Spark Plug Horror! Look! - PeachParts Mercedes-Benz Forum

Merkey · #1 10-21-2006, 12:39 PM

Looking for our hot misfire on my sons 88 300TE.
Car has done 67,900 miles.
I put these plugs in new about 2500 miles ago.
Oil was changed just before that, and has been changed again last week.
The car is loosing oil, but we thought it is mainly leaking from the pan gasket.
Coolant was changed when we did the leaking radiator... 100 miles ago. We used the correct Zerex clear stuff, and the level has not moved since.
we use 91 ron gas, and we did pull the ignition timing resistor yesterday, to see if it made any difference. It didnt.
I planned to do a compression test this morning...
I pulled these plug about 5 mins ago...
We started the car from cold... drove it into the garage and pulled the plugs.

I was stunned by the condition of the #1 plug... enlarged pic below. Plugs are in order... left #6 to #1 on right.
Duty cycle was set to about 45% last time I did it about 2000 miles ago... it was about 70% before.

I will do a compression test now and post when we are done.
I will clean the plugs up and check the duty cycle again.

What the hell are those deposits????
I have never ever seen anything like that before!

Ideas?

Gilly · #2 10-21-2006, 12:45 PM

Yeah, you need valve stem seals, and badly. Possibly guides to, but you're at pretty low miles to need them. Fairly low for the seals too, but it's old enough that the seals have probably hardened over time.
Gilly

jhodg5ck · #3 10-21-2006, 12:49 PM

the resistor style plug isn't helping your cause any either.. Get some proper non-resisotr plugs (NGK, Beru, even champion if you must..).

But yes, VGS look to be in order given the overall low mileage.

What weight oil are you running? If you're not running 20/50 (Dino) I would switch.

Jonathan

manny · #4 10-21-2006, 12:53 PM

I can see the misfire on # 1 for sure ( bridged gap ).
That greyish fluffy-looking stuff, is ashes that are left over after the burn.
Conventional oil used?
Of course " Gilly " is right about the valve guide seals.
AGE is the killer of them, so is not running the engine, as for example on vehicles that are store for extended periods of time.

Gilly · #5 10-21-2006, 12:56 PM

Manny, can you do me a favor and drop the quotation marks around my user name? It's just my nickname. Tanks
Gilly

Merkey · #6 10-21-2006, 01:04 PM

Thanks Guys!
I guessed it was oil being burned!
The plugs were bought from Phil!
Did we get the wrong ones?

Oil was 5/30, but we put in 20/50 this time.

Ok we just did a compression test with my Craftsman good quality gauge.
1/ 180
2/ 180
3/ 185
4/ 185
5/ 195
6/ 190

Would the oil leakage past the seals account for the hot misfire?

david s poole · #7 10-21-2006, 01:29 PM

yes no doubt about it classic case of screwed up valve stem seals.replace them and the plugs and the car will run like new.

Chas H · #8 05-28-2007, 02:50 PM

That's a nice kit. Who makes/sells it?
Congrats on job well done.

Merkey · #9 05-28-2007, 04:00 PM

The spring compressor was off Ebay... I looked and the same one is marketed under a few names. Kinetic, or Schley or JTC, but all the same.
I think I paid about $50.
The two black towers fit on two of the cam towers, and the long bar goes in to them to act as a leverage point. We used the holes either side of the center. The red handled lever arm goes under this bar and the spring hold down goes in the first of the 5 holes. It works great!
The best moment was when we realised that you cant pull down on the exhaust valve springs on #5 & 6 because of the firewall/battery tray area.
We reversed the spring holder into the hole right on the opposite end and pushed up to compress the spring. You have to be strong tho!

ps2cho · #10 06-05-2007, 07:55 PM

So we did the Stem seals but the misfire was still occuring.

After some testing with my dad (Merkey) we established that there was no electrical connection on the ignition wire #1 and so we used a makeshift spark plug from one laying around and the misfires instantly were reduced to a small shake.

So we thought that this was the problem all along and the last few misfires were most likely coming from the other plugs.

So today I purchased a brand new set of Bosch Ignition leads and hooked them all up and the misfire is still there....GRR!!!

Also, on spark plug #4, I can hear ticking, or the spark...so we were thinking and it could have been possible that we mixed up one of the small little metal things on top of the valve's when we replaced the stem seals, because I know that we mixed them up (they looked identical so we just guessed it would be ok)

^I dont know the name of it....its silver and is between the clamp and the valve. You can see a shine from it in the picture....thats the thing.

Grrr...Could the last misfire be coming from that ticking spark plug #4? Could the distributor be a possible problem?

Also on a side note, 2 weeks after doing the stem seals, I checked the spark plugs and there is 0 deposit

So the job was successful.

t walgamuth · #11 06-05-2007, 08:01 PM

the valve retainer? a tapered thing in two halves?

tom w

Merkey · #12 06-05-2007, 08:46 PM

No, the valve shim directly under the rocker ball that bears on the valve tip.
Am I correct in saying that the valves have hydraulic lifters and therefor need no adjustment?

brewtoo · #13 06-25-2009, 01:26 PM

Quote:

Originally Posted by ps2cho

Also, on spark plug #4, I can hear ticking, or the spark...so we were thinking and it could have been possible that we mixed up one of the small little metal things on top of the valve's when we replaced the stem seals, because I know that we mixed them up (they looked identical so we just guessed it would be ok)

OK, It's been a long time since you asked the question but I didn't see the answer later in the thread. The part you are asking about is called a Ball Socket. I am very familiar with that part because a mechanic dropped one of those into my engine at some point in the past. For years it banged against the oil pump screen and eventually broke through, went into the oil pump and locked it up completely when it lodged between the gears. That caused the sprocket to rip off of the front of the oil pump. You can imagine.

Anyway, that's what it's called and they do not come in different sizes.

You never did say what was the cause of your misfire...

ps2cho · #14 09-05-2007, 01:53 PM

Just to do an update to solve this misfire:

We did some tests on the spark plugs by pulling them out and there was a really weak spark on plug #1 (I am assuming that is why it caused the most oil on that 1st plug as opposed to the rest). So then we used another spark lead and it was MUCH better. So then I went out and replaced the whole set with some brand new Bosch Ignition Leads.

This made the shaking considerably better and there is no longer any chance of stalling. It IS still there though and you can still feel it quite reasonably at idle. What would be the next step into finally resolving this horribly irritating problem?

ps2cho · #15 09-08-2007, 09:56 PM

Bump.

Just ordered a set of NON-Resistor spark plugs. Could this possibly be the solution to fix everything? Or do you guys think this will just help?