Replacement engine block for a 1970 280sl

[mjc7989]

My 1970 280sl has been performing sluggishly for some time. I took it into my mechanic for a compression test, and it was determined that one of the cylinders was basically dead. After removing the cylinder head and examining the block, it was evident that a previous owner had bored out the engine at least twice. As a result the cylinders were very loose and in fact the "dead" cylinder had half of the ring sheered off of it. The other cylinders were also so loose that they have recommended replacing the engine block completely. The cylinder head is fine and in good shape, so I intend to reuse it. my question though is the following:

1. Can I replace the block with an engine block from a 1970 Mercedes 280 SEL? Does it matter that chassis number are different W108 instead of W113? Will the block fit?

2. If the block is not from a 1970 280sl, will the value of the car be affected?

3. Are other Mercedes fuel injected engine blocks from models from the same era, 1970, 1971 essentially able to be used in the 280sl?

4. There are a lot more options to obtain blocks from other donor vehicles other than Pagodas. Does anyone have a sense of what a fair price is for a complete engine, or separately, just for the block itself?

 Many thanks!

[stickandrudderman]

The short answer is yes, you can use the block from the 280SE.
You'll find the search function very revealing........

[Shvegel]

I don't think value will be affected between a replacement 280SL block and the SE block. However, the value of not having the original block the car was delivered with will be effected.  I would recommend having your mechanic cut the corner off the old block where the serial number is. That way if you or someone else should ever want to stamp a correct  block with the serial number off the original block you will have a pattern for finding the proper stamps.  Of course this is frowned upon but it does happen nonetheless. 

[mjc7989]

I appreciate the responses and suggestions. I would never have thought of preserving the original serial number, but will certainly do so now.
 Thanks again!

[ja17]

You will also have to change some items over from your SL engine..................tachometer drive gear misc, aluminum engine mount supports. front crankshaft pulleys etc.  No big deal. The 280SL and the 280SE engines of the era a basically the same. However the early and late 280 series engines are different from each other no matter if they are an SL or SE.  There is an early version and a late. You must keep the correct head with the correct block. An experienced eye can see the difference just by looking at the head or engine.  Otherwise you may have to research the engine number to make sure it is compatible with your head before you do the switch. As mentioned there is a lot of already posted details on this subject. Take a look and get back with us with more questions.

[garymand]

I can understand why they might want to replacce the block, but with what? I can understand a rebuilt short block by a knowledgeble pro builder who understands these motors.  Finding a used 280 short block -in good enough shape just to swap it out is highly unlikely.  That is an enormous amount of work to put back a tired nearly worn-out short block.  I hope you mech doesn't think that is easier and less expensive that sending you block out to a machine shop and buying new oversized piston and ring set. 

How many miles are on the block?  if it is less than 200K, I doubt it has been oversized twice.  sounds more like just rings were put in and the gaps are so big, it was out of spec to start with.  These tolerances are not like what ordinary mechanics are used to.  There is a lot of reading here on rebuilding tolerances and the importance of having no ridge or going oversize if you do. 

[Shvegel]

If there is any question as to the skill of your mechanic then have a machinist come over and measure it.  It does seem odd that second oversize has been reached.

[luke-44]

Hello to all and my first posting on the 113 site!

Gosh, how many miles must be on the block such that it has exceeded a second overbore (basically the original  engine + 2 rebuilds)? Is this a common issue on these cars?

Isn't saving an original matching number block something you try until all options are totally exhausted? I know it sure is in the Porsche world.

My other question is simple: can the block not be saved by a good machine shop? What about sleeving the block if a 3rd oversize of piston is not available?

[Wayne]

I've just been through this myself, I've also been to two machine shops in the uk and have to say what a waste of life it has all been....not to mention the money wasted.
I took some good advice off the forum,with some members being exceptionally helpful and some a about as useful as a chocolate fireguard.
I've bought an engine from a donor car with all the extra bits that go with it , this means I've got stacks of spares for the future. I bought a 280 se motor which was seen running,I got virtually everything that goes under the bonnet that's useable so have lots of spares. I also bought another auto transmission for spares so I've got that saved too.
I'm not looking for concourse or looking to sell,I just want to enjoy so don't really care about the long term value. I have to say it's all well and good changing the engine number so it looks original but is this not fraudulent and misrepresentation to the future buyer,I would say so
In a nutshell I've wasted time on the so called experts and the machine shops and ended up doing it myself and I'm far happier I've done it this way as I'm now in control. In this respect I dictate the pace of the work and how I spend my money, I won't allow another garage to do my work in their own time and at their own pace(because they can) unbelievable people put up with it.
I do feel that some out there see us as cash cows
So  if you want to move forward then go and get a donor car or engine and get your motor moving

[ejboyd5]

Have someone who knows what they are doing measure the block.  These are very tough engines making it difficult to believe that it has had enough hours (miles) to have already reached the second oversize on the cylinders.  There are many alternatives for saving the original block - switching to a different block of an unknown history may not be the most economical solution.

[ctaylor738]

I would recommend having your mechanic cut the corner off the old block where the serial number is. That way if you or someone else should ever want to stamp a correct  block with the serial number off the original block you will have a pattern for finding the proper stamps.  Of course this is frowned upon but it does happen nonetheless. 

This is a first on this forum to my knowledge - facilitating fraud!

[Cees Klumper]

This has actually come up several times before Chuck. I'm just glad that common opinion is that 'matching numbers' is really not that important for our cars.

[Shvegel]

Chuck,
At what point was I facilitating fraud?  I told the OP to save the corner of his block so IF he or someone else wanted to reproduce the stampings they would have a guide.  The National Corvette Restorers Society specifically allows re-stamped blocks in Concours judging.  Maybe the time will come that the MBCA also will allow it if they do not already.  At no time did I say he should stamp it and pass it off as original or worse to sell it to an unsuspecting buyer. 

[ja17]

Maybe that is why the factory leaves the serial area blank on replacement blocks. In this way they can be re-stamped? Having the correct number stamped on  the correct block is a good thing. Fraud happens if the buyer is told that the block is the original that came with the car when new. I believe most harmful fraud happens on verifying correct mileage and odometer readings. Here the buyer is actually robbed of years and miles of usage which he has paid for.

[Shvegel]

300 Sl roadster with a block re-stamped. No fraud as it is listed for sale as such.

http://www.autosportdesigns.com/inventory/stock/446/mercedes-benz-300-sl-roadster-1957

Joe, this is from our own Technical manual:


I have an engine with the correct original number as per my data card. The engine does state on a separate label "DAIMLER BENZ ORIGINAL AUSTAUSCH MOTOR". This means original replacement engine.

It is possible that the original engine number was stamped into the exchange engine by MB when the customer ordered his new block. This would make some sense, although at the same time, MB would then take a risk that more than one block with the same number would be in circulation. So more likely is that the shop that fitted the block, stamped in the data card number in the block, at customer's request.

Achim: to answer your question: yes! Exchange engine means that a new (or factory rebuilt) engine was ordered by the dealer when the customer/owner came into the shop with his blown or bad engine. When the new engine came in, it got the number of the old engine, basically your data card engine number stamped in by the authorized MB shop. The old & blown engine went back to Mercedes and was then rebuilt too, got a new "DAIMLER BENZ ORIGINAL AUSTAUSCH MOTOR" label but no number until it was then sold ("exchanged") again.

Would that mean there was some kind of punch kit that the dealer used to punch the number into the block? Would there be any such kit available? I would like to stamp the vin # back into the front frame rail near the air filter canister on my SL, which had the entire front end replaced(firewall to front) and the vin # was never stamped there.

Achim again: I think so. The well equipped MB shops had (or have) a lot of nice tools. As they do car-accident repair as well (at least in Europe), I suggest they also have the number punch kit.

[ctaylor738]

My opinion is that you "facilitated" by explaining to a newbie (who thought it was a great idea) exactly how to go about falsifying the serial number on a used replacement (and probably incorrect) engine to make it look like the original engine that came with the car, presumably to increase its value.  You allude to this in your statement "... the value of not having the original block the car was delivered with will be effected (sic)".    My further opinion is that this sort of fakey-doo constitutes fraud and a "how to" has no place on this forum. 

This is very different from the "factory replacement" situation.

Cees Klumper in an earlier post (http://www.sl113.org/forums/index.php?topic=18033.0) called grinding-and-re-stamping "deception."  You yourself called it "regrettable."  I would certainly agree with those characterizations. 

So why are you suggesting it, along with instructions? 

[49er]

 When my block was replaced at 20k miles back in 1970 under warranty by the Mercedes dealer from who I bought the car from, it came back with no numbers stamped. I do have the service work orders detailing this replacement and are part of the car's legacy now. I am curious if there are any owners that knew their block was replaced by MB under warranty  and had the original block number stamped at the time of the replacement or was my dealer's service department just a little lax?

John

[mdsalemi]

Let me get this straight: there are (were?) NO identifying serial numbers on replacement blocks from MB? How would they check or track quality, or even warranty w/o one? This is puzzling to me.
Maybe the quality isn't all that it is reported to be, if 49ers car needed a new block at 20K miles?!

[garymand]

Wow, tell us the story behinbd a replaced block at 20K.

[49er]

 The early 280s had a problem with excessive oil consumption which was the case with mine. Here is a link to a previous thread in which Benz Dr. detailed the problem.
http://www.sl113.org/forums/index.php?topic=15740.msg108313#msg108313

 There were a few "quality" problems with these cars in the early days. I had my water pump replaced three times and the master brake cylinder replaced twice, all under warranty. Things apparently got sorted out and things have been rock solid since. I am knocking on wood as I type:-)

John

[mdsalemi]

Well, John that all makes perfect sense. Sounds like a bad run of water pumps or incorrect installation.

I still don't get how an entire block could be sourced and replaced with no serial number or other identifying marks!

[Shvegel]

Michael,
Unmarked blocks are not uncommon across marks.  I have an unmarked 911 2.4 engine in my garage.  I also have a brand new unstamped BMW S38 from a 1988 M5/6 as well.  I would assume that a replacement engine supplied from US stock would be unstamped where one from the factory might be stamped with the correct serial number to correspond to the car. 

In order to appease Chuck I must amend my advice to mjc7989 :  Find a block that is the same casting and send it to the factory for re-stamping. A factory technician stamping the block with the number of the block that came out is apparently AOK.

[tel76]

Michael,
The 2.8 mk iv block that I am at present re-building was purchased from MB in the 1980s, it does not have an engine # stamped on it.
My understanding is that replacement blocks from the factory came this way.