420SEL @ 245K, What to do? - PeachParts Mercedes-Benz Forum

Hit Man X · #8 11-30-2016, 06:38 PM

Quote:

Originally Posted by Mighty190

I would not do a valve job on a 250,000 mile engine. Its going to need bearings and rings soon enough. I would look for a complete engine on car-part and see if you can find a "euro specialist" in your area to swap it in for a reasonable price. A quick search shows there are plenty of 4.2 m116 engines out there for $1500 and less. That would also be a good time to do seals on the transmission if its been in there for a while.

I say this because this is not an AMG or otherwise special engine. I don't even bother with head gaskets on anything over 200,000 miles unless its a rare engine that needs to be rebuilt.

Another option is to see if you can just find a lower mile clean car with a price delta less than what you're looking at for repairs. Then let someone who is a more DIY get your car and keep it going.

Obviously you know nothing about the bottom ends of the M116/7s of this generation. You are the one that should be doing a search for information.

I vote for the top end. This style V8 beats the hell out of the top end every 100k, bottom ends do not go bad on them. Ask any tech. Only issue is the initial up front labor due to the block usually needing Helicoils. Once the block has the steel threads, top ends are easy.

Remember, I did a top end on my 300SEL around 270k, car has 320k on it now. Cylinder walls were beautiful and I have 160-170psi on all six...and the M103 did not have the Alusil linings these V8s have installed.

One of the shop owners on here had a customer's 420 that had around 700k before a rod bearing failed from what I recall. Steve Brotherton I believe.

Just one example - http://www.peachparts.com/shopforum/1789665-post8.html

TXV seals are not super hard. 134A is just going to leak due to molecular size. Run R12 since the rest of the system is new or R152A for R12 head pressures and $4/can.

Think of it this way Kris, if you spend say $4k for the top end... what can you buy that is worth a damn for $4k that does not need $5k put into it?