E30 M30 SWAP writeup.

[Garageaholic]

COOLING
E28 stock radiator is slim enough to fit inside. Grind off 2 tabs that the original M20 radiator sat on as the E28 535i radiator still has to go down 4-5 inches. The top of the radiator will line up with two holes that should be present on the E30. You can grind down the tabs with the engine in or out of the car. It’s just a lot easier with it out.

View looking forward with engine removed. The tabs in the Red circles must be grinded down so it’s completely flush as if it was never there. The radiator will then sit on the shelf denoted by the blue arrows and depending on your lateral position, it will mount to the Green circled holes. The bottom of the radiator will still need to be secured to the subframe somehow. Be creative. The E30’s from 83-92 vary slightly with where and how many holes are present, so if you must drill to screw it in, then so be it. Picture thanks to Jared Squires.

Here are the hoses I used:
Upper radiator hose: E32 (heater core) OR E28 Hose (no heater core routing)
Lower radiator hose: E28


Upper radiator hose is part 1. As you can see it has a little hose coming out of it…. This smaller hose going to the heater core will need to be cut and re-positioned in order to mate with the E30 heater core inlet/outlet pipes at the firewall. Some E28 versions do not have this extra hose. You might have to make a tee or go without heat. Lower radiator hose is part 2. Pretty straightforward and cheap to buy or find. I suggest buying it for $13.

Other heater core hose: E30 (needed to modify to tee back to the heater core as well). This is part 13 in the diagram). It’s a 3 way hose (all same diameter) and goes to the following 3 places.

• • Coolant tank reservoir
  • Heater inlet/outlet (doesn’t matter)
  • Thermostat housing

Coolant reservoir: Keep your E30 ’88-91 reservior (pictured above). It’s perfect and should remain in the same spot to function correctly (above the driver wheelwell).

For part 13 in the above diagram or Part 1 (small hose end) of the other diagram, you can use a brass fitting (barbed nipple) to connect hoses to make virtually whatever you want. The barbed connector you want is part number 32-097 from www.fittings4less.com. It’s a barbed brass mender. If you run out of hose, you can always go to autozone or whatever to pick yourself up some 5/8” coolant hose.
Here is a pic of the 5/8” coolant hose being routed in between the manifold and brake booster. It could be a possible culprit for an air bubble , so be careful as you bleed.


Again, I used the following website MANY times for all fittings I needed for the various jobs on my conversion You can get the brass fittings to tee any size line at the following website:
www.fittings4less.com. This website has ANYTHING you need to rig fuel lines, coolant lines, high pressure, low pressure. They have a wide selection and customer service is great.

Bleeding the system:
Bleeding the system is a bitch… ask anybody who has an M30 in an E30. Overheating is a constant issue if not dealt with properly. There are many techniques used to bleed the system. This depends on whether or not you have a heater core for heat. I do have a heater core, so the plumbing is a bit more complicated. You need to be very careful about air bubbles in the system. This is because when the engine gets hot, the air will expand and possibly explode your hoses and leave you stranded.
I finally got my temperature at a little bit past the ¼ mark when driving and right at the ½ mark when in traffic with the electric fan on. This is good enough for me. On a really hot day in standing traffic, the temp goes past ½ mark, then once I start moving, it slowly goes back to where it’s supposed to. Here are a couple techniques I used to bleed the system.

• • do it with the engine running, so the coolant pump can move the coolant around as you pump it. Do it when the engine’s cold so by the time the engine starts getting up to temp, you will have filled it already.
  • Hold the coolant reservoir physically as high as possible. I mean like 2 feet higher than the engine. You might want to have a friend hold it up for you as you pour the 50/50 mix into the tank. When you’re done, screw the cap on (when it’s still in the air), then install it in the engine.
  • Pour slowly! Let the mixture get into the actual engine and level off. If you pour too fast, you could create air bubbles trapped.
  • Last but not least, try to have the car at a steep upward angle so that the front of the car is at a really high, steep angle. Jack up the front of the car, park on a hill, whatever. Doing this will force the air frontward and upward toward the bleed screw.

Try to test this after you think you’re done by letting the engine sitting for about an hour after you bleed. Squeeze the upper radiator hose. You shouldn’t hear any air going through the system and it should be pure coolant filling the reservior every time you squeeze. That is a good sign that you properly bled the system.
You can check to see if the heater core is working by obviously turning on the heat. If you have air in the system, it could be trapped there and the heat simply won’t be that hot. It should be really hot when you turn it on.

For the coolant sensor installed on the engine, please use the M20 sensor. You can either remove it from your M20 engine or buy a new one. For compatibility reasons, the M20 temperature sender must be used.

[Garageaholic]

ELECTRIC FAN
I have a stock E30 2 stage electric fan. It cools the engine “ok”, but I could definitely do better. I was thinking of getting an E32 fan due to the larger fan blade diameter.
These fans suck a lot of amperage! (16-20amps), but it’s worth it for the cooling that it does. You can have many setups, but I will highlight 2 options.

• The fan will run off of a low temp switch from the E28 535i radiator. The switch will be low temp switch and close at 82C. I got it from www.bavauto.com and here’s what you do. You run the switch inline with the fan and inline with the battery and have a fuse in the circuit for safety. Make sure it’s thick wiring, or the insulation will melt. I’m thinking 8 gauge is find. Like I said, it’s very high amperage ( I haven’t measured it).
• You can always forget the radiator switch and run a switch yourself to the fan. For this, I would use a relay. That way, you won’t have to worry about any melting or fires in the cabin where your switch is. Here is a diagram of how I wired for the switch. This way I can turn the fan on and off whenever I please. I have low amp line and the high amp line fused for safety.

Stock E30 fan Stock E32 fan


What if the fan itself isn’t enough? Well, maybe your fan isn’t installed close enough to the radiator itself to make a substantial difference. In this case, you need to make a shroud over the circumference of the fan. It will not prohibit air getting to the radiator, it will channel the air that is being blown by the fan to the radiator to ensure that all the air goes THROUGH the radiator. This makes the fan work a little harder, but it makes a huge difference in the operating temperature of your engine, especially in traffic.
I had a space between my cooling fan and the radiator. This was bad because when I turned the fan on , most of the air blew outwards instead of going through the radiator. This was ineffective approach and I thought how to get most if not all the air blown by the fan to actually go through the radiator. Well, a shroud makes this possible. You can make it out of sheetmetal, plastic sheet, or any other pliable waterproof material. Here are a couple of before and after pictures.

Here, Without a shroud, Because the radiator itself puts up air resistance, air flows to the area of least resistance, that is to the sides where it can leak out…

[Garageaholic]

ELECTRICAL
Assuming you meet the following conditions…
-You have an 88-91 E30 motronic 1.1, 1.2, or 1.3 All compatible
-You have an E32/E34 engine motronic 1.3

You have 2 options here…

1. If your E32 came from an automatic transmission car, then you might want to consider option 2. If not, then you will have fun wiring and bypassing the automatic transmission park. My E32 came from an automatic car. I tried fervently to wire it up, then gave up and simply went to option 2. If you must, then good luck. The E32 engine that I bought has 2 plugs. I tried to take the regular ECU from the M30 engine (ECU 0 261 200 179), and put slap it on. On the C-101 plug (by the fuse box on firewall), there is a round engine plug. Take the harness from my E32 engine and plug it directly in. That should send gauge signals and ignition stuff through. All in all, it should have been a direct plug-in. Unfortunately it wasn’t and I couldn’t figure out which wire went where. Take a look a what it looked like trying to find the automatic park:


2.Take the E30 engine wiring harness that you had when you removed the old engine and lay it across the M30 after the M30 is dropped in your car. Extend some wiring to meet certain sensors (they are in different positions than in the M20). Think about it. The harness is made for your car specifically. You can use the same M30 ECU that came with the engine (automatic or manual car, doesn’t matter). All of the sensors on your M20 will be exactly the same on the M30, just in a different place on the engine. Same crank sensor with same number of wires, oil pressure switch, oil level sender, coolant sender, temp sensor.. carbon canister…etc. Obviously the C101 port will match up fine because IT’S FROM THE SAME CAR. All of your gauges should work perfectly with no calibration needed. Think about it as your car not knowing that a different engine was even dropped in. I do not know if a 13 button OBC will work. I hooked up an analog clock, so didn’t bother with that stuff. I had a supereta, so needed a new tach plug and tachometer to meet the 7k.

Example of motronic 1.3 ECU connector. Note that it has 3 rows of pins. That is common on all E34 and E32 M30 engines as well as any E30 made after 1988.


If you have a different E30 or M30 than what was highlighted here, then please refer to this spreadsheet and it should guide you to the proper wiring technique for any combination of E30/M30 you might have. Thanks to www.r3vlimited.com Rs4pro3. He is so knowledgeable and created this table.

These are simply links to the infamous “Mitchell diagrams”. http://www.autolib.diakom.ru/CARS2/index.html. The engine compartment files are probably the most important, but I included the fuse box diagrams just in case you need to trace a wire all the way back. As another route you can take, there is another link to wiring diagrams just to double check yourself. These diagrams are more like the Bentley manual wiring diagrams. They are probably more helpful in many ways, but the files are very large.

http://wedophones.com/BMWManualsLead.htm

[Garageaholic]

IGNITION/STARTER
I used a starter from an E28 535i. I got lucky and found one lying on the ground at a junkyard underneath the car. The bolts are difficult to get on, particularly the obvious one. I don’t remember if it’s 17mm or 19mm, but it is one of those. I highly, highly recommend installing the starter prior to dropping the engine/tranny in the car.

Don’t forget about starter wiring. You can do this after the engine/tranny has been dropped in the car. You will need the obvious power wire. You can use the one from your E30 if you like, or get a 2 gauge wire from homedepot or something. Make sure that the loop on the end is clamped on bigtime if you do the homedepot route.
Now on to the other wire for routing. You will take the black wire with the yellow stripe and wire it to the starter. Remember that the starter is already grounded. You already hooked up the power. Now you need that “switch”. That ignition switch wire is the black with yellow stripe and you will see on the starter, there are two tabs to attach that wire on the solenoid. Read carefully as I show you which one to mount it on. If you properly install the starter, and you look at the driver side of the engine, you will mount the wire on the tab that’s on the top of the solenoid.


The E30 ignition coil is fine for the swap. No need to use the E28 coil. You can change out the spark plugs and wires if you wish to as well.

[Garageaholic]

SHIFTER MECHANISM
You have many choices here with the shifter mechanism. This depends on the transmission you get. I will talk about the option that I went with. Since I got the E28 transmission, I had to use the plate style shifter. I have heard that if you use a newer tranny, from an E32 or E34, you can use the E30 shifter and arm. It’s simply different hookups on the transmission itself. Like I said, many ways to skin a cat. I’m going to cover the way I did it, and I think it was the harder of the two, so that should benefit anybody reading this
Pictures of my setup:

As you can see, I had to shorten and weld NOT ONLY the shifter plate, but also the shifter selector arm. This was very tricky because I kinda had to feel how long to make it. Word to the wise: Do this I the engine/tranny has been dropped in. I can’t imagine how you would do it without any frame of reference.

• Cut the plate in half
• Have a friend sit in the driver seat. You under the car with both halves. Attach the one half to the transmission via the two hex bolts. Forget about the shift rod for now. Line up the other half of the plate overlapping the first half. There will be about an inch or two (depending on engine position) of your shifter plate. Have your friend in the driver seat tell you when the shifter would be in the center of the hole. Then, make a mark, take it apart. And weld it together. I bolted them first, then welded, just for security.
• Now for the selector rod. This is very important how you do this because if it’s not right, you will have problems shifting.
  • Too short – 2nd and 4th gear will hit the console
  • Too long – 1st, 3rd, 5th gear will hit the console
  • Just right, the neutral position of the shifter will be right in the middle of the console and all gears will shift perfectly, including reverse.

I replaced all nylon bushings. They are yellow and look like thin plastic washers. I replaced 4 of them. It was tight, but then again, tight is good. It means minimal play in the shifter.
I also used AND highly recommend a short shift kit to prevent any scraping of the shifter in the console, ruining my shift boot. 40% reduced throw, so I was happy.

Now in order to retain the shifter mechanism to the frame of the E30, you must think smartly about it, lol. The first iteration of this, I had no rubber bushing in between the shifter mechanism and the body (highlighted by Yellow circle in first picture) . I bolted it tight! Bad idea. Turns out that under coasting conditions, I could shift fine, but hard acceleration or turning situations I forgot that the tranny/engine DO MOVE, so having the shifter practically welded to the frame was a bad idea. That’s why you can see in the first picture that I decided to put a rubber bushing. That allows about ¼” to ½” of play for the tranny to move around under hard acceleration. Now I can easily shift under any circumstances. I will leave this to your imagination. It’s not difficult if you can be creative and have a lowes or homedepot near you. I initially ruled out using the actual BMW part. I just didn’t think it would be compatible, but it most definitely could be.

[Garageaholic]

BRAKES/BRAKE BOOSTER
Hooks right up. The master cylinder is not a problem and is in the way of nothing in the engine compartment. The brake booster vacuum hose that comes from the intake manifold of the E32 engine hooks right up to the brake booster of the E30. Another very simple modification, but very important.

[Garageaholic]

DIFFERENTIAL

There are many different options for picking the right differential. Some of these differentials are too high for highway speeds. Some are too low for fast acceleration. Many of these differentials (bolded) are featured in E30’s. Many of them can be grabbed from E28, E24, E32. Just swap the output flanges and the rear cover from that of your current E30. It’s as simple as that. I do not know the entire differential compatibility between BMW’s in the 80’s-90’s. Not to mention, it’s out of the realm of the M30 swap, so here is a brief overview.
4.10 Doable, but way too high and might lose first gear
3.91 Drivability on the highway will be tough. Compromise top speed
3.73 Perfect for a lightweight flywheel operation. I agree with Jared on this one.
3.64 In between. If you can get your hands on it, go for it
3.46 Probably a real good all around gear. Kind of rare to get though
3.25 I have in my M30 turbo. I love it. I cruise around highway at 2500rpm at 70mph
3.15
3.07
2.93 Better for higher turbo M30’s <12psi
2.79

[Garageaholic]

AIR CONDITIONING
Because the M30 is already heavier than the M20, I decided not to install air conditioning. Think about it. You have the compressor, all the plumbing, the condenser. It’s just cumbersome and if you’re going to ride this thing hard like the rest of us, you might want to consider not using it. Just keep the windows down! If you must, then be aware of the following things happening:
1. The extra power and torque you wanted, will be gone and going all to the A/C
2. If it’s that hot outside, your M30 is probably running on the hot side to begin with, Running the A/C will overheat it for sure.

[Garageaholic]

THROTTLE MECHANISM
The E30 throttle cable and cruise control should mount right up to the Stock M30 linkage. Remember that you must use the M30 bracket on the intake manifold. Just bring the throttle cable around. Shorten or lengthen as necessary and install. The M30 throttle is simply at a different position, but works exactly the same as the M20 mechanism. As far as the cruise control computer cooperating with the rest of the car, please refer to “cruise control” section

[Garageaholic]

WIPER WASHER FLUID
The E30 ix reservoir will fit where the battery would go on a regular E30 car. If your E30 has the battery in the area by the passenger shock mount, then you must relocate the battery to the trunk for two reasons.

• In many states, you need a working windshield wiper system to pass inspection.
• You will be a fool to keep the battery in the front due to the weight distribution. Convertibles have their batteries in the front. I don’t know much about converting a battery to the rear. It can’t be too difficult.

Since my car has the battery in the rear, the front is a perfect place to store it. It will be a very tight fit, however, but definitely doable. Refer to picture:
The pump fits fine within the reservoir. If your reservoir fit on top of the passenger wheelwell, then you might have to get a different hose that is longer to accompany the extra couple feet of distance.

[Garageaholic]

CRUISE CONTROL
If your car was equipped with cruise control before the swap, then the cruise control should still work fine after the M30 is swapped in. Just make sure that you connect the wire in the back of the instrument cluster. That wire reads the speed and adjusts as necessary. For me, the wire connects to the Green connector on the back of the instrument cluster. You will need to adjust the cable to make sure it’s taught. In the above picture, it’s the one on the bottom and it’s pretty loose, I need to tighten it.

[Garageaholic]

CARBON CANISTER
The carbon canister is mainly to there to maintain the pressure in the fuel tank when fuel is depleted to prevent a negative atmospheric pressure. Just trim the tube to a shorter length and hook up to the E30 canister that should already be there. Make sure M30 engine has it’s own valve, sensor, and tubing to hook up to the E30 canister. I think it has the tubing, not sure about sensor and valve.

[Garageaholic]

FLUIDS
6.1 Qts of regular 10W30 oil
ATF for manual transmission
Anti-Freeze- blend with 50/50 ( I used regular water and never had a problem)
Steering/wiper/brake/etc…

[Garageaholic]

AIR INTAKE SCHEME
I had a cold air intake, but since I went turbo, I have this old cold air intake shortened specific for E30M30. It’s not K&N, but it worked great.

You can also use the intake from any stock E28,E23,E24,E32,E34 airbox. The E32,E34 boxes are much more aesthetically pleasing, however any of them will work. They look like this:

[Garageaholic]

TROUBLESHOOTING/ FAQ
Engine won’t even turn over
Check your Starter wiring.
Is your battery hooked up/ properly charged?
I have an E32 735i Battery in there and it gives me all the cranking amps I need.
My electrical system performs just fine.
Did you ground the engine to the chassis
Engine won’t start
Ignition coil hooked up
ECU hooked up
Fuel hooked up backwards
Need new distributor cap/rotor
Tachometer not working
Instrument cluster
Speedometer not working
Check sensor at differential
Car still overheats
Fan not “hugging” radiator
Car idles like crap
Too rich
Maybe your crank sensor is loose. Check on front flywheel.