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  #1  
Old 04-19-2000, 02:54 PM
chupr98's Avatar
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I recently had the cylinder head of my 103 engine rebuilt. At that time I felt the bore and decided there wasn't enough wear to do the bottom half. After I put the head back and noticed the spark plugs are little sprayed with oil still. My mechanic suggested the oil rings could have been carboned up. My question is what is the best way to clean the oil rings without tearing down the engine? Additive? High detergent diesel motor oil?

Thanks
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  #2  
Old 04-19-2000, 03:26 PM
LarryBible
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chupr98,

If you're engine was to a point of low compression due to valve problems, you increased it's compression by doing the valve job. This in turn increased the cylinder pressure, which very well may be the cause of extra blow by past the piston rings. I hate to be negative, but I doubt that you're dealing with stuck rings.

However, there is something that wouldn't hurt to try if you do it properly. I am going to give the warning before and after the explanation. The warning is, DON'T CRANK AN ENGINE WITH LIQUID IN THE CYLINDERS, LIQUID DOES NOT COMPRESS.

What I saw done successfully years ago, was; take out the spark plugs and squirt Marvel Mystery oil in all the cylinders. Let the car sit overnight with this soaking on the top of the pistons. Before replacing the spark plugs the next morning, turn the engine over several rounds with the starter to blow out the liquid. DON'T TURN THE ENGINE OVER WITH LIQUID IN THE CYLINDERS, LIQUID DOES NOT COMPRESS.

After making the mess blowing the liquid everywhere in the engine compartment, replace the spark plugs, start the engine and warm it up.

This is something that we did successfully years ago, before catalytic converters, fuel injection and oxygen sensors. I would wait to read comments from others before trying this. It could be that Marvel Mystery Oil may not be healthy for one of these components. Or it could be that there is a better solvent for this purpose that will not be unhealthy for your engines modern components.

Even if the Marvel Mystery Oil passes approval of the pro tech's, don't put too much hope in this curing your problem.

Also, plan on changing oil after this operation.

Good luck,

------------------
Larry Bible
'84 Euro 240D, 516K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in
Mercedes automobiles

[This message has been edited by LarryBible (edited 04-19-2000).]
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  #3  
Old 04-19-2000, 06:03 PM
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Now that the head is back on, do a compression leakdown test. If you have significant leakdown, the rings will have to be done. I don't know how the plugs can be "sprayed" with oil. What do you mean exactly? The top compression rings if good should prevent major oil from getting into the cylinders. Oil control rings are designed to trap oil from below and inside the pistons and provide lube to the cylinderwall/piston interface. Are you confident that the work on the head was done by the book. What parts were replaced, i.e. seals, valve guides, etc. what was the mileage and why the rebuild??

------------------
Jeff L
1987 300e
1989 300e
1987 BMW 325
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  #4  
Old 04-19-2000, 06:31 PM
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We have had good luck freeing stuck oil rings using GM's (AC Delco) product X-66p. This is a pop-top can. For real effect we have poured some into the cylinders (through the spark plug hole) and hand cranked the motor through a couple revolutions. This is some nasty stuff don't breath it or get it on your hands. Also don't leave it over a few hours sitting on aluminum.

We usually let it sit for a half hour after cranking by hand. Spin it once by the starter with the ignition disabled to be sure there isn't enough in the cylinder to cause damage (place rags over the holes to keep the stuff out of the air). Do all this cranking with the spark plugs out. Also it should be done to as hot a motor as you can stand working on.

After this we suck the rest of the can through a plenum port (center of intake)into a running motor allowing enough to pass that the idle is affected. After using up the can stop the motor and let it sit for twenty minutes then start it back up in a well ventilated area, where you won't alarm anyone. When you start it back up all that carbon is going to burn and make the area look like a brush fire.

The instructions for everything but the first hand flushing are on the can.


------------------
Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician
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  #5  
Old 04-19-2000, 06:43 PM
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Hi JEFFSR, thanks for the reply, the head was off because I was getting a very low compression in cylinder 2, also all spark plugs were sprayed with oil(ceramic were not white hot but with some oil spots). New valve guides, seals, 3 angle valve job, head bolts were installed and resurfacing of the the head. Compression is a lot better now (150 psi +/- 5 psi) but oil is still present on the ceremic
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Old 04-19-2000, 07:34 PM
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Well, you could go with what Steve suggests. He probably has better knowledge and experience than I. But...The compression still seems on the low side for a recently done head. What is the mileage on the engine? Do you see any smoke from the exhaust at any time. Do the plug electrodes actually get fouled or is the insulator just getting spotted? Sometimes you will see weird types of plug fouling due to use of certain type of gasoline . How is the car accelerating? Do you see any evidence of blowby in the air cleaner housing? When you looked at the cylinder walls, were any of them scored, was there much of a ridge at the top of the cylinder?? BTW, when you checked the compression, did the tech assess the leakdown rate??

------------------
Jeff L
1987 300e
1989 300e
1987 BMW 325

[This message has been edited by jeffsr (edited 04-19-2000).]
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  #7  
Old 04-19-2000, 09:55 PM
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Hi Steve, thanks for your help, do you know the GM cleaner is O-2 sensor friendly? BTW Jeff mentioned the compression seems a little bit low, do you know what is the compression for a totally rebuilt 103 engine?
(with the rings done as well as the head job)

Thanks
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  #8  
Old 04-19-2000, 11:21 PM
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As I recall, when I did the head on mine, I checked the compression after it was done and I was getting between 168-172 PSI. But, this was after shaving 12 thousandths off the head to level it out. I think that factory should be around 160-165 PSI. My engine had 165k on it when the head gasket blew. As Donnie reassured me, the bottom of the 103 engine is pretty sturdy. Guess so..

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Jeff L
1987 300e
1989 300e
1987 BMW 325
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  #9  
Old 04-19-2000, 11:41 PM
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Yes the GM X66p is desined to decarbon modern engines with multiple exhaust O2 sensors.

I wouldn't worry about your compression if they are all the same. There is so much difference from gauge to gauge and technique to technique that numbers aren't really the issue. BTW I had an instructor tell me once that the relative pressure should be the compression ratio times the atmosheric pressure in psi.

Besides if you have a ring problem causing your consumption problem it won't show on a compression test as that checks the compression rings not the oil ring.

If you have equal affects on each cylinder I would condemn the valve guide oil seals even if new. It is the weakness of these motors. I have also seen techs place the seals on the wrong valve thinking they are the same. I also only would use factory valve guide oil seals.

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Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician
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  #10  
Old 04-20-2000, 08:31 AM
LarryBible
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I knew that thirty years of chemical technology that included walking on the moon would produce a better solvent for removing the carbon than Marvel Mystery Oil.

But thirty years ago, it worked good. The x66P sounds like some of that technology.

Thanks for the info. Steve.

------------------
Larry Bible
'84 Euro 240D, 516K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in
Mercedes automobiles
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  #11  
Old 04-22-2000, 08:54 PM
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Hi everybody who helped out, for my own curiousity, I test drove a 300E (103 engine)with very low mileage(38000 km) yesterday. I did felt some power difference, may be that where the lower compression (150 +/- 5 psi) comes into play. May be oil is fouling the plugs as well. I guess there is no quick fix short of tearing down the engine if I want 177 HP back, Right
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  #12  
Old 04-22-2000, 08:57 PM
LarryBible
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chupr98,

Are you not going to try the procedure that Steve Brotherton outlined above? It sounds like it would be worth a try.

Good luck,


------------------
Larry Bible
'84 Euro 240D, 516K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in
Mercedes automobiles
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  #13  
Old 04-22-2000, 09:07 PM
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I'll repeat my previous questions:What is the mileage on the engine? Do you see any smoke from the exhaust at any time. Do the plug electrodes actually get fouled or is the insulator just getting spotted? Sometimes you will see weird types of plug fouling due to use of certain type of gasoline . How is the car accelerating? Do you see any evidence of blowby in the air cleaner housing? When you looked at the cylinder walls, were any of them scored, was there much of a ridge at the top of the cylinder?? BTW, when you checked the compression, did the tech assess the leakdown rate?? Also, which W124 do you have and what year is it? If you are really convinced that the oil control rings are your problem, then try what Steve suggested. We'll try and get some of your horses back. How's the fuel economy also?? I've got the time if you've got the patience to wade thru this inquisition.


------------------
Jeff L
1987 300e
1989 300e
1987 BMW 325
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  #14  
Old 04-23-2000, 05:04 PM
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Hi jeffsr, thanks again for all the sincere help you guys are providing, there has been more fun communciating with you guys than I had with those local so called Mercedes experts around here. BTW, the car is a 86 300E with 140,000 km,it doesn't blow any blue smoke, very little blowby in the air cleaner( don't know whether it is from before the head job or not). When I had the head off, there wasn't that much of a ridge on top of the cylinder wall, that's why we didn't do the bottom at that time. No scoring on the cylinder wall according to the engine builder. Since I live in the Vancouver area, 90% of the driving is stop and go, I can feel a little bit of slight misfired in front of a red light . The sympton goes away if I go on the freeway for a little while. The spark plug's electrode are not white hot like most other car's, it has a little brown spots on them but not oil soaked. It accelerates OK, not as good as the one I test drove with 38,000 km the other day, gets stronger when it gets up speed of 30-40 mph. Gas mileage is around 18 mph, I think it is acceptable since I don't have another 103 engine to compare with. I don't expect miracle for a 140,000 km engine to perform like a 38,000 km. I will settle for a smoother idle in stop and go situation. I think my main objective now is to fix the misfired problem (oil getting on the spark plugs). The lower compression (150 psi +/- 5 psi) are lost forever due to combination of ring and wall wear. Again thanks for all the help.
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Old 04-23-2000, 05:14 PM
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I think you're dealing with an ignition problem. Have you ever replaced the wires, rotor and distributor cap? If not, those parts are now old enough to warrant replacement. If there is no oil fouling on the plugs, then it's not likely that rings are the main problem. You might consider getting the engine 'scoped by a tech who knows what he's doing. But, if the ignition parts mentioned are original, I'd get some new stuff and see if that helps. It sure won't hurt..

------------------
Jeff L
1987 300e
1989 300e
1987 BMW 325

[This message has been edited by jeffsr (edited 04-23-2000).]
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