GregMN's 1991 W126 350SDL Has A New Home - Page 11 - PeachParts Mercedes-Benz Forum

Usaguy · #**151** 10-31-2019, 12:32 AM

Nice pictures congrats on the work.

Quote:

Originally Posted by Squiggle Dog

I used 220 grit sandpaper on a sharpening stone to make sure the block was clean and flat.

220 grit is too fine for cast iron and a sharpening stone can go through the sandpaper and scratch the surface, use a sanding block.

120-150 grit for cast iron

150-180 grit for aluminum

you want the surface a little rougher so that the gasket grips and doesn't fail prematurely. There is a specific Ra (surface rougness) range specified in the manual if you want to be perfect.

Squiggle Dog · #**152** 10-31-2019, 01:49 AM

Quote:

Originally Posted by christuna

Nice pictures congrats on the work.

220 grit is too fine for cast iron and a sharpening stone can go through the sandpaper and scratch the surface, use a sanding block.

120-150 grit for cast iron

150-180 grit for aluminum

you want the surface a little rougher so that the gasket grips and doesn't fail prematurely. There is a specific Ra (surface rougness) range specified in the manual if you want to be perfect.

Thanks for the compliment and information.

I guess that's what happens when a person gets their information off of the internet. I was actually worried that the sandpaper I used was too rough. I read that the surface is supposed to be smooth because the gasket "floats" between the head and block, which expand and contract at different rates. The idea of using the sharpening stone was that it's flat and rigid. Fortunately the sandpaper was heavy duty.

vwnate1 · #**153** 10-31-2019, 06:16 PM

It's good to read old timers discussing this sort of thing .

Some here may have dealt with older blocks having malleable cast iron that resulted in the deck pooching up around the threaded holes for the head studs .

? How to repair back forty + years ago when these (NOT Mercedes !) were new and so often had weepy head gaskets that held compression yet leaked oil & coolant ? .

Use a LARGE flat file across the holes, work like a charm .

Also many would hand paint a 1/2" wide stripe of flat white house paint around the perimeter of the deck or lay strands of copper wire.....

When finished this engine should have more dollar value than the chassis it's installed in

.

Keep going .

Actros617 · #**154** 10-31-2019, 08:41 PM

I thought I'd share this might be helpful for any OM602.xx, OM603.xx (both 3.0L and 3.5L) family engines,thought its for W124 engine manuals are all the same for other chassis models. However it does not contain the OM601 (2.2L I4)
Mercedes Benz Model 124 - OM602, OM603 Maintenance Manuals

Squiggle Dog · #**155** 10-31-2019, 11:18 PM

Quote:

Originally Posted by vwnate1

It's good to read old timers discussing this sort of thing .

Some here may have dealt with older blocks having malleable cast iron that resulted in the deck pooching up around the threaded holes for the head studs .

? How to repair back forty + years ago when these (NOT Mercedes !) were new and so often had weepy head gaskets that held compression yet leaked oil & coolant ? .

Use a LARGE flat file across the holes, work like a charm .

Also many would hand paint a 1/2" wide stripe of flat white house paint around the perimeter of the deck or lay strands of copper wire.....

When finished this engine should have more dollar value than the chassis it's installed in

.

Keep going .

Thanks!

Quote:

Originally Posted by Actros617

I thought I'd share this might be helpful for any OM602.xx, OM603.xx (both 3.0L and 3.5L) family engines,thought its for W124 engine manuals are all the same for other chassis models. However it does not contain the OM601 (2.2L I4)
Mercedes Benz Model 124 - OM602, OM603 Maintenance Manuals

Thanks! I have the factory service manual on CD, but it doesn't play well with 64-bit Windows.

Squiggle Dog · #**156** 10-31-2019, 11:19 PM

ROLLGUY was kind enough to loan me his chain crimping tool. Even though I mushroomed the ends of the pins with a hammer, using the proper tool will give extra peace of mind and is how it should have been done the first time.

The crimper fits on the chain as in the picture and one pin at a time gets squished down. The tool gets tightened between 30-35 Nm.

Here is the master link after a good crimp. You can see the scars from when I hammered the ends of the pins.

The other side of the master link was crimped from the factory, but only very lightly (and not as much as the rest of the chain), so I crimped it down more.

83w126 · #**157** 11-02-2019, 06:49 PM

It looks like I'm going to have to do this to mine too, I have put about 10k miles on it and never gotten it hot and it has been fine until now, but it has pressurized the cooling system enough that the radiator is leaking around the top tank.

Squiggle Dog · #**158** 11-02-2019, 10:19 PM

There were some dents and scratches on the valve cover gasket surface of the head, so I carefully sanded them, cleaned them with brake parts cleaner, and then filled them with J-B Weld. Then I leveled them with 320 grit sandpaper on a sanding stone. Now there shouldn't be any leaks.

I removed the timing pointer for the crank because I wanted to derust and paint it. When I put it back on, I noticed that it is adjustable, so I had a big problem as the timing could be off by as much as 4 degrees and I no longer knew where top dead center was.

It was a lesson in not loosening the bolt on the crank pointer, and also that you don't know if it's been messed with before, so I guess you can't necessarily trust the pointer to be accurate. Fortunately, I found a solution. I already had a compression tester fitting installed into the prechamber so I would feel it shoot out air at me so I would know if the piston was in its compression stroke. But, the crank turns once, while the cam rotates twice. It seems that the only thing that determines if the piston is in the compression or exhaust stroke is the cam, right? So, it really shouldn't matter, I wouldn't think--just set the crank to top dead center and then line up the cam marks.

Anyway, I fit a piece of clear tubing over the end of the compression tester fitting and pushed a small funnel into the end so I could pour in oil. I turned the crank to 10 degrees before top dead center and then slowly and carefully poured oil into the funnel. I found that it would burp itself and air bubbles would come up as I was rotating the crank. Eventually all the air bubbles were purged.

I very slowly turned the crank and could see the oil level rise up. Once the piston reached top dead center, the level would immediately fall. I turned the crank slowly in each direction until I found the exact point where the oil level was at its highest. I then adjusted the crank pointer accordingly and tightened it in place. I checked my work several times and am sure I got it within 1/8 of a degree of accuracy.

One big screw up is out of the way, and now I am sure that the crank pointer is accurate. I see that the cam is 1 degree advanced, however. Perhaps that is due to the height of the head gasket or having an old chain tensioner installed which has no oil pressure. But, that's probably a good thing as I plan to advance the injection timing from 15 degrees to 14 degrees. Apparently advancing both the cam and injection timing can yield higher performance (I think Doktor Bert ran the OM617 in his 300SD with the cam advanced 2 degrees and the injection pump advanced 4 degrees).

Squiggle Dog · #**159** 11-04-2019, 09:48 PM

After calibrating the crank pointer and confirming the cam timing was correct in relation to it (other than being 1 degree advanced), I removed the plug on the side of the injection pump and rotated the engine until I could see the tang for the timing tool. For those curious, it was at 13 degrees after top dead center on the exhaust stroke, which goes to show how much the timing can get off when the chain is replaced. Then I installed the tool to lock it into place.

The left hand threaded center bolt was removed and the installation cage was added, which can actually be left on the engine when the vacuum pump is installed.

I unbolted the injection pump and the cruise control and slid out the pump enough to replace the O-ring (part number 012-997-83-48).

After the O-ring was installed, I rotated the crank to 14 degrees after top dead center on the compression stroke and inserted the injection pump. 15 degrees after top dead center is stock, and 14 degrees was specified on later engines. I figure one degree advanced will slightly boost performance and will compensate for the 1 degree the cam is advanced. The timing chain will stretch at some point, anyway, eventually bringing the timing to stock specs.

The new German-made Laso brand chain tensioner arrived. Now the engine is timed and the external parts are being put back together. I'd like to have the car driveable by the weekend, but you never can tell how things will go.

Squiggle Dog · #**160** 11-11-2019, 11:07 PM

There was a rounded out hex key screw in the EGR valve housing. I ended up having to cut a notch in it so I could remove it with a flat blade screwdriver.

This upper radiator hose connector was cratered from corrosion, so I filled the depressions with J-B Weld and sanded it smooth.

Inserting used upper chain guide pins was difficult as they weren't perfectly straight. I'd get them partway in, and they wouldn't go further. So, I used a socket, a bolt, and some washers to pull them back out to try to straighten the pins.

I inserted a screw into the threaded ends of the pins, and banged on the screw head with a hammer in order to not damage the pins, but one of them bulged out anyway. So, I had to grind it smooth again.

After a lot of grinding and filing--and then hammering--I got the pins to fit, using sealant on the collars.

Squiggle Dog · #**161** 11-11-2019, 11:14 PM

I replaced the grommet on the dipstick tube bracket and the O-ring on the dipstick.

I sanded the sealing surface of the trap oxidizer delete pipe.

I filed the mating surface of the turbocharger flat.

I applied graphite grease to the sealing surfaces of the exhaust and installed a new metal gasket. Graphite grease is supposed to bake and fill in imperfections in the surface.

The 350SDL uses a fast glow system, which requires a two-pin temperature sensor.

vwnate1 · #**162** 11-12-2019, 11:26 AM

Wow, you're doing a bang up job here .

I usually remove the flange studs and use a really W I D E fine bastard file I bought decades ago to true up flat sealing surfaces ~ those who don't understand it will cringe in horror but I've corrected many sealing issues this way as you did .

You must really like whomever owns this car for the good job you're doing on it ~ the devil is always in the details and most Mechanics like to do flat rate and skip anything not absolutely necessary .

I wonder of the dipstick tub's upper grommet is the same as my OM617 ? it came loose recently and wobbles ~ not weeping any oil (yet) but it being loose bothers the heck out of me .

dude99 · #**163** 11-12-2019, 10:10 PM

So I'm just going to say it, you should do this for a living. I know you've been looking for a job that would work around your condition, and working for yourself would allow you to do that. If you were near me, I'd seriously hire you to do the work on my old Mercedes that I don't have time to do. If you started advertising on these forums, I bet you'd rack up some work, and anyone that's seen your threads would be stupid not to believe that you're better than the vast majority of Indi shops and dealers out there...

You have a gift, I would seriously urge you to consider it... and as I have before, you should also be filming all this for a YouTube Chanel. It would be gold...

ROLLGUY · #**164** 11-12-2019, 10:43 PM

Quote:

Originally Posted by dude99

So I'm just going to say it, you should do this for a living. I know you've been looking for a job that would work around your condition, and working for yourself would allow you to do that. If you were near me, I'd seriously hire you to do the work on my old Mercedes that I don't have time to do. If you started advertising on these forums, I bet you'd rack up some work, and anyone that's seen your threads would be stupid not to believe that you're better than the vast majority of Indi shops and dealers out there...

You have a gift, I would seriously urge you to consider it... and as I have before, you should also be filming all this for a YouTube Chanel. It would be gold...

Totally agree. I started out with a 1982 300CD, and after fixing it (learning in the process), I bought another car for parts. I started selling parts off of it, and several people that came to buy parts asked if I work on these cars. What started as a hobby, has later become a way to make a living. I have been exclusively working in my driveway on Mercedes-Benz Diesel cars for about 10 years, and it has served me well. I have plenty of work, and even have to pass on some because I don't have the time. It does help that many of my friends and some of my family drive these cars. God has given me the talents and abilities to do this work, and I really enjoy it. I believe you have been given those same gifts and abilities as well. Do what you enjoy (we can all see that you enjoy doing what you do), and earn some $! There are not many shops that will work on these cars, so you already have a niche market. You can do it! Also, I am sure you have the support of this community.

vwnate1 · #**165** 11-13-2019, 09:20 AM

FWIW, Rich here does good work .

I had him do an AC upgrade and I love it .

He didn't steal the original tool kit, swap my brandy new spare tire for an old bald one or any of the other myriad B.S. I've seen Shops, Dealers and Mechanics do over the years .

He didn't smoke in my car and leave ashes either

.

When you find a Tradesman who enjoys doing the work, stick by them ~ I used to get endless negative comments about my doing careful works on even the battered old $75 VW Beetles that the owners took poor care of, I take pride in every aspect of my work .

I agree that if you have the ability, interest and working location this is a good way to keep your self current and make some good pocket change .

Never, EVER get sideways with the neighbors ~ they'll make your life living hell .