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  #16  
Old 10-19-2022, 09:52 PM
Todd Miller's Avatar
1966 250SE Coupe Owner
 
Join Date: Jul 2005
Location: San Luis Obispo, CA
Posts: 411
You're welcome. I've successfully used auto haus az for a long time, for OEM parts. Rock auto can also be a good source for OEM, or decent quality parts.

Hopefully surfaces aren't warped. There may be small coolant ports that are blocked with corrosion. I'd suggest replacing the thermostat, and using the version rated at 80*C/180*F vs the hotter version that I see some websites recommending as original. I'm not a fan of running higher coolant temps in engines with alloy heads on cast iron blocks, unless it's modern F.I. and the factory requires it for the function of the system. That's just my opinion.

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1966 W111 250SEC:
DB268 Blaugrün/electric sunroof/4 on-the-floor/4.5 V-8 rear axle
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  #17  
Old 10-23-2022, 02:27 AM
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Join Date: Nov 2014
Location: Las Vegas & N. Cal
Posts: 270
Actually when removing the head bolts (1) First clean them as they may have Gunk in the way where you attach your tool ( Compressed air with a rag helps a lot )
(2) Your going to need a Long beaker Bar and hold down on the bolt as you brake it free, you well hear it click Free > Just brake it free don't remove it yet > you want to brake them all free just a little first
(3) Start in the middle and work outward in both directions as you go
(4) once you have broken them free then you can remove all of them.
( if the head of the bolts are damaged you must replace them < > if the Threads are damaged replace / if the bolts are stretched replace .
****************
BEFORE REMOVING THE HEAD :
I suggest placing the Motor on #1 Cylinder up with the timing mark aligned on Crank Pulley < Then > you can look on the Cam Gear for the Marks showing everything is aligned ( Back Side of Gear a I remember & Mark on the CAM ) A Dab or Paint on Cam Gear and Marks will be a Help putting it back together.
At this point you unbolt and tap the Cam Gear Chain attached off the Cam >. your going to need to tie the Timing chain upward to perhaps a stick of wood holding it up
or it will slip down and you will loose your cam timing , I rubber bungee / Zip Ties is a big help here .

Now you can place a Handle on why experience is well worth it
********
Before all of this I would run a screw in gauge compression Test on a warm motor !!!!!! normal is about 150 LBS
Your lucky you can still get ahead Gasket for that motor

Once apart check for a cracked head , any good machine Shop and do that and straighten and resurface the head as necessary for about $300 to $400 not including a valve job

Last edited by aluminum; 10-23-2022 at 02:43 AM.
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  #18  
Old 10-23-2022, 09:51 AM
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Join Date: Jul 2017
Posts: 199
I am going to use the services of a MB mechanic that has a lot of experience with these older engines. It won't be until December that the work will start.

The progression of discovery will first be installed gasket inspection upon head removal. Then possible corrosion or damage from the water passages because of leakage. Unless the head is perfectly straight and there is no indication of temperature damage then an evaluation of the head will indicate if the head can be repaired and/or milled.
Because the the engine has only 85,000 miles my hope is that the bottom end is good enough to go with. If not then I have access to another M130.980 later version engine that could be ground up refurbished or I could just refurbish my engine. Either way its major engine work. I hope I can drive the car another 10 years minimum. In which case its worth it. Cosmetically the car is in very good condition with no rust.
Can you evaluate a bottom end without a compression test? How?
Brad
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  #19  
Old 10-23-2022, 11:21 AM
Todd Miller's Avatar
1966 250SE Coupe Owner
 
Join Date: Jul 2005
Location: San Luis Obispo, CA
Posts: 411
If the engine was good running, with solid oil pressure instantly on start up, and during hot idle, you have good crankshaft bearings, and good rod bearings. So if that's the case, you can assume that's all good. Wet and dry compression tests will show condition of compression rings, but not oil control rings, as well as how well the valves are sealing against the head (if the wet compression number increases substantially, you know the compression rings are leaking air pressure).

If this were mine, I'd remove the head and ship it to Metric Motors in SoCal.... unless I had an amazing machine shop locally. I'd purchase a straight edge from the Snap-On tool guy and check my block for being straight, and if it was fine, I'd wait for the head to be finished. Head gaskets and valve cover gaskets, etc are readily available from all of the common online sources like auto haus az and rock auto.

I'm glad you're having a knowledgeable MB tech do the work. It's kind of a tough job due to the size and location of the head, and the timing chain situation can be dicey because it's easy to have the chain come off the fuel injection pump sprocket and knock the pump timing out of wack. So you think you have it all back together, and the engine won't start, or runs poorly, and you can't figure out why.....oops, lost the pump timing!

While you have it torn down, it wouldn't be a bad idea to replace the engine mounts (the right side takes the mount with the red dot of paint on it, because that's the version made with harder rubber. You can probably use 2 red-dot mount though. Replace that little front engine strut, down low, and consider replacing the transmission mount and it's boot. Also take a peek at the fuel injection pivot plates and their 3 bushings up on top of the intake manifold. There is one nylon bushing, out in the open, and 2 bronze bushings pressed into the pivot shaft area of each plate. These like to wear, and it creates a bunch of play, resulting in inaccurate timing between the throttle plate and the mechanical injection pump. If you have no play, great. But if there's play, a set of bushings, and resetting the linkage rods if needed, will actually improve the engine performance very noticeably. There's one more pivot point on that same side of the engine block. If that one is worn, you replace the pivot bolt, the metal bellcrank plate, and the bushings. All of this stuff is still currently available from Mercedes.

Looking forward to hearing about your progress.
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1966 W111 250SEC:
DB268 Blaugrün/electric sunroof/4 on-the-floor/4.5 V-8 rear axle
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  #20  
Old 10-29-2022, 09:01 AM
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Join Date: Jul 2017
Posts: 199
Todd,
Thank you for your thoughtful reply.
Fortunately I replaced all rubber components on this car three years ago so I am good to go on all mounts. I will take the opportunity to run down a couple of pesky oil leaks. Not from the head gasket though.
The engine will be evaluated when its disassembled.
I will be taking the opportunity to switch out the Bosch FIP. I have a freshly rebuilt and calibrated R24Y pump with a space cam from an R22 that has been calibrated to R22 specs.
Also going to convert the distributor to a 123 Ignition programmable and convert to a vacuum load advance from the throttle body. I want to use as much advance as possible while having the ability to back off the timing from the phone app if needed to accommodate lower octane fuel.
Brad

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