n00b here. Saying Hi and asking for help.

[droidmode]

So I'm new to the forum here, but lurked for a bit.

I've owned a 325i E46 for a few years (kept it stock) and just recently purchased a '86 325e E30 with a bad motor.

I'm in the process of doing a motor swap on the E30 with a motor from a '91 325i E30. I have the dme (ecu), engine harness, intake, afm sensor, headers, plus the other accesories, i.e. water pump, alternator, spark plugs etc.

Now my question is what will I need to do to make the swap work? Will I need to cut wires on the harness? Or is it plug and play? If i do have to cut or relocate wires on the plugs, which ones need to be cut, and where? Anyone have any diagrams or pictures showing which wires need to be cut or altered?

This will be the first motor swap that I am attempting and I want to get it right.

Thanks in advance.

[DesktopDave]

I don't recall if the '86 has the early rectangular plug on the fusebox, or the round C101 type plug. If it has the round plug it's almost a plug-n-play setup. IIRC pin 19 in C101 is a ground on the early car and the ABS power on the later car. Don't plug them in until you've sorted that out (I ignited a wire when I got hasty). I just cut the wire (red/yellow IIRC) and left the ABS system disabled.

The eta also has a little white 3-pin plug (by the DME) that you'll have to splice into the B25 wiring harness so your tach & economy meter will work. I just chopped the end off and soldered it into the B25 harness.

If your recipient is an automatic, you'll need to jump the harness at the transmission interlock, and plug the reverse switch harness into the chassis plug. The manual tranny reverse plug is wired into all e30s, usually buried in the carpet by the shifter or taped into the auto tranny shifter harness. I never did get the cruise control working, but I'm sure there's a way if that's a big deal to you.

I did the same swap more or less. The early & late cooling systems are a little different too - easiest way to do the swap is to bolt the early B27 water pump onto the B25. I used the entire eta cooling system on mine. Radiator, expansion tank and hoses. Alternatively you can easily update to the M20B25 "I" cooling system too, but you'll have to figure a way to mount up the B25 expansion tank on the driver's wheel well.

The B25 might have an oil cooler attached. You can convert to the B27 spin on if you grab the filter nipple, or install the oil cooler into the eta chassis. There are some mounting points, but mine were in the wrong spots. I just deleted it.

Did you download the ETMs for both cars? You picked just about the easiest swap on earth - don't worry about the small stuff. This swap was my first one too, and it was a lot easier than I thought it would be.

[droidmode]

I don't recall if the '86 has the early rectangular plug on the fusebox, or the round C101 type plug. If it has the round plug it's almost a plug-n-play setup. IIRC pin 19 in C101 is a ground on the early car and the ABS power on the later car. Don't plug them in until you've sorted that out (I ignited a wire when I got hasty). I just cut the wire (red/yellow IIRC) and left the ABS system disabled.

The eta also has a little white 3-pin plug (by the DME) that you'll have to splice into the B25 wiring harness so your tach & economy meter will work. I just chopped the end off and soldered it into the B25 harness.

If your recipient is an automatic, you'll need to jump the harness at the transmission interlock, and plug the reverse switch harness into the chassis plug. The manual tranny reverse plug is wired into all e30s, usually buried in the carpet by the shifter or taped into the auto tranny shifter harness. I never did get the cruise control working, but I'm sure there's a way if that's a big deal to you.

I did the same swap more or less. The early & late cooling systems are a little different too - easiest way to do the swap is to bolt the early B27 water pump onto the B25. I used the entire eta cooling system on mine. Radiator, expansion tank and hoses. Alternatively you can easily update to the M20B25 "I" cooling system too, but you'll have to figure a way to mount up the B25 expansion tank on the driver's wheel well.

The B25 might have an oil cooler attached. You can convert to the B27 spin on if you grab the filter nipple, or install the oil cooler into the eta chassis. There are some mounting points, but mine were in the wrong spots. I just deleted it.

Did you download the ETMs for both cars? You picked just about the easiest swap on earth - don't worry about the small stuff. This swap was my first one too, and it was a lot easier than I thought it would be.

I don't know which type of plug is in the car, I will need to check. So if it is just a round C101, I can just cut wire 19 for the abs and be done with this part, right?

With the white 3-pin plug, which wires have to be spliced on the B25 wiring harness? So I'll be able to just cut the wires off the 3-pin plug, solder them into the harness, and then the plug goes in the parts bin?

My '86 eta is automatic, I am stumped one this "you'll need to jump the harness at the transmission interlock, and plug the reverse switch harness into the chassis plug." "taped into the auto tranny shifter harness. I never did get the cruise control working, but I'm sure there's a way if that's a big deal to you." Does this step matter so my reverse works, or will this be for the reverse lights? I don't mind not having cruise control.

For the cooling, I do have a new water pump on the B27, so I'll be swaping that out and putting it on the B25 and keeping my stock cooling system.

I have no idea if the B25 has a oil coller attached, I'll have to check.

I have not downloaded the ETMs, (I dont know what that is lol). Do you know where I can download them from?

I'm hoping that the majority of this swap is plug and play as I'm not super comfortable cutting wires on an engine harness, but I'm not stranger to cutting and soldering wires. I just don't wan the car to randomly burst into a fire ball while I'm just trying to cruise down the street. Haha.

Sorry for all the questions, just want to get it right.

[modernist]

Electrical troubleshooting manual. http://wedophones.com/BMWManualsLead.htm

Enjoy