M30B35 Swap FAQ

[Shawn D.]

Now I am thoroughly confused. I thought we had to use the old B34 pan (and B34 oil pump pickup) in place of the e32/e34 B35 pan because of subframe clearance issues.

Yes, e32/34 b35 oil pan fits: Bimmerguy2002, draztik
No, need to use old b34 pan: ismellfish2, Shawn D.

It's important to note the order of the comments. Matt corrected me after I made my comment. Matt has proven that the E32/34 oil pan fits and covers the flywheel.

[Jean]

Bradley - thank you for the wiring diagram.

After looking at the e28 vs e30 c101 I see that they are different My luck

http://www.briangt.com/gallery/albums/a ... 8iC101.jpg

[Jay Bee]

I'm messing around with my wiringloom in my e28.
It was originally an euro m535 with abs.
I compared my c101 with the one from Brad.

I do have a pin9 wire?????
i dont have the 16 and 17, but thats not so important.

I was wondering, what does number 9 do.
I downloaded some scheme's but cant find out what the niner does.

[washington]

The b35 obviously makes more power and has a smoother torque curve.

Yes it does BUT the majority of the power is in the engine management system. Using the old low compression motor is best (if you can find the right block) The 3.5's with the domed pistons have issues I stay away from. Using an old 3.5 with the updated motronic will get you way more power but you do loose a little becasue of the engine.

[Jay Bee]

Washington, i did read the entire topic.

My car is a euro m535 11th april 1985
It does have abs.

I like to know what pin 9 does of the c101 fuse box connector.
In Brad's lay out it schould be empty but my e28 has a wire.
I dont think the data from the new engine is important.
Because the e34 wire is almost the same as in Brad's scheme.

[Brad D.]

Yes it does BUT the majority of the power is in the engine management system. Using the old low compression motor is best (if you can find the right block) The 3.5's with the domed pistons have issues I stay away from. Using an old 3.5 with the updated motronic will get you way more power but you do loose a little becasue of the engine.

I disagree. The b35 head and cam are far superior to the b34 components.The combustion chamber design also seems to be a touch better as wel, requiring less timing tha a b34. A FI b35 will consistently make more power than a b34 with both running Megasquit. This is due to the better head, cam and higher CR. Also 9:1 CR is perfectly fine for a DD FI car.

[SamSpade]

I had to shave off 0.3 mm from the M30B35 head. Can I use the stock headgasket (11-12-1-730-223) or should I use the oversize +0.3mm one (11-12-1-730-224)?

I already have the 223 so if there aren't any issues using it I wouldn't want to buy the oversize.

[john1180]

Could you tell me what the number is on the preferred 1.3 DME?

[Brad D.]

179

[Mark Goddard]

Hi,

Been reading this post with interest, I have a euro spec E12 with later E28 mechanicals, my engine has the B34 type manifolds, it has the BMW roundall on the cam cover, and 3.2-3.5 on the intake, its pointing the finger at being the 182 bhp B34, which is a shame because when I bought the car I thought it was the full 3.5. Im wondering if im running the 1.0 DME or the 1.3, from the posts I need to look for 179 or equivalent, any more tips on identifying what ive got,
Car has stiffer suspension/lowered slightly, full E28 rear subframe and a 7 series LSD,

Thanks

[Bimmerguy2002]

The only way you would have 1.3 would be if you didnt have a cold start valve, reference sensors on the tranny, etc...
You would have a crank trigger on the passenger side of the balancer.

[Mark Goddard]

I have what I think is a crank sensor, if its at the front of the engine, looks like a big metal disc about 9" across, about 1/2" thick, has a peg sticking out of it then a sensor on a bracket. But, I also have a cold start valve, I know that because it was disconnected when I bought the car and it was hard to start on a cold day, have I got a mix of 2 systems,

[Bimmerguy2002]

You need to look further, i forgot to emphasize that the harmonic balancer has teeth on it. 1.3 does NOT have any kind of provision for a cold start valve.

[Shawn D.]

I have what I think is a crank sensor, if its at the front of the engine, looks like a big metal disc about 9" across, about 1/2" thick, has a peg sticking out of it then a sensor on a bracket. But, I also have a cold start valve, I know that because it was disconnected when I bought the car and it was hard to start on a cold day, have I got a mix of 2 systems,

That is not a B35 harmonic balancer -- that's a B34 balancer. The B34 has the single peg, the B35 has the "60-2" wheel that looks like a square-toothed gear with two teeth missing.

[Mark Goddard]

So its looking like I have an M30B34, I believe these came in different BHP ranges, my head has 86 stamped on it, so im thinking its a 1986 engine. I heard that the 182 BHP has dished pistons, ive tried to feel with weld wire down the spark plug hole with no success. Is there a way to determine BHP physically any other way, I think ive read that some 1986 B34's had 208 BHP, how can I tell.

[Bimmerguy2002]

The US b34s came with 182 HP, no matter what year.

[Mark Goddard]

So if my engine was advertised as a euro spec, chances are it may not be, ie where would a Euro spec B34 come from in Canada. Im wondering why it would have been swapped from the 2.8 that was in it unless the engine was toast, this US spec probably isnt that much more powerful than the original 2.8, however torque/reliability/parts availability may be better.

[Zaffer]

I would like a little more elaboration on the pinning of the harness. I take it if I were to do the swap, I would use the plugs off my old engine harness and put them on the 1.3 harness. Is this correct?

Also, to reiterate another question above, is it possible to use the trans. out of the e32/e34 without having to modify the rest of the drive train, or does one have to stick with the trans. that came in the e28?

[Bimmerguy2002]

Brad could clear up the E34 harness, but the super eta harness you just extend wires and thats all. You dont use anything from the 1.0 harness with that since it would be obsolete.

[Canuck YYC]

So if my engine was advertised as a euro spec, chances are it may not be, ie where would a Euro spec B34 come from in Canada. Im wondering why it would have been swapped from the 2.8 that was in it unless the engine was toast, this US spec probably isnt that much more powerful than the original 2.8, however torque/reliability/parts availability may be better.

Euro-spec engines aren't impossible to find - rare, but not impossible. Don't forget that E28/E12 owners are somewhat rare and cultish - the general population doesn't see what we see in these cars (and they sure aren't willing to spend the time and money to repair/maintain them). Thus, when grandad's imported 635i falls through the maintenance cracks and ends up in the hands of young-n-dumb Billy, it's only a matter of time before that Euro 3.5 shows up on Kijiji or Craigslist somewhere.

In the E12 world, the B34 swap is more exalted than the B35 swap into an E28 is here. Unless you managed to score one of the few 535i E12s, you ran the 2.8L North American (read emission choked) with somewhat less than the 165hp of the Euro cars. If you truly have a Euro 3.5, they're rated at 218hp - that's a pretty substantial jump and well worth the swap.

[Mark Goddard]

Thanks Canuck YYC,

I think its an M30B34 now ive researched the ECU. I guess it was changed to a more 'modern' and more widely available unit, from the 2.8 it used to be.
I think the cheapest option to squeeze a little more out of the M30B34 may be to fit a Mark D'Sylva EAT chip, ive e-mailed him so hoping to get some figures from him. Car already has E28 mechanicals/suspension etc, and lowered/bisteins/7 series sport LSD, getrag 265 etc. Would like to break the 200 bhp barrier with at least 230 lb/ft of torque. Need to ditch the electric seats and elecrtic windows, dont like weight.

[Bimmerguy2002]

You need to do the m30b35 swap to get those numbers, especially go to motronic 1.3.

[Zaffer]

If I remember correctly, doesn't the m30b35 make 208 hp? What does that number jump to if it's chipped? I am seriously considering doing the swap in a year or so and would like to know more about what kind of numbers I can see.

Also, anyone have any more info. on the question I asked concerning the pins and connectors and how it's done?

[MrNic3Guy]

I was reading this thread and thinking of doing this swap in the furture. I was checking out Wikipedia, and it said something about known problems with M30 motors. Is this really true?

http://en.wikipedia.org/wiki/BMW_M30

[edit] Known Problems [1]
These problems may not necessarily apply to all versions of the M30 engine.

-An "oil spray bar" is mounted above the camshaft. This hollow metal tube has perforations on its underside that spray oil over the camshaft and rocker arms, but with time the two banjo bolts that hold the bar in place can loosen. As a result, oil passage through the spray bar will get restricted, and some of the camshaft and rocker arms may not get cooled and/or lubricated properly, leading to fatal wear.

-On some models, the return valve in the oil filter housing fails with time, thus making oil run out after stopping the engine, instead of keeping it in the housing. While not a critical problem, it results in the engine needing up to five seconds to build up proper oil pressure upon engine start. BMW replaced the oil filter housing with a more durable valve around 1991.

-While not a problem by design, the spacing between the valve rocker arms and the valves must be adjusted approximately every 30,000 km (20,000 miles). Failure to adjust might lead to poor running, increased fuel consumption, and engine wear.

-The engine fan is mounted with a viscous coupling that expands when heated. As the engine becomes warm, the coupling gets a better grip on the fan, thus leading to increased rotation of the fan, and more airflow. If this viscous coupling fails, the fan will only rotate relatively slowly (as driven by the engine by a V-belt), and will not provide sufficient cooling, leading to overheating. Overheating can extremely quickly lead to engine failure, such as a destroyed headgasket or a warped or partly melted cylinder head.

Makes me really think about it now.

[MrNic3Guy]

If I remember correctly, doesn't the m30b35 make 208 hp?

http://en.wikipedia.org/wiki/BMW_M30

[Bimmerguy2002]

I was reading this thread and thinking of doing this swap in the furture. I was checking out Wikipedia, and it said something about known problems with M30 motors. Is this really true?

http://en.wikipedia.org/wiki/BMW_M30

[edit] Known Problems [1]
These problems may not necessarily apply to all versions of the M30 engine.

-An "oil spray bar" is mounted above the camshaft. This hollow metal tube has perforations on its underside that spray oil over the camshaft and rocker arms, but with time the two banjo bolts that hold the bar in place can loosen. As a result, oil passage through the spray bar will get restricted, and some of the camshaft and rocker arms may not get cooled and/or lubricated properly, leading to fatal wear.

-On some models, the return valve in the oil filter housing fails with time, thus making oil run out after stopping the engine, instead of keeping it in the housing. While not a critical problem, it results in the engine needing up to five seconds to build up proper oil pressure upon engine start. BMW replaced the oil filter housing with a more durable valve around 1991.

-While not a problem by design, the spacing between the valve rocker arms and the valves must be adjusted approximately every 30,000 km (20,000 miles). Failure to adjust might lead to poor running, increased fuel consumption, and engine wear.

-The engine fan is mounted with a viscous coupling that expands when heated. As the engine becomes warm, the coupling gets a better grip on the fan, thus leading to increased rotation of the fan, and more airflow. If this viscous coupling fails, the fan will only rotate relatively slowly (as driven by the engine by a V-belt), and will not provide sufficient cooling, leading to overheating. Overheating can extremely quickly lead to engine failure, such as a destroyed headgasket or a warped or partly melted cylinder head.

Makes me really think about it now.

The 1st one is just taking the valve cover off and putting loctite on the bolts
The 3rd one is just a valve adjustment
The 4th one a fan, is normal wear item.

[MrNic3Guy]

These are some things that would need to be done, before dropping in the motor. Kind of important.

[Bimmerguy2002]

Same with the m20, its no different. Some n00b who has never opened an engine probably wrote that, its not bad stuff, its ignorance.

[MrNic3Guy]

[fastpat]

Well, I was all set to yank the e24 B35 wiring harness I'd acquired and buy a Super eta harness, but this FAQ has convinced me of the goodness of staying with the B35 harness after all. It fits the engine, I'll do the connector swap.

Great write up, superlative illustrations, the pin out description .jpg and the pin out diagrams, are what's been needed for a long time.

Thank you for going to the trouble in accomplishing these things.

Here's my photo's of the B35 engine, anyone is welcome to use them to illustrate this swap.