I know this has been discussed probably 100 times, but I want to know how to do this swap. I want to use the '89 motech and all of the wiring with the 2.5l engine, and merge it with the '84 chassis. Does anyone know how I can do this? I have a c101 connector and everything, I just need a little assistance. Anything will help, including links to pre-existing threads on this. Thanks R3V!
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I had to enlarge the hole in the firewall by about 6 mm to get an '87 325is harness through it.
The O2 sensor is different. 3 wires on the early, and 4 wires on the later one.
There is no mount for the G103 ground from the later harness on the shock tower.
You will need the later radiator, and the overflow tank.
Are both cars manual?
There may be some fun with the drive shaft. Different size output flange... Later models have a different center support bearing (I think).
(Of course, I have not got mine running well yet.)
Good luck. -
Yeah, so both vehicles are manual. Im taking the trans from the '89 and the m20b25 from the '89 and putting it into the '84 325e. I've read a lot of threads about the '87 harness being more or less plug in play, is that true? Because I want to just use the '89 harness in the car, but I'm not sure if that is even possible.Comment
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Yes, the '87 harness was plug 'n' play. I did bring the exhaust over. The O2 sensors are on different locations on the E vs IS, and have different connectors.
You might need to bring the whole drive shaft, depending on length of transmission, and output flanges (or, you can change the output flange)...
I had an issue where the shift carrier for an '87 325e was shorter than the one from the 325is.Comment
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Thank you so much 007, really appreciate it. I will keep adding to this thread if I have any other questions, but my main take away is just get a '87 wiring harness and I will be good to go for the most part. Thanks!!Comment
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Only 87 models had the larger driveshaft.Originally posted by Tinkerer007 View Post
A late model coolant conversion is not needed, but if you want to keep the early system you need to use an early water pump (or install the pump from the '84).
OP will need to source an early driveshaft with the early CSB.
The 89 harness and the 84 chassis is explicitly NOT plug and play. The c101 on the body needs to be changed to the later round style, and two or three splices need to be made at the DME connector to send signal to the cluster. The 87 harness is only recommended because it already has the separate plug by the DME connector to feed the cluster. I did an 89 swap into my 86 and it was plug and play besides the tach feed.Comment
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Andre,Originally posted by Andre3127 View Post
Was your 89 to 86 swap an 89 i to an 86 e? Not to jump on the OP's post here but wanting to confirm my 89i motor/trans and harness will work in my 86e as well as determining what I will need for parts/modifications.
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