My Custom 1980 W116 300SD Project Part 2 - PeachParts Mercedes-Benz Forum

Squiggle Dog · #1 12-04-2017, 09:06 PM

This is a continuation of this thread: My Custom 1980 W116 300SD Project which documents the refurbishment, maintenance, and mild customization of a daily driver 1980 Mercedes-Benz W116 300SD. I am resuming progress on the vehicle after taking a long pause during which I was working many hours while suffering from a life-long sleeping disorder that makes working full time impractical. I am once again unemployed and now have time to work on the car again. Despite a long period of no maintenance and a 2+ hour commute each day in brutal Arizona heat, it didn't let me down.

Since my last post, I attempted to seal up some leaks in the transmission. My 722.120 transmission had leaking piston cover O-rings, even though I have paperwork showing it was rebuilt in 1991. I read that while it is possible to replace the O-rings in the B2 and B3 piston covers simply by pressing in with your hands, the spring pressure in the B1 piston cover is too great.

A special factory tool is recommended my Mercedes, but the transmission must be removed from the vehicle since it takes a lot of room, and there is only 70mm (3") of clearance between the transmission and the tunnel. I have heard that it may be possible to use this tool with the transmission still in place if the exhaust pipe and driveshaft are removed, and then the transmission is lowered down as far as it will go. This is a lot of work.

I don't have a lift and doing the above would have been difficult. Feeling that I'd rather just pay someone else to do it, I called an independent Mercedes-Benz repair shop asking how much it would cost. The shop said that it would be too difficult for them to do, and they referred me to a place that specializes in German transmissions. I called the transmission shop, and the mechanic said that he wouldn't do the job without completely removing the transmission from the vehicle. This would have been expensive and would have put me without a car for a few days.

So, I decided to make a tool that would allow me to replace all of the piston O-rings with the transmission still in place and without having to lower it or remove any other parts, because that is just too much work.
CAUTION: If you make your tool any less stout than I have made mine, it will probably fail and you will not be able to finish the job. Use your ingenuity and good judgment.

I bought 3/4" hollow square steel tubing at my local hardware store. Solid aluminum bar would work as well, but it is harder to find. You need at least 14" of it--more if you make a mistake. I cut the long piece to the length of the transmission (235mm), and the short piece 120mm.

I got some 30mm long bolts the same thread pitch as the ones for the transmission pan and drilled a couple holes for them in the tubing. The holes need to be offset all the way against the edge on one side. This is to clear the valve body, and you may still need to grind a little material away at one edge (it starts at about 80mm in from the right side to about 90mm in, if you look at the picture above). The center of the bolt hole on the left side is 12mm in front the end, and the center of the right bolt hole is 21mm from the end. The center point of each should be spaced 202mm from each other.

I used a 4" long bolt (about 3/8" thick) with a thin locknut going through the center of the tubing. The center hole for it is 107mm from the right. The stronger the bolt, the better. Even this one started to bend under the spring pressure.

I drilled a hole through the short tubing so it would go through the bolt. The tubing will crush during use and cause a big disaster if you do not reinforce the hole with round tubing. I had to buy a long piece of 3/8" ID round steel tubing, cut, and grind it just small enough to slide into the square tubing. It keeps the tubing from collapsing and from it catching the threads and binding. You must do this or just use solid bar stock for this piece.

Then I drilled a long, slotted hole at the other end of the short square tubing so I could attach a 23mm socket. I put a thick washer inside the socket and then used a bolt going through it, with a locknut on the inside of the tubing. I tightened it just enough for it to stay in place, while still being able to slide as needed.

Squiggle Dog · #2 12-04-2017, 09:07 PM

The first step to the piston cover O-ring removal process is to put the transmission in park, set the parking brake, chock the wheels, lift the car as high as you need, then put a stand underneath.

Clean the transmission very well. Compressed air is useful. The slightest piece of dirt can cause mechanical problems if it gets inside, not to mention it can get caught in the sealing surfaces.

The control pressure rod clamp will be in the way of the B1 piston, so completely remove the nut and bolt and then slide off the clamp and set it out of the way.

Loosen the bolt holding the dipstick tube to the intake manifold. Put a container underneath the transmission and remove the drain plug at the dipstick banjo bolt. Let the fluids drain out. Also remove the plug in the torque converter to let it drain (you'll have to turn the engine over until the plug is at the bottom, either by using a socket on the crank, or on the power steering pump pulley bolt [some advise against using the pulley bolt]). Once drained, remove the pan and continue to let the fluid drip out into the container.

The exhaust pipe clamp was in the way, so I loosened it and slid it out of the way.

Now the tool can be bolted to the transmission. Make sure to put the socket through the new O-ring before compressing the piston, otherwise you won't be able to get it in.

Squiggle Dog · #3 12-04-2017, 09:10 PM

I started with the B1 piston (the trickiest one, for which this tool is required). The socket can be positioned to the ideal place.

There is a washer and bolt on each side of the arm. Each one should be snug against the arm. The inner one is loosened, then the outer one is tightened. This helps keep the arm from tilting. Have patience and make sure that the piston is being compressed evenly on all sides. The socket can be repositioned with much care. Don't rush it and make a mistake!

Once the piston is compressed just enough to remove the circlip, pry it off at the notch with a flatblade screwdriver.

Turn the arm nuts the other way, loosening the outer nuts while tightening the inner nuts. Be very careful to not let the tool go off center or slip off. This could very easily become a disaster if you are not patient and meticulous. Turn out the arm just far enough to reach the O-ring with a pick. If you go too far, the metal piston ring further in could pop out, and there is also a pushrod which could pop out of place. Fortunately, my tool stops against the tunnel before going too far. Remove the old O-ring and install the new one. Don't get them mixed up or let dirt get inside.

Before pushing the piston cover back in, take a look inside the transmission by the corner of the valve body to make sure the pushrod is still in the hole. You can't see it in the picture, but it's right where the 8 is. If it's popped out, you'll have to stick something up in there to push it back in.

Start turning the arm nuts inward to compress the piston cover, doing whatever is necessary to make sure it goes in straight. If it tilts, it will bind up and the O-ring can get cut on the sharp hole edges. Once it's in far enough, push the circlip back in place. I put the gap at the bottom, so it has a weep hole effect.

Then slowly let the arm back out and make sure that the piston is rested back up against the circlip and not tilted. Congratulations, you have done the first one!

The tool can also be used on the B2 piston, which is under much less tension. Same rules apply.

Squiggle Dog · #4 12-04-2017, 09:12 PM

I did not use the tool for the B3 piston on the other side. I pushed in the piston cover with my hands, removed the circlip, then let it out to rest against the tunnel. It can easily fall out of place! Once again, make sure that the pushrod is still in the hole.

Push the cover evenly back into the transmission being careful to not cut the O-ring on the sharp edges. It may require a helper to put the circlip in place while you hold the cover.

Assemble the parts you removed with a new filter, pan gasket, and crush washers, then add transmission fluid, following the procedures in the manual. If all goes well, you won't have any more piston cover leaks.

Part numbers for piston cover O-rings:

B1: 000 997 47 48 64

B2: 000 997 48 48

B3: 008 997 35 45

Squiggle Dog · #5 12-04-2017, 09:13 PM

It turns out the worst offender was the control pressure rod shaft seal. But, it didn't look like there was any seal visible from the outside.

I purchased a service manual for the transmission (REVISED EDITION), and it seemed to completely omit the seal.

So, I opened up the original transmission that came from the car to get a better look. Sure enough, the shaft seal is placed on the INSIDE of the case and it cannot be replaced without the transmission being completely disassembled. I can't believe how stupid this is. The shop that rebuilt the transmission years ago probably didn't even replace it. On the next series of transmissions, they placed the seal on the OUTSIDE where it can be replaced without tearing the transmission apart. If I rebuild the original transmission, I want to have the outside of the case bored out to fit an external shaft seal.

Right now I have a transmission that's been completely resealed and doesn't leak EXCEPT for the control pressure rod shaft seal which leaks profusely. I have to keep a tray under my car because it leaks so much transmission fluid from it. I tried pushing an O-ring inside the shaft seal bore, but it didn't work. I might try a square-profile ring next because it may seal better. This transmission shaft seal leak is the only leak I have on my car and it is irritating me.

Squiggle Dog · #6 12-04-2017, 09:15 PM

I live in Arizona, home of 120 degree Fahrenheit summers, where it can be over 90 degrees even in winter, so I really, really need air conditioning already (I've suffered through 7 summers and was commuting 1-2 hours each way in heavy traffic at one point for over a year). And not just air conditioning, but GOOD air conditioning. I actually started on upgrading the air conditioning system over 2 years ago, but stopped working on it when I started my last job as I had no time.

I removed the Delco R4 compressor, which has a bad reputation and isn't very efficient. The pulley was seized and had a hole in it.

I bought a Sanden compressor adapter bracket from ROLLGUY on the PeachParts forum. It is very well-made and came with a bracket for supporting the oil cooler hoses.

dieselbenz1 · #7 02-21-2018, 09:50 AM

'When I was out taking pictures today, I was joined by several jackrabbits running around and having a good time. There are also coyotes out here that come into the neighborhood to say hi. They look exactly like one of my dogs, and I am starting to wonder if she is part coyote. She doesn't mind them when they walk past us at night, and she makes howling and yipping noises with them. She also has strange mannerisms like sneaking up on other dogs or people, pushing them hard with her crutch tip nose, and then running away. She is also very feral and skittish like a coyote, and was found as a stray in the desert.'

Great looking car! I once had a half breed coyote and border colie he always howeled half the night on a full moon or when he was lonely. Some people would come for blocks to watch him howl.

SonnyMorrow · #8 02-21-2018, 01:49 PM

I love your write ups on this car, what a fun thread to look through! Your radiator guy seems like a jerk, and as you said, I guess some people just don't have any sense of aesthetics. Good job on those hubcaps though. I'm going to have a few of mine done soon on my '84 as you can see someone tried to paint one of them to match before, and its about a 20 footer job. I guess you really do need the Mercedes template in order to do a good job. Keep the posts coming. Hopefully soon I'll start a thread like yours with my '84, it looks like fun. Take care

dude99 · #9 02-21-2018, 07:24 PM

Amazing job as always! Glad to see your back at it!

Squiggle Dog · #10 03-20-2018, 10:54 AM

I am likely going to be leaving the Mercedes scene. My financial situation is dire due to a sleeping disorder which makes it difficult to work, and I have a lot of time-consuming self-improvement I want to do, anyway. It's getting way too difficult to maintain and restore a W116 and all these rubber, vinyl, and plastic parts just don't last in the Arizona heat. My 300SD is in extremely good mechanical condition, so now is a good time to sell before something breaks that I can't afford to fix.

My 1967 Universal fintail station wagon was going to be restored into a daily driver, but it's a huge welding project and completely unrealistic. I bought it several years ago and had hopes that by now that I'd have a decent income and able to restore it, but I was delusional. It's also getting increasingly difficult to get any parts for these old cars and there are just so many expensive rubber and vinyl parts to replace.

I also have thousands of dollars in debt that I can't pay off any other way. If I can sell these vehicles and get out of debt, it would be a huge relief. My roommate has cars I can use if I need to drive somewhere. If I do purchase another vehicle, it will be something simple and utilitarian like a Willys Jeep station wagon powered by some kind of diesel powerplant.

I will likely have both of my vehicles listed on eBay in the near future. They are great cars for someone with a decent income, but that's not me. I have to be realistic and make some changes in my life.

dude99 · #11 03-20-2018, 07:35 PM

wow..... I'm at a loss of words after all the fantastic work you've put into her.. I hope somone on the forum picks it up...

I do however encourage you to reconsider selling the w116. You can continue to drive it even if a few plastic\rubber things wear out, it doesn't have to be perfect. The 617 will continue to get you where you need to go long after everything else had broken around it. I seem to remember you were almost at this point a while ago and chose not to sell it...

Maybe try selling the wagon first, maybe it will net you more than you think and you'll be able to keep the w116.

Squiggle Dog · #12 04-30-2018, 10:38 PM

I ordered some compressor fittings as the ones I had ordered years ago didn't seem to be angled correctly. I ordered a #8 45 degree and a #10 180 degree, both without service ports because there isn't enough room at the back of the compressor for that to be a suitable location. I ordered a couple service ports that I will put inline with the hoses. I also ordered several feet of #8 and #10 barrier hose I so I can make my own hoses and will then have them crimped at a shop.

I started trying to remove the center console. It's a difficult task, anyway, but it seemed really stuck even though I thought I had all of the screws removed. I also removed the front seatbelt guides but it was still not budging. The plastic braces of the console were already broken and the parts were never able to be attached to it securely, and it started to rip. Finally, in frustration, I tore the console to shreds. It turns out there were two screws still holding in the console at the rear. Oh, well. I felt really upset about destroying the center console as it's not like you can just buy spare interior parts for these cars. Good luck finding a used brown center console (and brown dashes in good condition are completely impossible to find).

I do have a spare brown console that I removed from a car I parted out. The plastic braces are in good condition, but the vinyl is cracked all over. It will have to do. I ended up destroying the corner of the dashboard when I was pulling it out. I really despise W116 interiors. I also gave the glovebox door a few punches because it kept popping open when I was trying to loosen the zip ties for the wires that were attached along the bottom of the dashboard.

I look at the automatic climate control and can't believe anyone would make something so complicated.

I removed the heater box. I'm going to do what I can to simplify the system. I pulled out the manual system I have and it turns out the heater box is cracked and broken. Rabbits chewed up much of the wire harness and cables. Even the manual system seems overly complicated with vacuum controls all over. I might end up ditching the Mercedes climate control entirely and make something using universal controls and wiring.

pj67coll · #13 05-01-2018, 09:39 AM

Quote:

Originally Posted by Squiggle Dog

Even the manual system seems overly complicated with vacuum controls all over.

What are the vacuum controls for on the manual system?

- Peter.

Squiggle Dog · #14 05-01-2018, 12:27 PM

Quote:

Originally Posted by pj67coll

What are the vacuum controls for on the manual system?

- Peter.

There is a vacuum switch at the outer lever on the driver side, and another vacuum switch at the outer lever on the passenger side. There is a vacuum line running between the two, one going to them from the vacuum supply tank, and then one going from them to a vacuum pod on the heater valve on the firewall.

Then there is a vacuum switch at the air conditioning temperature switch, which activates a vacuum pod on the blower motor housing, which opens and closes the recirculating air flap.

pj67coll · #15 05-01-2018, 03:47 PM

Quote:

Originally Posted by Squiggle Dog

There is a vacuum switch at the outer lever on the driver side, and another vacuum switch at the outer lever on the passenger side. There is a vacuum line running between the two, one going to them from the vacuum supply tank, and then one going from them to a vacuum pod on the heater valve on the firewall.

Then there is a vacuum switch at the air conditioning temperature switch, which activates a vacuum pod on the blower motor housing, which opens and closes the recirculating air flap.

So the heater valve on the firewall is opened and closed by vacuum rather than a physical cable as on the 123? Interesting. Same for the A/C recirc. Wonder why they used vacuum on the manual system and not on the 123?

- Peter.

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