Hey guys, so I started the big-job, trying to replace the head gasket on my W201 M103, while at it also resurface the head, check the valves, replace seals, replace lifters, replace springs (got dbilas 13 lift springs to have a reserve) and cam too (have a dbilas 264 cut with 11 lift), maybe valve guides if needed.

Now the head is off and soon to be shipped to the machine shop, I just have the springs to pull, but while cleaning the block surface, I overdid it a bit between the 2nd cyl water-ways, btw between the water-ways there is a lot of head gasket material for some reason, guessing because on the head side thats one big opening covering basically both water-ways, Im curious how bad is this, its not contacting oil paths and on the head side this whole area is one single opening too, kinda why Im guessing the old gasket left a lot of junk here .. but still it worries me, need some advise






Thank you in advance !


Best,
Daniel

 

I would not worry about the pitting on the block side between the coolant ports. Like you say, on the head side it is wide open between them anyway. I think water gets trapped there and over time finds a way to etch the iron block. Mine was as bad as yours when I pulled the head a few years ago.

It is however important to have a clean mating surface between the head and the block. So my experienced machine show strongly advised me to use a block sander to plug the holes and sand it thoroughly. It has to be a wood block, nothing else that is flexible. Any kind of rubber padded sanders will have disastrous results. No issues in the last 20K miles since I went thru what you are doing now. Before and after pictures attached as reference

- Cheers!

 

Thank you, yes I was thinking it may have been the water too, cyl1 also has some pits, smaller though and looking at the old gasket, its a mess, esp around those areas, a few show clear indications (rust) of water making contact between the two channels
Ive been sanding with 400grit (planning to move to 800 after) and a cork-based pad, but could go wood, my block is at TDC though so cyl1 and 6 are fully up, I dont want to sand those, since I believe they have some coating on, so I kinda have to go around those, doing just the edges

Btw slightly offtopic/ontopic question, I pulled the tensioner cap but didnt pull the whole tensioner as I managed to remove the chain just fine, dont have an m17 and I cant seem to find one, can I just reassemble ? or it needs to be pulled and reset ?

 

Like I said, do not use a cork sander. You will be sorry. It has to be a block. Make your own by stapling your sand paper around the edges.

The pitting in the cylinder is normally due to oil burning and the carbon crystalizing an being crushed against the head. If you see pits on both chamber and piston top. I spotted some on yours. Mine coincides with the cylinder that has the lowest leakdown number. (my cylinder 5 in the photo's I believe)

 

A cork sander will start dishing around the edges. Trust me on this, I know. Switch to a block sander ASAP.

 

sure thing, I have some good plywood I can make a flat good one

 

Dolucassi gives great advise and the results of his work show it. Also, MB recommends timing chain replacement @ 100,000 miles. It's also best to replace your tensioner at the same time. You might as well take the "while I'm in there" view and take care of these things now rather than risk future catastrophic engine failure.

 

190efan reminds me I did not adress your chain tensioner question. Not sure what you will do with the chain however even though I tried very hard to keep everything lined up I had to realign the chain and reset the tensioner. Don't be surprised if you need to do that at the end.

I will always advise to reset the tensioner it is very simple and should be done.

 

Thanks guys, yes, I do actually have a chain set on the ready, however I thought of that as a separate project, Id like to have the head back on and everything aligned to go for it, pull the front cover and do that front-side

 

You might as well replace both your timing chain and tensioner now while you already have your engine opened up. Then you won't have to worry about either of them failing in the near future.

 

You are right, I would just like to put the head back on first, worried about messing with the timing )
Im also considering getting a different chain set, the one I got is Swag, which is basically Febi and that was a while ago, since then I havent heard the best of Febi :/

 

For the timing chain and tensioner, OEM is best. It might be more expensive up front but in the long term, it's what was designed for your car, it will work the best and last the longest which will wind up saving you money. The MB engineers set the W201 timing to pretty much not be adjusted. Messing with the timing might result in a whole new set of issues.

 

Do you happen to know who the OEM is btw ? as with many these do get outsourced Im sure
Yes, Id def avoid messing with the timing, why I want to do this job with the head back on and making sure nothing turns when replacing it

 

OE chain manufacturer is IWIS. If you go to the Mercedes dealer, they will sell you an IWIS chain and link in a Mercedes Box. That is what I have sitting in a box still to be installed.
I did not have the guts to replace mine just because I was afraid to mess up peening the link. You will need a tool to peen it.
That being said, I would get the chain from the dealer and spend the extra $20 if they still sell them. Only then will you know it is an exact fit.
Also asses the score marks on your tensioner. If they are really deep that will need replacing too but that is a bigger job.
Most importantly assess how far are you off from the tensioner ratcheting all the way. That would mean the chain has stretched quite a bit.
Also, do not assume your timing is completely correct before you removed the head. The stretching does move it a little bit. The sprocket is designed to move it by +/- 1/2 the sprocket teeth spacing by rotating the sprocket alignment by 1/3rd turn. And make sure the chain is super tight on the guide side opposite to the tensioner side.

Same goes with the head gasket. Get yours from the dealer. You will be happy. Make sure you also replace the rubber short coolant hose to the thermostat housing.
Also replace the O-ring to the coolant return hose from the heater core to the block. Mercedes still had all these parts in stock 4-5 years ago.
Same goes with the head bolts. I assume you will replace those too. You should.

- Cheers!

 

Thank you dolucasi ! ya, may end up getting the chain from the dealer, I buy some things from the dealer, but usually what I cant find in a good brand. That's the thing, the Swag one comes ready to go, don't need to peen it, that part was convenient, but I worry bout the quality. I did get the full set of guides too and the plan was to do a 3rd stage of the project, this car has become a full project as of late, I'm at the 2nd stage of the engine now, as well as interior (had to re-upholster, impossible to fix the door panels, oh and body works ) hunting down rust spots and getting ready for the bodyshop
The history of the car actually goes quite a while back, my dad bought the car in 97, with about 120k km on it, it was his daily for a while, then it was my daily, but we barely put another 120k between us, then it sat for a while, then it turned into a full project ) Last year I redid the whole suspension, everything except the H&R springs, dropped the sub-frame, cleaned and replaced all I could ) and I rebuilt the k-jet and went over everything fuel and ignition, which ended up all new except the coil, the car ran perfectly, but I had a minor leak under the head, near the first cyl, and I decided to move on to the head and valve-train. I have all the gaskets, even that o-ring in the back (man was that a pain to get btw), and of course new bolts. I try to replace all rubber consistently, every single gasket and o-ring (for example the gasket inside the valve cover), as well as hoses, (Im down to one single rad hose which I still cant source, the long one coming from the expansion tank to the rad), I even got the two hiding behind the firewall ) gaskets I tend to get Elring, it seems to be the OE for MB anyway, hoses I mostly got from the dealer as I couldn't source em otherwise anyway, even the dealer was a pain, long order times, with some failing to come through and having to try again a year later )) Im a bit on the edge of EU here and things arent that plentiful unfortunately, even had to order some stuff direct from Germany through a relative, hes kinda sick of my addiction by now ))

 

Thanks for the timing chain OEM Dolucassi. I didn't know what the OEM for that is. I think your advise for using OEM products for this job is very wise. My engineer father would only use OEM parts because of better fit, better quality and better part longevity. In my parts search last year, I found out that the MB Classic Center is the better parts source for the W201 than the MB dealers are. The MB Classic Center has put their parts catalog online now and of course I can't off the top of my head remember the web address. Given the age and mileage of the car, I would think it would be wise to replace the tensioner too so as to not risk a tensioner failure in the not too distant future that might be catastrophic for the engine. Dan190, I think you would be wise to heed Dolucassi's advise. Saving a few bucks up front by using less expensive parts now could wind up costing you alot more in the future. Just my 2 cents and what I would do if it was my car.

 

Dan190, I was where you are now, 4 years ago with my valve job. I wanted to replace the guides, tensioners, chain when I did the valves. I bought all the parts and did not pull the trigger. All my parts are OE Mercedes of course.

I did not go with the completed chain (swag or Febi) method because that is an entirely different job. It requires you to remove the entire front end lower timing cover. That is when you also replace the oil pump chain an guide as well because you can not loop a complete chain around the existing oil chain. It also requires the removal of the crank pulley, etc etc. and all this is indeed independent of a head gasket replacement. And when all the front end is open, you may as well put in OE chain. You can have it peened in a shop if you do not trust yourself. BTW the oil chain OE is also IWIS.
The completed chain installation should be coincided with a water pump replacement. Those two are a better pair than head gasket and complete chain replacement without peening.

If I were you, I would carefully inspect the tensioner plastic, how far it is stretched, etc. Take pictures and post here and perhaps we can give you feedback and advice.

 

yep, that was the plan, funny thing, I was there already ) I had a failure of the harmonic balancer a while back, so I had to pull most of the front end and the crank pulley entirely (replaced the crank gasket, the pulley and the balancer)
I was going to repeat that, but going further and pulling the covers off, and yep, I got both chains .. but .. swag )) will reconsider the brand, but still feel its a separate job and will be my 3rd iteration on this engine

 

Practice makes Perfect!

- Cheers

 

No offense but my engineer father always taught me to work smarter not harder and to do things right the first time. It makes no sense to me to not change out the chains, tensioner and water pump while you've already got your engine pulled apart. You also don't want to cheap out on the parts needed for this job because you'll be back doing this same job again when the cheap parts don't last and fail early. I agree with Dolucassi that pictures of your plastic tensioner would be helpful for us to see to help us to help you determine if your tensioner should be replaced. I would also suggest viewing your tensioner with a magnifying glass to look for tiny hairline fractures in the plastic that can also lead to a failure.

 

I read the posts about sanding the block cylinder surfaces. I hate to state this but sanding material is course. It will get into the oiling system at some point. No way you are going to sand and not have some get in there where it can damage your bearings and other parts. If you absolutely need to clean the head surface Fel Pro Engineering would recommend using a piece of Machine Steel, in your case maybe a piece 3" x 6" and at least 1/4" thick should work, wrap this Machine Steel with your 600 grit sandpaper and lightly go over the block surface. Why, because any high or low spots can cause the gasket to fail. It allows only a small amount of variation of surface before failure. A block of wood is not flat, a sanding block is not flat. A piece of machine steel is flat. A head gasket can't compensate for your mistakes sanding.
I have used sandpaper with a piece of flat steel to clean up a block. I know the risk, I wiped out all the cylinders with an oiled rag hoping to pick up all I could of the sanding material but I know I will not get it all out It was a risk I chose to take but I knew the risk involved. Proper installation is normally a life of the engine install. Put the same gasket and head on uneven surfaces and your life may only be 20,000 miles before gasket blows out. Not the gaskets fault. That would be fault of the installer. If you feel forced to clean it flat best solution is engine removal and having a shop deck the block flat again. Second best might be to leave it alone and install the new gasket and repaired head. Third best is to use machine steel and dress the block with some 600 grit and very carefully vacuum and clean after the fact and know some grit will now be inside your engine. Based on the damage you show my guess is that cylinder head does not provide much clamping force in the area between the cylinders where you are seeing the erosion. That means it does not seal that area well and maybe they are not concerned about that area at the factory. The important sealing is around the cylinder, the fire ring, around any water port that can allow coolant to reach the oil and around the perimeter to keep coolant contained inside the engine water jackets. Some heads also have hight pressure oil passages that pass from the low block to the head, those would also need a great seal. Keep wood and other pads away from the block or head it takes you the wrong direction. Making it look pretty before install is not important at all. Having a flat surface for the gasket, head and block to mate is most important. Combustion pressure is the hardest part to seal, the fire ring can only seal on a flat surface, if you mess around with sand paper and do not use a machined flat steel sanding block you are asking for early failure. When MLS multi layer steel head gaskets first came out, I think it was around 1998 the block surfacers in most machine shops could only provide a surface with a roughness of 120 RA. The new MLS gasket technology was a great improvement in sealing but needed a surface of 15-20 RA, smooth like glass almost. The latest versions of MLS are more forgiving but even the latest versions can only work with an RA of 60 or lower.
The initial process advised by the gasket manufacturer was to take the piece of machine steel and with 600 grit paper give the block 10-12 very even swipes across the entire block deck. These swipes would lower the RA or measure of roughness from 120 down to an acceptable 30-40 RA which worked with the Fel Pro designed MLS gasket. OEM gaskets still needed a RA less than 20.
Years later the decking machines were upgraded to cbn cutters that could leave a mirror finish if desired but the early machines could not provide an acceptable surface for MLS technology.
You can always spot MLS technology because MLS is exactly what is says, Multi Layers of Steel, it may be 2,3,4 layers thick and the layers are held together with rivits. The rivets protrude from the gasket into areas where the extra thickness will not interfere with assembly.
If your engine does not use MLS technology the statements above still apply because the Fire Ring has to have a flat surface to seal. ***** nilly sanding to make it look good before assembly is sure to leave low spots around the fire ring, your eyes won't see them but the gasket will and they can cause failures. I worked in this field for over 30 years and had to go evaluate hundreds of head gasket failures over the years. Hundreds is probably not accurate, we sold millions of head gaskets and failures always had to be evaluated. This is basic stuff and well known in the industry.
I do not wish to step on toes, just to share some engine building facts.

Hope this helps.

West

 

West, you make an excellent point, few in fact, problem is I don't know how else to clean the block surface, the parts around the cooling ports are way to stuck on to just scrape off :/ its actually bad design, the opening on the head is way larger, covering both ports on the block and the space between, and the gasket cant possibly stay put between those two ports, it will naturally rise one way or another, this leads to corrosion and lots of very stuck residue there. Agree that sanding isn't best, to clear the debris I was going to oil wipe, pour new oil to pass through, flush the old oil, fill it, run engine for 5mins or so and flush again, then pour some more to pass through, and only eventually fill up and run the car. But... flatness issue, I agree is an issue .. I just hopped I wouldn't affect it so much by sanding lightly .. I dont know how else to manage this without having to pull the block, I will look for a piece of machined steel to upgrade the sanding block, that much I can do of course

Btw what about copper spray for gaskets ? anyone know if that stuff helps ?

Oh and ya, the gasket isnt MLS, but I agree that this doesnt change things and proper flatness is key

 

West makes excellent points and a great write-up however, there are not a lot of other options when one is going with a gasket replacement at 200Kmiles with the engine in the car.
If the block is not skimmed a tiny amount the surface is not going to be smooth anyway. Also non MLS gaskets should be more forgiving than MLS.

On the cleanliness side, when I did mine all the ports were tightly plugged, including the cylinders. You may see my in progress picture that I even have heavy duty red paper between the cylinder wall and the piston gap in case some dust gets thru. Once the sanding was done, it was carefully vacuumed, then ports unplugged, vacuumed again and wet cleaned.
And after the installation the oil and filter were replaced after a few minutes of running and again after a very short period for the final filtering.

Also the wood block that was suggested by the machine shop who has been in business 30+ years worked fine for me. But a steel block might even be better assuming it is perfectly manufactured and meant for this job. Corners and edges would have to be tapered but I assume they come like that.

Long story short, I'm at 20K+ miles since the head gasket replacement and I see no ill effects so far.

 

On the copper spray question, It is my opinion that none of the M103 head gaskets would want copper. I have not heard of that being applied for this engine.
I have seen it done in other applications.

 

The fire ring staying flat is the most important issue. That holds all the pressure of combustion. It needs to be flat. A .001" variance in say a 1" section of the fire ring next to where you are sanding could prove very bad for gasket life so keep that in mind when choosing to sand.
I have also sanded on a block to help prep it but I fully understand what risk I took on, just wanted you guys to understand also and have tips to avoid failure. I do not make it accepted practice to do this but I rebuilt a diesel, it did have MLS gaskets and it had some porosity I wanted to address before installing the rebuilt heads. Take all precautions to keep the grit out and know some will get in there and just hope it does not cause damage. I saw many engines wrecked by sanding particles when those high speed sanding discs came out and mechanics were using them to speed up the overhaul jobs. Once the material gets stuck in engine bearings it can cause lots of damage. Yours is an old engine so I might do the same but as mentioned be aware of the danger, use a flat stock of machined steel. Keep in mind that .001 or 1/1000" variance in flatness can cause fire ring problems. They actually say up to .003 variance in a 6 cylinder is acceptable but they are referring to head or block warp over the 2' of length end to end of the head not a .001 dip over a 1" area where sanding took place. So be smart and get it running again.

Copper coats have been used for years, it is a very soft coating and the purpose is to help fill in any low spots to help sealing. It will help seal water ports, low pressure ports, it is no help sealing combustion where you will have 600 to 4,000 psi trying to blow out.

Some Mechanics do it for 30 years and are outstanding, always learning always getting better. Some put their head in the sand and will not pay attention to new advances and changes. A lot of technology keeps moving daily. I left the business 12 years ago now, the Piston, Piston Ring and Gasket technology is already making me obsolete. You have to keep up or you fall behind. I have had some of those 30 year guys insist it is OK to re use TTY head bolts, they are wrong. Torque to Yield bolts are exactly what they call them, you torque them till they start to break! This limits how much clamping force is put on the gasket. Prior to TTY bolts every bolt could be re used with no limit for the most part. Engineers found that mechanics were over torquing engines, if the head bolt was supposed to apply 85lbs torque the mechanic wanting a really good job would apply 90 or 95 lbs to make sure it was good. This was found to distort the cylinder bore, a distorted cylinder bore does not seal as well as a round bore causing oil consumption. Other engines with over torqued head bolts could distort the main bearing bores causing more issues. This started in about 1985 when manufacturers got better at casting blocks and were able to make the same block with much lest cast iron or aluminum involved. I know of one block where from one year to the next 35 lbs were removed from the block. 35 lbs of cast iron. That new block had to have TTY bolts to avoid distortion. It looked just like the old block but did not perform the same. It took years for the mechanics in the field to accept and adjust to this type change. Your mechanic may be top notch and I hope he is, the other guys are bad for the industry.