Was driving my 735i (E23) and all of a sudden a loud bang like an explosion then loud rattling noise coming from the front. What could it be? Please help! Hit Man X! Where are you!!
Oh and when I looked under the hood there was a loose spark plug wire.....
Need more info
The only times I've experienced something like that it was a backfire and it blew the AFM boot off.
If you have a spark plug wire dangling loose, that's not so good. Is the spark plug it was attached to still in the head?
Did you look at see if things like the fan were still in 1 piece, or all the belts still there?
--Jay3->Sic gorgiamus allos subjectatos nunc
84 €735i manual, 88 528e/i
Motronic 1 and 1.3 wiring
Transmission & Diff gearing sheet
Found the spark plug not in the head apparently blown completely outIMG_2128.jpg
Are you saying you have a lose plug wire and the plug blew out of the block? Bordering on the impossible here. Unless the block itself is cracked where the plug screws in. Where are you at now with it?
1990 735I (Auto) E32 Feb 1990 to Present
1996 Z3 Roadster (5 Speed) E36/7 Jan 1999 to Dec 1999
1983 733I (5 Speed) E23 April 1983 to Feb 1990
https://www.youtube.com/watch?v=2d4tHoHGaJo
https://1drv.ms/v/s!Av20xCMMocSsyEpl...h_oOk?e=ekIcAT
Yes apparently that's what happened. The wire was off the plug and the plug was out of the block laying inside the engine compartment. I took a few minutes to look around, haven't had time to do much with it. Maybe the plug was loose to begin with? Maybe not properly torqued and loosened? Just here looking for suggestions. Have not driven the car much in two years.... Thanks
Last edited by lassiterd; 08-16-2017 at 09:33 PM.
You can see combustion/exhaust on the top of the plug past the hex, indicating that it was loose in place and firing away and blow by was putting soot on the plug.
That's what I was worried about; certainly a rare occurrence on an M30. Hopefully it was just never torqued the last time. In that case, just put it back in. If the plug was over-torqued it could have stripped the threads. Once they're weak enough the heat cycles will finish them off. It can be repaired with a helicoil, maybe also a Timesert. Hopefully it wasn't #6, that's an awfully tight space. In that case it might be easiest in the long run to pull the head and get it checked & freshened up.
Last edited by DesktopDave; 08-18-2017 at 10:51 PM.
Yes, just my luck it's #6, going to change them all out this week and take it from there.
FWIW, I did change the spark plugs a couple weeks ago and she started right up.....
Last edited by lassiterd; 09-04-2017 at 08:57 PM.
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