Is this an M90?

[WISE9UY]

Hello E9ers,

I have access to this engine and would like to seek the input of those that know the difference between the M30 and M90. Is this an M90 or has someone put an early intake manifold on a later 3.5 block? I have done a fair bit of research but trying to interpret it all has me questioning what I have? There is the common reference to the raised water passage but I have not seen a picture showing what this is. Here are some images of the motor.

Any interpretations greatly appreciated!

 

[Bob]

3.5 w/"L"-jet. Definitely looks m90. The painted "L" just flaked off.

 

[srennoc]

that is a 80/81 US spec l-Jet harness,throttle body & dual port distributor.. plenum has A supports vs straps to valve cover-Not m90
Short water jacket m90's were available from factory in late 81'... most m90 blocks had a long water jacket length to the starter in 79 to 81
no oil cooler ports on oil filter housing
it could be a b34 dirty motor... do a compression check
what is the date stamp on the block and head? vin # at starter boss? that will tell you what you have

T

 

[Gary Knox]

Certainly looks like my engine on the exterior, and mine is an M30 - I'm pretty sure!!! The head on mine is an '81, and the fuel system was from a 635 engine with Motronic controls. The 3.5 block was bored and stroked to 95 mm square - so Metric Mechanic owner told me.

 

[Peter Coomaraswamy]

Hi srennoc, in reading your post above you mentioned that with the block embossed VIN you can tell what engine block it is; I have the VIN WBAEC310XB5591552, Can you tell me which block this is?

Thanks,

Peter

 

[Markos]

Hi srennoc, in reading your post above you mentioned that with the block embossed VIN you can tell what engine block it is; I have the VIN WBAEC310XB5591552, Can you tell me which block this is?

Thanks,

Peter

Well according to realoem you have a 635CSI built in February 1981. That sounds like an M90 to me. RealOEM vin lookup works fine for 17 digit vins. It gets confused with the 7 digit vins.

 

[OCCoupe]

This is my m90 which is out of a 1981 car, hard to see; but the water jacket as srennoc points out is longer on my motor.

 

[Bert Poliakoff]

My E24 with an M90 has a build date of May '81. It is a first year Motronic and according to Andreas Hartz of Mobil Traditions in Germany, original. '81 was also the last year of the M90. My engine does not have a raised water package, but verified as an M90 by the "L" stencilled on the block, and bore size when torn down for the rebuild as. The "81 also uses a 1 year only engine harness and a rare 002 ECU.

 

[Peter Coomaraswamy]

I'm so confused

 

[twistinglane]

Following up on Markos's post, I also see this on realoem for VIN from Peter: "You Have Selected: 6' E24 BMW 635CSi. Type Code: 5331".

My question, does someone know where can look up the meaning of the type codes??

 

[HB Chris]

If you look in RealOEM for a part number and search for all applications, every model will have this four digit number displayed. In the US, there were unique numbers for 2800 vs. 3.0 and stick vs. auto and 74 models as well. This told the assembly line where the coupe was destined and carb vs injected as well.

 

[twistinglane]

Thanks, Chris. Have you seen a listing of these type numbers anywhere?

 

[WISE9UY]

that is a 80/81 US spec l-Jet harness,throttle body & dual port distributor.. plenum has A supports vs straps to valve cover-Not m90
Short water jacket m90's were available from factory in late 81'... most m90 blocks had a long water jacket length to the starter in 79 to 81
no oil cooler ports on oil filter housing
it could be a b34 dirty motor... do a compression check
what is the date stamp on the block and head? vin # at starter boss? that will tell you what you have

T

Thanks for the feedback everyone. The compression test was 150psi cold with ambient temp of 65F at about 900Ft to be very precise.

What do you mean by "plenum has A supports vs straps to valve cover"...namely what should I be looking at?

I will be with the car tomorrow and will look for the vin on the starter boss as I am pulling the starter bolts anyway to remove the gearbox. This motor is currently in an E12 528i so it certainly is not as it came from the factory. I also considered if it was a "dirty" b34 and will infact compare more closely the block to the b34 but have to pull that out of storage.

Thanks again!

 

[HB Chris]

The log plenum is held above the intake manifolds by two upside down Vs or the A support as Terry calls it.

 

[Markos]

The log plenum is held above the intake manifolds by two upside down Vs or the A support as Terry calls it.

Here's a pic of the "A supports" on a very dirty CSI. They connect the plenum to the upper studs on the lower intake manifold

 

[twistinglane]

Let's write up a FAQ on m30/m90 engine identification . Looks like this thread has good bit of what is needed. And I remember some earlier posts and pictures. A FAQ could be a help to many... I'm willing to work on, but would just be compiling others contributions...

 

[WISE9UY]

Let's write up a FAQ on m30/m90 engine identification . Looks like this thread has good bit of what is needed. And I remember some earlier posts and pictures. A FAQ could be a help to many... I'm willing to work on, but would just be compiling others contributions...

This is a great idea. There are other good pieces of information out there, but what would be great is a thread with pictures to definitively show what to look for as well as the specifications.

Here is a good list of M30 engine variants that I have come across:

http://www.bimmerforums.com/forum/showthread.php?1952450-M30-vs-M90

While the thread is titled M30 vs M90, I am still not clear so a few pics could help with that.

 

[Ohmess]

Attached below are the three pages for BMW M30 engines that I extracted from a BMW remanufactured engine list that was published in 1999. It appears the listing was prepared to assist BMW technicians in determining which remanufactured engine would be appropriate for a particular vehicle.

The listing provides a cross reference between an older BMW designation and the then current designation, and also also provides a cross reference to BMW part numbers. There is no separate M90 engine information in this list.

Our vehicles did not originally have these powerplant designation codes, but if they were used on M90 engines this information might be helpful in identifying them.

 

[Bert Poliakoff]

On the E24 forums, this question frequently pops up. Understanding the M90 stopped being in production after model year 1981, maybe 1982, the vin # was stamped into the flat above the starter motor location. Again, the vin only was stamped. On the later post 82 cars, we have determined that the engine number is usually not consistent with the vin. There weren't any identifying numbers, again, just the vin. For those of the owners that found the build sheet under the rear seat and/or checked the vin on several sites, what was and is apparent is that there was never any mention of an M90 engine. All references to the motor only say M30

 

[2275xxx]

Hello,

Here is a guide to tell if you have a M90 from a E24 or a E12 (other than the white L).
I do not have the VIN information for M90 engines from E23 cars, but I will try to find.

As far as I know (please correct me if something is wrong)...
all M90s from E24s have the "3.5" cast on the left side of the block AND a VIN where the last seven digits start with 55
all M90s from E12s have the "3.5" cast on the left side of the block AND a VIN where the last seven digits start with 41

If your engine is from an E24 and has 3.5 cast on the left side and it has any other VIN, it is a later 3430ccm unit
(VINs with 7 last digits starting with 06, 07, 12, 18, 32, 81 or 94)

If your engine is from an E24 and has a VIN with the seven last digits starting with 55 but no "3.5" cast on the left side it is either a 3.0 or a 3.3

An alternative way to tell what type of 3,5 you have is to check the date code cast in the middle of the right site of the block.
The month is the letter in the middle of the 4 or 5 digit code.
Letter I was not used so August is H, September is J and December is M.
Example: 23L79 is 23 November 1979 and 8B80 is 8 February 1980

The 3453ccm unit for the E24 was manufactured until 03/1982
The 3430ccm unit for the E24 was manufactured from 12/1981
I doubt it was very different for the E23, so most engines can be identified easily.

Regards,
Marc