190e 2.6L Pictures of my pistons and cylinderhead before a valve job.(links)
 

The car is a 93 190e 2.6L. I pulled the head off for a valve job and fix my oil consumption problem. Cylinder # 3 has fouled the spark plug almost every 500 miles with a lot of carbon oily build up. I will have more pictures after the head is back on the car this weekend.
http://www.msnusers.com/MB1993Engine...hoto&PhotoID=6http://www.msnusers.com/MB1993Engine...hoto&PhotoID=3 http://www.msnusers.com/MB1993Engine...hoto&PhotoID=2 http://www.msnusers.com/MB1993Engine...oto&PhotoID=10 http://www.msnusers.com/MB1993Engine...oto&PhotoID=11 http://www.msnusers.com/MB1993Engine...hoto&PhotoID=7 http://www.msnusers.com/MB1993Engine...hoto&PhotoID=4

Please comment..
 

What do you guys think happened in cylinder #3. Look at the valve too.
Meza

I have managed to add links as the pictures did not load. please take a look and email me with any questions/comments.

All I get is a "sorry can't find that page" message.

Just looks like burning oil to me. Check for valve giude wear and the valve stem oil seals.

Like Neil said - Just a head rebuild should resolve all that. Try to clean the tops of the pistons before putting everything back together if you can.

Most recent pics show REALLY clean pistons, cylinder walls, and resurfaced block! :D

What kind of oil and fuel did you run in that engine Meza? This is not to start another oil thread, just to satisfy my curiousity....

HOW DID YOU CLEAN THE PISTONS???? THEY LOOK GREAT!!!

I REALLY hope you did NOT use a scotch brite wheel or other gasket removing wheel on a drill to do all this cleaning! The grit from that operation will wear out the motor so fast that you'll be taking it apart again before fall!

Did you do a leak down or compression test before disassembly? If you did, then you know if the problem was ring or valve related. I fully expect that this much oil in the chamber has to come from the piston/cylinder, not the valve guides on that hole.

Unless you KNOW that the problem was valve guide related, you really should pull the piston from that hole, and if you can feel a ridge, carefully remove the ridge with a ridge reamer before pushing out the piston.

If you DID clean everything with a gasket cleaning wheel, you will have to figure a way to thoroughly flush the grit, preferably before starting the engine, and I don't mean simply relying on an oil drain.

Best of luck,

The cylinderhead was picked up from the machine shop today. I will have pictures as soon as I take them. The shop said that cylinder# 3 valve guides were fine and all the seal are still holding fine. His statement worried me. I did not do a leak down test or a compression test before disassembly which is a mistake. I am thinking about doing a leak down test after I put the head (Is that possible without causing any damage?)If it is the piston on cylinder #3, I will need some help on what to do or may just endup selling the car. I have pulled several BMW cylinderheads and never seen this condition. The car builds up pressure quick when I take off and the engine was smooth before disassembly. The top of the block was carfully cleaned with a blade followed by a scotch brite on a rotating wheel. However, the wheel was dipped in oil and each piston was set at TDC. I used electric contact cleaner spraying around the ring area then suck it with a shop vacuum and whipe it with a shop towel. When the piston is lowered, I can see a ring of dirt. I wipe again and again. This is how I got them polished. Any comments would be welcome and appreciated. I will have more updates as soon as more work is done.
Question: How hard is it to only remove piston #3 to put new rings and do I have to do the whole block?

The cleaning job you have done surely looks good, but I would not even try to start this engine if it was mine. Even if everything looks nice and shinny, there are all kind of residus on the lower part of the cylinder wall , side of pistons, rings and oil pan. You have also introduced a lot of debrits in the oil and water passages.
At this point, you have 2 solutions:
1) take the engine out, dismentle, clean or replace worn parts.
2) re-assemble everything without doing further work on it and sell the car to a non-friend.
JackD

JackD,
I got two cans of electric part cleaners and sprayed well the area around the piston rings and it was pretty clean using a shop vacuum at the same time. I re-oil the cylinder wall and lower it slowly, wipe and clean again. I even attached a straw to the tip of my shop vacuum nozzle and went around that area several times. I did this over and over and it is pretty clean. I taped all the water and oil holes before I did the cleaning. Also, don't you think all that carbon on top of the cylinder is abrasive? I work in the diesel fuel industry (test engineer) and I test diesel fuel injectors with abraisive material like Aluminum oxide (Alumina), lapping compound, and Arizona dust. I know what kind of damage they could do. Carbon is a solid and it is an abraisive too. I have done this job on BMW engines 3 times and haven't had any problems. I hope I am right and everything will be ok.

Cylinder bore condition
 

I have looked at my cylinder bore and I can clearly see the cross-hatch pattern equally on all cylinders. I raised every piston to TDC and applied a side load with my hand in different directions to see if the piston would move even slightly, however, I couldn't detect any movement. By the way, the car has 204K miles.

Type of oil used
 

In an answer to JetForeman question, I have used Castrol GTX and Mobil 1 10W30, 10W40, and 20W50 depending on the season. I got the car with 136 miles and now it has 204 miles. It had this oil consumption problem since I got it. It increased from 1quart/1000 miles to about 1quart/400 miles. Cylinder # 3 used to foul the spark plug every like 3-4 miles. I still have all the spark plugs that I pulled out and will take pictures of all and post. The electrode in one of them was bent possibly due to a worn valve guide.

Meza,

I had a similiar problem with a ford. I placed alternately each piston in the middle of its stroke and pored a fixed amount of atf in each cylinder. The liquid and the volume is unimportant. Measure the amount of time it takes for each cylinder to empty. A piston ring failure will be immediately noticeable.


Good Luck,

RandyR

The cylinderhead has all new valve guides, new seals, and new springs. A three angle valve job was done too. I hope that would take care of the problem and everything will be ok. Also, other parts that I will replace:
New timing and oil chain
New oil pump (while I am there)
all new chain guide rails (timing and pump)
New hoses
New idler pulley
new transmission cooling lines
new pan gasket
Transmission filter kit

Great Idea RandyR. I may just do that tomorrow after I get back from work.
Meza

My valve stem seals are reversed
 

I took a closer look at the cylinderhead after my wife picked it up and found that the black seals were put on the exhaust side and the yellow ones on the intake. I told the machine shop not to mix them and gave him the MB manual in case he need to look up anything and still did it wrong!!!!!!! It's going back first thing in the morning and must have it back the same day. He had it for two weeks. I guess I'll have to be late for work!

Okay Meza, you have come this far, don't put the head back on until you have fixed the bottom end problem.

I have never done it, but my Haynes manual says that you can block up the engine by loosening the motor mounts and raising the block. By doing this, you are supposed to be able to get the pan off without pulling the engine.

Remove the pan, disconnect the rods and keep the caps in proper orientation with each rod. If the bearings look good, just reuse them but in their EXACT original position and well oiled upon reassembly. Push out the pistons and clean off the scotchbrite residue from EVERYTHING. Replace the rings after thoroughly cleaning the pistons(not with scotchbrite please,) use a ring compressor and put the piston back into place.

Since you are seeing crosshatch everywhere, you should not have to mic the cylinders.

Putting the head back on to do a compression test is the WRONG approach. If you find a bad ring on 3, you will just have to pull it back off.

Again, you've come this far, now finish it up and you will be happy with the car, rather than starting over with another.

Good luck,

even if you have cleaned the visible part of the cylinder wall, there is still a faily long portion of the cylinder wall you can't reach., below the piston tops. Part of your scotchbright is now sitting on the piston rings.
Since you intent to replace the pan gasket, I would strongly suggest you take thoe pistons out and clean, clean, clean.
If you intent keeping the car, this extra effort will prevent you from doing this job again in a few months.
But it's your car.......
JackD

just for future reference....What is the correct way to clean the pistons?

The correct way to clean the piston tops is by scraping off the carbon. Don't do this with anything like a chisel or screwdriver that has sharp corners. In fact a piece of hardwood would be better to ensure that you do not scratch any grooves into the piston tops. Any scratch or gouge will provide a place for a crack to begin.

Once the pistons are out, since the tops are already cleaned, just clean them well in solvent, and then break an old ring and use it as a scraper to carefully scrape the carbon out of the ring grooves before installing your new rings.

Goetz makes good replacement piston rings.

Good luck,

When you're done replacing the piston rings and all is buttoned-up you may want to know how to properly break the engine in.

Below is a link which, for the most part, describes a method commonly accepted amongst the rebuild crowd. Credit due to members at the PP BBS for the link....

http://www.mototuneusa.com/break_in_secrets.htm

Best of luck!

Here's a pic with explanation......



"These Honda F3 pistons show the difference.

Both came out of race bikes, and their owners used the same type of fuel and oil. The only difference was the break in method they used...

The one on the right was broken in as per MotoMan's instructions.

The one on the left was broken in exactly according to the owner's manual. The resulting leaky rings have allowed pressure to "blow by" down into the crankcase on acceleration, and oil to "suck-up" into the combustion chamber on deceleration.
Needless to say, this bike was slow !!

It's up to you:
The loss in power from an easy break in and the resulting poor ring seal can be anywhere from 2% - 10% !!"

hmm... Im kinda skeptical to that theory. Isn't that comparing apples to oranges???

Always perform a compression test on each cylinder before digging into an engine with only a high oil consumption problem. Many shops just recommend doing a head job because thats how they'll make money when in fact 190Es are known to get a big improvement from just replacing the valve stem seals (check out MBs TSBs on 190Es high oil consumption). I worked on a friends 2.6l 190E car with same oil burning, spark plug fowling problem as yours. I replaced all his valve stem seals with the head in the car. It was a 1/2 day job and now, more than 8,000 miles later the oil burn and plug fowling has gone a way. The carbon in the combustion port will eventually burn away. The valve stem seals are very2 cheap.

Don't be surprised if the old valve stem seals look perfect. All of the ones i replaced were intact and only a bit stiffer from heat/age. But in the end it made all the difference with new ones. If your shop screwed up the installation then they probably didn't bother using the insertion tool (actually just a dinky plastic sleeve) that come with the new valve stem seal kit. The insertion tool prevent the valve stem from damaging the seals as they slide on. For the piddly cost you should have them put in a new set of seals and make sure they lubricate the insertion tool with motor oil.

Sorry guys but I will not remove the pistons. I just don't think the way I cleaned the pistons will cause all what was described. Even the wheel I used was not new from the box. it was more than half way worn out. If you all see the pictures, one of them (Piston #1) was clean and the other 5 still need cleaning. Well, it was cleaned by hand using a worn out non abraisive scotch brite on a sponge from my kitchen sink. I did that with all of them and then used the air drill to polish the top and I was careful. For the past 80K miles (since I bought it ) and the oil consumption problem was there. I have kept the oil level right because I checked it almost everyday. If I do have a problem with my bottom end, then I will overhaul the whole bottom end and not just put rings or sell the car. I just don't have time to do all that work decribed. It sounds easy, but it's time consuming and I don't have all that time not to mention my 1 car garage that I can't even move in it.

I'd not recommend much cleaning of piston tops for the very reason indicated -- abrasive residue in the rings. Just scraping the bulk of it off with a scrap of wood is fine -- the rest will burn off fast enough when you get the head on.

You will find out if there is any in there soon enough, I suppose.

If you've not overheated it and it has visible crosshatching, the rings are fine. If it has been overheated, the spring in the oil control rings can anneal, preventing the scrapers from removing the oil from the cylinder wall, so it will "pump" up into the combustion chamber.

There won't be any excess blowby in this case, as the compression rings are fine.

However, I suspect all the cylinders would be affected, not just one, and the amount of oil that can dribble down past worn-out guides is astonishing -- the head on my brother's 300D was actually dripping oil when we took it off. Quite enough to produce the fouling you saw.

The diagnosis here is that new seals only fix the oil consumption problem for a few months.

Best of luck -- it's a nice car when it runs, and I'm sure you will appreciate not having to fill the crankcase every other day!

Peter

Psfred,
I like your comments and I hope everything will be fine. I am almost sure my seals were the problem and the condition you saw is no surprise when it has been leaking for 100K miles getting worse day after day. Time will prove who's right or wrong!

I forgot to mention that although I did not do a compression test, I did attach a vacuum gage a few months ago and the needle read in the green zone (As far as I remember, it was 15-16 psi).

I wish you the best of luck. The scotchbrite really leaves a lot of grit. I think that if you don't change oil and filter really frequently for the first few miles, you're going to be sorry. Even then you may have a serious price to pay.

Good luck,

Thanks Larry
 

I alraedy have three new filter and two cases of oil and will change the oil three times in the first 1000 miles to be safe. I really don't think grit material got in the engine. I was extra caerful and used a tape and a shop vacuum to block the water and oil holes.
Question:
I will the oil pan tomorrow. Is it possible to spray inbetween the piston and piston bore with a cleaner. I am istalling a new oil pump and chain. I have noticed a big oil spot on the block wall below the exhaust manifold for cylinders 4,5, and 6 and also in the back of the head which suggests a leaking head gasket. The machine shop also mentioned that the head was slightly worped in the middle and they machined 0.007 of an inch off the head surface.
Meza

Correct me if I'm wrong but wouldn't it be ashame not to pop out the pisons since you have the heads off and will have the pan off as well? It seems that most the hard work is done at that point. I once rebuilt a 4.5L MB engine with 150k miles that was burning lots of oil (1qt/500miles). The oil scraper (bottom) rings were completely caked and allowed oil from the bottom end to work up into the combustion port. Changing the rings fixed that problem and 100k miles later it still isn't burning oil between oil changes. Didn't even need a rebore (just a light honing). Of course if you are not going to keep the car you might as well not even open the oil pan. If you are opening it up then you must be planning on keeping it. If you take out the pistons you'll need a ridge reamer else you'll destroy the pistons. Might as well replace the rod bearings while you're there.

Good luck

You mean you're taking the pan off?

I really hate to keep harping, but my gosh, taking the pan off is the biggest part of the work you have left to re ring this engine while it is apart. It would be so little trouble to just finish it up.

Best of luck with your project.

Have a great day,

Ok larry. I discussed this with my wife. She doesn't know much about cars, however, since she's the one driving the MB and really likes it and want to keep it, I will order new rings and put them on. I will need help. I have never done this before. How to use a ridge and a ring compressor? How to pull them out, put the ring and so on. Those done this before, please participate and help me. I will be very careful and do one at a time. Those that are on TDC will be first (1&6) then (2 &4) and finally (3 &5). I will need to know the torque on the bolts. The set made by Geotze goes for $171. By the way, when I look them up on Fastlane for example, I am given two choices:

-10-014906
-12-034368

which one do I use and what is the difference? It's a 93 190e 2.6L engine

Meza

Is the engine out?
If yes, put it on an engine stand (they can be rented). Turn it over and unbolt the connecting rods. Use a ridge reamer to clean up the ridge at the top of the cylinders. A ridge reamer can be borrowed from Autozone. Once the ridge is removed and the connecting rods are unbolted you drive the pistons (with connecting rods attached) out threw the top of the cylinder. Now you can clean up the pistons, install the new rings, clean up the cylinder walls and re-install the pistons/rods. Pay REAL CLOSE attention to driving the pistons back into place. YOU DO NOT WANT TO TOUCH THAT BEARING SURFACE ON THE CRANK with the connecting rods bolts. I always slip a rubber hose over them and let the hose straddle the crank. This is very important. Make sure you install new crank/rod brgs too. They are pretty cheap. Come back with questions as necessary.

Before I started on the rings I'd check for a ridge -- if it is less than a couple thousandths, you can ignore it, I think. If more, you probably need to sleeve and rebore rather than just stuff new rings in.

To check, just scrape you fingernail up the side of the cylinder bore on a cylinder with the piston down -- my guess is that you will find a barely perceptible ridge about 3 mm or so from the top. If it stops your fingernail, you want to use the reamer to cut it off JUST enough to let the rings pop over it. If it won't catch and hold your fingernail, best to leave it alone and just push the pistons out, the rings will jump it.

What you want to avoid at all costs is cutting enough material out to leave a rigde the other way -- wider at the top -- which will make it impossible to re-install the pistons.

Too much advice?!?>

Peter

I went through this with my 1989 103 engine. at 220K. There was absolutely no ridged to talk about. These blocks are probably carved from a solid granite block as there was absolutely no wear on the cylinder walls.
I also needed to replace the oil pan gasket (major leak).
First, unbolt the connecting rods. The order has no importance. Make sure you keep the connecting rod caps with the rod they were with. Do no mis-match the rod/bearings/caps. A gentle tap with a piece of wood from the bottom is all that is required to get the pistons out. Make sure you clean the ring grooves. You can get (rent) a the tool at any good auto-parts store. It is a kind of narrow scraper that fits in the ring groove. Do not remove any metal, only carbon and deposits.
Installing the rigs is easy. be carefully not to brake or bend the rings while installing on the piston. Go slowly. The ring compressor tool fits around the piston when the rings are installed. It makes it much easier to re-introduce the piston in the cylinder. Again, a little tapping with a piece of wood is helpful.
Rod bearings: Look at their condition. They should be ok with your relative low mileage. For more assurance, you may want to replace those too. (not expensive). Your oil pressure should go up a little.
Again, at the stage your at, this is the smartest thing to do.
JackD

Alternate the ring gaps so they dont all line up in a row. this will assure good compression. Lubricate w/ motor oil the rings, wrist pin and bearings when you reinstal. Make sure the ring compressor tool is lubed along the walls where the rings slide through. Do not pound the pistons out or in. Light tapping should do with the bottom of a hammer (the wood part) or a dowel.

I doubt you will need to rebore. Can someone else in this forum comment on the need to hone the bores with a drill mounted honer? I recal when i reringed an engine I honed only enough to break the glaze and set up the correct cross hatch pattern.