I'm rebuilding an OM617.951!
 

Hi guys and girls,

I'm about a year and a half into rebuilding this engine from a 300SD. I've always wanted to rebuild an engine and it would give me great experience.
I'm a 25yr old Mechanical Engineer so it's good to have hands on experience. The plan is to finish this engine and swap it into a Jeep Wrangler TJ. I want a super- reliable all terrain car that can burn multiple fuels for adventures! It's been a good learning experience and I hope some pictures will help you guys out.

I found this engine on Craigslist for $300. The previous owner said it had 300,000 miles on it, and was low on compression. After deciding to put new rings in it, he stripped one of the head bolts and gave up. It had no manifolds or turbo, but had a few brand new parts and was partially dissasembled. I dove in!

I'm using the Haynes Manual and the Most of the Mercedes 0m617 manual that use to be available on w124performance.com Luckily I printed out what I needed :-)
EDIT: Manual is available here!:http://www.furi-dorifto.com/tech/MB_w124_Manual/W126/Index/617index.html
I'll start from the beginning with pictures. Enjoy!

A re-ocurring theme in this project is stripped bolts. Holy crap. Be prepared to get some splined bolt removers and stripped head sockets.
The stripped head bolt was removed in about 30 minutes by drilling a hole for a splined bolt remover, putting a wrench on it and hammering the top.
If all else fails, I resort to a grinder and vice grips.

With the exception of the piston rings, cylinders and coolant passages, everything was in remarkable shape for the mileage. I was starting to realize what all the praise is about.

I had a machine shop measure my cylinder diameters, they were .0065" over the limit. I ordered 5 new sleeves to go with new rings.
All new bearings were put in, even though the existing ones were in good shape.

Don't forget to mark the flywheel before removing it. An impact gun really helped with these 12pt bolts. I had to use a grinder on three of them.

photo barrage continues..
 

You can see the Piston Rings are worn to pieces. The carbon soot is baked on to the top. The scratches might have come from removing the pistons. I was a bit impatient on grinding down the ridge on the cylinder sleeves. I should have just taken the crankshaft out first.

The bearing cradles have heat marks, but were really smooth so they aren't much cause for concern.

Block Work
 

The journal surfaces on the crankshaft were beautiful.
Next step was block work.
My machine shop charged $422.10 for:
Hot Acid Bath cleaning of block, removal and replacement of new cylinder sleeves, boring of cylinders to spec, and "decking" the top of the block.

It looked so much better afterwards!

Rebuilding gets expensive with these buggers quick tho. :eek: thanks for the share.... never opened a 617 in my time... Yet! Keep up the updates!

Painting the Block and Pistons
 

I used VHT Engine Paint (from Auto Zone) in a primer and Cast Iron finish for the block. I think it came out pretty well. About 2 coats of each. I saw a cool trick on youtube on masking. Just lightly hammer the edges and it cuts the tape perfectly. Your ears will ring, but it's great.

I bought new piston rings by Goetz. Make sure the engraved "TOP" is facing the right way on these! I wouldn't recommend the Harbor Frieght piston ring expander for this. Spend a little more on one.

All my new bearing clearances were good. This is a tedious but necessary task with plastigauge.

Yes it can get pricey. I did some estimating before I started. The skills are worth a lot too. An engine rebuild has been a bucket list thing for me.

Heres a photo with the oil pump put back on with its new chain and tensioner. Next pic is the head gasket ready to go.

I took the head to a different shop to put in 5 new exhaust valve guides, do a 3 angle valve seat cut, vacuum check, and test my springs. This was $205.15. My exhaust valves are now near the limit of thickness. I believe the sodium makes them softer.

That's all the pictures I have for now. I will try to answer your questions but forgive me if it takes a while.

I think I see cracks in your head...

The Haynes manual is like a ten year old waving back an 18 wheel truck - it is well meaning and enthusiastic but at that crucial moment unreliable.

Do not believe the conversions from metric (Nm) to old money until you've checked them. Some of them are wrong. Always check the FSM.

Am I the only one who finds it sad that A he is going through all this work and planning to burn alternative fuels and B is going in a Chrysler product?

Nice thread though.....

I'm planning to repower a Jeep as my w126 body has declined

Welcome to the Forum. :) Hope to see you around here for a long time.

That is a great job you are doing, and thank you for the detailed pictures and step by step as you are putting her together.

Rebuilding a 617 engine gets expensive as you go along, just don`t cut corners and it will last a long time.

I just got my 617 Flywheel matched balanced to the auto one, and resurfaced, that was $100.
Be sure to use new FW Bolt, they are a one time use. I got them for $5.80 each from our MB dealer in Monterey, Ca. Dealer list is $7.25. www.benzpartswholesale.com Jim is one of the parts guys and has been there over 30yrs and quite helpful. FED EX shipping on those would be $9.60 though, :( that is a ways from you. Iam about 25 miles from them. :)

I was excited when the Fed-Ex drove up and delivered them and I wasn`t charged the shipping. :)


Charlie

A 617 rebuild is on my bucket list as well. I have done other engines, but never a 617. Your play-by-play is helpful. Thanks, Rich

Great info, thank you for posting with us.

Nice write up, thank you.

Injection Timing Device
 

Thanks for the feedback guys! Nice to hear it helps.

I bought a extra, incomplete engine for $240 a few months ago. I figured it would pay for itself to replace bolts and parts that may break. I was right!

My om617 came with a rare(?) vacuum pump with two diaphragms. I decided to take the vacuum pump off my parts engine, and that required changing the Injection Timing Device. This went from rotary driven to cam-like driven pump, by changing the faceplates.
I now can use the simple vacuum pump with one "inlet" hose.

Putting it back together was tough. I broke a woodruff key trying to put it together. I used my alternate engine for the spare. There was a design change at some point and this steel bushing went from 2 pieces to 1, or vice versa. It caught the key during install

All new timing chain rails were put in with the original pins. Some of these were very tough to remove. Slide hammers won't cut it. A metric tap set is handy in case these are damaged too.

Another reason to check the FSM...

...Did you check the end float on the intermediate shaft?

If that clearance is too great you end up with dead vacuum pumps.

Great job so far!

There is a custom $350 4x4 "tucked in" oilpan available-might want that for the jeep.

Make sure you get teh pistons, rods, etc. to match each other in weight. Each rotating assembly should be the same for the smoothest engine operaiton.

Consider ditching the vacuum pump-in my opinion it's a pain and a belt driven or electric unit can supply vac to the brakes (see: Ford F350s).

The rear main has a surprise pin in it.

If you want to borrow my MB brand 12pt socket for the head bolts let me know and it's yours for deposit+shipping.

Port the head while it's off-the short side radius and neck closest to the valves are restrictive.

Your valve guides are probably shot (mine were at 220k)

If you want to go crazy performance on the build check out superturbodiesel.

Plan on installing an EGT probe pre-turbo while it's all apart (comes in handy later)

Great work and great prices. Rebuilt engines are an amazing $8000, though I saw an engineer-rebuilt one go for much less on ebay. I am also one of the few to tackle this. My 85 300D engine died at 330K. Some say CA models have problems. Something was bouncing around in #1 cyl, but chunks of piston were missing around the rings, so maybe that was the source and not a piece of ceramic catalyst.

So far all I did was disassemble the engine and put in new liners, but haven't taken it to a shop to deck the block and hone the liners. I read a number of comments here on how to remove the liners, but mostly speculation. I ended up driving a screwdriver down the gap, which ripped the cast-iron, amazingly quick and easy. People even fussed how that could damage the block, but I also am a mechanical engineer so ignored that chatter. I heated the block and chilled the new liners, but still had to work hard with a sledge hammer to get them in (with a thick plate on top). You can tell when they seat on the bottom ridge from the sound. Liners are cheap (I paid $11 ea). Still, you got a great price from the shop.

New pistons are $550 ea, though a place sold a set for ~$800 on ebay a year ago. I got a set of used ones for $100 from a guy here. Some day I expect a manufacturer will step up and make new ones for ~$400/set as you see for rarer U.S. engines (forged). Still you'll never see the $85/"set of 8" you see for small-block Chevy.

Where did you get your heads rebuilt? I wonder if they removed (or replaced) the pre-chambers. That requires a special tool (~$80). Seems most head shops would need to to pressure-check the head against their flat rubber plate (if they could seal the pre-chamber hole). Was it a M-B specialist?

I found a complete repair manual on-line. According to my notes, it was www.toddcomputer.com/Mercedez-manual/300D-repair-manual.html (link no longer works). I recall that you need to use a special anaerobic sealant to attach the aluminum main oil pan (lower block thingy). That sound like high-temp super-glue, but search here. I got a continuous timing chain (no link) off ebay cheap, which is smart when doing a total rebuild like yours. I would have kept the "2 tube" vacuum pump. Rebuild kits are only $12 for it vs $120 for the 1-tube. It does fail more often though. VW's have electric vacuum pumps for brake booster that one might use. My timing chain pins came out fairly easily using the "bolt on stacked washers" trick, but it was a little tedious adding each washer.

I left my engine where its at because I found a used engine on craigslist for $300. I was taking a chance, and figured maybe just good for parts, but it works great. The camshaft looks new from what I see thru the oil filler. No blow-by at all. It is in the car now, but not even driving that car (currently have 7 vehicles for 3 drivers). I'll continue with the 617 engine when I get time.

Re:
 

Hey Simpler=Better! I've had your STD thread bookmarked for months. Very cool build you did.
I'm planning on modifying the steel part of the oil pan for clearance. Merc4x4 has a pan for $265 but I don't want to mail a core. I reused my pistons; my ring lands were in spec. I already had my Head rebuilt and it's torqued down now, but thanks for the offer. I found 12pt bits at Northern Tool.
I've considered the electic vac pump from your thread. Did you use an off the shelf item or a junkyard pump?
What's the benefit of taking EGT pre-turbo?

I haven't settled on an electric vac pump yet (My project is shelved until I get out of my apartment) but there are a bunch of cheap pumps to choose from. I'll probably just use an F350 unit because my only vacuum consumer will be the VNT turbo. (I'm planning on manual brakes, transmission, and climate control)

The pre-turbo EGT is preferred because it's more accurate. If you measure post-turbo it's a delayed reading, and always reads low (est 300* low). If you've got it all apart there is no reason to not tap a hole in the manifold. If you're tight on cash just put in a brass plug for the time being

If I was doing it all again I would have been a *little* more aggressive with the porting and measured each neck to match them (probably another 6 hours) but I got itchy and wanted it back together :p Still, I'm definitely going to flow more than a stock head.

Head Bolting Pictures
 

Pic 1: I noticed an object in the #1 prechamber after it came back from cleaning. After much finagling with picks, I removed a broken glow plug tip.

Pics2-5: Head went on with all new bolts, old washers. Valves have all new seals, and my original springs were in spec.Took my time with this crucial torquing sequence. I labeled bolts with a grease pencil. The final 90deg. torque was a good workout.
Next went the cam shaft, sprocket &timing washer, and the rocker arms.
This about brings me up to date.

*wipes away tear* It's beautiful!

I would recommend timing the pump on the engine stand, it's easier on your back that way.

You probably already know, but use only BOSCH glowplugs with a small amount of high-temp copper antisieze on the threads.

Looks great. I trust you're going to paint it.

Very nice work. I need to do one for my wagon, so you have me thinking about starting it soon.

Great work, I'm right behind you and just ordered most of the parts yesterday. Except for getting new'ish used pistons I was able to shop around and get most everything for $800, but then again I already had a few head bolts from a parts bag that were never used and my core engine was a rebuild that never happened so it had new bearings and rings which can be around $300.

I'll keep watching and I agree, So sad going in a HEEP :) I'm putting mine into a Land Cruiser!!

It looks like the Wayback machine caught your link. I didn't test every sub-link, but it looks like the PDF are there.

300D Repair Manual

Jerry Kemp
1970 IH Scout 800a - soon to be OM617 powered

Can you share a link/URL for that oil pan? I may need one for my IH Scout 800a swap.

Thank you,

Jerry Kemp

Recycled
 

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