chris505 - 2/14/2010 9:03 PM

Oh tool envy.



Your #2 plug should show burnt oil if the rings are really bad, try plumbing no more than 20 PSI of air into the #2 plug hole, then listen to the dipstick tube for rushing air as you turn the rotating assembly to where both valves are closed, is there air coming out of the dipstick tube, the exhaust, the intake?

Warren T - 2/14/2010 9:25 PM

OK...I've figured it out...you're faking all these problems to get to play with all those YUMMY tools...right...
Warren

G-AMG - 2/15/2010 7:31 AM

I think I like your idea of Carbon Crud binding one of the piston rings... Because?
This whole symptom of weird idle came on SUDDENLY and only two days ago.

Now, the $64,000 question... Assuming my testing shows a leaking ring (via the Dipstick Hiss Test), do I dare doing one of those "SEAFOAM" cleaning methods mentioned on several sites??

What is your experience with a "mechanic in a bottle" for such situations??

Thanks again for your help..
G

hipine - 2/15/2010 11:40 AM

Just a couple things to think about.
1- how repeatable are the compression measurements? The rubber stopper method is never as good as a thread-in adapter, but can be okay. Verify with more than one reading before drawing conclusions, especially as your numbers seem odd (see 4).

2- Did you lash the valves before the test? One late/early valve will throw off compression. It's so easy to do a compression test I do one after every valve lash, even on the diesel. Saves asking questions like you did at first about "...who knows what it really was..."

3- Looks like you only checked #2 with oil. Check them all with oil before you decide there's something wrong with just #2. Most likely they all go up.

4- What is the compression specification on the M110? I didn't note it in the CGW article, but my truck ran like a champ with readings around 7 bar. Seems to me the reading in bar should be right around the engine's compression ratio as with the engine cranking with all plugs and trottle open, filling efficiency shouldn't come into it so you should be starting from 1 bar of pressure (0 gauge reading), and raising it a # of x that's equal to the compression ration, minus a little leakage. Thus I was happy with 7 bar on my M110. Very strange to see readings of 11-12 bar coming in on an M110. Maybe # 2 is the only cylinder that's right! Or maybe I'm not thinking straight.

5- If it comes to such things, the only really effective fuel system additive is BG44K. Use as directed.

-Dave G.

EuroTruck - 2/15/2010 3:08 PM

Patrick,

 

Love the key chain..............you have a sense of humor to go along with the fine tools.

 

We've used seafoam extensively around here to stabilize old gas in trucks that have been stored for months.  Every time a truck rolls in from Europe, we add seafoam to the tank and it insures that things run smoothly.

I've never used it for your intended purpose, but I have poured Marvel Mystery Oil into the cylinders of engines that have been sitting for years before I turn them over by hand.  It's said the the MMO loosens the rings and helps with cleaning up the cylinder walls.

 

-SP

chris505 - 2/15/2010 2:46 PM



Carbon buildup on ring landings can be from bad/unburnt fuel, or burning/breathing too much oil, or running too cool/never reaching operating temp, or my favorite, never revving past 3000RPM (some people are afraid to do this, little do they know its the worst thing that can be done to these engines)

Never used Seafoamf, so I cant say, but all the old MBZ mechanics that mentored me hated that kind of stuff with zeal, but these guys were of the oooold school, to them the w126 was "too damn complicated", they had a couple cheap trade-in 300SLs as shop cars to play with, way back. The only additive I can recommend is Lubro Moly diesel purge.

I would next double check you compression after driving for a bit, also inspect cap/rotor, check plug wire resistance, remove the valve cover and look for any tight valves, see if any of the cam lobes have wear marks all the way around, an improperly seated valve can give wacky compression readings.

460332 - 2/15/2010 7:29 PM

That is a very, very dirty engine, but this is a clean write-up as you don't mix the Hazet tools with Stahlwille or Snap-On, as you confused us with in earlier write-ups!

G-AMG - 2/16/2010 3:38 AM

Well folks... There is nothing like the "experience" from the G-Gurus.....

Thanks a zillion Chris505!!!!

I took your advice and "drove the crap" out of the truck (dohhh! am I allowed to say 'crap'?)... Cruising along at "near redline" during an unusually "Spirited" drive.. I came back and repeated the Compression Check..

READ' EM AND WEEP!!

Attached are the results...

So, the Chris505 theory proved correct...

Just as quickly as the "Rough Idle" appeared??? Now GONE!!!

I am sooooo stoked!! Thanks to all!!