khalloudy

Hi all,

I pulled my spark plugs out of my car. They have approximately 8k on them so they should be pretty new, but when we pulled them out, they were sooty and full of debris cooked all over them. Not all of them exhibited this behavior, but a few. I am attaching pics for feedback. A few words to mention:

Pulled engine apart like 15k miles ago to replace the head gasket when the water impeller failed. Previous to that, the car never used oil or smoked at start or anything. After the rebuild, i have been using oil on a regular basis to which i have to check my oil every month or two and top off. The car smokes at start intermittently when in use and does not smoke if it is stored for a few days or weeks. Actually it sometimes doesn't smoke at all at start, very random! I do have oil in the breather line (significant... if i put my finger in the line it will drop oil out!) Anyways here is what i am thinking and i am looking for any feedback

Valve guide - maybe, but why after the rebuild?
Valve guide seals - they were changed at rebuild, could they have been misinstalled causing a leak?
Injectors - could they be bad or getting old or something? could be causing a bad spray pattern condition?
Bad connection in the breather system under the manifold causing the engine to suck oil?
I did smell the smoke and it was definitely not burned oil, more like hydrocrabons unburned....

Any help is useful as this is getting too long in the tooth and is bothering me.

Sincerely,

khalloudy

Anyone with any thoughts on this? come on there must be someone

UKKid35

A little more light would be good, it's very difficult to see the business end of those plugs.

UKKid35

Did you use the seal protectors when installing?

(ignore the washers in the photo)

khalloudy

Paul,

I am not sure if they did... should i ask about the seal protectors? what are they and what part number is it? I will have my valve covers off soon and we can redo the valve guide seals then. This sucks... i think someone messed up big time.

Sincerely,

jon928se

First thought - find the macro button on your camera.

Second thought - What your plugs show could well be the result of the 1/2 mile trip just before you pulled the plugs and don't reflect the previous 8k miles?

Third thought - Porsche doesn't actually recommend the use of the multi electrode plugs on the S4 (only on the GTS - no idea why)

Attached is a pic of a 35,000 old mile NGK V grooove that had only done short trips just before it was pulled. Only real degradation of this plug was that the gap was now 1.1mm instead of the 0.85mm it was originally gapped at.

What was the usage of the car before the plugs got pulled?

If you havent actually made the 928 engine work hard it won't reward you.
To quote the wsm about testing the Auto trans ( I think this is quite funny) "If local conditions do not permit testing at approx 140kmh..."
This was written by Germans who don't actually understand why other countries have speed limits on their Autobahn/freeways/motorways.
What I am trying to say is that to actually exercise the 928 engine you are going to have find somewhere to make it work really hard for longer than a traffic light drag race. the pull the plugs for an accurate assesment of what the engine is doing.

Jon

UKKid35

The protector goes over the tip of the valve where the sharp edges for the keeper would otherwise damage the seal as it is fitted.

You can almost certainly replace the inlet valve guides with the heads on and engine in, but some of the exhaust seals may be rather more difficult, clearance for the seal removing pliers is going to be awkward. Don't forget to use a dowel in the spark plug hole to confirm that the piston is at the top of the cylinder before removing the valve keeper. You will also need a valve spring compressor that bolts to the head.

khalloudy

Jon,

I drive my car hard and regularly... yup i do put the car to work on a daily basis as far as speed and accelerations are concerned... i love to put the 928 to its true use Before we pulled the plugs, i did a 10-15 miles run to my mechanic shop from my work... so it was a good run. The previous set of plugs before this were similar just not as dirty I guess.

Paul,

I will have to ask my mechanic about potentially re-doing all the valve guide seals as my confidence seems low and i have a feeling they were not installed correctly. The car NEVER used oil before and now it does so there is a potential there; unless oil is being lost at the breather system level.

Do you guys think it could be bad fuel injectors? or what are the other potentials?

Sincerely,
Khaled

jon928se

Khaled




Start with the basics - what did we do just before the change occured? Maybe the head job 15k ago was the start of the problems from what you have said? In which case Paul's (UKkid) diagnosis could well be the answer.

What else did you do?

UKKid35

The easy test for valve seal failure is smoke under engine braking, not sure how that works with an auto though...

I once drove a Nissan Urvan Campervan 10,000 miles round Australia in 6 weeks. When going downhill you couldn't see anything behind at all except smoke. It used about 5lts oil per 50ltrs gas.

Garth S

Regardless of the cause, all plugs look suprisingly similar .... ergo ... each cylinder is experiencing identical conditions of operation: therefore, that rules out a single bad valve guide - or even three ( ditto for injectors if that is fuel fouling - can't be sure from the pics).
It is highly unlikely that all valve guides went **** up at the point of rebuild - unless some wise soul reamed them with a cutting tool. Similarly, even if the new seals were installed without the 'condom' as Paul points out, it may be a stretch to think that they were equally damaged in all 8 cylinders.
If your fuel economy remains reasonable and the engine is making power, then spark and fuel are likely OK ( check fuel consumption to be sure) .. and can be eliminated as common causes to effect all 8 holes. As the plugs have a 'juicy' look in the pics, oil remains suspect #1, especially with the noted consumption.
This may point the question as to which way can an oil mist be aspirated into the phlenem for equal distribution with the intake air ????

No, I've no answer - just trying to tie the commonality of the plugs to the probability of "equal screw-ups" in stem seals, etc.

FWIW, attached is a pic of a 10 year old set of WR8DS from a 16v ( the W7DRS from the S4 were even cleaner and a lighter tan) - I screwed them back in after checking gap, and the engine screams ... but the point is that a dry, light brown plug without deposits is a healthy one.

UKKid35

On a previous car I kept regapping plugs over a 10 year 100,000 mile period and eventually the car started misfiring and generally running badly. The plugs looked ok but had broken down internally, so now I do occasionally replace plugs...

khalloudy

All,

this is pretty interesting. I did not have any oil injestion/use issues nor did i have the smokey start till after the rebuild. This is also mated to a vibration at 1600-1800rpm. At the rebuild, the only thing we did not do was the valve guides, but it should not be an issue as it was not before (my car had 165k on it). The smoke at startup began immediately after the rebuild as well as the oil use. It was attributed to the new rings sealing in. I am not happy at all. This cost me 8k in work and something went wrong.

1- Car did not use oil. period.
2- Car did not smoke. period.
3- Car did not vibrate (even with the collapsed motor mounts). period.

I do not want to keep throwing money at it without root causing the issue (with all the money spent on this car until now, i could have bought an awesome GTS). I do suspect someone ****ed up bad. The ammount of crud/soot or whatever on the spark plugs was extensive on the majority of the plugs though a couple were clean. I feel it is going south as the last time we pulled the plugs 6k miles ago, only 2 showed the deposits... now 2 did not show so it is progressing into the worse. Is there any way to figure out if it is oil or fuel related? and if it is oil, what can cause it? if fuel, what is causing it?

P.S. I think i only saw a couple of tan plugs, the rest were black literally and full of charred deposit.

Sincerely,

piccardo

(Normal)
Light gray or tan deposits and slight electrode erosion
(Oil Fouling)
Wet, oily black deposits on the insulator and electrodes
Symptoms: Poor starting, misfiring
Causes: Worn piston rings, cylinders and valve guides * New or recently overhauled engines * Fuel mixture oil content too high (two-stroke engines)
(Carbon Fouling)
Dry, soft black carbon on the insulator and electrodes
Symptoms: Poor starting, misfiring, faulty acceleration
Causes: Faulty choke--overly rich air/fuel mixture * Delayed ignition timing * Bad ignition leads * Plug heat range too cold
Broken Insulator
Insulator is cracked or split
Symptoms: Misfiring
Causes: Severe detonation * Incorrect tool/torque applied during installation or removal * Careless gap setting

RealTech

Khalloudy- You need to take alot better pictures of your plugs. Don't Take anything except the electrodes. Light them as brightly as possible.
Also, you talked about oil consumption, What about coolant? Do you have any leak down at all? What are you using for coolant? I need to see a real picture of your plugs but the reddish color concerns me. Burnt oil is not black, fuel is. Did you say how the car starts and drives. It should be determined whether the ecu is seeing the temp sensors correctly. Very often, a blown head gasket car will degrade the o2 sensors( or kill them) and it goes unnoticed by an inexperienced(or amateur) tech. There are so many things that could cause you to be out a/f-wise it is ridiculous.
I didn't scour your thread, but did you say who replaced your head gasket?