Author Topic: Spark Plug Help  (Read 9527 times)

dragoncar

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Spark Plug Help
« on: March 03, 2016, 05:24:19 PM »
My fuel economy has taken a dive and I changed my plugs early.  Most looked good, but one of them looks like this (sorry for large photo)



Any ideas on what this means?  Is that oil fouling or fuel deposits?  I haven't yet determined if my fuel economy has improved, or if I have noticeable oil burning, but I don't want to have to keep changing out iridium plugs.
« Last Edit: March 03, 2016, 05:26:27 PM by dragoncar »

Al1961

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Re: Spark Plug Help
« Reply #1 on: March 03, 2016, 05:33:53 PM »
My guess would be oil fouling too. Maybe run a compression test to see how the rings are.
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dragoncar

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Re: Spark Plug Help
« Reply #2 on: March 03, 2016, 05:40:11 PM »
My guess would be oil fouling too. Maybe run a compression test to see how the rings are.

I don't have the tools for compression test -- is it cheaper to DIY or take to shop?

If I do it myself, is there any problem putting the same plug back in?  More importantly, should I have just cleaned the above and put it back in vs. using the new ones?  They aren't breaking the bank but they aren't cheap either. 

Al1961

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Re: Spark Plug Help
« Reply #3 on: March 03, 2016, 05:57:38 PM »
You can get a compression test tool for ~$35. Probably cost more to take it in to a service centre. The thing is, you can absolutely get oil fouling from a leaking valve guide. All a compression check can do is confirm or rule out excessive ring/cylinder wear. It won't tell you anything about the state of the intake valve stem seal or guide.

You'd be surprised how much oil can be sucked down the guide by manifold vacuum. Gotta get into the engine and remove valve springs to test valve guide clearance with a dial indicator. Easily enough done if there are rocker arms. I wouldn't even bother trying myself if it is an overhead cam engine. Way less pain/time to take into a shop in that scenario, but $$ in labour.

I'm not a mechanic, just a hobbyist that has rebuild a couple engines over the past several decades....

How many miles on this engine?
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dragoncar

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Re: Spark Plug Help
« Reply #4 on: March 03, 2016, 06:32:39 PM »
You can get a compression test tool for ~$35. Probably cost more to take it in to a service centre. The thing is, you can absolutely get oil fouling from a leaking valve guide. All a compression check can do is confirm or rule out excessive ring/cylinder wear. It won't tell you anything about the state of the intake valve stem seal or guide.

You'd be surprised how much oil can be sucked down the guide by manifold vacuum. Gotta get into the engine and remove valve springs to test valve guide clearance with a dial indicator. Easily enough done if there are rocker arms. I wouldn't even bother trying myself if it is an overhead cam engine. Way less pain/time to take into a shop in that scenario, but $$ in labour.

I'm not a mechanic, just a hobbyist that has rebuild a couple engines over the past several decades....

How many miles on this engine?

It's a 14 YO honda with "only" 79k miles (I say only because the iridium plug interval is over 100k).  I'd also hope that's low enough to make ring/cylinder problems unlikely, but I have little knowledge.  I believe it's DOHC. 

I'm willing to learn to repair almost anything, but currently I have little conception of how a valve guide works (I get pistons). 

So if this is 79k miles worth of build-up, is it worth "fixing" the problem?  Can I just lower my interval to 60k miles and use platinum plugs instead?  I guess I'm trying to determine the cost benefit of having someone rebuild the engine.

Perhaps I'm getting ahead of myself and should just do the compression test and report back.  If my fuel economy improves in the next tank, then the problem was missing due to crud right?  I didn't get any check engine light.

I also saw a last-resort maneuver where you fill the plug hole with marvel mystery oil and hope it dislodges any crap causing ring troubles.  Does this sound stupid?
« Last Edit: March 03, 2016, 06:34:49 PM by dragoncar »

Janningc

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Re: Spark Plug Help
« Reply #5 on: March 03, 2016, 06:39:59 PM »
The rings could be a issue but it isn't where I would start. You may have a leaking valve cover gasket which will allow oil into the plugs also. Was just the threads and electrode covered in oil or was the porcelain covered too? If there was oil on the entire plug it would be a clear indicator of a bad valve cover gasket.
A leaking gasket is not too terribly tough to replace if you have a weekend afternoon to spare.

I would say overall to not be too worried about it this time around. Put new plugs in it and drive it for 30k and check again. Could have been a very slight difference in plug gap that made it not fully burn. If you pull them out in 30k and end up with the same thing then I would diagnose deeper.
I personally think marvel mystery oil is some good stuff but I would never pour it down my cylinder. You can't compress a liquid.




dragoncar

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Re: Spark Plug Help
« Reply #6 on: March 03, 2016, 07:33:10 PM »
In my earlier reading I started to hope it was the valve cover gasket but there was zero oil on the non-threaded side (aside from whatever is shown coming up the insulator, but the hex nut thing was clean.

Thanks for the advice.  30k is a long time for me... The car might rust away before then (I'm now around 3k miles per year

Posthumane

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Re: Spark Plug Help
« Reply #7 on: March 04, 2016, 11:28:22 AM »
Valve guide wear (or rather valve stem seal wear) is indeed the likely culprit, although if the car sits for long periods then rings could be an issue too, since you could get rust buildup in the cylinder which will wear them prematurely. One way to check for ring wear is to see if you have a lot of blowby. Take the oil cap off (carefully) when the engine is idling and see if you have a bunch of exhaust gas coming out of there.
Valve guide wear is evidenced by a burst of oil smoke when you first give it some gas after idling for a while (like taking off from a light). Some oil pools in the intake manifold while the vacuum is high, and then gets ingested and burned when you have more airflow.
You could also get oil coming into the intake manifold through the PCV valve if you are getting a lot of blowby. It would be more common to see oil on all the plugs in that case, but there are some exceptions.

Btw, you are fine to clean and gap the plugs rather than replacing them, right up until the electrode is worn down to its base or you have some other problems like a cracked insulator.

dragoncar

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Re: Spark Plug Help
« Reply #8 on: March 04, 2016, 12:03:13 PM »
Valve guide wear (or rather valve stem seal wear) is indeed the likely culprit, although if the car sits for long periods then rings could be an issue too, since you could get rust buildup in the cylinder which will wear them prematurely. One way to check for ring wear is to see if you have a lot of blowby. Take the oil cap off (carefully) when the engine is idling and see if you have a bunch of exhaust gas coming out of there.
Valve guide wear is evidenced by a burst of oil smoke when you first give it some gas after idling for a while (like taking off from a light). Some oil pools in the intake manifold while the vacuum is high, and then gets ingested and burned when you have more airflow.
You could also get oil coming into the intake manifold through the PCV valve if you are getting a lot of blowby. It would be more common to see oil on all the plugs in that case, but there are some exceptions.

Btw, you are fine to clean and gap the plugs rather than replacing them, right up until the electrode is worn down to its base or you have some other problems like a cracked insulator.

Thanks, to confirm:

Car sits for perhaps a week at most, not too long usually. 

Smoke- none at ignition or otherwise viewable in mirrors at highway speed, acceleration, or acceleration after engine braking down hill, but I haven't yet followed the car with someone else driving.

PCV - other plugs were fine so I read that it's unlikely culprit

Blow by- no detectable air volume from oil filler

If I clean and replace old plugs do I reduce the torque value to account for compressed gasket?

dragoncar

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Re: Spark Plug Help
« Reply #9 on: March 04, 2016, 12:05:57 PM »
Also there was previously a low, slow puttering noise coming from the exhaust that went away after I changed plugs. 

But now I'm noticing a whining noise from the right rear side :(.  Haven't yet checked to see if it's the exhaust, transmission, or pump issues.  I never noticed it before but apparently it is common in my car so maybe it was always there

Just filled my tank (it was maybe 1/4 tank when I changed the plugs).  Mpg seems to have already improved but I'll have to see how the full tank goes.

I do drive a bit more in winter since I am not badass enough to ride my bike in the rain

HipGnosis

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Re: Spark Plug Help
« Reply #10 on: March 04, 2016, 01:26:13 PM »
A Honda with 79k that you drive 3k/yr with ONE fouled plug?
You have NOTHING to worry about.

Pull that one plug, once a year, and clean it.  Or replace it with a platinum.

Do NOT 'fill the plug hole w/' ANYTHING! 

But...  you should have checked the belts when you did the plugs, and have a brake shop flush and change your brake fluid.


FerrumB5

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Re: Spark Plug Help
« Reply #11 on: March 04, 2016, 01:41:14 PM »
Which cylinder is that? Do you have to add oil often?
(Iridium plugs don't run 100k miles, no plugs do. It's just not practical to save $25 every 50-60k to extend engine life and fuel economy)

bobechs

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Re: Spark Plug Help
« Reply #12 on: March 04, 2016, 02:02:28 PM »
A Honda with 79k that you drive 3k/yr with ONE fouled plug?
You have NOTHING to worry about.

Pull that one plug, once a year, and clean it.  Or replace it with a platinum.

Do NOT 'fill the plug hole w/' ANYTHING! 

But...  you should have checked the belts when you did the plugs, and have a brake shop flush and change your brake fluid.

This.

Your basic problem is inside your head; that's where the critical adjustment needs to be made.

As for the car, just feed it the occasional plug.  The engine won't last forever that way, but it wasn't going to last forever any other way either.  It will fine without any heroic interventions.

dragoncar

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Re: Spark Plug Help
« Reply #13 on: March 08, 2016, 09:47:24 AM »

Thanks hip gnosis and Bob.  I'm planning to do all belts next year (7 years since the last time) and probably brakes too.  When I do brakes I flush.  I've been trying to learn to do these things myself -- obviously if I have to pay mechanic prices for maintenance it makes the value proposition of a relatively infrequently driven car even worse.

I'd get rid of it, but it's not much of a drain on my budget (so far) and would not fetch much these days

Which cylinder is that? Do you have to add oil often?
(Iridium plugs don't run 100k miles, no plugs do. It's just not practical to save $25 every 50-60k to extend engine life and fuel economy)

I don't know the numbering, it's the driverside-anterior plug. I've never had to add oil except for regular changes.

Ecky

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Re: Spark Plug Help
« Reply #14 on: March 08, 2016, 10:59:03 AM »
I recommend replacing the PCV valve. The part should be ~$5-10 and is generally very easy to replace on Honda motors.

http://www.agcoauto.com/content/news/p2_articleid/197

Quote
A failed PCV valve may also cause noise. Some will produce a whistle or whine and others can produce a low moaning noise. The easiest way to verify the problem is to temporarily block the vacuum source to the PCV valve and see if the noise changes or goes away.

On some vehicles, a bad PCV valve can cause oil to blow onto the air filter element. An oily or dirty spot, near the PCV inlet hose is a symptom.


Ecky

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Re: Spark Plug Help
« Reply #15 on: March 08, 2016, 11:06:07 AM »
There are quite a few things that can cause economy to tank. Low MPG is natural during the winter, but off the top of my head, a few things that can cause economy to drop are:

Dramatically low cylinder pressure - I expect you'd probably be burning a lot of oil though

Bad PCV valve

Clogged EGR  - can pull the EGR valve itself off and pour some solvent into it. EGR passages in the head often be accessed by pulling the intake manifold off, and it'll be behind a plate. Definitely DIY'able

Bad thermostat

Bad spark plugs

Bad O2 sensor

Vacuum leak

Bad MAP / MAF sensor

Clogged catalytic converter

~

Definitely start with the PCV though, and check EGR if it doesn't improve.

acroy

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Re: Spark Plug Help
« Reply #16 on: March 08, 2016, 11:57:03 AM »
One bad plug means something is wrong on that one cylinder. It could also cause the economy drop, but it is possible the bad plug and fuel economy drop are unrelated (bad tank of gas, etc).
I suggest start with 2 simple cheap things:
1) Run a bottle of Seafoam or equivalent through the gas. Let the level go down to 1/4 tank or so, pour in the whole bottle, and drive normally. It is great cheap cleaner for the fuel system.
2)Pour a bottle of auto-RX into the oil, drive 500-1000 miles, then change to a nice oil if you are not already (Mobile 1 is a safe bet and there are coupons to make it cheap)

The Seafoam treatment has solved many a minor issue on my cars (works great on small engines too, lawnmowers and such). Lumpy idle, difficulty hot starting, etc.
The AutoRX treatment is a good cleaner for the oil system. If you have the time and ability, an alternative is to pop off the valve cover and inspect for sludge buildup. Using high quality oil will result in little to no sludge.

I'm a big fan of cheap/easy chemical cleaners, especially on cars (like yours) that do a lot of sitting.

One instance:
Some years ago, DW's car was smoky on startup. It would burn a little oil, then clear right up after 10sec or so. Compression test, etc was fine. Other owners on the forum had similar issues and were starting to panic: rebuilding heads, entire engines, etc. It turned out that the (very delicate) oil control rings had enough gunk built up they would not seal 100% on cold startup. An ounce of Seafoam in each cylinder, rotate the engine gently by hand, let it sit for a a few hours, and the issue solved.
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dragoncar

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Re: Spark Plug Help
« Reply #17 on: May 02, 2016, 01:12:12 PM »
Thanks, all.  My MPG went back up to mid 20s for a tank, but is now back into the teens (don't recall if it was one or two tanks of good mpg but obviously we are talking under 1k miles.

After I replaced plugs, the puttering stopped but has since returned.

I haven't pulled that plug yet but suspect it will be fouled again.

Will try some of the suggestions above and now I guess will have to get a compression test done, etc as I can't be replacing/cleaning the plug every 1-2 tanks

dragoncar

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Re: Spark Plug Help
« Reply #18 on: May 02, 2016, 01:17:37 PM »
"You can't compress a liquid"
"Don't pour anything into the cylinder"

Maybe I misunderstand how engines work, but with the spark plug removed, there is zero compression right? The liquid can come right back out the hole it went into?

auxym

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Re: Spark Plug Help
« Reply #19 on: May 02, 2016, 05:43:37 PM »
"You can't compress a liquid"
"Don't pour anything into the cylinder"

Maybe I misunderstand how engines work, but with the spark plug removed, there is zero compression right? The liquid can come right back out the hole it went into?

Yes. But if there is anything left (it doesn't take much), you risk water lock, which is "quite bad". I guess you might also risk small amounts leaking into the crankcase (oil), which might or might not be bad.

Disclaimer: I know little about engines, and the stuff I know is either from textbooks or messing around with smaller 2 strokes.

ncornilsen

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Re: Spark Plug Help
« Reply #20 on: May 03, 2016, 12:10:33 PM »
Thanks, all.  My MPG went back up to mid 20s for a tank, but is now back into the teens (don't recall if it was one or two tanks of good mpg but obviously we are talking under 1k miles.

After I replaced plugs, the puttering stopped but has since returned.

I haven't pulled that plug yet but suspect it will be fouled again.

Will try some of the suggestions above and now I guess will have to get a compression test done, etc as I can't be replacing/cleaning the plug every 1-2 tanks

Do you ever go wide open throttle through two or three gears?  Really let the car have it?

A car is a little bit like a person. If you loaf around in it all the time, it's passageways gunk up with crud and it's life expectancy is shortened. I car really should get opened up and run good and hard once a month or so.

dragoncar

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Re: Spark Plug Help
« Reply #21 on: May 03, 2016, 12:23:16 PM »
Thanks, all.  My MPG went back up to mid 20s for a tank, but is now back into the teens (don't recall if it was one or two tanks of good mpg but obviously we are talking under 1k miles.

After I replaced plugs, the puttering stopped but has since returned.

I haven't pulled that plug yet but suspect it will be fouled again.

Will try some of the suggestions above and now I guess will have to get a compression test done, etc as I can't be replacing/cleaning the plug every 1-2 tanks

Do you ever go wide open throttle through two or three gears?  Really let the car have it?

A car is a little bit like a person. If you loaf around in it all the time, it's passageways gunk up with crud and it's life expectancy is shortened. I car really should get opened up and run good and hard once a month or so.

Yes I do because I always heard you should engage VTEC occasionally to keep the second cams oiled or something like that.  Not sure if true but always fun

ncornilsen

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Re: Spark Plug Help
« Reply #22 on: May 03, 2016, 12:40:33 PM »
Fun indeed.


acroy

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Re: Spark Plug Help
« Reply #23 on: May 03, 2016, 12:56:14 PM »
I would not bother with spending money on compression test. It'll tell you 'yeah it's sick' but it's not likely you'd pour $2-4k into this car for an engine, correct?

See my post from above, run some good cleaner(s) through it. I suspect gunked-up oil control rings. If you want to be aggressive with cleaning:

- remove all 4 spark plugs
- add 1oz of Seafoam into each cylinder through the hole
- turn the engine over (by hand, slowly) a couple times to disperse the solvent
- let it sit 24-48hrs
- replace plugs and start as normal. This will give the rings a good soak.

Of course, be ever so careful not to let any foreign material into the cylinder. You are performing open-heart surgery any time the engine is open. Keep it clean!

If it is worn valve guides rings, there is no fix for it besides $$$, likely as much as the car is worth.
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dragoncar

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Re: Spark Plug Help
« Reply #24 on: May 03, 2016, 01:29:15 PM »
I would not bother with spending money on compression test. It'll tell you 'yeah it's sick' but it's not likely you'd pour $2-4k into this car for an engine, correct?

See my post from above, run some good cleaner(s) through it. I suspect gunked-up oil control rings. If you want to be aggressive with cleaning:

- remove all 4 spark plugs
- add 1oz of Seafoam into each cylinder through the hole
- turn the engine over (by hand, slowly) a couple times to disperse the solvent
- let it sit 24-48hrs
- replace plugs and start as normal. This will give the rings a good soak.

Of course, be ever so careful not to let any foreign material into the cylinder. You are performing open-heart surgery any time the engine is open. Keep it clean!

If it is worn valve guides rings, there is no fix for it besides $$$, likely as much as the car is worth.

Thanks, I do plan to do this when time allows. 
« Last Edit: May 03, 2016, 03:56:01 PM by dragoncar »

sokoloff

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Re: Spark Plug Help
« Reply #25 on: May 03, 2016, 02:20:47 PM »
Use the original torque setting. You're "supposed" to put on a new gasket, but I never worry about that on street cars (I do on piston airplanes).

You drive 3K miles a year. Put in a new Iridium plug and drive the car. It's not cost-effective to worry about even a fairly steep milage drop. 3K miles at 25 mpg is 120 gallons/year. 3K miles at even 15 mpg is only 200 gallons/year. The difference of 80 gallons/year is less than $200. It will take "forever" to earn back the cost of an engine rebuild and more than a year to earn back the cost of taking to a shop to "have a look" (and that's assuming that the "take a look" turned up something obvious and free).

Change the plug and then pretend you never saw the problem. Only if you see another symptom show up would I bother looking further.

Edit: math
« Last Edit: May 03, 2016, 06:14:36 PM by sokoloff »

dragoncar

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Re: Spark Plug Help
« Reply #26 on: May 03, 2016, 03:58:24 PM »
Use the original torque setting. You're "supposed" to put on a new gasket, but I never worry about that on street cars (I do on piston airplanes).

You drive 3K miles a year. Put in a new Iridium plug and drive the car. It's not cost-effective to worry about even a fairly steep milage drop. 3K miles at 30 mpg is 120 gallons/year. 3K miles at even 15 mpg is only 200 gallons/year. The difference of 80 gallons/year is less than $200. It will take "forever" to earn back the cost of an engine rebuild and more than a year to earn back the cost of taking to a shop to "have a look" (and that's assuming that the "take a look" turned up something obvious and free).

Change the plug and then pretend you never saw the problem. Only if you see another symptom show up would I bother looking further.

Thanks -- I've started driving more recently but it's still not going to be worth a costly repair.  I'm more than willing to throw my own time, and tens of dollars at it, to try to fix the problem. 

dragoncar

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Re: Spark Plug Help
« Reply #27 on: June 22, 2016, 11:10:04 AM »
I would not bother with spending money on compression test. It'll tell you 'yeah it's sick' but it's not likely you'd pour $2-4k into this car for an engine, correct?

See my post from above, run some good cleaner(s) through it. I suspect gunked-up oil control rings. If you want to be aggressive with cleaning:

- remove all 4 spark plugs
- add 1oz of Seafoam into each cylinder through the hole
- turn the engine over (by hand, slowly) a couple times to disperse the solvent
- let it sit 24-48hrs
- replace plugs and start as normal. This will give the rings a good soak.

Of course, be ever so careful not to let any foreign material into the cylinder. You are performing open-heart surgery any time the engine is open. Keep it clean!

If it is worn valve guides rings, there is no fix for it besides $$$, likely as much as the car is worth.

I removed this plug again recently -- it actually still looks fine (no wet deposits).  I did a seafoam treatment on that one cylinder for 24 hours (not all cylinder mostly because I only had a little left). 

Turning over the engine by hand looked near impossible without removing components, so I disabled the fuel pump and used the starter motor to eject any remaining solvent.  A lot of black crud (and a little solvent) on the towel. 

Reinstalled the plug, and lots of smoke.  Ran a little rough for a mile and then I drove it for a few more miles.  The puttering is gone again, so likely it's from that one cylinder getting crapped up?  Anyways I'm going to leave it alone again for a loooong time.

Thanks for the help everyone