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Your machinist suppose to measure pistons, add clearance and hone individually for each piston size. In my case i had this size because i had original MB pistons with racing coating by professional company.
How much clearence you would recommend for this engine?
@arsupisemnet I have one more question, if You would be kind enough to help me. I know some of my questions sound stupid to a professional, but I want to be sure about proper way of doing the rebuild, so that I'm sure my mechanic did all of it as it should be.
So now, the question(s):
Ive got the 41930CP rings. There are three sets of rings and my question is which one goes where. I also have a set of original MB rings.
So my understanding is these should be used as it goes from piston crown to bottom:
1. 41930CP rings (black side or silver side?)
2. 41930CP rings (black side or silver side?)
3. OEM MB oil spring rings - what about top and bottom oil ring? OEM MB or 41930CP?
This is not a first time i hear but it is a case when you have reasonable doubt in case with using Plastigauge. Last main journal been freeze tight (when you need to apply some torque to move crank, once it turned it is spinning with small effort). Plastigauge shows that i have 0.001 inch clearance, there dial says "nope" you tight as a tight could be...
Waiting on new set of main bearings. Will try either use stock uncoated or only coated lower halves (the ones caring load) depends on the measurements. Based on what i see crankshaft has a no wear at all
I have problem with my Mercedes dealer spare part guy
I wanted to buy new main bearings and they wanted to know what size/ colour is crank
Am I correct,that G-G-G-G-G marking on crank means yellow 54 colour?
They say ggggg is not size mark
I measured crank today.After polishing size is:
63.945
Doesn't matter, both the same size, spacer is thinner on MB. You keep old spacer from whatever rings you have and instal outside scrapers from new kit.
Upper halves sizes stamped on the block. Lower halves sizes laser etched on front of the crankshaft. G stands for Gelb which is yellow in german that gives you bearing color and coding
I am looking for a shop that would do exactly the job shown by Asurpisemnet.
I have two badly overheated m278 motors, the second was supposed to be a good replacement…
I called many machine shops around here, all refused. They seem to specialise in certain work (marine engines, elevators, etc.) and therefore refuse any other.
Anyone knows a machine shop that would undertake such a repair? I have two engines like that, the second one was supposed to be a good replacement..
Alternatively, anyone has any experience with the Chinese imports? Apparently, they are currently producing a vehicle that looks like Jeep, but has innards of 2013 MB GL 450, so new M278 engines are produced there. https://handwiki.org/wiki/Engineering:BAIC_BJ90
To sleeve your block with cast iron sleeves 2000, if you want ductile iron sleeves it is 3200, to put motor together 700, to rework heads 350 each including surfacing. You would need MB main and connecting rod bearing at about 100 each set, head gaskets at about 150 each, we might reuse your head bolts based on condition, short block gaskets and seals at about 200. Piston rings at about 100. For pistons either you can use original without scoring at about 50 to recondition and apply coating, and replace scored ones with used of ebay (at about 150 piece plus 50 to recondition), or a new ones for about 400 a piece (not fake chinese pistons off ebay). I do have assembled short block available for 6k, however the price reflects by the price of the components used and core.
Thanks, that is comparable with what a new Chinese engine would cost including shipment, based on quotes I got from Alibaba suppliers so far.
I have two full cores, both badly overheated, with all scratched cylinders (based on scoping photos). What would be the logistics? Should I send you both to pick and choose good components from both to make one?
How about camshafts, particularly exhaust ones? I think You mentioned them only in passing, how difficult is to get a good one on eBay.
Well, logistics is extremely simple. Put both engines on pallet and ship to machine shop address (with forklift) where i do custom work. I will pull both apart and will source all the better parts from it, you might have all 8 pistons will less to no wear (it is not the rule to have all of the damaged usually have 2 or 3 out), or camshafts with minimal wear needed only polishing, which makes things easier for you (you just pay for reconditioning and coating in pro shop where they coat racing pistons). While waiting on coating i will sleeve your block and pre-bore (usually 0.005 inch less final size) and once pistons ready will assign and hone individually to each cylinder. Sleeves will be flanged and since both engines went hot i will put flanges about 0.020 inch above cylinder sufrace and deck it to the height of block exterior walls (exactly, since i know that your existing cylinder walls collapsed from temperature). For the heads same thing - pull all apart, choose better parts, regrind valves, cut seats, replace guides if needed, put new seals, surface heads and put all together.
Last edited by arsupisemnet; 04-20-2023 at 09:20 PM.
Curious on what your turn around time is on an M278 rebuild? Cylinder 1 on my 13' E550 is badly pitted and scored. I'm weighing my options to see if its worth even rebuilding or just biting the bullet and selling the whole vehicle as a parts car.
I can turn things in under two week based parts availability. Personally if you don't inclined toward keeping car around i would just recommend to put it on Copart, without saying that you have engine issues, will be Run and Drive, so bunch of used crap dealers will ****** it for good price.
To sleeve your block with cast iron sleeves 2000, if you want ductile iron sleeves it is 3200, to put motor together 700, to rework heads 350 each including surfacing. You would need MB main and connecting rod bearing at about 100 each set, head gaskets at about 150 each, we might reuse your head bolts based on condition, short block gaskets and seals at about 200. Piston rings at about 100. For pistons either you can use original without scoring at about 50 to recondition and apply coating, and replace scored ones with used of ebay (at about 150 piece plus 50 to recondition), or a new ones for about 400 a piece (not fake chinese pistons off ebay). I do have assembled short block available for 6k, however the price reflects by the price of the components used and core.
What kind of surfacing are you doing to the heads? Given that timing is chain driven, would taking off material not shorten the distance between the crank and the cams, ie; throw codes?
Hi, I went through this entire thread and first of all thumbs up, great job on this engine, outstanding write up, it was very interesting the entire story beginning to end.
Well, I was wondering where I could get in touch with you to send you pictures and more details about the engine I am trying to get repaired.
Thank you
Originally Posted by arsupisemnet
I am going to follow another M278 complete custom rebuild. Donor is a "coffee table" by some of the forum members with about 40k of mileage.
[QUOTE=arsupisemnet;8813793]It cost me nothing, I do machine work myself[/QUOT]
Nice work! Just curious, will you offer your service to members? I’m thinking of drop in a basic sleeves for my engine. Not looking to build for high horse power. No machine in my state is willing to do the drop in sleeves.
03-30-2023, 10:21 AM
