Replacement engine - Origins

[Bonnyboy]

Following on the heels of the thread about matching numbers it got me thinking. Does anyone know the process for an engine to become a replacement engine.      I have been told that the engine in my car, Benita the Sleeping Beauty - 69 Euro - is a replacement engine from MB.  We expect that it was replaced sometime in the late 70's early 80's. 

Would it have been a brand new engine  or would they be a rebuilt engine using some new parts or all new parts?  Does anyone know?

ALSO...Anyone from Vancouver remember someone from the Royal Vancouver Yacht club in the early 80's driving a White Pagoda?  I have Royal Vancouver Yacht Club stickers on the soft top and hard top.  It would be nice to get some history.

Ian in North Vancouver BC

[Cees Klumper]

I suppose there were always three alternatives when an engine needed rebuilding: rebuilding the original one, replacing it with some other, previously used, engine, or getting a new replacement engine from the factory. The replacement engines came without a number and the installer could punch in the original engine number (which presumably many did, and so those cars only appear to have the original engine when in fact they do not). Also when another, used (usually sedan) engine was installed, either rebuilt or not, the installer could elect to grind off the original number and punch in the number that was on the original Pagoda engine, something that can still be done today.
Rebuilds can be anything from disassembly, inspection and replacing just a few parts, to replacing everything possible. For example: does one keep the pistons and only replace the rings, or replace both; only grind the valves or replace them; replace or not the crankshaft and camshaft? Sometimes someone will say that the engine was rebuilt when they only did the head and not the block. In any case, there are various tests that can be done to determine the condition of the engine (compression, leakdown).
And it would appear to me that, in days gone, it may have been cheaper to order a new engine from the factory than rebuild the original one, because there are just so many replacement engines around. At least a few years ago, new engines were still available from Mercedes, but they cost close to $30,000 so it's definitely cheaper to rebuild an existing one. It seems like in the old days the price differential was reversed - but is there anyone who has actually ever bought a new factory engine here who could confirm this?

[Atazman]

Hi Cees.....

In answer to your thread....... I did buy a new Mercedes short block for my 250 SL in 1984.  Cost was not bad back then.... about $3500.  I just took my tag off the old engine and saved it.

[Cees Klumper]

Thanks Don!

[49er]

My replacement engine (short block) was "free" as the car was still under it's new car warranty. Best deal of the day:-)

John

[TR]

My '71 280SL also got a new free engine at 21,000 miles.  Not sure what the issue was though.

[49er]

Mine was replaced at the 20241 mile mark and 20 months after delivery. The car had excessive oil consumption. They, MB, reconditioned the valves and seats as well as replacing the engine. Here is a copy of the Work Order and it only took them two days to swap out the engine.

John

[Bonnyboy]

I called Mercedes Benz Classic centre today and John in Parts told me that my number plate on the engine corresponds to the part number for a rebuilt rather than new engine for a European car and that I should remind the suppliers that the engine is a Euro model rather than an engine rebuilt for the American market just incase there is a different part number.  John didn't know off hand what the differences were but suggested that the cam and pistons and related items were probably different for sure.   

Does anyone know what else I should watch for under the hood being a Euro car with a Euro replacement engine. 

Ian in North Vancouver 

[Benz Dr.]

One of the main reasons for engine replacement under MB warranty was due to heavy oil consumption. This was a  MB design problem and it was faster and easier to replace the short block than it was to correct the problem at the dealerships.

Connecting rods in early 280SL engines had a small hole drilled through the big end of the rod on the thrust side of the engine. A smaller hole in the rod bearing that lined up with this larger hole provided for extra oil to be sprayed on to the cylinder wall. Later engines had holes drilled on both sides of the connecting rod to provide for extra oil on both sides of the cylinders, and this is where the problem became so bad that the company replaced some of these engines under warranty. All of the late 280 engines were built without extra oil holes to correct this problem.

 During rebuilding I use bearing shells that have no additional oil holes. The rod bearings currently available do have one small hole in the center of the cap which is used only for oiling the piston pin on early 230SL engines.

The problem arose when the company realised that all of this extra oil from these oil holes was causing the engine to drink oil. They did away with any extra oiling holes and oil consumption dropped to normal levels. Spare short blocks with the revised connecting rods were provided under warranty and the old blocks were reconditioned with the new style rods if the block was still within factory tollerances. Worn blocks wwere probably scrapped. If you ever have a factory replacement block apart, look to see if it has the conecting rods without any oil holes or if the holes are covered by the rod bearings.

 For MB, changing the short block made more sense than rebuilding it due to down time and the fact that the whole bottom end had to come apart. The same effect could be had from simply changing the rod bearings but I imagine they didn't do that as a matter of principal.
 
 

[49er]

Thank you Benz Dr. for educating me! As I recall, I was told by the service manager only that there was a "manufacturing defect" when my block was replaced all those years ago and I was never really sure what that "defect" was and assumed it had something to do with the piston rings. Now I know. The car sure did "drink oil" and the new engine cured that problem.

Thanks again

John