'81 633CSI Nightmare

**LucidWerkz** · 07-14-2022, 05:27 PM

Hello everyone, My name is Dan.

I am mainly here for some odd things that I am not familiar with. The only other old BMW I built and own is my E30 with a M60B40, 6-speed swap widebody track car. So, I am very familiar with E30s. Here is a pic.

But let's stay on topic with the E24, I just picked up this 1981 633csi 5-speed manual, and to say the least this thing is cool, but it looks like a nightmare.
It runs and drives, but previous owner who got it in a trade, says the exhaust will get red hot after idling for around 30min. I haven't tried it myself, mainly because the cooling fan wires are not even connected to anything.
It appears that the motor has been rebuilt, it runs surprisingly smooth with no excessive engine ticking or anything, the exhaust was rotted out, and after giving it some throttle it seems to sputter on engine decel.
As I am going over the car, I am seeing things that I could use some help on, here is some pics of the car:

I know this is a common issue with the alternator, its bushing and not being aligned, there was a spare alternator in the trunk, It has solid mounts from the 5 series?

Here is the intake, I think its just the early model manifold with an Aplina sticker slapped on it.

Does anyone know what these buttons are for, the top one looks like the fader Left to Right?
I have no idea what the middle one is, nothing really changes that I can see.
And the Rocker Switch, im not sure, it does not have fog lamps.

This Spare ECU?

Also came with this Miller Intake.

Some Random Pictures of the Engine Bay, if you see anything odd let me know LOL

Some how the A/C belt has flipped upside down, not sure how that happened.

THEN the Fuel Pump Wiring, I assume this is some kind of Manually adjusted duty cycle for the fuel pump, as When I turn the knob the pitch of the fuel pump changes and if turned down the engine will drop rpms. Has anyone seen something like this?

Thank you in advance, any help would be appreciated.

**RSheiman** · 07-15-2022, 10:20 AM

Fader or balance, rocker switch looks aftermarket, other is probably a breaker for the windows.

If it has a cat, it may be clogged.

Front right ring bracket is missing the charcoal canister which is no big deal, line from the trunk to the canister to the intake to burn gas fumes from the tank. Line needs to be intact or you will smell gas in the car/trunk though.

Fuel pump thing is beyond me, is there a FPR up front?

**DesktopDave** · 07-15-2022, 08:36 PM

The red-hot exhaust could also be caused by a stuck cold-start injector, that's not uncommon. Same general setup as the M20B27. It's pretty easy to get at on the early manifold, but nearly impossible on the B34 with the infernal late model M30 manifold design.

I can't see the pics, but I'd guess that's an M20 alternator. It's not a perfect fit, ends up ever so slightly misaligned for the drive belt, but I've run them that way for years with no problems. It'll work pretty well.

Be aware that '81 was a crossover year for the M30. The older Jetronic analog injection systems were upgraded to the Motronic 1.0 DME. Given the info you've shared, it's possible that you have some interesting/frustrating Frankenstien motor there.

**LucidWerkz** · 07-16-2022, 09:08 PM

Originally Posted by RSheiman

Fader or balance, rocker switch looks aftermarket, other is probably a breaker for the windows.

If it has a cat, it may be clogged.

Front right ring bracket is missing the charcoal canister which is no big deal, line from the trunk to the canister to the intake to burn gas fumes from the tank. Line needs to be intact or you will smell gas in the car/trunk though.

Fuel pump thing is beyond me, is there a FPR up front?

Appreciate the info, There is no aftermarket FPR, just the factory vacuum controlled one on the fuel rail.

Originally Posted by DesktopDave

The red-hot exhaust could also be caused by a stuck cold-start injector, that's not uncommon. Same general setup as the M20B27. It's pretty easy to get at on the early manifold, but nearly impossible on the B34 with the infernal late model M30 manifold design.

I can't see the pics, but I'd guess that's an M20 alternator. It's not a perfect fit, ends up ever so slightly misaligned for the drive belt, but I've run them that way for years with no problems. It'll work pretty well.

Be aware that '81 was a crossover year for the M30. The older Jetronic analog injection systems were upgraded to the Motronic 1.0 DME. Given the info you've shared, it's possible that you have some interesting/frustrating Frankenstien motor there.

Thanks for the info!
Yeah I do believe this was frankenstiened together. I will look into the cold start injector cause after it sits for a while it is hard to start up it takes like 5 minutes of on/off cranking to finally fire up. Maybe its flooding the motor?

And I am not sure what happened to my post, its gone now?

**LucidWerkz** · 07-16-2022, 09:35 PM

I'm guessing there is a thing for new members for posting pictures and stuff. I understand but now all the stuff i wrote in the first post is gone. Anyone have an Admin I can contact?

**marc79euro635** · 07-16-2022, 09:38 PM

Glowing exhaust can also be from ignition timing being retarded too much.

**LucidWerkz** · 07-16-2022, 09:48 PM

Originally Posted by marc79euro635

Glowing exhaust can also be from ignition timing being retarded too much.

Thank you I will check that as well, even though I haven't had a chance to see the exhaust glow myself, something is keeping me from wanting to see it. Just incase it causes any damage, I think I will start by removing the exhaust and checking for restrictions, then move to checking the cold start injector and ignition timing. thank you!

**LucidWerkz** · 07-16-2022, 11:26 PM

Update:
Here are some more pics of the 633csi

I got all the interior out and prepped for some deep cleaning and new seat leather

More to come soon!

**e24mpwr** · 07-26-2022, 01:15 PM

Your pix are Imgur, which for some reason banned Bimmerforums several years ago.

If you choose a new hosting, I'd guess you have enough posts that pix will work.

If that doesn't work, PM me. I can't flip the switch to enable posts, but I'll figure something out. Cheers!