Valve Stem Seal Replacement M103 engine

General Information
Get the stem seal kit, new valve cover gasket, the two breather hoses that go from the valve cover to air cleaner housing and intake manifold (if you have never changed them they will be very brittle and probably break), two cans of brake cleaner to clean inside of valve cover and the oil pipe that sprays oil on the camshaft. Also get a meter of that clear plastic vacuum hose, you'll most likely see some under the air
cleaner housing that you'll want to replace.


Disclaimer

I offer no opinion relative to the difficulty of this job. That will depend on experience. Some may think it’s easy while others may think it’s difficult.

The procedure I’ve outlined is what worked for me. Standard safety procedures and precautions, including the use of safety goggles and proper tools and equipment, should be followed at all times to eliminate the possibility of personal injury or improper service which could damage your car or compromise its safety.

Should you find an error in these instructions please let me know so I can correct it.

Tools are available for Rental at http://www.peachparts.com/shopforum/showthread.php?t=126728
valve spring compressor: K-D 2078
valve seal pliers
tool to connect air to spark plug hole & whistle
6 drain plugs
all these tools are made in the USA

Tools you will need: (based on how I did the job)
27 mm socket
½ drive ratchet
torque wrench-rocker arms 21nm, spark plugs 20nm, valve cover bolts 8.5 nm
good supply of shop air (capable of providing 75 psi), not sure how many CFM are required; mine has 61 gallon tank and puts out 11.3 CFM @ 90 PSI
small pencil magnet (sears craftsman)
sockets in a variety of sizes

Parts you need:
valve cover gasket
two breather hoses
valve stem seal kit-exhaust have yellow coated ring and intake have black coated ring, use install sleeve when doing intake seal

Remove Air Cleaner
detach breather hose from top valve cover to intake manifold and to air cleaner housing
remove three 10mm hex head screws that hold filter housing and disconnect electrical connector on intake and lift entire housing off with hose connected to the air filter housing

Fan Shroud
remove fan shroud, the part that you turn and pull out

Remove lower engine cover

Remove Valve Cover
remove valve and cover plate inside of valve cover that is held in place by phillips head screws and clean out with brake cleaner
remove bolt that holds transmission filler tube to head and push to side a little
plug six oil drain holes in head with plugs, stick each down hole about 2"
remove oil pipe and spray out with brake cleaner
pressure wash valve cover to blast off as much peeling paint as possible. I got most all of it off. Obviously this step is not necessary.

Changing Seals
I did one cylinder at a time as follows:
1-remove spark plug, however, prior to removal you may want to use compressed air to blow clean the area where the spark plug is fitted to remove any grit that might fall into the cylinder when you remove the plug
2-screw in pipe with whistle on the end
3-turn crankshaft clockwise very slowly by means of the ratchet and 27mm socket, keep turning until whistle starts to blows
4-keep turning slowly, the whistle will blow a few more times depending on how much you turn the crankshaft, when the whistle stops you are at TDC, to be positive you can remove the tool with the whistle on it and insert a tiny streamlight or similar LED flashlight into spark plug hole and you will see the top of the piston
5-make sure the socket is on the crankshaft bolt and that the handle of the ratchet rests against the A/C compressor that way the engine can not turn when you supply air
6-if you removed the tool with the whistle on it you need to reinstall that tool in the spark plug hole. Then remove the whistle from the top of the tool and attach air supply and pressurize cylinder to 75 psi, which is about 5 bar which is pressure specified in the Service Manual for Engine 103
7-unbolt rocker arm
8-as you lift off rocker arm use pencil magnet to remove ball socket on each side, note orientation of ball socket for proper reinstall later
9-compress spring and remove valve collet halves with pencil magnet
10-remove valve spring
11-remove old seal with pliers
12-install new seal, use the correct one for intake or exhaust and use the assembly sleeve for installing the intake seals only, you place it over the valve stem, put a little oil on it and slip the valve stem seal over the assembly sleeve and then press the seal in place with your fingers, then pull the assembly sleeve straight up to remove it, put oil on exhaust stem seals also to aid installation, the assembly sleeves are not used to install exhaust seals
13-reinstall spring & collets
14-do same for other side Air pressure should not be removed until both the valve springs are reinstalled, i.e., the collet halves are properly installed.
15-reinstall ball sockets, & rocker.
16-Go through same process for the rest of the cylinders

When you have done all cylinders remove the drain plugs, reinstall oil pipe, bolt holding transmission filler pipe to head, fan shroud, valve cover, breather hoses, air filter housing, & electrical connector to intake hose

Ron:

Thanks for taking the time. A nice addition to the DIY section no doubt.

Perhaps it's just me - the wife says I'm "slow" smometimes, but I'm not quite sure I follow items 4 & 6 in the "Changing Seals" section.

On a separate note, I'd like to ask where you found a threaded TDC whistle?

Thanks again.

__________________
Mike Murrell
1991 300-SEL - Model 126
M103 - SOHC
"Fräulein"

The whistle is not threaded. I got it at the hardware store. It attaches to the fitting on the pipe I made that you also attach the air suppy. I use a small piece of tubing to attach the whistle to the pipe. My camera is not talking to the computer, so for now no photos.

Check the changes I made to instructions and see if they help.

Sounding like an english teacher, I'd place a period between the word "it" and "remove" in item 6.

__________________
Mike Murrell
1991 300-SEL - Model 126
M103 - SOHC
"Fräulein"

A small suggestion. To avoid getting gritty stuff on the spark plug hole threads, either give the hole a good blowing out before removing the plug or, after removing the plug, clean the hole with a length of 1/2" heater hose attached to shop vac hose. I suppose most DIYers already know about this but for those who don't...
Regards, Dan

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2012 E350 Bluetech

Maybe add alternatives to checking TDC and air-line fitting?

- I checked TDC with a piece of coathanger wire, marked with a piece of masking tape where the wire is positioned at TDC at the rim of the spark plug hole.

4a. Alternatively, check TDC with.....

(Perhaps add to tools you'll need?)
- You can make a tool for the air line with a piece of pipe brazed to an old plug that has had the porcelean insides removed, a piece of hydraulic hose, and the appropriate air fitting. I suppose you could braze the fitting directly to the plug too, but my plug holes wouldn't allow the air coupling to fit in, and I found the hose convenient.

6a. Thread homebuilt air-line tool into spark plug hole and apply air (90 - 100lb) to pressurize cylinder.

Attached Thumbnails

 

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1986 560SL
2002 Toyota Camry
1993 Lexus

I do have two questions.

Can you give details on your spring compressor?

I assume the piston is raised to TDC and the crankshaft held there so a valve cannot fall into the cylinder? As a practical matter, if you left the pistons down and used 75 lbs or so of pressure, what are the chances you would drop a valve into the cylinder?

Thanks

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2012 E350
2006 Callaway SC560

The are a number of ways to check for TDC, the service manual for 103 engine describes another method too that deals with arrows on the flywheel damper are aligned with the TDC pointer and the cams of the respective cylinder are facing up.

The tool I made is basically the same as yours. I used a K-D 901 for the fitting and a pipe instead of hose.


Spring Compressor is K-D 2078

I think piston needs to be at TDC so you can properly pressurize the cylinder, but I'm not sure.

Don't know what would happen if pressurized cylinder and piston is not at TDC.

This may be a stupid question and please forgive me if it is, but I read several times in this forum that as long as the cylinder is at TDC it is impossible for the valve to fall into the cylinder. Is that right? If so, is this true for most MB interference engines?

JL

I've done this on other engines and as long as each cylinder is raised to TDC before the work the valves cannot drop into the cylinder. However, be deliberate as when you get busy you can forget to raise the next cylinder.

An alternative is to place a section of clean rope into each cylinder somewhat filling the cylinder so that the valves cannot fall, with enough length so that that all the rope doesn't drop into the cylinder.

I might also mention that you probably will have a very sore back from leaning over so much. I think I rigged up some type of body board to lay across the fenders to help lay on for some of the time.

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JD

Maybe a little explanation on "use installation sleeve when doing the intake" . I assume you are referring to the plastic tube that comes with the sleeves. How is it used?

JL

Thanks to all who have made suggestions as to how to make my DIY instructions more clear and complete.

I going to change the title of thread to Valve Stem Seal Replacement M103 Engine and send lnk to whunter so he can have a link to this DIY in the proper forum.

If anyone has more suggestions feel free to post them here as I can alway edit DIY instructions assuming a link is provided to this thread. I'm just not sure how they do that.

I am not sure what a TDC is, but when I was changing the valve seals, I used a compressor with a (screwed it in the sparkplug hole, you need a special tip for that) and the air pushed the valve stem up and kept it there - so there was no way for it to fall down, no matter if the cylinder was at TDC or not.

Thanks. That's the answer I was looking for. How much air pressure did you use?

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2012 E350
2006 Callaway SC560

Not sure, I had used a small compressor - had it at almost full and then reduced the pressure to just enought so that the valve doesn't fall in. I don't think that too much pressure will push it out out.