Oil pump on 3.5 l conversion

Sven

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I am working on adapting the 1991 735i engine to fit my coupe. Should one use the entire oil pump assembly (including sprocket and chain) from the 3.0 engine on the 3.5 engine? Or, can one use the main body of the 3.5 oil pump with the "suction arm" from the 3.0? It seems that replacement parts for the 3.0 pump are hard to find. The original pump from the 3.0 has about 115k miles on it. Obviously it will need to fit the 3.0 oil pan.

Also, has anyone used the oil pump chain tensioner from the newer engine with the larger oil pump sprocket from the 3.0?

Here are some photos of the two engine bottoms and oil pans.

As an aside, the oil filter housing on the newer engine sits up high and is easily accessed from the top of the engine. Remove the lid, lift out the filter - no mess. I probably will not use it since is will make the engine bay look less original. I already have Carl's top bolt filter housing on the 3.0 which works ok.

1972 pump:
71a72c465c4f08d2d6ae01972d7c5d51.jpg


1991 pump:
9418487775ed42b5705a6f7d8caf1595.jpg


Pans (1972 is the lower pan):
faf566e2e9effcf56da82f1ec776c3cc.jpg



Thanks,
 

x_atlas0

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Sven

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Thanks.

It turns out that a lot of these parts are interchangeable. The inner and outer rotors are all the same (except the early ones have a press on flange for the chain sprocket). I was able to use the old pump neck, added a new metal shim between the neck housing and rotors and will use the sprocket, and chain tensioner from the 1991 motor. This allows me to eliminate the shims where the pump mounts to the bottom of the block.
 

rickysbmw320i

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I just did this yesterday so i will put in some input.
From the m30b34, I removed the whole sump and oil pan. the sumps seperate from the neck and the oil pump housing. I put the m30b34 housing on the m30b28 sump neck and used the little splined sprocket with the 15mm nut. I also used the longer bolts from the m30b28. Doing this, I had no problem with anything and did not even have to mess with the chain length.

-Rick
 
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