Hi guys,

Although this is my first time on this site I might have an issue here that might even make the most seasoned Benz veterans here scratch their heads. I bought a 1993 2.3 L, 4 cylinder, 190e a few months back. It has 94k miles on the original motor. Since I owned it, it had an issue with starting when warm. Cold start is really fast generally. Yet the car drives really well once you get it started. Did a complete tune up, changed Oxygen sensor. Then I decided to do a compression test and a leak down test and surprisingly got these results:

1st cyl - 105 lbs; 25 % leak
2nd cyl - 80 lbs; 85 % leak
3rd cyl - 75 lbs; 85% leak
4th cyl - 50 lbs; 85% leak

How could this be possible, given the car runs so well? Some history on the car: owned by an old couple; always dealer-maintained, no major service done to it. It was stored in a barn for about 5 years, by their son, since they passed away. Any way there are just some stuck valves/rings that some good old additives can fix?! Or am I just being delusional here. Could this engine just crap out this soon (94k)?

Any thoughts would sure be appreciated.

S

 

As posted and answered on another forum, the problem is your rings are stuck. There were likely no precautions taken when storing the car and either the crud or carbon stuck them.

In order to try to free them, remove the plugs, put a good healthy dose of a solvent in each cylinder, maybe half cup, and let sit at least over night.
diesel fuil or Marvel Mystery Oil are two possibilities. Cover the engine to contain the fluid when you crank the engine over without the plugs. Replace plugs, drain oil and replace with a high detergent synthetic and run it a while, and hope. If that doesn't free the rings, the only recourse is replacing them.

 

Ok. Just to be clear, would I completely drain the oil two times (i.e. before putting in the solvent, and then after letting the solvent sit). In other words, before I put the Mystery oil/diesel fuel into the cylinders, would I make sure all the oil is out first? Also, what is the best way to cover the engine so none of the fluid comes out. And do you prefer Mystery Oil over Diesel fuel, or the reverse?

Someone also recommended that I drain a quart of oil out, and replace it with a quart of Mystery Oil...then run it for a while. I was also thinking of putting Fuel Injector/Carb cleaner in the gas. Does all of this sound promising?

Thanks,

S

 

I wouldn't drain whatever is in the crankcase at all until I was through with the effort to free the rings. I would add about a quart of whatever solvent you elect to use to what I have in there. After all, the only reason you're adding anything to the crankcase oil is because of the slight benefit you might get from the mixture splashing onto the bottom of the cylinder and through the small weep holes in the pistons. Not much is going to get to the rings to help the loosening process so I personally feel there isn't much of a short term benefit to anything in the crankcase oil. When you're done with your effort you'll want to drain the oil anyway, then replace it with a high detergent synthetic in the hope that over a few hundred miles the little bit that gets to your pistons and rings will aid the effort to loosen the stuck rings. I'd use diesel fuel in the crankcase initially.

The only time I tried something like this I used Kroil in the cylinder head. Kroil is a penetrating oil and industrial solvent. Others recommended Marvel Mystery Oil which I've never used for anything; I was just going with the flow in that suggestion. Kroil I've used for many things and it's quite good as a solvent for carbon in cleaning gunpowder residue out of gun barrels. It's also a penetrant. It has a pretty high concentration of Naptha and works very well to loosen rusted bolts, and that would be my choice to place in the cylinders. I'd put about half cup in each cylinder, plug up the spark plug holes to prevent evaporation, (I'd use the spark plugs, about one turn in,) and let it sit overnight at least, maybe longer if you can wait. I'd add a bit more in the morning and let it sit some more.

When I'm ready to check the effort, pull out the plugs, cover each hole with a towel, blanket, or anything to prevent what's in there from blowing all over the place when you crank the engine over. Crank the engine over for about 30 seconds, or until all the corruption is blown out of there, replace the plugs, fire it up with the oil and diesel still in the crankcase and let it idle, watching the oil pressure and temperature. Let it idle for 15-20 minutes watching both temp and oil pressure. Stop it, drain the old oil and replace with the good synthetic. Remember the filter! Then drive a few hundred miles and check your compression.

After maybe the first 50 miles maybe pull the plugs, put two or three squirts of whatever solvent you elect to use, replace the plugs and run it after letting it sit 15 minutes or so. Can't hurt and it may help.

If the rings are stuck, as I believe they are, they aren't exerting any pressure against the cylinder walls. Getting whatever it is that's holding them out of the very tight groves, is a major problem. As I told you in the other forum, it may still require an engine teardown with removal of the pistons, cleaning of the ring grooves and replacement of the rings, but this effort is worth it on the 30% chance it will work.

 

The thing is, I actually just changed the oil a couple weeks back, so it is full. I dont think I can add a quart of solvent to the oil tank without draining a bit out first. Am I correct?

In that case, should I drain a quart of motor oil out first?

Another question, which might be a stupid one: when I put the diesel in the spark plug holes, where will it end up?

The car is now being stored at a friends a really long ways away (after the tow) and I dont have the opportunity to be there for more than 4 or 5 hours tomorrow, and dont know the next time I can get back there. Just thinking if I could put the diesel in the sparkplug holes for a few hours, then put Mystery oil/diesel in the crankcase (after draining out a quart), then try her out and see what happens. Could this work? Also, are you saying that for the valves to get set free, more attention should be paid to the spark plug holes than the oil-crankcase, at least on the short-time end? Thanks.