M103 Valve Stem Seals Done!
 

I just replaced the valve stem seals on the 90 300E. With 166K, it has been using about a quart of oil every 1,000 miles, which isn't too bad. I haven't done valve stem seals before, so I decided to go for it. The parts are dirt cheap and why burn extra oil?

It was pretty easy with some advice a while back from Donnie and numerous posts by Larry and others on the subject. Thanks guys! I did have to buy a few tools. It took me from 9:00 pm (after the kids went to bed) until 1:30 am when I took my test drive and declared the job complete. This included a new serpentine belt and belt tension damper (little shock), but I spent most of the time on the seals. There’s definitely a learning curve involved, but by the time you’re about ½ way done, things are moving along pretty smoothly.

I bought a Craftsman 3/8 drive, in-lb torque wrench. It goes up to 250 in-lb and is perfect for this job. I didn’t want to guess at the torque values since all the bolts go into aluminum threads. I also got an overhead valve spring compressor. It was a “Powerbuilt” brand from Kragen. It worked okay, but I wished I had bought a better one. The last thing I got was a telescoping magnet tool (Craftsman) which I used to catch the ball cups when removing the rocker stands and also to pull the keepers out of the spring retainers. I temporarily converted my compression tester into a tool for hooking up compressed air to the spark plug hole to hold the valves in place. It worked great. I bought the seals and a new valve cover gasket from Partshop for about $20 total.

I’ll find out over the next couple of months whether this will help reduce the oil consumption. The old seals weren’t cracked or hard, but I could see that the sealing lips on the ID were worn flat.

The job wasn’t too bad, but is a bit of a back-breaker since you’re hunched over the engine the whole time.

Don't it make you feel good when you are finished :)

Valve Stem Seal Replacement
 

Thanks for sharing your seal replacement success story. I'm gearing up to do the same job on my '88 260E.

Using compressed air to hold the valves in place is a good idea. How many psi did you set the compressor at?

John,

My manual says "no less than 6 bars", which is about 90 PSI. So I set the line pressure at 100 PSI and it worked fine. One note about the compressed air though: If you're not right at TDC for the cylinder you're working on it will turn your engine over! I didn't want to hover on the brink like that so I turned each cylinder just past TDC and put a breaker bar on the crank nut with the handle against the shop floor. So when I pressurized the cylinder it would try to turn in the correct direction and the breaker bar would hold it in place. That worked well.

One other tip: If you don't already know the trick to get your hood opened straight up (90 degrees), you need to know about it before attempting this job!

Will this type of valve spring compressor work?

http://www.sears.com/data/product_im...7627000-dv.jpg

Somebody on this site stuffed some rope into the cylender to hold the valve shut. That sounds like a good idea.

PA_Joe,

That type of spring compressor is for use with the head off of the engine. Although it isn't a picture of a Mercedes engine, you want to use this type:

Thanks Dennis

That's what I thought...

All the details...
 

I’ve received a couple of e-mail requests for additional detail, so here it is.

First, you’ll need a manual to get the proper torque specs for your engine. Mine is a 300E 2.6, and it takes 21 N-m for the rocker stand bolts and 8.5 N-m for the valve cover bolts. Those were the only specs I needed.

The only tool I was missing was a 27 mm socket for turning the engine over. I used a 1 1/16 inch socket that worked fine with all the spark plugs out, but didn’t fit perfectly.

First I yanked the valve cover and the plugs. I pulled the distributor cap off so I could keep the wires routed in the valve cover and remove the cover, wires and cap from the car as an assembly.

Then I brought the #1 cyl to TDC on the compression stroke. Just look in the plug hole and you can see the piston come to TDC. Then look at the rotor – if it’s at about the 10-11:00 position, you’re there.

Pull out the 3 small bolts and remove the oil piping from the top of the rocker stands.

Pull the 4 bolts (13mm socket) from the rocker stand for cyl # 1. Wiggle the stand a little and use a magnet to catch the ball cups from the top of the spring retainer. Set these out carefully so you can put everything back where it came from. I used a flat piece of cardboard on the air cleaner to keep things nearby.

Pressurize the cylinder – see my note above on going slightly past TDC and holding the engine in place with a breaker bar.

Compress the valve spring (intake or exhaust first, doesn’t matter), rap it lightly with a very small hammer to un-stick the retainer from the valve stem. Use your magnet to pull the keepers out and lift the spring off.

Take the old seal off with a screwdriver or your fingers if you can. Be careful not to slip and scratch the valve stem. Wipe the little bit of sludge off of the guide with a lint-free rag. Smear some fresh oil on there afterwards. Give the valve stem a wiggle – fairly snug? Good, the guides are in good shape.

Take the correct seal (Exhaust valves are larger in diameter than the intakes), smear some oil in it to lube it for assembly, put the little plastic tube over the valve stem and slide the seal in place until you feel it pop into position. Take some needlenose pliers and remove the tube. Note: these tubes come with the seal kit. You’ll know what they are when you see them.

Reinstall the spring and do the other valve. Then remove the air pressure.

Stick the ball cups on the valves and reinstall the rocker arm stands. I ran the bolts down diagonally going a little tighter each time and then did the final torque setting with the torque wrench.

Here’s a trick…
Look on your valve cover for the firing order. Do the cylinders in the order of the firing order. That way you always know which cylinder is coming up to firing position next.

Major warning! Don’t drop any small parts or you’re screwed. Use your magnet and take whatever steps are needed to keep those ball cups and retainer clips under control.

Be patient and don’t do the job when you have a time constraint. By about the 3rd cylinder things are more routine and you’re cruising right along.

I’m really glad I did it. Okay, now I have to find something new to worry about!

Here’s a picture that should help. I was always wondering what the heck it was going to look like in there. In the picture I have taken off the rocker stand for cyl # 1 and have the spring and seal off of the exhaust valve. If you want the .jpg file so you can zoom, shoot me an e-mail.

Darn, can I e-mail the picture to someone who can re-size it and post it?

Thanks.

Dennis,

THANK YOU!

Sixto
91 300SE
81 300SD

Does anyone know the conversion to foot pounds?


First, you’ll need a manual to get the proper torque specs for your engine. Mine is a 300E 2.6, and it takes 21 N-m for the rocker stand bolts and 8.5 N-m for the valve cover bolts. Those were the only specs I needed

From the site http://www.efunda.com/units/convert_units.cfm?mode=short&From=387
the conversion is 1 foot-pound to 1.355818 Newton-meters. Therefore, 21 N-m is 15.488 foot-pounds and the valve cover bolts at 8.5 N-m are torqued to 6.27 foot-pounds.

Do you go to 15 foot-pounds or 16 on the rockers? I would probably go to 6 on the cover bolts.

Easier yet, as MBDOC pointed out, multiply the Nm by .7 so that 10nm = 7ft lbs, 70nm = 49 ft lbs etc.

Hope this helps!

~Paul

____________________
'91 300E, 206k miles

Thanks Vaughn and Paul

One thought on holding the motor. It sounds like a lot of work. We place the engine to power stroke by watching the cam (add air slowly to see direction engine will spin) and let the engine turn til it stops. The air still holds the valves up even if the piston is down.

I worry a little about the act of holding the crank bolt. I would hate to loosen it as that is what the direction of rotation would do. Its a real mess when the balancer falls off.

Steve,

I thought about that, but with the plugs out, I figured that it wouldn't stop turning over until the piston was at the bottom and the exhaust valve would probably be opening by then.

With the piston very close to TDC, the effective lever arm of the crank is very short, maybe a quarter of an inch. The torque applied to the crank nut is very little. I did the math to make sure I wasn't going to loosen the crank nut and have the engine turn over. It was an extra step to hold the crank in place, but I thought it worked great.

Thanks for the pro perspective though!

Dennis

Per Dennis' request, here's a pic of his valve springs:

Dennis said:

http://www.members.aol.com/buckweeat/m103.jpg

Thanks Steve,

I've done this on small block chevys and I didn't remember being concerned with the position of the piston once the rocker was off.

Paul your engine is clean.... wow... what your secret

Newton who?
 

I asked that very question myself a while back, here's the link:

[URL=http://http://www.peachparts.com/shopforum/showthread.php?threadid=9137&highlight=newton]

What is your oil consumption now? I just rebuilt the M103 in my 2.6 and it still consumes about a quart every 1000 miles or less. (I've put in 3 quarts in a little under 3000 miles since the rebuild)

Just about the same. how many miles om your motor? did you replace the valve guides, rings, getting any blow-by

PA_Joe,

That's actually my engine. Paul helped me re-size and post the picture. Thanks Paul!

I don't think it's especially clean right now, but I do clean it once a year or so. I use a Craftsman 5 hp pressure washer with a Honda engine. I LOVE that pressure washer. I turn the pressure way down. I spray the whole engine with degreaser and let it soak a while. After blasting it off it looks new again - these MBZ engine bays clean up nicely. I know all the pros and cons, but I like it clean.

mplafleur, it has only been about 2 1/2 weeks since I did the work, and maybe 500-600 miles. I checked the oil a couple of days ago and it hadn't used any. I have about 2,300 miles on that oil, so I will be changing it in a couple of weeks. In a 3,000 mile interval, it tends to use a quart in the first 2,000 and another quart in the last 1,000. I attribute this to the oil breaking down and thinning. I'll report back after the next 3,000 mile run and let everybody know if my oil usage was reduced. Since the sealing lips on the inside of the seals were worn flat, I have high hopes that the consumption will be history.

PA_Joe,

I may be out your way next week. I have to go out to our electronics plant in Lansdale for the week. The plant is actually between Lansdale and Norristown.

Mike,

I have a client in Norristown so I'm there often. Let me know...

A picture is worth a thousand words
 

I was worrying if my valve spring compressor would work on the m103 springs but it looks like there is plenty of space. Thanks!

Oil Consumption
 

I've replaced the valve seals on my '88 300E too. The oil consumption stopped for ...say 20K miles, then slowly creeped up to the usual 1 quart/2000 miles.
nice post.

Joel

Joel, did you check your valve guides when you did the seal job?

I didn't check mine either. I told the machine shop to check them and they said they were OK. I didn't verify them though.

valve guide clearance
 

Capn C,
Sure did. don't remember the actual clearance, but it was the typical just out of bounds number. I guess what happens is since the stem height is a bit small, the area gets too hot and wears the guide to a certain point and then stops. At that point, the oil flowing through the worn guide cools it to the point that it no longer wears. The seals replacement reduces this for a bit, but that's about it.

Joel

There's a reason for my curiosity. I getting my valves ground soon and I'm concerned about the guides. I will replace any guide that needs it but I want to make sure the tolerances are correct. My fear is that after all this trouble the repair would only be temporary and Castrol would have to increase production again to handle my consumption.:rolleyes:

guide tolerances
 

While I don't disagree that out of tolerance valve guides drink a bit of oil, I do happen to think that if the oil consumption is not a problem and the seals do a fair job at reducing this - the cost of a valve job in this engine is simply too high for the benefit.
I would check to see if the new valve guides are a different materail too, otherwise in 50 - 100K miles you will end up the same problem.
Hope this helps.
Joel

M103 valve guides
 

Any M103 motor with 160,000 miles is going to have valve guide wear to some signifiant degree. Doing seals alone at 160,000 miles (assuming that the guides have never been done) is like putting a Band Aid on a bleeding artery. It may buy you 10,000 to 20,000 miles of reduced consumption, but the guides will need to be done. At our shop, we rarely do valve guide seals alone on any M103 over 100,000 miles.

Thanks for the inputs Ed.

The so-called bandaid only cost me 20 bucks! (seals + valve cover gasket)

When it comes time, I'll do the guides. For now, everything is great. There definitely weren't any valves loose in the guides.

Last weekend I pulled the vale cover and striped the cracked buildup of paint. Spent 4 hours cleaning and sanding and three coats of gloss black engine paint. I made up a extension with a cutoff valve for the cylinder pressure. Pressurized the first cylinder and heard a hissing sound coming from the crankcase. # 1 and 2 are leaking down and # 4 intake cam lobe is wiped out. I put it back together and it runs fine but the oil at 3k smells like 50k. My guess is the head gasket is leaking into the oil passage and the breakdown of the oil cause the cam to go. I just got this car in October and knowing what I know now I doubt if it was serviced regularly. 87 300E 128K

I though I got a good deal at 5K with a 6month warranty. Then 20days later the transmission went and I found out the dealer never sent the money to the warranty company. 2k for the transmission and 7 hundred to the lawyer. Add another 5 hundred for parts and a hundred hours of my time cleaning and servicing The car is ivory and looks great from 5 feet way but closer it’s not a cream puff (the color hides many sins).
Let this be a lesson to nubees I owned my own shop for 12 years.

I found a rebuilt head complete with cam and lifters. The question is do I continue throwing money into this or should I start over now that I know what a good 300e looks like. What is my old head worth as a core?

Sounds like you're upside down in this car already. To get your money out of it you will most likely have to "drive it out". :( I've been throwing money at mine since I had it but I can't get back what I have in it. When people comment that I "drive a Benz, I must have money", I don't say "it's an old one" anymore. It takes as much to keep an old one up as it does to buy a new one! Somebody out there needs that head, put it in the swap shop.

Here's an M103 engine for sale....
 

...not mine. 82k miles is quite low if you're willing to do the work to put it in.

http://cgi.ebay.com/ebaymotors/aw-cgi/eBayISAPI.dll?ViewItem&item=600834028

~Paul

__________________
'91 300E, 206k miles

Thanks Paul,

Grand for the whole motor is a good deal but I’m not that energetic... head job yes... I'm too old to be rolling around on the floor…

What do you think I should ask for my used head?

Re: M103 valve guides
 

On the M103 engine -- that is not the message I got from Mr. Brotherton. He said that post 1988 engines had much improved valve guides and that replacing the seals tended to fix the problem for an extended period of time.

http://www.peachparts.com/shopforum/showthread.php?threadid=34708


See quote below -- brookspw



[

M103 valve guides
 

brookspw,

While it is true that the valve guides that M103 motors came from the factory with improved after April of 1989, no valve guide is going to last forever. While the old M103 valve guides could wear as early as 70,000-100,000 miles and the newer ones may last 100,000-120,000 miles, ANY M103 valve guide with 160,000 miles is going to be worn enough to cause serioius oil consumption.

M103 valve guides
 

brookspw,

While it is true that the valve guides that M103 motors came from the factory with improved after April of 1989, no valve guide is going to last forever. While the old M103 valve guides could wear as early as 70,000-100,000 miles and the newer ones may last 100,000-120,000 miles, ANY M103 valve guide with 160,000 miles is going to be worn enough to cause serioius oil consumption.