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  #1  
Old 08-09-2003, 07:39 PM
Rebe
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Angry oil consumption

I have a 1987 MB 190E with 56,000 miles on it. It consumes a large amount of oil. The motor doesn't leak a drop of oil, and I replaced the valve stem seals about a month ago. I took it on a 220 mile trip a week ago and it consumed about 1 quart of oil. It doesn't smoke and the compression tests 125 lbs. per cylinder. The motor is very quiet. I have been told it's the valve guides, but other people told me you can't pour that amount of oil down the guides in that many miles. Is there a way to tell definitely what the problem is? I have had some places tell me that they had real low tension oil rings in them and if the oil wasn't changed methodically they got stuck and that was the problem. I would appreciate any help you might be able to give me to solve the oil loss.
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Old 08-09-2003, 08:02 PM
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Use the SEARCH facility. This issue has been discussed hundreds of times.
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Old 08-10-2003, 12:35 AM
Rebe
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I searched the the previous data. I am still confused as to the reason the MB engines are so sorry and are oil burners. I can't believe engines with such low milage can consume that kind of oil. I read about head work, that was supposed to stop the oil but didn't. My main concern is if the valve guides won't stop the oil problem with the age of the car I wouldn't fix it if I knew ahead of time to a certain degree of accuracy what the exact cause was. Just to install valve guides they are talking 2g+ and to rebuild the engine 5g+. I have sometimes wondered if there can be another problem like the pvc system. My like one other on the database is very inconsistent on the oil consumption at times which is not normal with other engines I have had experience with. If you could possible help on this issue I would appreciate it. Also, is the leak down test a more accurate tell-tale than the compression test.
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Old 08-10-2003, 12:50 AM
Bud
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These engines are not oil burners. I just returned from a 4K trip and used slightly more than one quart of oil.

Between 1986 and 1990 these engines may experience excessive valve guide to valve stem clearance. Once the problem is resolved, there should be no more problems with oil usage.
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Old 08-10-2003, 04:01 AM
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If the head was done right, it shouldn't burn oil. The 87 190e has 217k miles, it does not use a quart in 4k miles.

What weight oil are you using?

Haasman
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Old 08-10-2003, 12:11 PM
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I appreciate the replies. I still have a couple of questions. If I just recently replaced the valve stem seal shouldn't I have noticed some oil consumption reduction. I always thought the oil has to get by the seals too! I have been using 20W-50 oil in the engine. I had used 10W-40 before. It doesn't make a nickels worth of difference as to the oil consumption whether the weight is lighter or not. If I tear it down and replace the guides is there a remanufacture on the guides or do you still have to use the original ones. If I have to use the original ones will the problem be back soon again? I talked to a guy the other day that had a mercedes 190E with 140K miles on it and it didn't use any oil so he tells me. I fail to understand why some will go so long without problems, but the majority of the others won't. Did Mercedes ever address this problem? I was told Mercedes don't acknowledge a problem unless the consumption is under 800K...per a Mercedes spokesperson!
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Old 08-10-2003, 12:54 PM
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I don't have the compression spec for your engine, but 125 psi sounds low. Absolute numbers are usually not as important as consistency. Was the throttle blocked open while the compression was tested?

When the valve spring is removed, you always wiggle the valve stems, and a good mechanic knows if the guides are worn excessively, but even if the guides are worn, new seals should definitely reduce the oil consumption.

At 56K miles there will be some wear, but it should not be excessive and the engine should not be consuming that much oil especially if the seals were replaced. The early seals were also more subject to deterioration. About mid-'88 viton seals were substituted and are more long lived, and these seals should be the current service replacements.

Inadequate oil change intervals could cause deposit buildup in the ring grooves and sticky rings, and the cam box would also be quite dirty. What did it look like?

Was the mechanic who did the work really qualified and, based on what you reported I would have to question if the seals were even changed. Worn guides and seals can generate that much oil consumption. A new set of guides and seals on my Cosworth Vega last year reduced oil consumption from a quart every 200 miles to a quart every 4-5000. All the guides had excessive wear and the seals were competely shot.

Duke
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Old 08-10-2003, 02:56 PM
Rebe
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Thanks for the reply Duke. Actually I was the one to replace the valve stem seals. I noticed that the old ones didn't look bad at all not cracked chipped or anything. I did make one mistale though. I didn't wiggle the valve stems in the guides to see if there was excessive movement. The new stem seals fit very tighly over the valves too. One thing I did notice is after running the engine if you shut if off, and open the breather cap there is white smoke that comes out the filler hole in the valve cover. Is this a good indication the engine has blow-by? Inside of the valve cover when I removed it the valleys and chain and all looked good and clean no slucge build up or anything. I am in the process of getting a leak down tester. They are quite expensive, and I am not sure if it will definitely tell me if the rings are stuck or shot or the guides are defective. If I hear air at the tail pipe and in the crankcase or other places as well. The inconsistency of oil consumption like some other users referred to ,also, is puzzling to me. One thing that has me held back from jumping head first into the engine is the age of the vehicle and the cost factor. A five to 6G repair bill doesn't fit the vehicle anymore. Thanks for your help.
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  #9  
Old 08-10-2003, 06:18 PM
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Yes, visible vapor when you remove the oil cap could be an indication of excess blowby. One thing you should check is the function and configuration of your PCV system. If the cam box is clean I wouldn't expect sticky rings, but you could try a high detergent oil supplement designed to free sticky rings or lifters. Also, API CI-4 HD diesel engine oil has a higher dose of detergent additives and may free sticky rings. These are low cost things to try before you make the commitment to pull the head or sell it.

A leakdown tester should not be that expensive assuming you already have a compressor, and you might be able to rent one at an auto parts store or tool rental place.

My original plan on the CV was to just replace the valve seals, but when I got the cam carrier off and was able to wiggle the valve stems, I knew the head had to come off. The worst valve guide had about .030" clearance based on stem and guide measurements. The best was about .010". The valve stems were only very slightly worn, but the guides were WAAAAY worn. It only has 70K miles, but lots of high rev time since about 4000 miles of the total is race track hot lapping, and for some unknown reason the guides on these engines have a reputation for rapid wear even though the layout of the direct acting DOHC valve train doesn't place any side load on the guides. - certainly less than the rocker arms used on the 102 and 103 engines. Some things in life are just a mystery.

Duke
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