Passed Smog today-- Yeaaaaa!!

congrats to you! thank goodness that we don't get hit as bad as other states! :-) later, dave AKA vwdoc1 chicago

snip

So he goes through the

congrats man! after all that work...it sure paid off huh? doesn't it suck to live in cali sometimes? i can't wait till i get mine running-i'm going to have to find a shop that knows the mpi kit too-only in norcal.

Man, you actually gave out the guys name that you paid off to pass emissions???

Wow... ;-)

I mean, no way an engine in as bad a shape as yours only firing on 5 cylinders can pass emissions anywhere, even in lax areas, let alone in California.... LOL!

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

William Oliveri wrote:

:-).

Yeah, it's funny. I replaced four of the six plugs with new before I went to have it smogged (I thought I had six with me but had only four) replacing #2 of course and when I drove it it missed, felt worse than before I did the replacement. By the time I got through with the smog (2nd station, drove about 10 - 15 miles) it started to even out and run smoother (computer adjusting?). I parked it at work and later went back out to see what the plug looked like and there was oil all over the threads of the plug up to the base of the thread. When I took the old plug (#2) out when I was changing for new and looked at it it didn't look as bad as before so at that time I'm thinking maybe Chris is right. There was some carbon on the oil ring and it's starting to blow itself out. When I pulled the new plug my hopes were dashed at that theory. Go figure.

Bill

Well, you know when mine passes emissions, I then just like to go and drive the thing and not worry about any repairs for another 2 years....

Mike

William Oliveri wrote:

I've been thinking about this a bit and there is another thing I might mention. You are getting oil on the plug for that cylinder, and it is getting up into the threads. Remember, the threads don't seal the plug to the head, the washer/seat on the plug does that. There is a small clearance between the threads in the head and the threads on the plug by design. With all the turbulence, pressure, heat, etc. in the combustion chamber, some oil is going to work its way up the threads and stop at the sealing surface. This is what is causing your plug threads to get oiled down. I still say you should drive it for a while and see if it clears up. More and more I believe this is a stuck oil ring on that piston and it may clear up with time. Unfortunately, I don't like or trust oil and gas additives for cleaning out engine deposits, so I don't know if anything like that would clear up a stuck ring. Just keep the engine in tune, change the oil regularly or maybe even a bit more frequent than usual for a few changes. Try and take the Jeep on a few longer runs at highway speeds when you can. This may help free things up and clear out the crud. This is all assuming that is the problem of course.

Chris

Thank you for your reply Chris.

Let me ask this. This (oil on the plug threads up to the base) is inconsistent at best. That is, I have not been able to recreate the scenario at will. The times this has happened is as follows:

1. Previous evening changed plugs. Next day drove about 10 miles with a couple stops in between. On final stop took plug out to have a look. Looked to be not bad. Replaced plug and went for a walk around flea marked for about an hour to hour and a half. Looked at plug again and found the oil on the threads situation.

1. Yesterday after smog test same effect only I didn't do the before/after, only the after. Found oil on the threads up to the plug washer.

If it was the oil ring as the source, wouldn't it be consistent or at least more consistent with oil on the threads?

My thoughts were that a single valve on this cylinder is causing the problem. There is what, less than 25% chance that valve is open at shut down (maybe even less)? Could it be this is the time when the oil is leaking down from the valve guide into the cylinder at shut of but only when that valve for that cylinder is open. Does this make sense?

The reasons I'm led in this direction is:

1. This happened after the engine was shut down and after the plug had been pulled and replaced.
2. This effect is inconsistent.

Thanks for any agreements or contradictions to my theory to help me better understand.

Bill

Grats man!! That's gotta feel good.

Bill, I don't quite follow the "oil on the threads" - If the sparkplug is a normal plug with a straight threaded portion and a squared-off sealing "step" with a crush-washer to seal, then the only way oil could get on the threads is if the seal isn't sealed! That area below the seal isn't gonna get oil from below if there is no way for it to "flow" meaning a dead-end with seal working properly has now way to allow oil to flow up there. (Unless the engine is upside down and gravity gets it there when engine is off) Next item: IF the plugs you are using are not the correct plugs for the engine, especially if longer than stock, the threads at the end will protrude into the combustion chamber. Usually if this is the case, they are tough to get out once carbon deposits accumulate on them, but you are getting wet plugs and changing often, so that isn't a problem. Are they the correct plugs for that engine and how are you certain of that? (I don't need to know, BTW!)

Did you ever do a compression test hot and a compression test cold and compare that? (When you are going to do a hot test, slightly loosen the plugs before warming the engine up (slightly loosen) so you don't run risk of tearing threads when removing hot. I want to know about the hot test vs cold because you had excellent compression cold. I want to know what that #2 does hot. I have had engines that started well cold and ran okay, ran better at higher speeds than lower speeds... Hell to start once hot, however. Compression was "normal" cold but almost non-existant hot, due to loose valve seat or crack in head or munched valve guide.

As you know, the oil has to come from somewhere. It should make no real difference if the valve is open or closed when engine is off - as soon as the engine starts, that oil that is puddled on the valve is gonna get into the combustion chamber. Oil that is fouling plugs isn't getting there when engine is off.

If #2 was the first cyl you put the new valve seals on and you had probs with that one (as compared to the others) is it possible that one of #2's new seals is not sealing? You said there wasn't much play in the guides on #2 (most on #1, right?) Or was there? What color are the valve stems? If a stem is significantly worn, the seal won't seal on it.

Just some random thoughts. Used to be a lot easier to diagnose with flathead engines! Smoke on a pull: bad rings; smoke downhill on compression (or taking off after long downhill): bad valve guides. Less apparent on ohv engines but same general idea.

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Hey Bushahaulic,

Thanks for the thoughts and additional test suggestions.

My theory regarding the oil on the threads follows the physics of a liquid flowing upward into a crevasse or area such as a plug. If you have a threaded item with a small clearance between the threads (Chris wrote "Remember, the threads don't seal the plug to the head, the washer/seat on the plug does that. There is a small clearance between the threads in the head and the threads on the plug by design") then a liquid will be drawn up into this area.

I haven't taken physics but I have seen the action of a liquid being drawn upward within a small gap or space. You could try to put to vertical sided glasses together. Place them close together and put some water on the table at the gap. The water will draw upward a certain distance within this gap.

I found this which is as close to my thoughts as I had time to look:

"Capillary action is the result of adhesion and surface tension. Adhesion of water to the walls of a vessel will cause an upward force on the liquid at the edges and result in a meniscus which turns upward."

They are talking about a tube and water in this case but the same principle applies.

My thoughts are the fluid (oil in this case) is flowing down from somewhere (worn valve guide, crack in the guide, don't know) and as it passes the plug (which by the way are cold plugs - short nosed, suggested by Hesco for the MPI Kit) it is drawn up into the plug cavity through this action.

Regarding the seals. I double checked them and found, if anything, they were too snug. These seals ride on the valve stem and as I understand it do not remain down by the head but "float" to various positions based on the action of the valve stem. I could, to be extra thorough, buy another set and replace the ones on #2 just to be sure. A new pack is only 10 or 11 dollars.

Regard> As you know, the oil has to come from somewhere. It should

Following my theory, the oil cannot pass down into the cylinder if the valves are closed. It will only accumulate a certain amount in the guide and be stopped by the closed valve. If the valve is open then the oil can flow continuously to allow all oil sitting on the valve and guide to flow into the cylinder.

Now, after all this is said I'm not disagreeing with Chris. In fact, I would it rather be the case if the carbon could be "blown" out. Contrary to popular belief, I would rather not tear this engine apart either for the head or the rings. I'd rather drive it as Mike said. However, I don't want to ignore the problem either.

Also, following Chris's scenario, how would the oil get into the plug hole after the engine is shut off. I can think that the oil is getting past the oil ring into the cylinder and pressed up onto the head and after shut down it flows by the spark plug hole again being drawn up into the hole. The only thing that bothers me about that is it would be more consistent. I would be able to recreate it far more consistently than with the "down from the valve guide" theory and I would see the effect more than I have.

Whew, that was a bunch.

Volley back at'cha :-)

Bill

Hey Bill - I have an oil lamp right here beside my keyboard! It's kinda nice instead of turning on the room lights! The hazard lanterns - those round jobbies that looked like a cannonball on fire? Haven't seen them for awhile, but I did see some in use in a road construction area in the "sticks" in Oregon sometime within the past ten years! One of the mail order tool companies was selling repro's just recently, too.

one here has

Yeah- and those old round oil pots they used to set on the road before they came out with Lectric Lites ®.