Oil fouled plug

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  #1  
Old 08-15-07, 09:39 AM
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Oil fouled plug

I have a '94 ford explorer, 4.0 V-6. It has quite a few miles on it, but I want to get as much use out of it as I can.

Anyway one of the cylinders may be a little weak, because after a few thousand miles it will start to misfire on one cylinder. And it's always the same one.

When I pull the plug on that cylinder it looks like someone dipped in tar then dropped it in the dirt.

Changing the plug solves the problem %100, but only temporarily.

The truck uses oil, but it does not smoke ever.

I'm assuming the plug is oil fouled.

Will switching to a hotter plug help keep the deposits burned off?
Is their some kind of plug cross reference chart I could find on the net or something to look up the number for a hotter plug? The guys at the auto parts store had no clue.

Or is that not a good idea altogether?

Any suggestions would be greatly appreciated.

Thanx

Jim
 
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Old 08-15-07, 09:50 AM
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No

The problem is "poor oil control"
The oil is leaking past worn valve guides or piston rings into the combustion chamber
It will douse a hotter spark plug just as easily

The numbers on the plug have the information you seek
I forget which numbers are which, but they tell you the heat range, and the next one up can be found
But it won't help your oil control problem
 
  #3  
Old 08-15-07, 10:03 AM
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The only way to contol the problem is first do a compression test, then do a "wet" test so that you can determine if the oil contol problem is from rings or valve train. Then you will have to REPAIR the offending part(s). Ahotter plug will repair nothing.
 
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Old 08-15-07, 11:11 AM
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Plug extender for fouling plugs

Years ago I had 70 monte carlo 350 in it, that did the same thing and on that plug I used an extender which placed the sparkplug further the the clyinder.Worked just fine all the way until I sold car.
 
  #5  
Old 08-15-07, 12:11 PM
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While a hotter plug won't "fix" the oil problem it should allow the affected plug to work better/longer.
 
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Old 08-15-07, 06:08 PM
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I noticed what I thought was poor engine performance just prior to complete misfire, but it grows on you so slowly it's hard to tell just how long you've been burning too much gas.

Also if the plug looks like that, I wonder what the valves and top of the cylinder look like...hmmmmm...can't be good.

I don't want to sink alot of money into this truck, but I also don't want to let this oil fouled cylinder continue to wreak havoc on the rest of the engine.

Maybe a plug one step hotter would help, but is there anything else I can do, short of a mechanical rebuild, to help keep this cylinder clean. (maybe 20w-50 oil?)

As always, you guys here are great, and I value all of your inputs.

Thanx

Jim

Oh, btw I think it is a valve stem guide, cuz it has a nasty inconsistent tap at first startup. Then goes away in a few moments.
 
  #7  
Old 08-16-07, 09:11 AM
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There are plugs that fire better in an oil contaminated fuel than others. Those plugs are available and if you aren't depending on them to fix the problem, but only live with it, they work..Ok at best. They can extend the serviceable life of your vehicle. But a worn part is a worn part.

In your case, I would determine what is leaking = how much to fix it. Start with what Jeff suggested. Do a compression check first and note the psi of that cylinder. Then squirt some 10w oil into the cylinder and with the plug out spin the motor over to blow out excess oil and to distribute the oil around the rings. Then check the compression again. If it has went back up about 30 lbs or more, you have worn rings/cylinder walls and the oil burning plug is the next step.

If not, the problem would be valve guides/stem seals. If it's a stem guide the engine heads would have to be pulled and reconditioned. I gather that is more than you want to invest. However, there are some types of intake seals that can be replaced with the heads in place. That isn't a DIY'er type of fix, but I would check into it.

Keep in mind, if one is bad others aren't far behind it.

The tapping you hear would be the lifters.

Hope this helps,

Bob
 
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Old 08-16-07, 02:46 PM
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Originally Posted by bobt View Post
Years ago I had 70 monte carlo 350 in it, that did the same thing and on that plug I used an extender which placed the sparkplug further the the clyinder.Worked just fine all the way until I sold car.
Same here. I coincidently put it in a 350 also.
 
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Old 08-17-07, 04:14 PM
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Thanx guys, I'm not looking to repair the worn part, only live with it.

Is that plug some special brand or variety or something or just a step or two hotter?

Thanx again.

Jim
 
  #10  
Old 08-17-07, 05:41 PM
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Yes a hotter plug will extend the life between changes, if it's oil fouled from poor rings. "Been there, done that"! I'd start with a # 2 higher than stock #.
For example: I believe your champion plug # is probably RS14YC6. Try a RS16YC6, and see how much longer it lasts. After that go 1 number higher (RS17YC6) at a time. Not sure how many more higher you can go, before tip hits piston, if at all, but a few numbers shouldn't be a problem. Check the champion site for explanation if your worried or curious.

http://www.championsparkplugs.com/faqmain.asp
 
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Old 08-17-07, 08:03 PM
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From the previous posts you obviously don't plan to fix the problem and are just looking for a big bandaid, rather than continue to purchase sparkplugs that are going to foul(it is only a matter of time)why not purchase a pneumatic sparkplug cleaner(Harbor Freight has one in their current flier for $6.99), then clean a plug, when you hear the misfire replace it with the clean one and clean the fouled one...... and the beat goes on. When someone says "quite a few miles" rather than the actual mileage I usually consider that as over 200K. Have a good one. Geo
 
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Old 08-18-07, 10:02 AM
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geo,

From personal experience with old oil-burner beaters, the trouble is, you can even put in a new plug and immediately it fouls and misfires. You have to solve it by some other means. Just my 2-cents.
 
  #13  
Old 08-18-07, 01:07 PM
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ecman;
I agree, however if you read the previous posts it doesn't look like jmnew is planning on fixing the problem, just looking for a bandaid. I had a 54 ford many years ago and carried a gallon jug of used oil with me so I could add some when the oil light came on, I worked at a service station and once a week I would have to clean the plugs. OH, to be young again. Have a good one. Geo
 
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Old 08-18-07, 09:07 PM
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I put in a new plug and it doesn't immediatly foul.

I usually get a few thousand miles out of it, but I'm sure it's not long before the deposits cause a subtle decrease in performance, sludge in the engine and decreased gas mileage even before it completely fails.

Hey geo, great idea with the plug cleaner.

My only worry though is, the deposits between the pocelain insulator and the threaded part were so hard I couldn't chip them free with a screwdriver. LOL

I'll have to check the Champion plug site and see what kind of plug I can try.

Thanx for everything, everyone.

Jim
 
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