I'm rebuilding an OM617.951! - PeachParts Mercedes-Benz Forum

navery · #1 09-19-2013, 08:41 PM

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!

navery · #2 09-19-2013, 08:59 PM

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.

navery · #3 09-19-2013, 09:09 PM

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.

navery · #4 09-19-2013, 09:19 PM

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.

navery · #5 09-19-2013, 09:29 PM

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!

jake12tech · #6 09-19-2013, 09:42 PM

Rebuilding gets expensive with these buggers quick tho.

thanks for the share.... never opened a 617 in my time... Yet! Keep up the updates!

navery · #7 09-19-2013, 09:43 PM

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.

navery · #8 09-19-2013, 10:05 PM

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.

vstech · #9 09-19-2013, 11:16 PM

I think I see cracks in your head...

Stretch · #10 09-20-2013, 12:31 AM

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.

cooljjay · #11 09-20-2013, 01:34 AM

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.....

oldsinner111 · #12 09-20-2013, 08:28 AM

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

charmalu · #13 09-20-2013, 11:40 AM

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