To rebuild or not to rebuild..78 4.5 M117

[PanzerSD]

Not that it needs it, but what is the average price of a rebuild of these engines? I understand a 617 costs anywhere from $2000 to $3500 in my area.

Assuming the works, new cams pistons bearings ect....
hehe never really used 'cams' in the plural before !

[bwostosh]

Don't let them scare you yet.
First how much will you do yourself?
Big price savings if you do.
70-80% of the total cost is getting the motor ready for rebuild.
By "rebuild" means doing everything prior to "re-assembly"
Like cleaning, machining, inspecting, parts gathering, decisions like replace starter, alternator, all fuel injectors, fuel lines, on and on.

You must pull the motor strip and clean everything, or pay them $100/hour to do easy but dirty work.
Then mic the bore and assess the condition and NEED for those expensive parts.
Pistons will cost much, chances are they are good.

Otherwise I have about $1600 into a rebuild, parts and valve job(s)
My labor not counting.

I am doing a 4.5 from a 300SEL

[PanzerSD]

I guess really the only thing I can't do myself is the actual machining and measuring.

I'd take it apart and clean it and take cleaned parts to my engine builder and he'd do whatever, and hand me machined parts and the parts that go within and I'd put it together. but $1300 sounds like a bargain! something to think about as there is another non-running 4.5 that I can easily buy. It was sort of part of the deal I made with my dealer about my 78SEL. he has a nother SEL for parts or whole. I buy as I need but if someone else needs then it's a race

[michaeld]

Panzer,

It's a partnership with a builder. I would tell him you'd like to save some money by doing everything you can on YOUR end to prep the job for him - and I bet ya he'd be pleased to give you some tips given you'll still be using his services for the "big" stuff.

You DEFINITELY want to be on the same page, to have a basic understanding of what you want (e.g. value vs. performance), and to give and get honest communication. There are numerous horror stories.

I had an engine rebuilt on a classic Chevy I had, and the builder became a personal friend. I removed the engine myself and removed all the components. Basically, I replaced those parts that were hard to access, and kept the stuff that were easy to install. He appreciated only having an engine to mess with in his shop. When he had the engine done, I took it home and re-installed it (and everything else), and it fired right up for me. I took a LOT of pictures for reference, and they helped a great deal. When he tragically died of cancer (after finishing my rebuild), I had developed enough of a friendship with the guy that I attended his funeral.

[Tony H]

There are so many variables. If you want to do a really quality job you will rebuild the heads with new guides, springs, have the cams and bearings mic'd, have the heads pressure checked, etc new cam and crank gears and guides and the list goes on. If the bottom end needs pistons add at least a few grand. A simpler job would be rings and bearings and maybe a simple valve job. Just depends how quality a job and what you want to spend.
I have heard the bottom end of these engines is bullet proof but one may need rings with enough miles.
Rebuilt engines go for upwards of $8000 but that is a very high quality rebuild-equivalent to new.

[loepke72]

I performed the overhaul on my 450SEL engine. The machine shop performed the cylinder head reconditioning, and simply cleaned the block and honed the cylinder walls. The car had at least 150,000 miles (probably more, what with the famous broken odometers these cars have), and the bottom end of the engine was in very good shape. The cylinders still had visible crosshatching, and the crankshaft had only minor wear on the bearing surfaces. Only finish honing was required on the cylinders since they had such little wear. I replaced the rod and main bearings since I was in there anyway, and the bearings themselves showed copper in spots. About the only thing wrong down there were the oil control rings being sludged. I was unable to locate a reasonably priced piston ring set at the time, so I cleaned the existing rings and reused them. Besides, they also showed very minor wear. New timing chain guides went in, of course, but the chain itself looked fairly recent, so it went back in. Long story short, everything went smoothly, with a good running engine and no oil leaks, and fresh G-05 coolant (I had quite a bit of Motorcraft Gold coolant on hand, which is the G-05 formulation used by MB). Only problem was that the machine shop used the old valve guides, and I am starting to get some minor smoke on startup, but I won't worry about that right now as the engine doesn't use much oil at this time. Now, if I could just get that damn K-Jet fuel system to work consistently...

P.S. the car gets about 15MPG, which seems about par.