1970 I knew absolutely nothing about electronics, it had not been taught to me at school (despite doing A level Physics) in any way .. and I could not get my head around it ...  one of the instructors sorted me out in 2 hours .. by comparing every aspect of electronics / electrics to basic plumbing .. and it really works ..

Battery - header tank
Voltage - pressure head
Current - flow rate
Resistance - pipe diameter
Variable resistance - hose pipe being bent
Capacitor - automatic toilet cistern
Switch - valve
Diode - non-return valve


etc etc etc ... :)

Might not make sense to many .. but it got me through the course  .. :)


Title: Re: Theory question re oil in plug wells
Post by: chrisgixer on 08 March 2014, 13:08:48
Yeeeep, they lost me at the start of ....   Well, the electrical bit. I'm still on "electricity flows, like water" ;D

Sort of, consider the flow as the current, the difference between the top and bottom of the pipe as the voltage (potential difference) and the bore of the pipe (e.g. the resistance to flow) as resistance
At the end of a long shift, if I'm seen standing with an empty water cup at an electrical socket, in stead of the water butt, I'm blaming you. ;D

It's no good Mark, I'm fine with stuff I can physically see. Geometry is fine for instance. Push rods and cams etc. I can see obvious faults with wiring as their visible, but component failure, if all looks normal or measuring stuff with a meter. No good.

Probably doesn't help that I have no need for electrical knowledge professionally either.

Telling me doesn't work either. (You may of noticed ;D ) I have to physically do stuff to absorb it. Not sure what learning style that is but it's probably not common to most, I guess. :-\
Title: Re: Theory question re oil in plug wells
Post by: TheBoy on 08 March 2014, 18:46:18
I have to physically do stuff to absorb it. Not sure what learning style that is but it's probably not common to most, I guess. :-\
Seeing as you've never won a Darwin Award, I guess you know when NOT to try something ;D
Title: Re: Theory question re oil in plug wells
Post by: chrisgixer on 08 March 2014, 22:43:40
I have to physically do stuff to absorb it. Not sure what learning style that is but it's probably not common to most, I guess. :-\
Seeing as you've never won a Darwin Award, I guess you know when NOT to try something ;D

As your someone who can't cope with simple suspension jobs, and drags me half way up the m40 to "fix something that's broken" only to find the tyres are worn out to the cords, do feel free to apply. ;)
Title: Re: Theory question re oil in plug wells
Post by: TheBoy on 09 March 2014, 09:11:40
I have to physically do stuff to absorb it. Not sure what learning style that is but it's probably not common to most, I guess. :-\
Seeing as you've never won a Darwin Award, I guess you know when NOT to try something ;D

As your someone who can't cope with simple suspension jobs, and drags me half way up the m40 to "fix something that's broken" only to find the tyres are worn out to the cords, do feel free to apply. ;)
Something was broken...  ...tyres.  I'm good at breaking tyres. Its a skill I have developed. A bloody expensive skill to learn though ;D
Title: Re: Theory question re oil in plug wells
Post by: chrisgixer on 09 March 2014, 10:53:07
I have to physically do stuff to absorb it. Not sure what learning style that is but it's probably not common to most, I guess. :-\
Seeing as you've never won a Darwin Award, I guess you know when NOT to try something ;D

As your someone who can't cope with simple suspension jobs, and drags me half way up the m40 to "fix something that's broken" only to find the tyres are worn out to the cords, do feel free to apply. ;)
Something was broken...  ...tyres.  I'm good at breaking tyres. Its a skill I have developed. A bloody expensive skill to learn though ;D
Clown car handling, in this case, was easily diagnosed while standing next to the car. You didn't even need to bend down to see it , it was THAT obvious. ;D ::)
Title: Re: Theory question re oil in plug wells
Post by: TheBoy on 09 March 2014, 11:31:21
I have to physically do stuff to absorb it. Not sure what learning style that is but it's probably not common to most, I guess. :-\
Seeing as you've never won a Darwin Award, I guess you know when NOT to try something ;D

As your someone who can't cope with simple suspension jobs, and drags me half way up the m40 to "fix something that's broken" only to find the tyres are worn out to the cords, do feel free to apply. ;)
Something was broken...  ...tyres.  I'm good at breaking tyres. Its a skill I have developed. A bloody expensive skill to learn though ;D
Clown car handling, in this case, was easily diagnosed while standing next to the car. You didn't even need to bend down to see it , it was THAT obvious. ;D ::)
They had a similar profile to the Kawasaki ;D
Title: Re: Theory question re oil in plug wells
Post by: Shackeng on 09 March 2014, 13:46:22
Yeeeep, they lost me at the start of ....   Well, the electrical bit. I'm still on "electricity flows, like water" ;D

Sort of, consider the flow as the current, the difference between the top and bottom of the pipe as the voltage (potential difference) and the bore of the pipe (e.g. the resistance to flow) as resistance
At the end of a long shift, if I'm seen standing with an empty water cup at an electrical socket, in stead of the water butt, I'm blaming you. ;D

It's no good Mark, I'm fine with stuff I can physically see. Geometry is fine for instance. Push rods and cams etc. I can see obvious faults with wiring as their visible, but component failure, if all looks normal or measuring stuff with a meter. No good.

Probably doesn't help that I have no need for electrical knowledge professionally either.

Telling me doesn't work either. (You may of noticed ;D ) I have to physically do stuff to absorb it. Not sure what learning style that is but it's probably not common to most, I guess. :-\

http://en.wikipedia.org/wiki/Empirical_evidence :y
Title: Re: Theory question re oil in plug wells
Post by: 05omegav6 on 09 March 2014, 14:16:59
Yeeeep, they lost me at the start of ....   Well, the electrical bit. I'm still on "electricity flows, like water" ;D

Sort of, consider the flow as the current, the difference between the top and bottom of the pipe as the voltage (potential difference) and the bore of the pipe (e.g. the resistance to flow) as resistance

That brings back memories !  When I started my flight engineer training way back in 1970 I knew absolutely nothing about electronics, it had not been taught to me at school (despite doing A level Physics) in any way .. and I could not get my head around it ...  one of the instructors sorted me out in 2 hours .. by comparing every aspect of electronics / electrics to basic plumbing .. and it really works ..

Battery - header tank
Voltage - pressure head
Current - flow rate
Resistance - pipe diameter
Variable resistance - hose pipe being bent
Capacitor - automatic toilet cistern
Switch - valve
Diode - non-return valve


etc etc etc ... :)

Might not make sense to many .. but it got me through the course  .. :)
When you put it like that... :y
Title: Re: Theory question re oil in plug wells
Post by: chrisgixer on 09 March 2014, 14:21:02
Yeeeep, they lost me at the start of ....   Well, the electrical bit. I'm still on "electricity flows, like water" ;D

Sort of, consider the flow as the current, the difference between the top and bottom of the pipe as the voltage (potential difference) and the bore of the pipe (e.g. the resistance to flow) as resistance
At the end of a long shift, if I'm seen standing with an empty water cup at an electrical socket, in stead of the water butt, I'm blaming you. ;D

It's no good Mark, I'm fine with stuff I can physically see. Geometry is fine for instance. Push rods and cams etc. I can see obvious faults with wiring as their visible, but component failure, if all looks normal or measuring stuff with a meter. No good.

Probably doesn't help that I have no need for electrical knowledge professionally either.

Telling me doesn't work either. (You may of noticed ;D ) I have to physically do stuff to absorb it. Not sure what learning style that is but it's probably not common to most, I guess. :-\

http://en.wikipedia.org/wiki/Empirical_evidence :y

Ah, indeed, practical types, as I referred to elsewhere.

As opposed to taking random bollards off the internet and re presenting as hard unequivocal indesputanle facts. Or impractical types.

Practical and impractical being far too small a pigeon hole, clearly.

See, some might say I haven't had an education. While I was over the fields on me bike, some might say I had an even better education, with practical hands on "Emperical evidence" encountered first hand.

To then be judged on the grounds of an education and qualification system that is based on all else except(by employers and managers mostly) really does grate my nerves, frankly.

...or maybe I need to accept other learning styles as genuine. (Snigger)
Title: Re: Theory question re oil in plug wells
Post by: Shackeng on 10 March 2014, 08:54:54
Yeeeep, they lost me at the start of ....   Well, the electrical bit. I'm still on "electricity flows, like water" ;D

Sort of, consider the flow as the current, the difference between the top and bottom of the pipe as the voltage (potential difference) and the bore of the pipe (e.g. the resistance to flow) as resistance

That brings back memories !  When I started my flight engineer training way back in 1970 I knew absolutely nothing about electronics, it had not been taught to me at school (despite doing A level Physics) in any way .. and I could not get my head around it ...  one of the instructors sorted me out in 2 hours .. by comparing every aspect of electronics / electrics to basic plumbing .. and it really works ..

Battery - header tank
Voltage - pressure head
Current - flow rate
Resistance - pipe diameter
Variable resistance - hose pipe being bent
Capacitor - automatic toilet cistern
Switch - valve
Diode - non-return valve


etc etc etc ... :)

Might not make sense to many .. but it got me through the course  .. :)

They had us weighed up Nige ::)

The thing that baffled me was when they tried to explain electron flow - in the opposite direction to current! I reverted then to "...connected by a suitable system of gears and linkages". :y
Title: Re: Theory question re oil in plug wells
Post by: Marks DTM Calib on 10 March 2014, 09:02:19
Electrical is easy (which is the above), electronic gets much more interesting and is where 'Maths' is much more involved.
Title: Re: Theory question re oil in plug wells
Post by: Entwood on 10 March 2014, 10:46:06
Yeeeep, they lost me at the start of ....   Well, the electrical bit. I'm still on "electricity flows, like water" ;D

Sort of, consider the flow as the current, the difference between the top and bottom of the pipe as the voltage (potential difference) and the bore of the pipe (e.g. the resistance to flow) as resistance

That brings back memories !  When I started my flight engineer training way back in 1970 I knew absolutely nothing about electronics, it had not been taught to me at school (despite doing A level Physics) in any way .. and I could not get my head around it ...  one of the instructors sorted me out in 2 hours .. by comparing every aspect of electronics / electrics to basic plumbing .. and it really works ..

Battery - header tank
Voltage - pressure head
Current - flow rate
Resistance - pipe diameter
Variable resistance - hose pipe being bent
Capacitor - automatic toilet cistern
Switch - valve
Diode - non-return valve


etc etc etc ... :)

Might not make sense to many .. but it got me through the course  .. :)

They had us weighed up Nige ::)

The thing that baffled me was when they tried to explain electron flow - in the opposite direction to current! I reverted then to "...connected by a suitable system of gears and linkages". :y

ahh yes .. that overstuffed, jumped up little scottish Flt Lt AEO instructor who delighted in bamboozeling every one with his theories of "holes moving backwards" ... thank the Lord for an old fashioned MEng instructor who actually believed in trying to get the students to pass the course, rather than said prats belief that failing students proved how clever he was(n't) ....

:)
Title: Re: Theory question re oil in plug wells
Post by: Seth on 10 March 2014, 13:55:17
That brings back memories !  When I started my flight engineer training way back in 1970 I knew absolutely nothing about electronics, it had not been taught to me at school (despite doing A level Physics) in any way .. and I could not get my head around it ...  one of the instructors sorted me out in 2 hours .. by comparing every aspect of electronics / electrics to basic plumbing .. and it really works ..

Battery - header tank
Voltage - pressure head
Current - flow rate
Resistance - pipe diameter
Variable resistance - hose pipe being bent
Capacitor - automatic toilet cistern
Switch - valve
Diode - non-return valve


etc etc etc ... :)

Might not make sense to many .. but it got me through the course  .. :)

'Water analogy' ... ;)
Title: Re: Theory question re oil in plug wells
Post by: Shackeng on 10 March 2014, 18:09:50
Yeeeep, they lost me at the start of ....   Well, the electrical bit. I'm still on "electricity flows, like water" ;D

Sort of, consider the flow as the current, the difference between the top and bottom of the pipe as the voltage (potential difference) and the bore of the pipe (e.g. the resistance to flow) as resistance

That brings back memories !  When I started my flight engineer training way back in 1970 I knew absolutely nothing about electronics, it had not been taught to me at school (despite doing A level Physics) in any way .. and I could not get my head around it ...  one of the instructors sorted me out in 2 hours .. by comparing every aspect of electronics / electrics to basic plumbing .. and it really works ..

Battery - header tank
Voltage - pressure head
Current - flow rate
Resistance - pipe diameter
Variable resistance - hose pipe being bent
Capacitor - automatic toilet cistern
Switch - valve
Diode - non-return valve


etc etc etc ... :)

Might not make sense to many .. but it got me through the course  .. :)

They had us weighed up Nige ::)

The thing that baffled me was when they tried to explain electron flow - in the opposite direction to current! I reverted then to "...connected by a suitable system of gears and linkages". :y

ahh yes .. that overstuffed, jumped up little scottish Flt Lt AEO instructor who delighted in bamboozeling every one with his theories of "holes moving backwards" ... thank the Lord for an old fashioned MEng instructor who actually believed in trying to get the students to pass the course, rather than said prats belief that failing students proved how clever he was(n't) ....

:)

That was the one :-X :-X :-X