Suggestions needed.

[jdhill]

My M110 was running ragged, pulled the plugs and found #1 and #2 are wet with oil, not fouled, wet. First thought was valve stem seals so ran a compression check, #1 is 152# and #2 is 154#. Backed that up with a leakdown test, all good. 2nd thought, somehow oil is getting into the intake manifold but then why aren't all plugs wet?? If there is a crack in the head and oil is being sucked into the two cylinders wouldn't that show on a compression test?? Any suggestions appreciated.

[Mike D]

Loose valve guides/bad stem seals will not always show up during a compression or leak-down test. There is also a vent for oil vapors which is located between the numbers one and two cylinders.

Do you have much "blow-by" when the engine is running and the oil fill cap is removed? Do you have the auxiliary vacuum pump on your engine?

http://www.peachparts.com/shopforum/vintage-mercedes/254274-why-im-replacing-head-my-m110.html

[97 SL320]

The first suggestion would be to have a better post title like " M110 # 1 and 2 plugs wet with oil. "

When plugs are clean but wet, this indicates they are not firing at all. You are likely seeing gasoline with maybe a bit of oil.

Have a look at the plug wires / cap . Ohm out the wires or move 1 and 2 to another cylinder. Look for a carbon line running down the cap where 1 and 2 plug into and under the cap where the terminals are.

Do you have an aftermarket ignition system? If the trigger wheel is damaged for cylinders 1 and 2 you won't get any spark.

Another possibility is the intake valves not opening due to a rocker coming off, I've seen this on other engines.

While this does not apply to your car, I've seen fuel injector wires rub to ground causing such a massive fuel dump the plugs never get a chance to fire but are still clean but wet.

[MCallahan]

Agree with above, two dead cylinders. Check for fire at the plugs and work from there. If the plugs are firing, could be fuel dump.

[jdhill]

Thanks for the responses, have been travelling this week, back on it Saturday.

[jdhill]

Should have said from the beginning this is a Megasquirt controlled, D-Jet fuel injected
M110 with EDIS wasted spark. Removed the #1 plug and connected the plug wire, cranked the engine (key on ) grounded the plug and got a barely visible spark. Plug wire is 1.1 ohm's resistance, ran a 14ga wire from the battery directly to the coilpack supply and removed the in line capacitor with same result, weak spark. Tried another coilpack with same result. All cylinders have the same weak spark or am I completely off the mark??
Had assumed there would be a bright, robust spark. Looked at a couple of videos on YouTube and they showed a major spark. Checked the gap, .8mm as recommended by Benz. (Bosch WR8DP) Any info appreciated.
Forgot to add, battery voltage is 12.2V.

[97 SL320]

What type of coil packs are you using? What car did they come from?

Did this setup ever run fine?

Are all the injectors the same color / part number?

[MCallahan]

Might try swapping to copper core plugs instead of resistor type (thats the R designation in the Bosch). True copper core are hard to find now. I found a 24pk box of these at the big warehouse NAPA store in town for less than $40. Working great in my wagon.

https://www.napaonline.com/en/p/ASP104BP

[jdhill]

Thanks for all the responses. Turned out to be a real comedy of errors.
Had been congratulating ourselves on finding a set of Benz plug wires for the M110 with connectors for threaded pins on both ends that would fit both the Ford coil pack and the Benz plugs. Turned out the coil ends, while it felt like they were fitting nicely, were not going over the pins in the coil packs forcing the coils to jump the gap to the wires. Also turned out the plugs were resistor type, as suggested, and the plug wires were 5K ohm resistive, So we made up a set of plug wires (1K, correct ends) that hopefully, will eliminate those problems and ordered a set of Bosch W7D plugs as specified in the owners manual.
Thanks again.