316i to 325i (M20) swap

[juggs]

Hello people i know this question has probably been done to death but ive still got a few queries about this swap i want to look into before taking the plunge!
Sorry if its a bit of a bore but any help would be much appreciated.

Just to lay it out on the table as to what i have and have not got i'll give you the run down.
I have already got my car for the conversion its a G-palte 90' 316i 2dr manual. I also have the donor car i picked up at the weekend for a steal which is also a 1990-G but a 325i 4dr manual in a stunning seven different shades of not so brilliant red.
I have / can get all the tools needed for the swap including an engine hoist.
Only problem is im a bit of a novice & im not exactly handy with a spanner, although im quite keen to have a go & learn so i could do with speaking to a few people who have done this conversion to get an idea on how hard it is.
I have done a bit of reserch on the swap and perchased a spanking new haynes manwel to try and help me along

Could anyone who knows about this conversion or even better someone who has done it in the past help answer these few questions for me or pull me up on anything (no matter how simple!!) i may have missed out about it.

Firstly some of the mechanicals-
Am i right in thinking that i can use the M20 lump, clutch & gearbox all as one unit along with the propshaft with my small case 1.6 diff with no mods to the diff or the 325 prop?
Do i need to use the front subframe/crossmember off of the 325 or will the engine drop straight onto the existing 316 one?
I take it that i need to swap the engine mounts/ gearbox mounts for those that are on the 325 or are they both the same (have not had chance to look at this yet)?
Will my 316i fuel pump be sufficient to deliver enough fuel for the new engine?
Both of the cars have PAS am i likely to encounter any problems to do with the pumps or anything to do with the PAS?
Also i take it i will have to swap over the rads? and i heard about some people having problems when mounting them, do i just need to nick the rad mounts off of the 325 and thats it problem solved?
I've also read about some differences when mounting the header tank and the brackett for the AFM or something? Compleatly in the dark about this could anyone shed abit of light on this or possibly a photo or two?
What is the easier or faster way to carry out the engine swap am i best dropping the subframe engine and suspension etc from the shell and lifting this up and over it or taking the engine up on the hoist and out of the bay?
Also are their any other potential problems im going to run into (bar my lack of skill ) along the way that i should prepair for to do with mechanical side of things?

Secondly the electrical side-
As both of the cars are G reg 1990's i pressume they must both be facelift models so its going to be near enough "plug and play" ?
Am i right in thinking that when removing the engine and gearbox im best taking it all out as one unit along with the engine wiring loom and can i just simply unplug this?
Can i just unplug this and away we go then plug it back into the same place on my 316 or am i best removing the 325 dash and using that to connect back upto the engine side of things?
Is this the c101 unit that people talk about like a kind of big black connector block thing that is by the bulkhead or am i talking jiberish??
Do i need to change over the fusebox or relays or anything like that?
What is the wiring warning sticky about does this only apply to facelift and non-facelift swaps as its kind of got me worried about burning the mrs garage down!, is it something to do with pin number 20 on that c101 unit what do i have to check for?
How do i check if my two wirring looms are compatable without ripping anything to bits on both cars?
Is their any wireing that will need splicing between my car and the wireing from the doner car?
What is the coding plug and what do i need to do to it regarding the swap, is this something to do with the clocks?
I also need to swap my earths round, correct?
Lastly would it be easier to just use the dash from the 325 as i will probably need it out anyway because im changing my heater matrix?
Again if anyone could point out any other problems im likely to come accross on the electrical side could you please let me know or if ive missed anything?
(oh and for those of you who haven't fell asleep)
Any other things i should get off the doner car or difficulties that you've had would be great to know as well because i dont want to start something that will never get done.
The end result could be two decent E30's going to the scrapyard in the sky and none of us want that do we!
Naturally i will be nicking the front brakes and struts if i get chance.

On a second plan if this swap is a bit out of my reach is their anyone on here who would be willing to have a go at this or could you recomend someone who would do it for a fair price as im on a pretty tight buget? The cars are both in Walsall W.Mids and they both drive at the minuite.

Sorry about the repetitive questions and babbling on but any help and advice via the board or pm's is much appreciated just drop me a line.
Thanks in advance

[jmc330i]

Firstly some of the mechanicals-
Am i right in thinking that i can use the M20 lump, clutch & gearbox all as one unit along with the propshaft with my small case 1.6 diff with no mods to the diff or the 325 prop?

You will need the M20 lump, gearbox, prop and diff. The 316i diff isnt really suitable, its not the best ratio for the 325i box and it might give up after some abuse from the 6 pot.

Do i need to use the front subframe/crossmember off of the 325 or will the engine drop straight onto the existing 316 one?

The front subframes are all the same, although the 325i will have a bigger ARB and the larger 51mm struts, which you you also ideally need.

I take it that i need to swap the engine mounts/ gearbox mounts for those that are on the 325 or are they both the same (have not had chance to look at this yet)?

When you remove the M20, just leave the engine mounts attached including the rubber mounts, although you might want to renew these anyway. The gearbox crossmember is the same, but you will need the rubber mounts from the 325i. You also need the gear linkage from the 325i - you can leave it attached to the box when you remove it, but be careful not to bend it.

Will my 316i fuel pump be sufficient to deliver enough fuel for the new engine?

The fuel pump should be fine, the pumps are all the same IIRC, just the pump carrier can differ, but that wont matter. I left the 318i pump in when I converted my 318i to 325i and it worked fine. - You might want to keep the 325i pump as a spare.

Both of the cars have PAS am i likely to encounter any problems to do with the pumps or anything to do with the PAS?

No problems. You might need to swap one of the pipes (the pump to rack pipe IIRC) for the 325i pipe, but I cant remember if I needed to do this or not.

Also i take it i will have to swap over the rads? and i heard about some people having problems when mounting them, do i just need to nick the rad mounts off of the 325 and thats it problem solved?

Yep, you need the 325i rad. The drivers side mount is the same, but you will need the shorter passenger side mount from the 325i - they just pop out.

I've also read about some differences when mounting the header tank and the brackett for the AFM or something? Compleatly in the dark about this could anyone shed abit of light on this or possibly a photo or two?

You wont have the mounting points for the 325i header tank on the 316i shell - you can cut them from the 325i and get them welded in. As a temporary measure, I used a bit Meccano from the inner wing to hold the header tank in place. It worked well and I havent changed it since.
The AFM mounts will be in slightly the wrong place - I think the 325i AFM will be a little too far forward to mount up. Again, I used some Meccano to hold it and havent changed that either as it worked fine.

What is the easier or faster way to carry out the engine swap am i best dropping the subframe engine and suspension etc from the shell and lifting this up and over it or taking the engine up on the hoist and out of the bay?

As youve got an engine hoist, I would say engine and box out of the top in one lump. Its a bit tight (the M40 is easy) but with a load leveller, its no real problem.
Having said that, as you really need to change the front suspension as well, you might want to look at dropping the complete subframe with suspension and engine attached and lifting the car off. Im not sure if an engine hoist will lift high enough though.

Also are their any other potential problems im going to run into (bar my lack of skill ) along the way that i should prepair for to do with mechanical side of things?

Very tight bolts/nuts. Very tight prop bolts were my headache - well broken finger ache to be more accurate. I had no problem getting them undone on the 325i, but the 318i was a real git.

Make sure you have undone everything that attaches between the engine/box and the car and get someone to watch as you slowly lift the engine.
Theres nothing worse than getting the engine half out, only to find the clutch pipe is still attached or the fuel lines - you can remove the fuel lines from the car (down by the passenger side chassis rail, near the bulkhead) and leave them on the engine. Check them over and replace if they are cracked or damaged.

You might also want to replace both the clutch cylinders whilst the engine is out. It will be much easier and best to do them in pairs.

Secondly the electrical side-
As both of the cars are G reg 1990's i pressume they must both be facelift models so its going to be near enough "plug and play" ?
Am i right in thinking that when removing the engine and gearbox im best taking it all out as one unit along with the engine wiring loom and can i just simply unplug this?
Can i just unplug this and away we go then plug it back into the same place on my 316 or am i best removing the 325 dash and using that to connect back upto the engine side of things?
Is this the c101 unit that people talk about like a kind of big black connector block thing that is by the bulkhead or am i talking jiberish??

Leave both the engine looms attached to their engines and remove complete. You need to pull the ECU plug out through the bulkhead and unplug the C101 (round black plug by the fusebox). Disconnect the earth strap from the chassis leg (but leave it on the engine mount arm - they are on opposite sides on each engine) and disconnect all the wires from the battery (the 325i will have a positive terminal on the bulkhead). Leave the big black starter cable on the 325i engine, you will still need this.

You do not need to swap dashboards or anything that drastic. None of the 'car side' electrics will need touching.

Do i need to change over the fusebox or relays or anything like that?

No, the fusebox stays where it is and the relays you need are all on the engine loom.

What is the wiring warning sticky about does this only apply to facelift and non-facelift swaps as its kind of got me worried about burning the mrs garage down!, is it something to do with pin number 20 on that c101 unit what do i have to check for?

That is one for Brianmooore to answer, but it should only be an issue if you are swapping in a non-E30 engine AFAIK.

How do i check if my two wirring looms are compatable without ripping anything to bits on both cars?
Is their any wireing that will need splicing between my car and the wireing from the doner car?

It should just be a plug and play affair. No wires will need splicing as its all done at the C101 plug.

What is the coding plug and what do i need to do to it regarding the swap, is this something to do with the clocks?

The coding plug (white plug IIRC) is found under the clocks, to the right of the steering wheel I think. You only need to remove the trim under the clocks to find it and it just swaps over from car to car - 5 min job. Without it, the rev counter on the 4 pot will go nuts as its getting the signal from the 6 pot engine - it is funny seeing the needle head up towards 8-9k rpm though.

I also need to swap my earths round, correct?

Yep, as above.

Lastly would it be easier to just use the dash from the 325 as i will probably need it out anyway because im changing my heater matrix?

You could I guess, but theres nothing to gain. Unless the dash from the 325i is in much better condition, I wouldnt bother.

Any other things i should get off the doner car or difficulties that you've had would be great to know as well because i dont want to start something that will never get done.

Naturally i will be nicking the front brakes and struts if i get chance.

You will need the front struts as the 316i will have the small 45mm ones. You might also need the rear disc brakes if the 316i has drums?

Dont worry about doing the swap, its pretty straight forward. I would suggest removing all this bits from the 325i in one go and label them if needed. Take photos to help remind you of what goes where.

I dont think Ive missed anything, and I hope it all makes sense.

Good luck with it and let us know how you get on


EDIT - just a thought, but you might also want to change the cam belt, tensioner and water pump whilst the engine is on the floor. Its much easier than doing it in the car and isnt all that difficult. I had never done it before and I just followed the steps in the Haynes manual ( ) and it was pretty easy.
Also maybe a fit a new clutch - again, its easy with the engine out of the car.

Heres a link from when I did mine - not much info but it might help keep you motivated - Click Me

[juggs]

JMC- Your a top man!
Couldn't really ask for much more help than that could i, thats pretty much gave me the right idea.
I was going to replace the clutch anyway as well as the cam belt i think this is a wise choice id be gutted if it needed doing once in the new bay!
Hopefully once i have got these bits i will starting the swap in the next 2-3 weeks money/time allowing.
I have also heard that the 320 flywheel is lighter than the 325 can anyone confirm this or whether its worth swapping over while the clutch is being changed?
Nice one for sorting me out that link you must be a bit of a dab hand to have done it in that kind of time though
Anyone else who's got any links to m20 swaps they have done would be great??
Are their any other things i have not considered about the swap anyone thinks i should look into?

[jmc330i]

No problems

I think the early 320i flywheels are lighter, but I dont know if they will fit the later engine (which you have). It could lead to more problems getting it all fitted together.
It would be easier to get your flywheel lightened and balanced. The later flywheels are the same between 320i and 325i AFAIK.

[Brianmoooore]

What is the wiring warning sticky about does this only apply to facelift and non-facelift swaps as its kind of got me worried about burning the mrs garage down!, is it something to do with pin number 20 on that c101 unit what do i have to check for?

That is one for Brianmooore to answer, but it should only be an issue if you are swapping in a non-E30 engine AFAIK.

Not so! This is an issue for all E30 engine swaps, even like for like, as I was doing when I discovered it! Should only apply to shells from around the facelift changeover period, but, considering the serious damage that can be done, is well worth checking. Open up the car side of the C101 and look for a wire connected to pin 20. If it's brown, cut it off, pull it back into the fusebox and insulate it. If it's red/yellow, it's part of the ABS system, so leave alone.

How do i check if my two wirring looms are compatable without ripping anything to bits on both cars?
Is their any wireing that will need splicing between my car and the wireing from the doner car?

It should just be a plug and play affair. No wires will need splicing as its all done at the C101 plug.

Shouldn't cause any problems with similar aged donor and recipient, but there were changes to the supply arrangements for the ABS, which involve the C101, as touched on above. Investigate further if the ABS doesn't work after the conversion.
If the 325 has a fluid and bulb check module (up by the interior mirror), it will be difficult to transfer this over to the 316 shell, as the relevant wiring is part of the main body loom.
I'd recommend you change the sump gasket while the engine is out, unless it's already been changed, as they are a weak point (after twenty years) and are difficult to change in situ.

[jmc330i]

What is the wiring warning sticky about does this only apply to facelift and non-facelift swaps as its kind of got me worried about burning the mrs garage down!, is it something to do with pin number 20 on that c101 unit what do i have to check for?

That is one for Brianmooore to answer, but it should only be an issue if you are swapping in a non-E30 engine AFAIK.

Not so! This is an issue for all E30 engine swaps, even like for like, as I was doing when I discovered it! Should only apply to shells from around the facelift changeover period, but, considering the serious damage that can be done, is well worth checking. Open up the car side of the C101 and look for a wire connected to pin 20. If it's brown, cut it off, pull it back into the fusebox and insulate it. If it's red/yellow, it's part of the ABS system, so leave alone.

Thanks for clearing that up Brian
I wasnt quite sure what the issue was and I must of been lucky not to have come across the problem when Ive swapped engines in the past