1976 240d w115 has been sitting and is locked.

[Todd Miller]

Examine the head gasket, and post photos of it. You want to make sure it wasn't blown, and having 2 center pistons rusted would typically mean the engine was overheated, the head warped and lifted in the middle, and that's how the water got in. Yes, I understand you found a rodent nest, but you still need to do your due diligence.

Unbolt the rods from the crank(for those 2 cylinders). See if you can get the crank to rotate into a position that the rods can be moved clear of the crank. Or at the least, that the crank is far enough away from the rod (one rod at a time) that you can use a wood block, and pound the piston downward just a little. The goal here is that you get the piston(s) down, out of the rust. Then you use a flex hone (ball turd hone) and your PB Blaster, and you hone away the rust, clean the cylinder with more PB, and then push the piston up and out of the block. DO NOT hammer directly on the pistons or the rods. Use wood blocks, wood dowels, etc. Diesel piston tops are very strong, so you have that going for you. Prior to hammering on the bottom of the rod, pop the bearing shell out, so that you can strike the center of the rod where the shell was.

You can also heat the pistons with a propane torch. Don't get them too hot. As they cool, they'll pull down the 50/50 mix that I mentioned above, and help them free up.

Take your time here, because with finesse, you COULD save this situation. If you get all HELL YA about it, you'll break something really expensive, and then be completely screwed. These are very expensive engines to work on.

[C4rest]

The head gasket is not blown. I just very closely inspected it. The previous owner also said they parked it running 10 years ago. 138,000 miles. The engine is still in the car. When I pulled off the lower oil pan I remember Not being able to reach cylinder 4, but I could be wrong. To do this would I have to pull the engine?

[C4rest]

I will post photos of the head gasket tomorrow as It is dark out. Thank you very much for your time.

[Todd Miller]

You can leave rods #1 and #4 connected. You need to get #2 and #3 away from the crank if possible so that you can pound the pistons down, out of the rust. You'll remove both rod caps and then try to rotate the crankshaft to move it away from one of the rods. If successful, stop, and go through the process of tapping that piston downward.

I forgot to mention that you need to put a sleeve over the rod cap bolts or they will damage the crank journal. Auto parts stores sell these, or you can use clear PVC hose from the hardware store. Protect that crank at all costs because if you nick a crank bearing journal, you're screwed. Mark the rod caps for which way they were installed, and which rod they came from.

[Sugar Bear]

Sorry to hear you didn't luck out on this, I was hoping Todd would be wrong for your sake but he is correct. Todd's advice to use finesse is crucial as some parts e.g., pistons may be reusable. Options which depend upon parts availability and machining procedures available to you are:

1: If the cylinder cleans up well with a glaze breaker and hone and it isn't tapered excessively you might be able to replace just the rings.

2. If the pistons are good and std liners are available you could have new liners installed and reuse the pistons with new rings.

3. If oversize pistons are available and 0.5mm would clean the bore the sleeves could be bored for the first oversize repair pistons. I did this option on a 240D with great results.

Going to have to figure out exactly what is needed and see what is available.

A used engine is an option but it's also a gamble unless you know the source or you get to hear it run and do a compression test.

Good luck!!!

[C4rest]

Yes it definitely is a bummer but I surely won’t give up and use patience. When I have a chance I will pull the lower pan out and see if I can reach the connecting rods for culling 2 and 3. If I can’t I guess I will pull the engine. Do any of you guys have any good sources for buying new parts or is it really hard?

[Todd Miller]

Sometimes you can get stuff on auto haus az and r0ck auto But I don't know about engine parts any more.

Metric Motors in Calabasas, CA is ground zero for building Mercedes engines, but I don't know if they sell parts.

Since you have so much of the engine torn down, you might as well remove it. I think that will be faster than fighting with the 2 piece oil pan.

[Sugar Bear]

Search on 1976 240D cylinder liners, about $30 each plus machine shop costs. New liners would be like starting over if the pistons are good. You may even be able to reuse the bearings if they are excellent AND they go back in the exact position from which they came.

Good luck!!!

[C4rest]

I think i’ll pull the engine inspect closer. I might try to spin the engine backwards too.

[aluminum]

Disassembly :
Most Likely You will ruin the entire motor if you don't free up the Motor * FIRST * so that it turns before "any disassembly " : Only turn it Clockwise looking from the Front of Motor / All removed Connecting Rod " Caps " must be returned to the same exact Rod
/ Same with any removed Main Bering Caps ( you can number such caps & Rods with punch marks )
* Most likely< if the head gasket did not > leak water into cylinders and the head is not Cracked then Moisture came into the cylinders Via the open Valves of those cylinders from the Manifold or Rat / Mouse Piss lol *
Use a long ( like 12 inches ) hard wood to knock out Pistons from bottom( like oak or old Hammer handle )
/ Place rubber tubing on Rod Cap Studs protecting Crankshaft.
/ If piston only go's up a little is ok to knock it back down and try again with ATF in cylinder until you knock it out ( if you can )
Note a Used Motor is much less then to rebuild the entire motor
****************
At this point if you get it apart without ruining the motor you can *Hone out *those Cylinders ( after learning the correct honing technique ) Then you can inspect the Cylinder Walls , Pitting Etc to see it it they can still be used.
A Patch Job is a bad Idea : at very least all new piston rings ( they install a certain way ) , Perhaps 2 pistons , hone all cylinders , Resurface Cylinder head , Valve job with new at least intake Guides and all new seals , Clean Oil pump Screen , Oil Pan , / Don't forget the Injection Pump most likely all gummed up / Fuel Pumps / Fuel Lines / Fuel Tank >
< Injector Pump info > https://www.benzworld.org/threads/what-type-injector-pump-1976-240d-w115-has.1692574/
Still want to do the Job ? a Shop would charge more then the car is worth > a DIT cost about $200 to $700 at a good price < to be determined after tear down >
Heck just the Head work depending on what machine shop quotes you could range from that amount V Grind> Re Surface> Install Guides seals Etc / Why that much ? because its work that requires Years of experience and costly tools
and to take a Good part of the day just for the head work alone is normal / Welcome to the newly indued costs from The Fed Chair creating inflation.
Good luck with your project ( Your going to need it )

[C4rest]

I still have not been able to get it to turn over. I haven’t spent to much time at it yet though. I have ATF and acetone on the cylinders now. I looked around a little for a used engine but I did not see any for sale. Where would be the best place to look for one?

[Todd Miller]

Mmm...my post from yesterday isn't here. I must have hit wrong button.

Here's how I'd approach this (which is how I've been offering advice already):

You definitely WILL get the engine to rotate. The difficulty at this point, is that due to the style of the upper oil pan, you can't really get to the middle connecting rods. If you could get to them and disco them from the crank, you'd be pretty golden.

So given that little snag, I start thinking about "time to remove the engine" vs. "time to continue to fight it...and still have to remove it." Especially since you have so much of the upper engine apart, which gives you easier access to certain parts of the removal process. IMO, it's time to take advantage of the time already spent, and just take the engine out.

Once out, you can either put it in an engine stand, or lay it on a sheet of plywood. A shipping pallet also makes a really nice place to lay an engine and work on it for tear down. You can also build an engine on these.

With the engine out, you can pop the pan off, mark, remove, and protect those con rods, rotate the crank out of the way, per cylinder you want to work on, and then give that related piston, a few smacks with a large ball peen hammer, and block of wood. The larger the surface area of the wood against the piston top, the better you'll transfer a lot of energy, safely. Drive the piston down out of the swollen rust area. Use a flex hone on a variable speed drill, with a bunch of WD-40 as cleaning solvent, and hone the rust out of the way. Clean the area with rags and lot of carb cleaner, and then spray it down with your PB Blaster. The piston can now be tapped out, from the underside, with a large diameter dowel, either striking the big end of the con rod (slip the con rod bearing shell out first), or by reach up into the piston and finding a spot along the wrist pin. Repeat for the other piston.

If for some reason, one or both pistons won't budge (but I think they will), you can break them apart with a chisel, from the top. This will suck to do, and is a last resort. Be very careful not to strike the top of the block, or the cylinder walls.

Once you have both pistons out, repeat the WD-40 honing process and cleaning, re-oiling process, and you'll have a good idea of the condition of those cylinders.

A little tip on running a flex hone. Initially for the rust removal, you can just leave the hone in one place, and barely move it up and down. You're just knocking out the rust build up at this point. When you go back after the pistons are out, you want to use a moderately rapid "up-and-down" motion, so that the hone lines you see in the layer of PB Blaster, are starting to look like 45 degree angle X marks. If you go too slow, your marking will just look like lines going around the circumference of the cylinder. If you go too fast, your X pattern will be much steeper than a 45.

[C4rest]

Thanks Todd, I am going to try this. I’m getting a hoist on thursday and i’ll try to pull the engine Saturday. I’ve had you mixture on the cylinders for several days but between school and work haven’t really had time to check on it. I will take my time and try this. Any tips on what not to do when removing the engine, or just loosen the bolts and pull it out? ��

[Sugar Bear]

Manual or automatic transmission? AC car?

There is a fair chance the driveshaft halves will separate during this adventure. Match mark the alignment of the halves in the beginning.

Been thinking about this and it may be crazy but here goes...As Todd mentioned the pistons might be reusable, if the engine is out and if you are able to get the crankshaft out depending on the rod cap positions, line the cylinder wall of the stuck pistons with insulating material e.g., styrofoam or layers of towels and pack the cylinder with ice on top of the piston to cool/shrink it before tapping on it to drive it out.

Disclaimer...I said it may be crazy ��...

Good luck!!!

[Todd Miller]

Originally Posted by C4rest

Thanks Todd, I am going to try this. I’m getting a hoist on thursday and i’ll try to pull the engine Saturday. I’ve had you mixture on the cylinders for several days but between school and work haven’t really had time to check on it. I will take my time and try this. Any tips on what not to do when removing the engine, or just loosen the bolts and pull it out? ��

You're education should always come first sir!

Come up with a way to support the transmission with the engine out of the car, before you remove the engine. Because the transmission has a rear mount, and a driveshaft at the back, it's fairly stable, and not very heavy. Simply hanging it from bailing wire, from above (board laid across the fender tops, or some locations on the firewall) is all you'll need.

You can use the head bolts, threaded fully into the block, to hang the engine from the hoist and lift it.

So.....remove the bolts for the 2 engine mounts and the engine will just be sitting there. Remove hoses, linkage rod, fuel lines, actuation cables, etc. from the engine. If you work in a clockwise manner, and work from the top, down, you'll have a better chance of not missing anything. Remove the radiator so that you don't bash it, and so the engine can come forward, away from the transmission, in order to get the flywheel and clutch assembly out of the transmission bell housing.

Be careful about what you spill on a concrete floor, if that's where you're working, and never put anything down on the floor to stand on, because either way, you risk leaning over the fender, having your feet kick out from under you, and falling face first into the engine.

Remove the remaining bolts from the transmission-to-engine connection at the bell housing, get the bell housing wired up to the firewall or whatever you want, in order to support the transmission, get the engine hoist hooked up, apply just a slight amount of lift, and then start pulling and rocking the engine, in order to drag the clutch off the transmission input shaft. Try to keep the engine and trans level to each other during this, because you don't want the end of the trans shaft to damage the pilot bearing in the rear of the crankshaft.

Once the engine is free it can be moved forward enough to clear everything, and lifted out. Sometimes the hood can just be raised up out of the way, if your chains to the engine aren't too long. Other times, it's better to get help, and remove the hood.

I like the idea of icing the piston tops in order to shrink them!

Personally, I would not remove the crankshaft (yet). Just take that upper pan off, mark and remove the #2 and #3 conrod end caps, put protectors on their bolts, and slide the bearing shells out. Once the rods are not bolted to the crank, grab the flywheel and see if you can rotate the crank away from one or both rods, in order to get the rod(s) to be free enough to worked with, as we've been talking about. If you can get a rod freed, make that the first piston you remove. This will make more sense as you are getting things apart and see how it all is together.