3.5 block identification

[sprintevo]

I am trying to find out what age block I have to help with an engine build. It is a 3.5

Only marks stamped on the side are 3.5. And the number 2.
On the starter motor housing the engine number is stamped as below this there are the combination of 34 6K B

Can anyone help me identify which version of the 3.5 block I have.
Ps this is a uk engine

 

[rudeuk2]

I can have a look tomorrow at my 635 lump for clues? Pics would help.

 

[frogisland]

Not as straight forward as you might hope. I have 2x m90's and 1xm30b34. They have quite similar blocks from the outside but all three do have their differences with external bosses, mounts etc. One of my m90's is from a very early 635csi and the other from an e12 m535i. The one from the 635 has the extended water channel on the right hand side, the e12 one does not (neither does the m30b34)

I'll try to remember to take some photos at the weekend. There should also be a date code on the left hand side (I have a '78, '80 and '86)

 

[frogisland]

Early m90 with extended water jacket/channel on intake side of engine. 93.4mm bore. Early version with double chain.











Later m90 without the water jacket/channel and single chain. Again 93.4mm bore. Otherwise the same on the external block....I'm only using the crank and distributor from this











m30b34 with single chain, 92mm bore, identical on the external block to the later m90, no water jacket/channel











Measure the bore, externally the same as a m30b34. Does it have the water jacket? Does anyone know when the change over occurred, as with chain double to single.

Piano top pistons anyone?

JP

 

[DerSchwede]

Following items were introduced to the M30 and M90 in 9/79:

Delete of the external water channel
Single timing chain
Bottom mounted oil level sensor unit

Prior to this the M90 had L-jet, after that Motronic I.

The M90 always had CR 9.3:1 with flat pistons. All other Euro M30 had piano top pistons except for the 185 bhp M30B34 with cat in the mid-80ies. Some US versions had flat pistons as well due to lower CR.

Cheers
A

 

[oilcan93]

great info and pics

Thanks for the great pics and explanations. That helps tremendously

 

[axco]

I also like to identify the motor I have in my E9. There is no motor serial number near the starter. This machined area is blank on my motor. The only marking I can see readily on the left side of the casting is 3.0 3.3. It does have however a single timing chain and no extended water jacket. Using DerSchwede comments this motor should be then a later M90 (after 1979) with either 3.0 or 3.3 liter displacement. Since someone changed the trunk batch to a 3.3 CSi my guess would be the motor is a 3.3 liter moter from an E12. But DerSchwede also said that the later M90 motors came with Motronic 1.0.
I need to know more about this motor since I'm still running D-Jet, original to the car but clearly not original to the motor. The car idles fine and also drives okay. However there is a hesitation when asking for power from a low RPM range and fuel consumption is at 15-16 MPG poor. I measured the CO and it is about 4.5% - too high and I cannot get it lower. There is also an issue with the idle speed adjustment. I can't get it higher then about 900 RPM. I'm convincing myself that I have a mismatch between motor and D-jet components i.e. vacuum sensor. Any thoughts?

 

[Bert Poliakoff]

M90 for one year, 5/81 through the new 82 model year are the 1st year with Motronic and, confirmed by many to be one year only on the 3.5 liter motors. All M90 motors were 3.5. 3.2 wil lnot be an M90. It will also have a white "L" on the drivers side below the intake manifold.

 

[wkohler]

On the info posted above, the M90s in E12 M535s most certainly had the extended water jacket. I have had two of them and seen several others. The motor to my current car is sitting in my garage and the number matches the car. 7/80 production.

In the 6ers, the 3430cc M30B34 came in for 9/82 production with Motronic and the 011 ECU.

 

[Bert Poliakoff]

The 81 model year M90 did not have the raised water jacket .When I first got my E24, the guys "in the know" on various forums told me my car was bastardized as there was no such a thing as an M90 without a raised water jacket and Motronic. As I said above, this was a one year only production. My engine has been rebuilt and I know for sure it has the M90 bore. After getting paranoid from mixed responses, I contacted Andreas Harte at BMW Mobil Traditions who verified my cars build

 

[twistinglane]

This is very useful to those of us who have been confused about these engines. A remaining question. (Maybe I've just been missing so far) How do you distinguish the later m90 (no water jacket, with motronic) from the m30b34? With engine in car that is...
Also I've seen blocks showing "3.2/3.5" or was it "3.3/3.5"... Which are those?
PS one of us should make this into a FAQ type item and share with related forums... Paul

 

[frogisland]

Just to confirm. The m90 above without water jacket came out of a e12 M535i, I helped to take it out and verified the engine number against the UK v5 registration document.
Dates kindly noted above re deletion of water jacket.

 

[Bert Poliakoff]

I believe only the pre 82 motors all have the vin stamped into a flat on the block just above the starter. The later cars do not have numbers stamped into them that match the VIN ofthe car they came out of.If pulling the head, all M90s will have a 93.4 or 94.3 stamped into the top of the pistons. The M90 pistons are flat top and contrary to popuar belief, are not 10:1 but rather 9.5 +/- compression.When my M90 was rebuilt, piano tops were used and made by JE Pistons with a true 10: .I am also running a 284 came and the engine also had a larger bore AFM, head porting and all boltons port matched. SFDon things it may not run right with the stock euro ecu, but I will see. If it doesn't I will go after market

 

[wkohler]

M90 compression is 9.3:1. I've never seen an M535i running its original motor that didn't have the extended water jacket. That's a new one for me.

 

[Bert Poliakoff]

Chris

I have done a lot of reaseach on this issue, and the M90 with Motronic, was a one year only motor and the last year of the M90 motor/designation.. The wiring harness is even one year specific, at least in an 81 euro 635.

I was confused on this when I first got my car. I hadn't a clue of the difference between Motronic and Ljet. A fellow on First Fives named Remy Davidson, from Austarlia, is who first enlightened me on this. Since that time, I have made contact with at least 20 fellows with 81 M90/Motronic E24s and I can't see why there would be a difference in post May of 81 5 series cars-the 82model year. Again, my car also confirmed by Andreas Harte of Mobil Traditions in Germany. I also needed a harness in better condition. I got it from Al Taylor who, again, verified the engine and injection. combination.

 

[wkohler]

I am not talking about your motor. That's a 635 thing. There weren't any Motronic M535s in the original 1410 and every car I had put eyes on whether from photos or in person has the larger water jacket. My motor (7/80) has the last seven of my VIN above the starter. Production for the original 1410 E12 M535s stopped in May 1981, as Europe moved onto the E28 and there was no 3430cc M30 available until 9/84

The motor from Paul G.'s white Euro 635 wasn't original to the car and turned out to be an 8:1 motor from a US car with an 8 digit production code above the starter. Pulled the head and found dished pistons. Likely changed after the car came to the US, so I'm not sure if that was one of the cars you were counting. It was definitely setup for the early Motronic though.


I'm not saying the motor posted earlier didn't come from an M535i but I've never seen one with that block. Remember we are talking about a hand-finished car here by small teams at BMW Motorsport. Anything could have gone in there.

 

[Bert Poliakoff]

Paul G's running car was an N/A car with the bumpers that came from his 81 euro that was torn apart, totally gutted and scrapped. The motor out of the euro car was another M90 with Motronic. When he sold the N/Acar, that motor went with it.

 

[wkohler]

The motor I'm talking about is the one out of the Euro. Ray has it now. He got it in the deal for the two US 635s. I was going to buy it until I found what it was. The Safaribeige 633 is L-Jet anyway. I don't just make this stuff up as I go along, Bert.

 

[sprintevo]

engine block ID

OK

checked the numbers and see that the 346K B corresponds to a M30 B34 - From the UK

What sort of compression would this motor have as standard?

it seems to be correct and ready for re build so considering putting back together and sourcing the parts later on for the M90 special