Rontgen's 1990 325iS Build Thread

[Rontgen]

Interior Resto! This started off as a dash replacement and as usual, turned into a way bigger project then we'd expected.

This is where we began:





We pulled the interior and found a surprise left by the previous owner - the ignition switch had been previously broken and was held together with packing tape. [emoji849]



Dash out!

[Rontgen]

Not much new to report, but did potentially solve some off-idle hesitation that we have been getting. The car runs great while driving, but seems to bog fairly badly when you stab the throttle from idle. I did some reading and found something that I missed during the air flow meter maintenance: the idle mixture screw.

This 5mm hex under the blue plug controls how much air bypasses the AFMs flap. It's essentially a controlled vacuum leak and the meter is calibrated using a CO emission monitor, which I don't have access too. I ran across a post on an E28 forum which mentioned that the factory- adjusted depth of the bypass screw should be stamped on the meter and after some clean-up, I was able to see ours: 17.7mm (0.697"). While this may not be a perfect adjustment per a CO meter, it should at least be in the ballpark.

I initially took a measurement to see where we had been since there was some evidence that the blue plug had been removed before. Sure enough, ours was set at 18.9mm depth. I've adjusted it to 17.7mm and the off-idle hesitation seems to be vastly improved. Picture below where the depth should be marked, zoomed in and circled for clarity:



In other news, I attempted to get the exhaust leak fixed at a local muffler shop with no luck. I also discovered several smaller leaks from the catalytic converter body and a rattling heat shield. I've ordered a new Magnaflow section 1, which should go in this week.

Interior resto is next!

[sam_]

that aerospace 303 seems pretty nifty

[Rontgen]

I'd pull that valve cover asap and check valves if you haven't, just did mine and its much quieter now and sounded nearly identical to yours

Thanks again for the suggestion. I went through the valve adjustment procedure again, this time setting the clearance to 0.007" between the cam and rocker. I found this to be much easier vs. measuring clearance at the eccentric (which should be 0.25mm/0.10"). In doing some reading it seems like the E28 M30 guys swear by this method and I tend to agree. Valvetrain is now much quieter than before.

The car goes to the muffler shop tomorrow to have the exhaust leak fixed and we should be just about ready to start on the interior restoration. But for now, the E30 gets a rest and my M5 gets some long-overdue love. New Bilstein B8s, Intrax springs, and an Eibach rear bar.

Thanks everyone!

[Northern]

This thread makes me want a nice clean 325i to drive and not do a bunch of dumb shit to...

[jeenyus]

great progress and what luck on that dash! makes me want to look for stuff on car part again.

[Rontgen]

Not much new to report, but we did AFM maintenance today. We cleaned the resistor trace and adjusted the wiper arm to move the contacts out of their 27-y/o grooves. I forgot to take a before picture of the scope, but it was ugly. Voltage would drop dramatically as the flap opened and then again at max opening. There was also a dead spot where opening the flap would cause no corresponding change in voltage.

After cleaning it up and adjusting the wiper arm, it's a nice smooth voltage transition from closed to open.

We're heading out to drive it shortly and first oil change will be this afternoon!

[Rontgen]

Thanks - I checked the valve lash with the engine on the stand, but it would probably be worthwhile to check it again now that it's been up to operating temp a couple times. I'm out of town on business again this week, so hopefully I'll get the exhaust leak taken care of next week when I'm back home. That should make it easier to hear any other noises...

[Dirty_30_IS]

I'd pull that valve cover asap and check valves if you haven't, just did mine and its much quieter now and sounded nearly identical to yours

[Rontgen]

Thanks! I think I'm going to have this piece welded in and that should solve the exhaust leak for now.

[sam_]

Looks great!

[Rontgen]

It's alive!!

Since the fuel lines were dry, it took several cranks to get fuel to the rail and build pressure, but once that happened it fired right up. First thing we noticed was a lot of noise from the passenger side, kinda sounded like a mix of valvetrain and exhaust leak. [emoji53]

More pressing was the fact that the car ran for a couple minutes and then began to sputter and die. Then, it would crank but wouldn't fire back up. Uh oh. I could smell gas, so I assumed it was flooded. I pulled the vacuum line off the fuel pressure regulator and gas POURED out of that line. Obviously the regulator diaphragm was leaking badly and this was the cause of my flooded engine. An hour or so later, we had a new replacement installed and cranked the car up again. Not surprisingly, it runs much better with a working regulator!

When we purchased the car, the catalytic converter had been replaced with straight pipe and the muffler section was trashed. We saved the OE front section (manifold to front of cat) just in case and trashed everything else. We bought a complete exhaust system from a parts car which appeared to be in good condition. Unfortunately, it looks like the parts car exhaust is leaking at the expansion joint between the manifold and the O2 sensor. Ugh. So, I'll either have the old front piece welded in at a muffler shop or just replace the whole thing. Still need to do some research...

By the end of the day, we got it cleaned up and put about 20 miles on it. Seems to run great!

Lots of little projects to follow. Thanks for reading!

https://vimeo.com/201598606

[stonea]

Nice build! Makes me wan't to keep my M20 and rebuild it.

[Rontgen]

And a picture of where we are as of quitting time tonight:

[Rontgen]

Rontgen's 1990 325iS Build Thread

Once we made it over the broken bolt hurdle, it was time to mate the trans to the engine. It seemed like no matter what we did with the clutch alignment tool, we just couldn't get the input shaft to go into the pilot bearing. After fighting it for an hour or two, we finally got the clutch disk at the right spot and were able to wiggle it and curse at it enough for it to finally slide home.

The rest of the weekend went substantially better. Lots of things to get accomplished and I think my son is now a believer in the old adage: "5% of the project takes 95% of the time"

Engine and trans are in, which was a piece of cake with the load leveler.

Driveshaft, heat shields, and stock exhaust are in. New Bosch O2 sensor installed

New Power Steering reservoir installed along with new feed and return hoses. I was able to bend and re-shape my original E30 pressure line for use with the E36 rack

Lots of wiring and trial-and-error to get it all laid correctly.

Installed upgraded alt-starter cable and engine ground from Bavarian Restoration.


At this point we have about a half-day of work left before she's ready to crank. I'm away on business this week so we may get a chance this coming weekend, depending on schedules. If not, the first weekend in Feb should be it!

Thanks for reading!