do we trust realoem.com ???

[tandersn]

realoem.com reports that both my cars have M30 engine, when I know for sure one is an M90 (raised water jacket is pretty hard to ignore). Both cars, VIN and engine stamp match. What gives?

They are both euro 635csi 78 & 79.

[alpinacsi]

Been discussed many times over the years but the m90 is basically in the m30 family and realoem does not distinguish between the two. Same goes for the m88 and s38.

[weedshoes]

For the later cars it is great, but this is not the first time I've heard of inaccuracies in cars predating the e30s.

[EuroGeorge]

RealOEM is merely a portal to BMW's database. I have used it for 147 years to research and order ALL my parts. Never had a bad part as a result. Other than the engine grouping for M30/M90 and M88/S38 it's spot on.

[FernandoBunster]

The M90 is an M30

[OBwan]

RealOEM is merely a portal to BMW's database. I have used it for 147 years to research and order ALL my parts. Never had a bad part as a result. Other than the engine grouping for M30/M90 and M88/S38 it's spot on.

Surely you are close to retirement by now. Did you work on the Focke Wulf 190?

[EuroGeorge]

The M90 is an M30

Yes, I know that. Some folks here do not.

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Surely you are close to retirement by now. Did you work on the Focke Wulf 190?

Well, that's a bit of a stretch. I have no idea why I typed that...I feel like I should retire. Geesh

[tandersn]

can you elaborate on your logic? The facts as I know them, are that the m90 is an m88 block with m30 head. The m88(m90) block has a raised water passage on the drivers side. This is part of the casting. If a block has to be cast in a different mold, then how are they the same? Also, a different head gasket is required. If they were the same, the same head gasket would be used.

[alpinacsi]

Really?

Different head gasket? What about the other m30 derivatives.

Castings? More than one casting for the other m30s.

M90 heads were cast with m90 on them and had revised castings later.

Anyway if you want to base your accuracies on this; go ahead. Realoem and like; are excellent resources and I wish these were available 15 years ago.

[Layne]

the m90 is an m88 block with m30 head.

That is not true. An M90 block is just an M90 block. It has the same bore and stroke as an M88, but is not the SAME block, or crankshaft, or connecting rods, or anything else.

An M90 is just a variation of the M30, in the same way that the 2.5l and 3.0l M30's are. They probably have NO parts that are exactly the same as the 3.5l's, but it's all the same design.

[tandersn]

I realize that wikipedia is not stone tablets, but when I put forth the 'facts as I know them', I got some info from http://en.wikipedia.org/wiki/BMW_M88#M90 where it literally says "It utilizes the same block from the M88". My only point here, is that, that is where I read the information, and while I don't take info from wikipedia to be 'stone tablets from god', I generally find it to be accurate.

I think I understand what you are saying, which could have been articulated better, with less condescension:

The "M30" is a class of engines, that the M90 (a specific engine) belongs to. The M30 (without any suffix) is not a specific engine. An M30B35 is a specific engine.

Is this accurate?

I think that my confusion was that I was interpreting "M30" to mean specifically "M30B35". While this is obviously an oversight on my part, in my opinion I feel it was an 'honest mistake'.

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p.s. the reason I even started this thread, is because the '79 euro I have doesn't have the raised water jacket on the engine. The numbers on the engine match the VIN, so it is original. So I was trying to figure out what engine that is. Will it be the M30B34?

[MrtnEbb]

Sounds about right.

The M30 went through many incarnations in its lifespan. There are even different "M90" versions, L-Jetronic(78-09/80) and Motronic 1.0.(09/80-05/82)

Yours(1978) is probably an L-Jetronic 3453ccm 3.5l, if it is original/has matching numbers, as you say. I have a 1981 635csi, it has a Motronic "M90"B35.

"M90"B35 engines have larger bore(93,4mm) and shorter stroke(84mm) than later 3,5l M30's, and uses a specific headgasket. You'd want the headgasket that is for the period 1978-05/1982, if you wanted one at all.

[danny2010]

Me and all the other techs use real oem, it's faster than loading the BMW one at our dealer, and I've used it to prove parts guys wrong. It's pretty accurate

[FernandoBunster]

I use BMW Fans ( http://bmwfans.info/ ). Although essentially the same database, I like its layout better.