What mileage to rebuild bottom end?
 

I haven't seen too many posts in the archives nor any listed here on having to rebuild the bottom end of the M103 at a certain high mileage reading nor even to change the piston rings. I have read of some burning oil, which is probably caused by the rings, but nothing siginificant to require a rebuild or a new crate motor.

So, at what point do the shops typically see these engines in for rebuild? Probably later than sooner, but what mileage is typical? I gotta know, b/c I have read some of these crate motors are about $5K....help.

Regardless of the car, overhaul of the shortblock, or really any other portion of the engine is not dictated by mileage, but condition. There are three main indicators of this, oil pressure(or lack thereof), oil consumption and compression.

Something may happen that makes this necessary at 4,000 miles, or 400,000 miles. Mileage will not be the indicator to go by. Use of the engine, maintenance and luck all have to do with when this will be necessary.

The head had to come off my M103 engine at about 170,000 miles, there was absolutely no ridge on the cylinder wall and the cross hatch was still prominent. I'm sure there have been other M103 engines that were completely worn out by 50,000 miles. It all depends.

Best of luck with yours,

Listen to Larry...he knows!

The bottom end of these engines are nearly bulletproof...so you shouldn't decide to perform a rebuild unless it calls itself to attention...and as Larry said, condition, not mileage dictates that.

It is unfortunate, but I can attest to the fact that rarely-driven vehicles actually suffer more damage than those that are driven regularly...cars are meant to be driven, and many of the materials used in the engine will break down and deteriorate over time simply by the corrosive effect of the fluids contained within...especially the pliable materials like rubber seals, wiring insulation, and gaskets.

My 73 Bug is (was) a full-out show car, and driven only to shows for the last twelve years. Externally, it appears to be in excellent condition, but mechanically, it's a mess! Improper storage for 5+ years sealed its fate!

My tech recalls a woman with a 1990 500SL that has around 5K miles and has had three water pumps replaced! Each one failed in the same manner...the seals blew from long-term corrosion!

Thanks for the repsonses to all. I see LarryBible's point, "depends". I guess I am used to American car engines typically being rebuilt at about 100K b/c that is their "shelf life" . Then again, to rebuild a small block Chevy is only about $1K-$2K.

So, taking this "depends" model, lets assume on a one owner M103, all maintainance, etc..... it could last even 200K +++ miles before you might have problems in there reflected by lower compression, etc.

So, at what point , do these parts start showing their age? There has to be an expected life, no? As an example diesel tractors have different powerplants (cat, Navistar, etc) and certain powerplants are spec'ed to last say 300K miles before rebuild, and if there is a customer need for high mileage, we then might order a powerplant 800K miles or one that will substain 500K miles before rebuild.

I am not complianing. I just don't want to miss something, and 200K miles from now find out I might have to spend $5K on a new engine :( . I guess that leads to my next question, how much would a typical rebuild run? I assume you would probably use the same crank and rods. Then add new pistons, rings, oil pump, etc. I read somewhere here that you can buy a new or rebuilt engine from MB, but I would prefer to have the original motor rebuild (if I ever ever get to that point) so I would still have a numbers matching car. :D

M103 bottom end
 

My 1988 300 E has 248,500 miles. I had the cylinder head off because of a leaky head gasket at 244,000 miles (it had been off once previously at 130,000 miles, for a valve job). There was NO ridge on the cylinder walls and no evidence of piston wear.

The car also burnt little oil before I had the head off, and since I had another valve job done while it was off, it has burnt none since. My bet is that I'll have to do yet another valve job before the bottom end goes south

Black, I should have specified I do not have an MB, I am in the research / entertaining stage of my purchase. I have narrowed it down to an M103 equiped W124. That is why all the questions. I have posted lots of questions, continue reading the archives ( I am on pg 15 of about 50+ on my M103 search :D ). I am reading a little each day...lots of info :rolleyes:


I don't want to get into a "this is better or that is cheaper" issue, but if you compare apples to apples (stock Chevy rebuild vs stock MB rebuild) that is what you pay on the Chevy ($400-$500 parts and $400-$500 machine shop) or buy a Chevy 4 bolt main 350 crate engine w/ 36Kmile / 36 mth warranty from Chevy for $1300. VS. ? on the MB ( I think $5K is what I heard, but am trying to confirm). I know a Chevy is not in the same category :D .

You have a point on the #'s matching issue. I definitly know it is not a collector car ;) but, I guess I am just used to "original". I pull back my comment on the #'s issue. The MB rebuilt engine sounds better! How much?

thanks

Back to the bottom end question - My opinion is that the life of the bottom end is based on the frequency of the oil changes the first 100k miles - remember my opinion. A couple of examples - I owned a '91 Mazda van 4 cyl. and the radiator came apart at 125,xxx miles - the wife was driving and did not stop until the vehicle did. Anyway, I had changed the oil and filter every 3k miles. The cylinders still showed good signs of cross hatching and it did not use any oil. The damage was to the piston skirts and rings. No telling how many miles that vehicle could have gone and I am sure the guy I sold it to is probably still driving it with that engine (sold it at 155k miles). Another example is a Nissan truck I purchased new in 1986.5 (Nissan hardbody -4 cyl). Again, I changed the oil/filter every 3k miles and the painting company I sold it to (at around 80k miles if memory serves me correctly) is still driving it with over 280k miles showing on the odo. I will say it looked like heck and idled pretty rough. I seriously doubt if they have ever even replaced the timing chain in that vehicle.

Now that I understand the nature of your inquiry, as blackmercedes said, it might blow up before you get it home, there are never any guarantees. But if you inspect it thoroughly as he recommends, and all is well, it would not be out of the question at all to see the engine run to 250,000 or 300,000 miles. Mine has almost 203K and is going very strong, and uses no oil.

Good luck,

Thank you guys for the info. So now I have minimals & / or ball parks of where it might happen...if it happens.

Now to confirm the last thing...MB rebuilt crate engine cost ? About $3500 USD ? That sounds very attractive...,maybe the $5K I had read in the archives was for another motor :confused: . That is for the motor, then I install or pay xx hours to get installed?

I concur with both comments on having the vehicle checked out by the dealer. I picked that up in the archives. Also, check the maintainance records on the car and have the dealer verify maintainance in his records .

The more I learn about this car, the easier it has become to make up my mind.... :D

Got MB rebuilt engine $
 

Ok, I decided to call one of the local MB dealers and get a price on a factory rebuilt M103. I got the info from the Autonation MB in North Miami, FL .

They want $4,200 for the M103 long block, with a $1,920 core charge. So that is in the ball park of what I had heard. Not bad considering what it could last :D , but they guy said it had 12 or 24 mth warranty, wasn't sure. So what warranty does it have? And are they rebuilt here in the US or in Germany?


So, to finalize my research, worst case scenarios:
1. The motor dies - I spend about $5K for the rebuilt motor and any other misc I need to do the swap.
2. I blow the tranny, and it will cost me about $1400 to get it rebuilt.

Now what about the a/c? I have read in the archives and my book (YES, i got my book - Frank something is the author I think :confused: - from AMazon yesterday :D ) that these W123 have a/c problems... What goes wrong, the compressor?
thanks

Typically the climate control unit or the evaporator are the A/C problems that happen with any frequency on the W124 models. The push button climate control unit is expensive...about $300.

The evaporator is even more expensive...the entire dash must be removed to gain access. If you farm out the work, it could run around $2000-$2500!

My evaporator died at 85K, and was fixed under the aftermarket warranty I purchased. So far, no problems with the climate control unit.

BTW, the tranny is also a robust unit. There are some that believe that tranny fluid should be changed around 100K miles while others say MB says it doesn't require fluid changes. Either way, it shouldn't call itself to attention unless it was severely abused.

When they built the 124, the first thing they put on the assembly jig was the evaporator.....then they built the car around it!!! I replaced the vacumn elements in mine. They just control airflow and required the COMPLETE removal of the dash. That was a six hour job and I didn't even go into the heater box. I would guess that would add another 4 to 6 hours!
:(