wiring harness removal?

[penpen]

anyone know the easiest way to remove a 89' m20 wiring harness so i can put it on a 87 m20?

blew my engine a while back and im stuck on this

[george graves]

Well, you just kinda start stripping it off and parts that are in the way that need to be removed, get removed.

Try not to bend the harness too much. It's 20 year old wires. They have undergone 1000's of heat cycles, so they are not as flexible as they once were.

[StereoInstaller1]

They have undergone 1000's of heat cycles, so they are not as flexible as they once were.

So THAT is what is wrong with me...too many heat cycles!

[Doughnut]

These poor old harnesses...

[penpen]

lol i mean like anyone have a tutorial or something? i have a diagram of the harness in my manual but... its not very descriptive

[jlevie]

It isn't hard to pull and re-install a harness. The first step is to label each connection while the harness(s) is still installed. Then disconnect everything in the engine bay and work the harness free of the intake and finally pull the DME side through the firewall. Installation is the reverse.

[penpen]

oh both my engines, dead and new are in front of my e30 so i guess it shouldn't be that hard


any other parts i should swap over to work on a 89 325i? the water pumps are different should i put a 88+ one in the 87' m20?

[h82crash]

Uh, are both engines i? or is the 87 an eta? What exactly are you planning? Sounds like you're putting the 87 engine in the 89 car. If you use the early water pump and other hoses on the late car you will need to use the early coolant reservoir that goes on the passenger wheel well. If you put the late water punp on the motor you will need the tee that goes on the heater hose the runs under the int manifold to run to your coolant res.

[penpen]

yup 12xk 87' m20b25 to replace my blown 132k 89' m20b25

do i swap the timing belt cover so i can use that hose with the pipe?

i know the 89 has a fuel rail, do i swap the 87s individual ones for the rail?

i might try to use the 89s coolant reservoir and just black the old ones hole somehow, but if i cant ill get a older style

[jlevie]

Since you are putting the 87 motor into an 89 body, you want to use the harness from the 89. That'll be easier than adapting the 87 harness to your car. Likewise with the injectors/rail, wather pump, etc. Once you have the 89 engine out swap parts from it to the 87 until it looks like the 89 engine did. Best to use a new water pump (for an 89) and change the timing belt.

Don't pull the harness with the engine. Disconnect the harness from the engine and leave it in the car, but mark each plug as you disconnect it from the engine.

[FredK]

Is the front harmonic balancer / timing wheel the same between the 87 and the 89? I am going to help penpen with this swap and I think the 87 used transmission bellhousing sensors to determine crank position, and the 89 used a sensor mounted on the lower timing cover, right?

[Hallen]

Is the front harmonic balancer / timing wheel the same between the 87 and the 89? I am going to help penpen with this swap and I think the 87 used transmission bellhousing sensors to determine crank position, and the 89 used a sensor mounted on the lower timing cover, right?

Nope, not on the 87 M20B25. It uses the front harmonic balancer for timing. The senosor is mounted on the side of the block on the right front. It should be the same as the 89... but I haven't worked on an 89 so I don't know for sure.