Author Topic: What's with the POS bleeder screws? (Read 2900 times)

a930rocket · « **on:** March 31, 2011, 07:36:47 PM »

Having buggered up my bleeder screw on my radiator, I bit the bullet and ordered a new radiator, along with a new fan clutch, water pump and thermostat.

Having filled the radiator up, I went for a drive. Came back and loosened the bleeder screw. Let a few bubbles out until coolant flowed out. Then I tightened the screw, but just as it got tight, it spun.

Am I so manly, I can strip it that easily? Do they really strip that easy?

What's the secret to tightening, but not overtightening it?

DesktopDave · « **Reply #1 on:** March 31, 2011, 08:00:18 PM »

I cracked one myself, have no idea how to avoid it. I just tighten it enough that it stops leaking & carry a few spares. Pelican carries a brass replacement, but I'd figure it'll strip the threads out of the radiator.

a930rocket · « **Reply #2 on:** March 31, 2011, 08:46:44 PM »

I'll take a closer look tomorrow and hopefully it's just the screw and not the radiator threads. I should gave ordered some extras when I ordered the new radiator.

It really is a piss poor design...

Home made iS · « **Reply #3 on:** April 01, 2011, 08:57:21 PM »

+ 1 on the piss poor bleeder

I found after breaking mine and not being able to get a another one (im in australia nuthin is easy to find for a bmw here)

I found a bolt almost the same size thread (slightly smaller) and right depth etc
used some gas sealing tape that u will find in any plumbing shop to bulk up the thread, screw in FINGERTIGHT , shouldn't leak (mine doesn't)
Thats it.....

Alternatively u could use a hex head grub screw style, it only has to cover the bleed hole underneath the cap to stop leaking. (looks prettier)

Worked for me, better than a shitty plastic bung that breaks way too easy for a "reusable" bleed screw.

may not work for everybody but i think its pretty simple.

DesktopDave · « **Reply #4 on:** April 01, 2011, 09:52:12 PM »

I'd be careful about using a screw there, it'll make coolant bleeding even more difficult...unless you're really on top of maintenance (like all us M42 nuts are).

I'm inclined to suspect that the screw self-destructs because it's designed to. Sure, the pressure cap should go first, but frequently it does not. The screw and overflow housing end up being the weakest link in the chain. It's (sort of) better that way...one of the weakest spots in the e30's cooling system is the heater core valve housing & seals...not a good place for a few gallons of 15psi coolant at boiling point!

From what I've heard, the plastic components in the system were engineering marvels when they were new. Then BMW had a few recalls from explosive coolant system ruptures in the early M50 & M60 models...and our last of the e30's is really the first of the new generation of DOHC BMWs (I've always amused myself that it's really 2/3rds of an M50B30). We've been stuck with them ever since. The only way to really 'fix' them is to engineer metallic replacements like water pump impellers, thermostat housings & aftermarket radiators.

My 318i often makes me think of Italian cars I've known & loved in the past...tremendous fun, but not really what I'd call robust. Certainly not overbuilt.

a930rocket · « **Reply #5 on:** April 02, 2011, 08:11:48 PM »

So far, mine seems to be holding.

I do have a bolt that has the same threads, but as Dave mentions, it has it's downside of not being able to bleed the system. I'd have to round it off and make a slot to be able to screw/unscrew it as well.

Maybe the brass bleeder screw from Pelican would be easier...