Fouled Spark Plug
 

#1 had a hard caked deposit.
I checked compression on that cylinder and it read: 180 psi and stayed there until I bled it.
I put a new spark plug at it came back fouled a day later. It had what looked to be oil.

1. I don't think it's the piston ring since the pressure held
2. I suspect a valve guide or valve stem seal
3. This must have contributed to my illusive stalling for sure.

Ah, let's not forget, this is a 1988 190E 2.3 8V.

I am now at a crossroad:
1. Should I do a complete head job?
2. Just replace the steam seal and pray that would do it.
What are your thoughts?

Oh, I also measured the vacuum at the intake and I was getting a fluctuation between 16 and 20 Hg at idle then it was nice and steady at higher rpm.
Could this be an indication of a worn valve guide?

Usually its the valve stem seals, and possibly the guides as well if its a real high miles motor.....it allows oil to be drawn in and burned....fouling the plugs. My 300E has been doing this to the #5 and #6 plugs.....I just clean them occassionally.....if yours fouls real fast then its time to do the seals and possibly the guides if its a 175k+ engine.

mine is so bad that I think it is the main culprit in my stalling saga:(

You're probably right there. You can get a leak down test done to show up leaky valve guides and seals. Or just get your head rebuilt.

I tested the vacuum at idle and the needle was dancing between 16 and 20 (mytivac) but it was steady at higher rpms.
I tested the compression on cylinder #1 and I got 180 psi and it stayed there nice and steady until I bled my tool. This eliminated the possibility that I have a stuck or unseated valve or piston ring wear.

Oil getting past a ring or a valve guide/seal will have no effect on a compression or leakdown test.

That's clearly the case, my worry was a worn cylinder ring which would make my eventual repair a pita.

These engines have a history of valve guide/stem seal oil leakage. I'm not sure if the stem seals can be changed with the head in situ. If they can, that would be the repair to make. Then see what happens.

Is that the only fouled plug? How are the vacuum hoses and the crankcase ventilation?

Yes, it's the only fouled one. All vacuum hoses are brand new.

Do I have to remove the cam tower to reach the stem seal?

Okay, I took the cam tower off after seeing this thread: http://www.peachparts.com/shopforum/showthread.php?t=168651

But how does one go from this
http://www.w124performance.com/image...valve_job2.jpg

To this
http://www.w124performance.com/image...valve_job3.jpg
???

I compressed the spring with the same exact tool but I couldn't figure out how will the spring come out? Then how will it go back in and lock in place?

You compress so that you can remove the retainer on top (fits into the groove on the valve stem). Note also his compressed air into the spark plug hole so the valve doesn't drop down.

I couldn't access or see the retainer... Is it a C or E clip? All I noticed is a loose spinning top where the hydraulic tapper meets with the valve spring.

It is a split keeper (2 halves) sitting on the retainer ring - you can see it in the picture around the stem. Use a magnet to pull the keepers once the spring is compressed.

Make sure you have cylinder on TDC and the valves held closed by compressed air. After compressing the spring, give the compressor a tap or two on top with a hammer to loosen the split collets or keepers that are positioned around the top of the valve stem. Block any oil drain holes in the head with paper towels etc as the keepers can get away. I keep a pencil magnet handy to retrieve them.
After you change the stem seal, place the spring and compressor back over the valve and push down on it as you replace the keepers. I use long tweezers and thick grease to hold the keepers. Once you are sure the keepers are correctly in place release the compressor and diesconnect the air line. I give the top of the valve a sharp rap with a hammer and punch to seat the keepers.

Okay, I was able to see the split retainer. I compressed the spring and hit to top of the tool to loosen the retainer but it won't budge. As I move up and down with the tool the valve goes down with it if I don't prop the bottom of the valve with a wooden block. I am right now testing this procedure on an extra head I have, so I have access to the valves on the other side.
I will use compressed air on the real job tomorrow; today is practice so I don't mess things up since this is the first time I am doing this.
I will try again after lunch...

I got it!
I just had to tap with a little attitude:D
The dis-assembly and assembly went great:cool: I now know that I can do it on the car.
My next question is the hydraulic lifters. I tried to take them out to see how they are in place (I have some new ones in a box) but they stayed in place with just a little play up and down. I turned them with my finger, I even held the back in place just in case this is screwed in but no progress. Do I need to punch them out? I would hope that's not the case:eek:
Anyway, is it a good idea to replace them as a preventive?

Oh, before I forget, how much play should there be between the stem and the guide? How does one figure out that it's ok?

The play will be minimal and inconclusive when you have compressed air in the cylinder as the valve will be supported by the seat. If you feel brave you can release the air from the cylinder and wiggle the valve stem, but never let go of it as it may drop out of reach into the engine. As to the spec for the guide play someone else will need to give you that or search out a repair manual.

Remember that just doing the stem seals could be a band aid for leaking guides too. This was the case with my 300TE until I rebuilt the head.

This was the tool I used
http://i135.photobucket.com/albums/q...prnigCompE.jpg

That's interesting, I thought replacing the stem guides was the realm of the non-mortals...
What's the name of that tool? Where did you get it? How easy is it to use and how does one figure out how far to seat the guide?

The shop I queried about replacing the guides claimed that the head had to be removed....is this the case? I suppose once the head is removed doing those tasks is not that big of a deal as long as one has the correct tools...

I intend not to remove the head for now even though I have an extra head that I can send to the shop ahead of time. If it's only the seal then I will be happy to postpone a major repair for another time after I go back and control my priority list of things to do in life. The 190E has taken up a lot of my time fiddling with the CIS to no avail yet the problem was much simpler (I think).
Now, how about them tappets/hydraulic lifts?

Sorry for the confusion, that is for the valve stem seals. As far as I know, the head must be removed for the guides. I removed my head and sent it off to the shop for him to clean, skim and rebuild. You can do it yourself, but for what its worth as it has to be sent off to be skimmed anyway, might as well just let the pro do it.

You should not have any consumption problems for the time being, but in the near future, you may start losing a quart every few thousand, by which time you gotta realize the guides are bad, not the stems....and all that burned oil is reducing the life of your cats.

Any idea why your guides were already worn with only 90k ish on the engine? How much did your mechanic charge to rebuild the head? (I may go that route someday on my 300E)

^^
Good question because my 190E has 100K miles.

My 300E is at 140k.....I've read that the guides last about 200k.....currently its taking about a quart of oil every 1000ish miles depending how its driven. I'll try just getting the seals done first though, hopefully it fixes the issue for a while....

Changing guides requires removing the head. It also requires regrinding the valve seats to make them concentric with the new guide. And since the seats are re-ground the valves need to be re-faced also.

Sounds like fun! :eek: (for a mechanic!)

So I managed to install the stem seals for cylinder #1 and after a mishap where one of the tower bolts snapped while torquing I managed to put it together hoping to avert a head swap.
The car started right up, idled okay but there were a couple of hesitations when I took it on a test drive while I pulled over to talk to a neighbor.
The exhaust smoke is black when I hit the throttle. It was getting dark for me to tell if it was more like blue or not...
I will check the plug's condition tomorrow morning then decide if I need to go for a head job. What are your thoughts?


here is some of the work:
http://s713.photobucket.com/albums/ww134/drewprof/Head_job/?albumview=grid

Ok, so this morning I pulled the plug and it was wet with gasoline.
I attempted to adjust the EHA and check Lambda's duty cycle but I couldn't zero in on a proper balance. I was getting a lean condition for the most part because I had disconnected the fan clutch sensor so the car went to 100 degrees. I am waiting for a new sensor because the one in the car if plugged in keeps the car at or below 80 degrees. I was told that the car should be at 90 degrees.
I guess my adjustments are fruitless for now until I get the sensor.
There is good news however! The vacuum gauge was steady indicating no loss of pressure due to valve guides or seals.

Please feel free to comment on a good fuel to air mixture adjument technique that I might apply next time after I install the sensor. In the mean times here are some of my results:
http://s713.photobucket.com/albums/ww134/drewprof/lean_rich_mixture_adjustment/?albumview=grid

One muti meter was measuring the current through the EHA while the other multimeter was measuring voltage between pin 2 and 3 of the socket on the driver side near the fender. I also traced the signal between those tow pins to watch how lean or rich the car was.

This would have been ideal but it was just for one moment before the car went lean
http://i713.photobucket.com/albums/w...g?t=1247071918

http://i713.photobucket.com/albums/w...g?t=1247071967