WTB: 4.6 engine, PNW area.

Lowblock · #1 08-12-2023, 02:20 PM

Looking to find a complete running 4.6 engine or one that is rebuildable. Im in oregon so looking for somewhere reasonably close. Let me know if you guys have anything.

Thanks
Dave

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Henn28 · #2 08-13-2023, 11:37 AM

Tough to find used given that they were only used for a few years by BMW, and good luck finding anything from Alpina, which continued to use the motor for a few more years after BMW.

Lowblock · #3 08-13-2023, 04:12 PM

Quote:

Originally Posted by Henn28

Tough to find used given that they were only used for a few years by BMW, and good luck finding anything from Alpina, which continued to use the motor for a few more years after BMW.

Well, aren't you just a great big ray of sunshine....thank you for your contribution.....

Henn28 · #4 08-13-2023, 05:07 PM

Ha, sorry if I wasn’t optimistic and bright enough for you. It’s a great motor compared to the 4.4…which is also a fun V8, but since I have been down this path already I can tell you they are hard to track down. I came across two in six months of looking before I bought a new one from BMW. One had new guides done and the other was a lump on a pallet, sitting outside it looked like. Neither had a fresh pressure/leak down test nor would the sellers do one for me.

The blocks are super durable, but if the bores are damaged then your options become very limited.. Not many shops will hone Alusil and liners get really expensive. The 4.6s had an issue with bore scoring in specific cylinder(s) and they really don’t like overheating for more than a few minutes if not caught. I got scared that I’d find problems after paying too much for a motor and then find block problems, and still have a motor that needed thousands in other work (chain guides, etc.).

At any rate, I’m sure you can find one eventually, but I’d insist on a pressure and leak down test. There is a great thread on Bimmerforums.com from a guy who bought two complete M62tub46 motors but both had bore problems due to (his opinion) an oil problem in one of the cylinders coupled with too much heat, or more like not enough cooling. He ended up having liners put in with custom forged pistons and rods. Fantastic project, if you’ve got the time and money.

****edit****
Found the thread, it’s a good read about one guys m62 (4.6) motor adventures.

https://www.bimmerforums.com/forum/s...6#post30867616

aureliusmax · #5 08-16-2023, 01:26 AM

Quote:

Originally Posted by Henn28

Ha, sorry if I wasn’t optimistic and bright enough for you. It’s a great motor compared to the 4.4…which is also a fun V8, but since I have been down this path already I can tell you they are hard to track down. I came across two in six months of looking before I bought a new one from BMW. One had new guides done and the other was a lump on a pallet, sitting outside it looked like. Neither had a fresh pressure/leak down test nor would the sellers do one for me.

The blocks are super durable, but if the bores are damaged then your options become very limited.. Not many shops will hone Alusil and liners get really expensive. The 4.6s had an issue with bore scoring in specific cylinder(s) and they really don’t like overheating for more than a few minutes if not caught. I got scared that I’d find problems after paying too much for a motor and then find block problems, and still have a motor that needed thousands in other work (chain guides, etc.).

At any rate, I’m sure you can find one eventually, but I’d insist on a pressure and leak down test. There is a great thread on Bimmerforums.com from a guy who bought two complete M62tub46 motors but both had bore problems due to (his opinion) an oil problem in one of the cylinders coupled with too much heat, or more like not enough cooling. He ended up having liners put in with custom forged pistons and rods. Fantastic project, if you’ve got the time and money.

****edit****
Found the thread, it’s a good read about one guys m62 (4.6) motor adventures.

https://www.bimmerforums.com/forum/s...6#post30867616

sent your old block to Poland they have rebuilders who can reapply the alusil

Henn28 · #6 08-16-2023, 09:34 AM

Quote:

Originally Posted by aureliusmax

sent your old block to Poland they have rebuilders who can reapply the alusil

Nikasil maybe? I thought that Alusil was the the follow-on to the Nikasil coating used in earlier all-aluminum motors that had the problems with sulfur fuel. Alusil was the process that physically incorporated the silicon into the aluminum block. I think the issue with repairing bores is that a normal hone or bore wont work. Some sort of special process is used that takes a fraction of the aluminum off the bore but leaves the silicon crystals exposed to a very slight degree for the rings to ride on.

Finding shops (at least in the US) set up to do this hone correctly is a challenge. The pretty high-speed Indy Porsche place near me (with a racing operation) won't do this work and reccommends sourcing a used block in better shape for their customers with trashed alusil blocks. On the plus side, the process makes for a very strong and durable block that can last a long, long time, but I think heat is the big enemy for these blocks.

My new shed/workshop is almost complete, and I'll be able to start the rebuild on the 4.4 that came out of my X5. Fortunately, 4.4 blocks are a dime a dozen online so if the block is bad I can likely source a good one.

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