Dead cylinder on '84 190E 2.3 - PeachParts Mercedes-Benz Forum

bigbrownbenz · #1 09-23-2006, 01:22 AM

So, about two weeks ago while flying down the highway to work (about 75mph), I felt an abrupt power loss (about 20-30%, i'd say, not a total loss) and the engine started running like a lawnmower. Opened up the hood and discovered (by pulling the plug wires) that cylinder #2 was not firing.

After a new distributor cap, plugs, and wires, still same symptoms. (Damn!) Ran a compression test to find out that cyl2 was only pushing about 10 lbs of pressure.

My mechanic (who is very honest and reliable, but not a MB specialist) tells me that the engine will need to be rebuilt/replaced. Anyone have similar problems with '84 2.3 engine? (Minding that the '84 engine was unique from the '85 and above).

john affleck · #2 09-23-2006, 01:57 AM

It doesn't matter what kind of engine it is; you need to perfect the diagnosis. Take the valve cover off and take a close look at the valves and springs; although itis very un-likely you'll find anything you can fix without pulling the head. If so, pull the head and look for problems; take out the valves and do a valve job; if one of the #valves is grossly damaged; and you can't find any bad marks in the cylinder, hone the cylinders by hand and put the head back on. If it wasn't the valves; take the engine out and overhaul it. I suppose it's possible to be the head-gasket; but that will reveal itself also. So you may not need to overhaul the whole engine; but some exploratory surgery is required. cheers jack.

bigbrownbenz · #3 09-23-2006, 02:02 AM

thanks. i was tossing around the idea of looking under the valve cover. I am not by any means an experienced mechanic, just know what i know from reading and experience on my own cars. if it ends up needing a full-fledged overhaul, then i'm just gonna say screw it and get an early C-Class like I've been wanting to.

Speaking of which, anybody have any tips on common trouble spots for the early C-Class ('94-'97ish)?

t walgamuth · #4 09-23-2006, 06:14 AM

from your description it sounds like a valve issue. but as noted it also could have broken a ring (unlikely), eaten a hole in a piston, unlikely, or blown a head gasket, more likely. i dont think i have ever heard of a sudden loss of compression except as a valve loss. but the hole in the piston seems possible too. if it were a hole in the piston when the car is running there would be a whole lot of violent blow by coming out the oil filler cap. it might even blow out the dipstick. a holed valve would make a lot of noise in the intake if an intake valve and in the exhaust if an ex valve.

in any case probably not an easy fix.

the only fix possible that wouldnt be too bad is if it were a stuck valve or a broken valve spring.

tom w

bpaz_ph · #5 09-23-2006, 09:08 AM

This happened to my wife on her way to work. It turned out to be a burnt exhaust valve. Cause was excessive oil burning.

david s poole · #6 09-23-2006, 12:28 PM

you may find that one or two of the rocker assembly bolts have pulled the threads in the head so very little opening of valves on #2.each cylinder has one assembly with four bolts.so you can lose just one and have the others okay.these are steel bolts into aluminum threads.[never a case of if only when] you will have three choices[1]find some bolts that are 10-15mm longer as there are extra threads in the hole[2]remove the assembly and helicoil the holes[3]go buy the c class.

bigbrownbenz · #7 09-26-2006, 12:33 AM

thanks for the insights, folks. i will definitely have something to look for when i perform my "exploratory surgery." Like I said, no funny noises, no excessive oil loss, just a John-Deere Mercedes.

I'll keep things updated.