1990 300SEL Valve Stem Seal Project Questions - PeachParts Mercedes-Benz Forum

Benz Mondi · #1 12-08-2016, 11:53 AM

Using the listed DIY project instructions found here, I have some questions.

1. Where can I find the tool with the whistle on the end and a fitting that I can attach to a compressor for pressurizing the cylinder to keep the valves from falling into the cylinder?

2. Would a valve stem seal kit (comes with the pliers) found on eBay be useful or should I just get the pliers itself.

3. There a protective cap advertised here that goes over a spring compressor tool to protect the surface of the head from damage. Should spent the $40?

4. In addition of a new valve cover gasket, I though I would also buy a can of the CRC Intake Valve Cleaner. Is it worth it?

5. Will renting a spring compressor kit from my local Autozone be suitable for this project?

6. Any other tips or suggested parts to purchase for this project?

Thanks,
AL

duxthe1 · #2 12-08-2016, 01:51 PM

Buy the OEM seals. Trust me.

Sugar Bear · #3 12-08-2016, 06:59 PM

1. Compression tester use the same thread if the fitting is removable.
2. Use high quality seals. Intake and exhaust are different, separate and mark the container at the onset. Don't see the need for any pliers.
3. Protective cap, I don't see the need.
4. Use high quality gasket, re: intake cleaner,this job will not provide additional access to the intake valves. Also, the 103 valves tend to stay very clean on their own.
5. Most compressors should work, lots of room to work on this.
6. a. Stuff the timing chain area and any other holes with rags to prevent an oops!!!
b. There are small discs on top of each lifter that stick to the rocker arms, don't lose them be on the lookout for them.
c. Do ONE rocker arm assembly at a time.
d. Use an inch pound torque wrench to tighten the rocker assemblies, they strip easily.
e. Turn the engine so that both cam lobes are on the base circle before removing and while torquing the rocker assembly.
f. Only the front rocker assembly has a half moon washer that controls fore/aft movement of the camshaft. That piece can and does fall out and be an oops!!! as mentioned in 6.a.

Good Luck!!!

Mxfrank · #4 12-08-2016, 07:07 PM

A leakdown test kit shoud work for pressurizing the cylinder. You should also install a crank lock, because the engine will want to turn when you pressurize.

Absolutely use Mercedes valve stem seals. This is one area where pennywise is pound foolish.

Benz Mondi · #5 12-09-2016, 10:26 PM

Wow! Thanks for all the info.
I'll make sure to get the OEM seals.
with over 200K on the clock, I've been told that changing the seals will only last for 12-15,000 miles if the real issue is that my valve guides need replacement.

1. If my guides are bad, how can I tell? is there a way that I can tell to what degree they are bad?

2. Since I don't need the special seal pliers, do the seals just slide down until they can't go any further?

3. Assuming I've pressurized the cylinder to at least 75 psi, will I be able to slide the seals with as much force as I can muster to put them into their proper place with a very low risk of the valves falling back into the cylinder, or do I have to be fairly gentle?

4. I'm planning to use lots of magnets to try and hold the little pieces in place during disassembly and re-assembly. Makes sense?

5. I see an excessive amount of crud build up in the valve train, More than I've ever seen in any of my previous cars. I'll clean all that mess up first.

I got his car from a relative of a buddy that neglected the car. Because it didn't have any peeling clear coat, almost dent free save a just a couple of door dings, other than the sun roof, everything works- even the a/c. It was too good to let it go straight to the junk yard. Though if this doesn't fix the excessive smoking, it might still quickly end up there. My Indy says he would charge between $400-700 to do just the seals.

Hit Man X · #6 12-10-2016, 12:40 AM

I had my head rebuilt and did the R&R myself for around $650 after all the dust settled. I would really consider this as the top end wears pretty quick (as do all the accessories) due to the RPM the 126.024/.025 turn on the freeway.

For what it is worth, I did stem seals on mine around 250k. It was a waste of my time as I still had the same consumption issue until I did the head around 275k.

If you do the head, use an OEM gasket. They sell for about $40 only.

Sugar Bear · #7 12-10-2016, 12:53 AM

I've been told that changing the seals will only last for 12-15,000 miles if the real issue is that my valve guides need replacement. Mostly accurate.

1. If my guides are bad, how can I tell? is there a way that I can tell to what degree they are bad? They will have play from the left side to the right side of the car. Exhaust usually wears worse, rock the valve back and forth.

2. Since I don't need the special seal pliers, do the seals just slide down until they can't go any further? Yes, they push onto the cylinder head/top of the guide. Almost no resistance over the valve stem, a friction resistance to push onto the head. They stay in place on the head and wipe the valve as it moves up and down. A small plastic protector should be in the seal kit , it slides over the valve before the seal and then comes off and gets re-used on the next valve.

3. Assuming I've pressurized the cylinder to at least 75 psi, will I be able to slide the seals with as much force as I can muster to put them into their proper place with a very low risk of the valves falling back into the cylinder, or do I have to be fairly gentle? Not much force required, cylinder pressure has no effect.

4. I'm planning to use lots of magnets to try and hold the little pieces in place during disassembly and re-assembly. Makes sense? Good idea.

5. I see an excessive amount of crud build up in the valve train, More than I've ever seen in any of my previous cars. I'll clean all that mess up first. A couple of runs on synthetic oil will work wonders on the clean-up.

I got his car from a relative of a buddy that neglected the car. Because it didn't have any peeling clear coat, almost dent free save a just a couple of door dings, other than the sun roof, everything works- even the a/c. It was too good to let it go straight to the junk yard. Though if this doesn't fix the excessive smoking, it might still quickly end up there. My Indy says he would charge between $400-700 to do just the seals.When does it smoke? What color is the smoke? Does it burn oil? Replace the spark plugs during this process.

Benz Mondi · #8 12-10-2016, 11:39 AM

Quote:

Originally Posted by Sugar Bear

I've been told that changing the seals will only last for 12-15,000 miles if the real issue is that my valve guides need replacement. Mostly accurate.

1. If my guides are bad, how can I tell? is there a way that I can tell to what degree they are bad? They will have play from the left side to the right side of the car. Exhaust usually wears worse, rock the valve back and forth.

2. Since I don't need the special seal pliers, do the seals just slide down until they can't go any further? Yes, they push onto the cylinder head/top of the guide. Almost no resistance over the valve stem, a friction resistance to push onto the head. They stay in place on the head and wipe the valve as it moves up and down. A small plastic protector should be in the seal kit , it slides over the valve before the seal and then comes off and gets re-used on the next valve.

3. Assuming I've pressurized the cylinder to at least 75 psi, will I be able to slide the seals with as much force as I can muster to put them into their proper place with a very low risk of the valves falling back into the cylinder, or do I have to be fairly gentle? Not much force required, cylinder pressure has no effect.

4. I'm planning to use lots of magnets to try and hold the little pieces in place during disassembly and re-assembly. Makes sense? Good idea.

5. I see an excessive amount of crud build up in the valve train, More than I've ever seen in any of my previous cars. I'll clean all that mess up first. A couple of runs on synthetic oil will work wonders on the clean-up.

I got his car from a relative of a buddy that neglected the car. Because it didn't have any peeling clear coat, almost dent free save a just a couple of door dings, other than the sun roof, everything works- even the a/c. It was too good to let it go straight to the junk yard. Though if this doesn't fix the excessive smoking, it might still quickly end up there. My Indy says he would charge between $400-700 to do just the seals.When does it smoke? What color is the smoke? Does it burn oil? Replace the spark plugs during this process.

No smoke up to about 1,200 RPM. Lots of blue smoke after.

Replaced with new copper NGK's after purchase, along with cap, rotor, OVP and MAS.

Car would not start when purchased. It actually had moss growing inside the dist. cap!

Sugar Bear · #9 12-11-2016, 11:26 AM

The symptoms for valve seals leaking is usually:
smoke on the initial start of the day,
a false start i.e., the 103 starts once then stalls, and
oil consumption @ more than a quart in less than 1,000 miles.

With over 200,000 miles you may consider doing a compression test or better yet a leak down test first. Auto parts stores may rent/loan the tester.

Blue smoke at 1,200 RPM's is more likely:
stuck, clogged worn or broken piston rings,
the oil returns are clogged in the cylinder head causing the oil level to rise onto the intake valve stems before finding its way back into the oil pan, and/or a blocked breather on the inside top of the valve cover.

Don't give up on it yet, the 103 motor is very durable. Consider doing the valve seals as planned, clean the top of the cylinder head making sure the oil return holes are fully open back to the oil pan, disassemble the breather inside the valve cover and thoroughly clean it and then use an internal engine cleaner to free up the rings.

If you wish to experiment you could even do a before and after compression test after the internal cleaner. I have not used but would look at AutoRX for this. Remember if you use a cleaner it will take time (weeks?) to work and there will be oil in the exhaust system that will diminish over a week or so after the problem is fixed. If you do a procedure and the smoke does not stop immediately don't get discouraged, give it time.

Good luck and keep us posted.

Benz Mondi · #10 12-16-2016, 04:17 AM

This valve stem seal work will be my project for this weekend.Anyone have or can point me in the direction of the torque settings for the rocker arm nuts I'll have to fiddle with? And any others I'll be encountering with this project?

Thanks,
AL

ps2cho · #11 12-16-2016, 07:53 AM

This is the best tool I have found to complete the job. You need a helper to have a magnetic tool ready as you compress the valve. Autozone may only have the regular valve spring compressors which won't work. It must be like the following:

New Engine Overhead Valve Spring Remover/Installer OHV/OHC Compressor Tool Set | eBay

You also need a good compressor. I recommend you buy a leakdown kit and do it since you are doing 90% of the work required to perform a leakdown test and you'll get a good idea of engine health.

Benz Mondi · #12 05-20-2017, 08:44 PM

(Here are the details...)

Final Update...

Put the new stem seals in with the help of the main hose from the leak down test kit I got form Harbor Freight. Went as planned, but took a little longer time since I had to do a lot of cleaning to the valve train and rocker arm assembly as I went along.I also cleaned the area uncovered once the rocker assembly was removed for each piston.

After the stems seals were in place, disappointingly, the blue some got worse. Rains came to CA so didn't do much until a few days ago.Assuming that I the smoke was coming from a needed head gasket or valve guide job or both, I needed to see if the transmission had any issues. I had convinced myself I could take on the removal of the head myself, but if the tranny was bad, I might as well just junk it.

I would do a midnight test drive around town to test the transmission because of all the smoke- no cars and all the nosey neighbors asleep. As she had always done, she fired up on the first try and had a smooth and steady idle.As expected a ton of smoke came out of the exhaust as soon as I put it in gear and back her out of the drive way she’s occupied for the past 3 months.The first 5 minutes, the smoke was so thick,that I could have been laying a smoke screen down for the Navy. But after 5 minutes of normal driving, the smoke seemed to diminish and actually disappeared! I then figured that I would use this time to get some new 91 Octane in her.I filled her thank ½ way. Got in the car turned the key and she started right up again.I then got out while the engine was running and walked to the back to see what I could see coming out of the tail pipe. By the time I got back there, she started to stall.Before I could get back in the car, the motor quit.I turned the key to get here started, but this time and for the next 10 minutes, she would not start.

I was stuck at a closed gas station at ½ past midnight with no one around- bummer. On what was going to be my last attempt before I wore the battery down, I decided to do something I learned from my first car back in 1976. I had a 1971 MG Midget.To get that pig started, I had to pump the gas pedal like I was trying to stomp out a fire.Since the 300SEL is fuel injected, this really isn’t going to help, is what I thought.Low and behold, she fired up and I quickly drove her the 5 minutes back to the house.She drove fine the whole time- no smoke, shifted as she should have, and idled nicely as I slipped her into the driveway. That was two nights ago. I’ll see how she acts tonight, but that will be for another thread.

Besides all the good tips learned about doing the stem seal work, a good one for all to keep in mind is this. Beware of using ATF with your engine oil.ATF is 10X smokier than normal engine oil.If you add it to your engine oil to help “clean” the oil system as I was advised, only do so if you are not experiencing any oil leaks into your combustion system.I believe that while I was running the engine before doing the stem seal job to “help clean the system” the mixture was actually seeping into my exhaust system and leaving a residue that eventually lead to all the smoke that I experienced. No head gasket or valve work anticipated... for now.

Benz Mondi · #13 05-20-2017, 08:49 PM

(Here's the details...)

Final Update...

Put the new stem seals in with the help of the main hose from the leak down test kit I got form Harbor Freight. Went as planned, but took a little longer time since I had to do a lot of cleaning to the valve train and rocker arm assembly as I went along.I also cleaned the area uncovered once the rocker assembly was removed for each piston.

After the stems seals were in place, disappointingly, the blue got worse. Rains came to CA so didn't do much until a few days ago. Assuming that the smoke was coming from a needed head gasket or valve guide job or both, I wanted to see if the transmission had any issues. I had convinced myself I could take on the removal of the head myself, but if the tranny was bad, I might as well just junk it.

I would do a midnight test drive around town to test the transmission because of all the smoke- no cars and all the nosey neighbors asleep. As she had always done, she fired up on the first try and had a smooth and steady idle. As expected a ton of smoke came out of the exhaust as soon as I put it in gear and back her out of the drive way she’s occupied for the past 3 months.The first 5 minutes, the smoke was so thick,that I could have been laying a smoke screen down for the Navy. But after 5 minutes of normal driving, the smoke seemed to diminish and actually disappeared all together! I then figured that I would use this time to get some new 91 Octane in her. I filled her tank ½ way. Got in the car turned the key and she started right up again. I then got out while the engine was running and walked to the back to see what I could see coming out of the tail pipe. By the time I got back there, she started to stall. Before I could get back in the car, the motor quit. I turned the key to get here started, but this time and for the next 10 minutes, she would not start.

I was stuck at a closed gas station at ½ past midnight with no one around- bummer. On what was going to be my last attempt before I wore the battery down, I decided to do something I learned from my first car back in 1976. I had a 1971 MG Midget. To get that pig started, I had to pump the gas pedal like I was trying to stomp out a fire. Since the 300SEL is fuel injected, this really isn’t going to help, is what I thought. Low and behold, she fired up and I quickly drove her the 5 minutes back to the house. She drove fine the whole time- no smoke, shifted as she should have, and idled nicely as I slipped her into the driveway. That was two nights ago. I’ll see how she acts tonight and why a new idle issue, but that will be for another thread.

Besides all the good tips learned about doing the stem seal work, a good one for all to keep in mind is this. Beware of using ATF with your engine oil. ATF is 10X smokier than normal engine oil.If you add it to your engine oil to help “clean” the oil system as I was advised, only do so if you are not experiencing any oil leaks into your combustion system.I believe that while I was running the engine before doing the stem seal job to “help clean the system” the mixture was actually seeping into my exhaust system and leaving a residue that eventually lead to all the smoke that I experienced. No head gasket or valve work anticipated... for now.

Mike Murrell · #14 05-21-2017, 01:49 PM

Besides all the good tips learned about doing the stem seal work, a good one for all to keep in mind is this. [/SIZE]Beware of using ATF with your engine oil. ATF is 10X smokier than normal engine oil.If you add it to your engine oil to help “clean” the oil system as I was advised, only do so if you are not experiencing any oil leaks into your combustion system.I believe that while I was running the engine before doing the stem seal job to “help clean the system” the mixture was actually seeping into my exhaust system and leaving a residue that eventually lead to all the smoke that I experienced. No head gasket or valve work anticipated... for now.[/FONT]

[/QUOTE]

ATF in engine oil?

Huh?

sixto · #15 05-21-2017, 02:13 PM

Catalytic converters might not appreciate ATF either.

Sixto
83 300SD can be yours
98 E320 wagon