1985 300SD shop "truck" daily driver 5 speed project - Page 5 - PeachParts Mercedes-Benz Forum

rwd4evr · #1 01-12-2021, 07:34 PM

Dead and rusted. Om603 is wasted, it was hurt and I pushed it hard to see how the pyrometer was working. 600+C° not good it seems. Broken ring or piston. It still runs but it's spewing out of any where it can, lots of oil some water too. I was preparing to put the om606 and 6 speed in it but once on the lift I just can't justify the time and effort on this car. It's really a mess. Rust holding hands. This car is donating it's front suspension and all brand new brakes and parts of its rear subframe to my w123 wagon build I'm going forward with now. I may revisit this truck thread if another car comes along that suits it but it's on hold. Going to start a build thread on the wagon since it's A LOT of mods and custom work planned out already.

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rwd4evr · #2 02-08-2021, 12:45 AM

So the original 300SD this thread was about is on my lift with a very serious rod knock. I picked up a replacement om617 at the pick a part junk yard from a very nice looking 83 300sd that had some strange front rocker and inner fender damage. Not sure if it was yard induced damage or why the car was there. No info on a vin search from auctions or municipal towing so it was a total crap shoot. Got 5 good compression hits hand spinning it so said f-it I'll take my chances. got it fired up last night strapped to a pallet. Seems very healthy. I'm going to turn up the fuel while it's out and set the timing and valves. Also going to check the auto flywheel balance and the 240d manual balance since it's getting 4 speed manual swapped while it's all out. Just lucked into a 280slc rear drives shaft and a 300se front driveshaft working out to be the correct length. The center bearing mount needs to be relocated forward about 6 inches but otherwise will be all stock parts.

https://youtu.be/R2c1TJtV0YQ

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rwd4evr · #3 02-09-2021, 12:58 AM

Woo hoo! Successfully dug further into a Mercedes diesel than I ever have. Opened up the injection pump and cranked the fuel screw all the way in. Readjusted the throttle stop and shutoff and reinstalled the oil filter housing. Happy to say the engine fired right up after and didn't run away or anything like that. Truthfully there is a little part of me that wishes I got the chance to see how much better the car is with just a stock motor and a manual.... But I don't imagine its an earth changing power upgrade just turning the fuel screw.
New center bearing coming Wednesday and taking the flywheel to the machine shop to be match balanced tomorrow.

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mike280 · #4 02-10-2021, 06:20 AM

Nice cars.
crank the pump

rwd4evr · #5 02-10-2021, 01:20 PM

Quote:

Originally Posted by mike280

Nice cars.
crank the pump

It's cranked. I'm being advised to turn up the torque capsule 1-1.25 turns as well. I'm a little nervous about doing multiple things at once. Especially on a basically unknown engine. Sure it starts and seems to run fine but I really don't know what it's going to do under load at all.

https://youtu.be/R2c1TJtV0YQ

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rwd4evr · #6 02-10-2021, 02:09 PM

Waiting on the flywheel. The 240d manual flywheel shows a .25Ooz imbalance on my wheel balancer. It's the smallest number so I don't know the exact number. The auto flywheel has a 35mm hole and I don't have a small enough mandrel so I don't know what it is. The 240d manual flywheel is getting resurfacing and match balanced to the auto imbalance. I'm building a clutch pedal to add to the auto pedal bracket which is identical to the manual besides an extension on the pedal axle which I'll turn on my lathe and run a bolt through the original hollow axle. I considered pressing it out and pressing a new one in but I don't think it's necessary. A 14mm bolt fits perfectly in the existing axle and is not going to bend or break with the stresses it sees. W123 pedal would bolt in with little issue but I need them for another car anyway. The w126 pedal I'm copying doesn't belong to me.

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rwd4evr · #7 02-11-2021, 01:38 AM

More progress. Clutch pedal axle taken care of. I drilled the existing hollow brake pedal axle out to put a 10mm bolt through, and turned a sleeve to fit it and some 16mm bronze bushings I had from an exercise machine. Using the tube for the top of the pedal too. I got the 1/8" steel cut to shape for the pedal. It needs two bends and two studs installed plus the foot pad. It will also be gusseted with a plate on top from the bushing tube wrapped around the upper bend and down the face of the pedal. Probably Overkill but it will be getting some clutch kicks for sure.

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rwd4evr · #8 02-11-2021, 07:58 PM

Picked up the flywheel today... Ouch. 285$ for the match balance and a resurfacing. It was pretty far off. 14g and 120° from the auto flywheel. Om616 being 4 and the 617 being 5 would make sense. So I guess it really is a good idea to have it done. Got my new centerbearing also. I'm aiming to have it driving in one week.

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rwd4evr · #9 02-14-2021, 04:10 AM

Had a couple hours to work on the pedal today. Almost done. Have to add studs for the master pushrod and overcenter spring pushrod, a full release stop tab and a couple braces.

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rwd4evr · #10 02-17-2021, 06:41 AM

Oh yeah! Didn't put a foot pedal on yet. I may get some aluminum ones so I'm waiting a minute. Also so close to out of welding gas it may run out mid weld. But all done otherwise. Super sturdy. Very happy with it.

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rwd4evr · #11 02-21-2021, 05:52 AM

All done. Turned the bump stops from nylon block I had. Up travel stop is adjustable to be sure it sits right and releases the master all the way. It won't bleed or work correctly if it doesn't. Almost bought pedals then though about it and made my own. Why stop at just the pedal arm? Counter sunk the holes and curved the pedal surface. Turned out nice. Just needs some paint.

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rwd4evr · #12 02-23-2021, 12:34 PM

Been tied up with other stuff but got this done last night. Turbo 617 with a clutch. Been dreaming about this for a very long time.

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HughO · #13 02-25-2021, 01:41 PM

Quote:

Originally Posted by rwd4evr

I am tired of 12-18 mpg in my v8 mountaineer. It rides ****ty and handles bad. I need a wagon or pickup and wont deal with a w124 gas car though. So I picked up a prettty decent 300sd dirt cheap and have some plans. I have most of the info I need but I need some opinions and real world experience if possible.
The plan is to swap in an AX15 5 speed from a dodge Dakota. I have the adapter kit intended to put a om617 in a jeep. The gear ratios are almost identical in the transmissions plus a .79 OD in the ax15. I will be doing some towing with the car as much as a car in flat tow or a dolly, probably not a car on a trailer. It weighs almost as much as my mountaineer and has better brakes and suspension so I'm not concerned with that. It's not hard to build a class 3 hitch into the rear structure. I will also probably down the road a bit be chopping the back roof off and welding the rear doors shut to make it a pickup. A early s10 cap will fit pretty well.
So my questions are about power and gearing. Has anyone done any towing (or driving for that matter)with a turbo 617 with the 2.88 factory rear axle ratio changed? I have 3.07, 3.23, and 3.69 differentials available. 3.69 is dumb since it would actually end up as a 2.91 final with od. All the gear change threads I've found are NA cars and have power issues. I had s 85 300TDt which felt like it had plenty of power to pull more gear on the highway. So I could go with a 3.07 to get a little more off the line and considerable reduction in highway rpm or 3.23 which has a lsd(really makes me lean this way) and would really help with off the line towing my drift car or parts cars and would still reduce higway rpm with a 2.55 final drive in 5th. The only problem I'm worried about is if it can't pull od on the higway with a load in 5th I'll be increasing cruise rpm havling to run 4 th. So at that point should I just leave the stock gearing and get awesome everyday mileage and probably have to run 4th on the highway?
On top of that how about practical power increase in a om 617? I remember years ago hearing about larger elements being installed in a NA300d om617(which I have). Any input would be great. I miss driving a Mercedes everyday so it's time.

Economically and practically, projects like this never make sense. We do projects like this for the interest and challenge. If you rarely tow you buy a used 20 or 30 yr old chev or F150 for a grand or two. You drive the MB the rest of the time. Both were designed for a specific purpose and repurposing rarely is worth the time or money and resale will be near zero. Just my two bits.

rwd4evr · #14 02-25-2021, 08:02 PM

Quote:

Originally Posted by HughO

Economically and practically, projects like this never make sense. We do projects like this for the interest and challenge. If you rarely tow you buy a used 20 or 30 yr old chev or F150 for a grand or two. You drive the MB the rest of the time. Both were designed for a specific purpose and repurposing rarely is worth the time or money and resale will be near zero. Just my two bits.

I tow on a fairly regular basis and I have a Mercedes salvage yard and parts sales business. When I'm not towing there's a good chance I need room for large parts. I can drive my mountaineer and use it for both if I need to but like I said at the very beginning of this thread, it rides ****y and gets less than great mileage. I don't really pay for diesel most of the time and a great handling fun to drive car that does the same thing as my truck absolutely makes sense. So I have about $1600 total in the 4 speed swap from a beautifully restored but tragically wrecked 240d, the car, the fresh motor and the flywheel work. I'll be putting it together so I'm not worried about reliability. It runs on free(ish) fuel I make. How do you figure it's not economical? If it tows my drift car or my utility trailer it does the same thing my truck does so how's it not practical? My 300sdl did this job perfectly but had a clutch fan fail and it hurt the motor. If it wasn't a rusty mess I would've swapped that for the extra wheelbase and bigger rear doors.
Would it be practical for someone paying for work on thier car or having it built? No. My mechanical and fabrication skills are quite a bit higher than most tinkerers so I really can do just about anything myself with enough time. Plus learning to do anything just adds onto my skills list for the future.
Resale? Have you seen how worthless a w126 is lately? My 4 speed car will be worth way more than a stock beater level 300sd if I ever decided to sell it.
I have 10 different Mercedes I can get in and drive if I want to but one that can tow and rip down a twisty road or get a couple hundred pounds of crap throw in the back is what I want to drive every day. At least until my 300+hp 6 speed wagon is done.

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rwd4evr · #15 03-11-2021, 04:20 AM

Big progress in the last two days. Motor and trans are in the car mounted up. Found a 280se manual trans crossmember I forgot I had. Perfect fit. Mocked up the DS and the length is perfectly acceptable. It's got about 3/4 inch of splines exposed at the center jont but that leaves 1.5 engaged. Went to mount the shifter and that stupid white plastic always fail end cap/bushing/spring retainer was missing from the 240d shifter when I got it. Didn't have one and wasn't about to wait to order a piece of garbage that will fail after 5 years anyway so I turned one on the lathe from aluminum and inserted a uhmw liner in it. So this was Tuesday, got the shifter installed after massacring the console for every part basically to be able to wiggle it around enough to squeeze the old Auto shifter out and drop the new manual shifter in. Phone was dead unfortunately.
So today I got started a little late and replaced the center bearing on the 280 SLC drive shaft rear half that I'm using which I then used to figure out a mounting set up for the center bearing which was now like 6 in or so further forward. I had planned on welding in new mounts or possibly picking the spot welds from the old mount and relocating it, I then realize that I would probably end up with an inferno in my car up on the lift after welding on the transmission tunnel, and I wasn't about to pull the carpet out of this thing. So I made a couple of brackets out of angle iron that bolt to the stock brackets and run up the transmission tunnel and a bolt in ahead of its new location with nutserts. They worked out very nicely and it's fully reversible(never gonna happen). The last bit of fabrication for tomorrow will be extending the shift rods 48mm. Should be ready to or close at least to running tomorrow night. I want to shake it all down Friday night delivering some pizza. It's my favorite way to fish out problems that are easy to deal with around town. Worst case I call a friend to tow me.