Worth Rebuilding a Euro 3.5L V8?

[Apodman]

Tempting, isn't it? A gray market '78 350 SL with a manual 4-speed! Probably more hen's teeth around than this combination.

The caveate is that the engine is siezed. Is it possible and feasible to rebuild such a rarity? I'm assuming aggressive cam profiles and less restrictive exhaust than the comparable US SL has. I realize the easier solution would be to put a used 450 engine in its place for far less than rebuilding the 3.5 to Euro spec's, right? But there goes exotic for the sake of cost and convenience.

Any thoughts, suggestions or encouragement?

Thanks, Alex

[ctaylor738]

The 3.5 is the biggest engine that you can hook a manual trans up to, and has got to be a blast to drive in a SL. But there are only a few adventurous souls in the 107 world who want a manual AND are willing to to deal with a specialized car.

Sure, it's possble. You might even find a used engine While it would be a great and satisfying experience, I would say it's a quarter-on-the-dollar deal financially. But it may just have a jammed chain or stuck pistons that clean up with a hone and new rings. What else do you know about it?

[j9fd3s]

what about the later 380sl/sel engines? do those bolt up?

[speedy72t]

It's not worth it all. I'll give you a few buck for it though. Seriously. why don't I every find these things. Isn't the 3.5 the same block as the 4.5? If it can handle the 3.5 it should be able to handle the 4.5 unless you drive it like you stole it. But Chucks absolutely right. You need to find out why it seized before you declare the motor shot.

[ctaylor738]

They will physically fit in the car, but the electronics and fuel system are compltetely different. They will not bolt up to the manual trans. Everything is different.

[Tomguy]

A 3.8 won't bolt to the tranny like a 3.5? They're both m116's. I would think they're compatible. Hell, I'd imagine a 5.6 would bolt on, although it'd probably tear the tranny apart.

I would also think the manual could handle the 4.5. Sure, the 4.5 has a bit more torque, but unless the 3.5's tranny is marginal as it is, it shouldn't be a big deal right?

Probably common in Europe but not over here, it sounds tempting, but I'd pop a 4.5 in it if I were you. I'd try to put it on that manual, it should bolt right in. And although I've never had the blocks apart for comparison, I'd think a 4.5 (m117) block is slightly taller than a 3.5's to account for the longer stroke. it might only be an inch or so, I don't know. But I doubt MB would make it two diferent numbers if it were the same block, as they kept the m116 and m117 designations when they increased the bore in future versions.

[Mark DiSilvestro]

Some Mercedes engines use a different crankshaft, depending on whether it's for a manual or automatic transmission. I don't know if this applies to the V8s, but I'd hate to find out in the middle of an engine swap!

Happy Motoring, Mark